JPH0640269B2 - Optical fiber sensor unit for automatic playing piano - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sensor belonging to a recording function system used at the time of recording in an automatic playing piano having not only a reproducing function but also a recording function. The present invention relates to an optical fiber sensor unit which is arranged below a keyboard to detect a depressed key and which is arranged behind a hammer shank to detect a hammer speed.

[Prior Art and Problems Thereof] An optical fiber sensor unit conventionally used as a performance information sensor of an automatic playing piano requires, for example, 2 points per key for detecting a hammer speed, and specifically, emits light. A total of four optical fibers, two on the side and two on the light receiving side, are required. Therefore, 176 × 2 = 352 optical fibers are used because one piano has 2 × 88 keys = 176 points.

However, in the case of the conventional optical fiber sensor unit,
As shown in FIGS. 3A and 3B, the light-emitting side and the light-receiving side optical fibers 2 connected to the light guide body 1 are all bundled together without making a distinction, and only in one direction to the right in the figure. It was guided and pulled out of the casing 3.

Therefore, the bundle of the optical fibers 2 becomes considerably thick, which is an obstacle to downsizing the unit. In addition, the optical fiber connected to the right side in the figure is short, while the optical fiber connected to the left side is long, which causes a difference between long and short. Therefore, the output of the light receiving element is large in the former and small in the latter, which makes detection difficult. In addition, since the length of the optical fiber eventually becomes 88 types, there is a drawback that the manufacturing, stock control and connection work of the optical fiber are very troublesome.

[Object of the Invention]

Therefore, an object of the present invention is to significantly reduce the space constraint by reducing the bundle (number) of optical fibers to ½ of the total number in any cross section, and to reduce the light from the light emitting element to the light receiving element. Automatic performance with the same fiber length for all keys and making the output of the light receiving element almost the same to facilitate signal processing, and to reduce the type of optical fiber length by half and greatly simplify its management. An object is to provide an optical fiber sensor unit for a piano.

[Structure of Invention]

In order to achieve the above object, in the present invention, a light guide (11) and a plurality of light emitting optical fibers (12 ') are provided.
And a plurality of light receiving optical fibers (12 ″), the optical fiber sensor unit for an automatic playing piano, wherein the light guide (11) comprises a plurality of light incident surfaces (17) and a plurality of reflecting surfaces (18). ) And each emitting optical fiber (1
2 ′) and each of the light receiving optical fibers (12 ″) are electrically connected to each other through the respective incident surfaces (17) and the respective reflection surfaces (18),
Connected to the light guide (11), the plurality of light emitting optical fibers (12 ') are bundled and arranged toward one end of the light guide (11), and the plurality of light receiving optical fibers (12 ") are bundled. , A plurality of light emitting optical fibers (12 ') are arranged toward the other end of the light guide (11), and the length of each light emitting optical fiber (12') and the light receiving optical fiber (12 "that is continuous with it). ) Is the sum of the length and is set to be the same over all keys.

〔Example〕

The present invention will be described in detail below with reference to the illustrated embodiment. In the optical fiber sensor unit shown in FIG. 1, 11 is a light guide, 12 is an optical fiber connected to the light guide 11, and 13 is a light guide. It is a casing, and the basic structure is 3A.
This is not much different from the conventional example shown in FIGS.

However, regarding the optical fiber 12, the light-emitting side comrades and the light-receiving side comrades are distributed to the left and right, and a common bundle 12A,
It is drawn out of the casing 13 as 12B. Therefore, the number of optical fibers 12 is 176 (in the case of a total of 352) for any cross section.

FIG. 2 shows the details of the configuration in an enlarged manner.

That is, the light guide 11 made of acrylic resin or the like has grooves 15 on its lower surface side that allow its entry at positions corresponding to the hammer shanks 14 of the piano. Each hammer shank 14
A shutter 16 that opens and closes the transmitted light is provided in the.

A light incident surface 17 is provided on the rear surface of the light guide 11 on both sides of the groove 15.
And the reflecting surface 18 are formed as a pair of left and right circular arc surfaces (or flat surfaces).

Then, the outgoing optical fiber 1
2'is the receiving optical fiber for the reflecting surface 18
2 ″ are connected to the light guide body 11 in such a manner that light is conducted respectively. The emission optical fiber 12 ′ is arranged on the right side in the figure, and the light receiving optical fiber 12 ″ is arranged on the left side in the figure. A fiber bundle 12A and a light receiving side optical fiber bundle 12B are formed.

[Invention effect]

As described above, according to the present invention, the light emitting optical fibers (12 ') are arranged while being bundled toward one end of the light guide body (11), and the light receiving optical fibers (12 ") are arranged.
Since they are arranged while being bundled toward the other end of the light guide body (11), the number of optical fibers can be reduced to "1/2" of the total number in any cross section, and space can be saved. It is possible to make the device configuration compact.

Moreover, since the plurality of light receiving optical fibers (12 ″) are arranged along the plurality of light emitting optical fibers (12 ′), the wiring route of the optical fibers is only one system, and the device configuration can be made more compact. It becomes possible to do.

Furthermore, since the sum of the length of each light-emitting optical fiber (12 ′) and the length of the light-receiving optical fiber (12 ″) that is in conduction therewith is set to be the same, the length of the optical path is set as a whole key. It is possible to make the output level of each receiving optical fiber (12 ″) the same over all keys.

Needless to say, the term “same” does not mean numerically strict precision. That is, in view of the above-described actions and effects, “the same” means
It is clear that the intensity of the light output from each of the light receiving optical fibers (12 ″) does not cause intensity variations.

For example, in the multi system, one light receiving element has a fiber output for 12 octaves per octave. Therefore, if each has the same output level, the subsequent signal processing becomes very easy.

Further, there are as few as 44 types of cutting length of the optical fiber, and therefore cutting and inventory management are very easy.

[Brief description of drawings]

FIG. 1 is an explanatory view seen from the front of an optical fiber sensor unit according to the present invention, and FIG. 2 is an enlarged detailed view. 3A and 3B are a front view and a side view conceptually showing a conventional optical fiber sensor unit. 11 …… Light guide 12 ′ …… Emitting optical fiber 12 ″ …… Receiving optical fiber 12A, 12B …… Bundle of optical fibers 17 …… Injection surface 18 …… Reflecting surface

Claims (1)

[Claims] 1. An optical fiber sensor unit for an automatic playing piano, comprising a light guide (11), a plurality of light emitting optical fibers (12 '), and a plurality of light receiving optical fibers (12 "). The body (11) has multiple light entrance surfaces (17) and multiple reflection surfaces.
(18), each light-emitting optical fiber (12 ′) and each light-receiving optical fiber (12 ″) includes an incident surface (17) and a reflective surface (1).
8) is connected to the light guide body (11) so that the plurality of light emitting optical fibers (12 ′) are bundled,
It is arranged toward one end of the light guide (11), and a plurality of light receiving optical fibers (12 ″) are bundled,
Along the plurality of light-emitting optical fibers (12 '), arranged toward the other end of the light guide body (11), the length of each light-emitting optical fiber (12') and the light-receiving optical fiber (12 ") conducting to it. The optical fiber sensor unit for an automatic playing piano is characterized in that the sum of the length and the length is set to be the same for all keys.