JPS62175035A - Wireless mike for utilizing infrared ray - Google Patents

Abstract

PURPOSE:To receive an infrared ray signal wave by a photodetector at the front surface side of the photodetector and to interrupt a noise wave from the third light source by providing a light shielding hood in which the aperture diameter is reduced, funnel-shaped and the inside surface is of the infrared ray absorbing constitution as the hood proceeds from the front direction to the rear direction. CONSTITUTION:A photodiode array 2, which is the photodetector, is provided in an equipment case 4 with a light receiving surface 3 as a front surface, and at the front surface side of the photodiode array 2, namely, at the side of the light receiving surface 3, the light shielding hood is provided. As the light shielding hood 5 proceeds from the front direction to the rear direction, the hood reduces the diameter of the aperture 6, is funnel-shaped and an inside surface 7, for example, is of the infrared ray absorbing constitution by the coating of an infrared ray absorbing color. The ratio to reduce the diameter of the aperture 6, for example, an angle theta formed with a central axis 8 is 30 deg., namely, the aperture angle is 60 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an infrared wireless microphone that operates by receiving infrared signal waves, and particularly relates to an improvement in noise prevention thereof.

(b) Conventional technology A conventional wireless microphone using infrared rays (1a) has a photodiode array (1a) as a light receiving element, as shown in FIG.
2a) on the front of the device case (4a) with the light receiving surface (3a)
was placed facing forward, and its light-receiving surface (3a) was further covered with a filter (10a) that cuts visible light and near-infrared rays.

(c) Problems to be Solved by the Invention The wavelength of the infrared signal wave used by the infrared wireless microphone is 950 nm. On the other hand, the radiation spectrum distribution of fluorescent lamps is as shown in Figure 3, and is 950n
It has a high specific energy near m.

Therefore, in the conventional wireless microphone using infrared rays (1a), even if waves with wavelengths around 950 nm are reduced by a filter (LOA), the level of noise from the third light source, the fluorescent lamp, does not fall to a negligible level. '11 F3
There was a problem that the operation was affected by the

The present invention has been made in view of the above circumstances, and provides an infrared wireless microphone whose operation is not substantially affected by the infrared rays (noise waves) of a fluorescent lamp, which is the third light source.

(Means for solving the niff problem) In this invention, a light-shielding hood is disposed in front of the light-receiving element.

The detailed structure is that an infrared wireless microphone operates with a light receiving element that receives infrared signal waves and an electric circuit that receives the signal from the light receiving element. A funnel-shaped light-shielding hood whose opening diameter decreases from front to back and whose inner surface absorbs infrared rays is installed to receive waves and block noise waves from a third light source. This is a wireless microphone that uses infrared rays.

(E) Function The light-shielding hood allows the light-receiving element to receive infrared signal waves, and also blocks noise waves from the third light source.

The light-shielding hood also absorbs noise waves from the third light source reaching its inner surface.

(F) Embodiments This invention will be described in detail based on embodiments shown in the drawings, but the invention is not limited thereby.

FIG. 1 is an explanatory diagram of the configuration of the main parts of an infrared wireless microphone (1). The photodiode array (2), which is a light-receiving element, is mounted on the equipment case (
4) is located within. Photodiode array (2
) on the front side, that is, on the side of the light-receiving surface (3).
is installed.

The light-shielding hood (5) has a funnel shape whose opening (6) diameter decreases as it goes from the front to the rear, and the inner surface (7) is painted with an infrared-absorbing color, for example, to have an infrared-absorbing structure. The rate at which the diameter of the opening (6) is reduced is, for example, the angle (θ) formed with the central axis (8) is 30', that is, the opening angle is 60°). The value 30' is determined based on the light-receiving ability directional characteristics of a general photodiode (2). In other words, the light-receiving ability directional characteristic curve of a general photodiode array (2) is as shown in Figure 4, and the angle with the center @(8), that is, the optical axis, is 3.
This is because the light reception level is approximately 80% at 0°, and the light reception level rapidly decreases at 30° or more.

Note that (9) is an electric circuit that receives signals from the photodiode array (2), and (10) is a filter that cuts visible light and near-infrared rays.

The operation of the wireless microphone (1) using infrared rays according to the present invention will be explained below with reference to FIG.

The infrared wireless microphone (1) is positioned so that the central axis (8) of the light-shielding hood (5) faces a light source (not shown) of the infrared signal wave. Here, when an infrared signal wave is sent from the light source, the photodiode array (2) receives the infrared signal wave through the opening (6) of the light-shielding hood (5).

At this time, infrared rays are also coming from a third light source, such as a fluorescent lamp (11), toward the infrared wireless microphone (1). Infrared rays from the fluorescent lamp (1) become noise waves. Even if the infrared rays A come towards the infrared ray wireless microphone (1), they will not affect the infrared ray wireless microphone (1) because they reach the outside of the Ui port (6) of the light shielding filter (5). Infrared ray B is filter 0
The infrared rays B pass through 0+ and reach the inner surface (7) of the light shielding hood (5), and the inner surface (7) absorbs the infrared rays B.

In addition, even if the absorption of infrared ray B by the inner surface (the sword is insufficient), the infrared ray B may reach the photodiode array (2) while being reflected by the inner surface (7). Each time it is reflected at (7), it is absorbed and its level decreases, and the level when it reaches the photodiode array (2) can be ignored due to the influence of noise.

Furthermore, the infrared rays from the fluorescent lamp (11) pass through a light-shielding filter (
There are cases where the infrared rays are reflected outside of the photodiode array (2) and directly reach the photodiode array (2). However, even in that case, the energy of the infrared rays is extremely small and has little effect on signal wave transmission.

From the above, the photodiode array (2) is hardly affected by noise from the infrared rays of the third light source, the fluorescent lamp (11), and therefore its operation is not substantially affected.

The filter (10) filters visible light J3 and near infrared rays, and transmits infrared rays that are signal waves.

(g) Effects of the Invention This light is an infrared wireless microphone that ensures reception of signal waves and whose operation is not substantially affected by noise waves, which are infrared rays from a third light source.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an embodiment of the invention, Fig. 2 is an explanatory diagram showing its operation, Fig. 3 is a diagram showing the distribution of the radiation spectrum of a fluorescent lamp, and Fig. 4 is a photodiode. FIG. 5, a diagram showing the light-receiving ability directional characteristics of the array, is a diagram corresponding to FIG. 1 of the conventional example. (1)...Wireless microphone using infrared rays, (2
)...Photodiode array (light receiving element),
(3)... Light receiving surface, (4)... Equipment case, (5)... Light shielding hood, (force...
...Inner surface, (9) ...Electric circuit, 00)
······filter.

Claims (1)

[Scope of Claims] 1. An infrared-based wireless microphone that operates with a light-receiving element that receives infrared signal waves and an electric circuit that receives signals from the light-receiving element, on the front side of the light-receiving element:
The light-receiving element receives infrared signal waves and blocks noise waves from a third light source.It has a funnel-shaped opening diameter that decreases as it moves from the front to the rear, and its inner surface has an infrared absorbing structure. A wireless microphone that uses infrared rays and features a light-shielding hood. 2. The wireless microphone using infrared rays according to claim 1, wherein the opening angle of the light-shielding hood is about 60°.