JPS60112006A - Reflection type photosensor head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a reflective optical sensor head using optical fibers that can detect an object in a non-contact manner.

[Prior art]

Using an optical fiber as a light guide, the light supplied by this light guide is projected onto an object to be detected, and the reflected light or blocked light from the object is detected as the original signal and converted into an electrical signal, which enables detection. The original sensor device that performs various controls is a non-contact sensor and has no effect on the object, so it is used for measurement and control, and is used for 'TFC, optical fiber. By using this, minute sensing is possible, and the head is equipped with electricity.
It has the advantage of being safe because it does not generate heat. For this reason, a number of proposals have been made regarding optical sensor heads using optical fibers (1), and they are beginning to be put into practical use in industry.

To explain the conventionally used original sensor head in Figs. 1 and 2, Fig. 1 is an explanatory diagram showing a transmission type optical sensor head using optical fibers, (1)
(2) indicates an optical fiber for transmitting light, and (2) indicates an optical fiber for receiving light. When using this transmissive optical sensor head, the light emitting element (
4) is guided through a light transmitting optical fiber (1) and projected onto, for example, a moving detection target (6), and the light receiving optical fiber (2) receives the presence or absence of the target. Element (5)
[(No.
fnu public e/su)i! Since it requires a large amount of space to install, it has the disadvantage of requiring a large installation space. On the other hand, FIG. 2 is an explanatory diagram showing a reflective optical sensor using R1 original fiber, and this reflective optical sensor head combines a transmitting optical fiber (1) and a receiving optical fiber (2). However, since the head part can be made into a single head, there is no need to consider the installation location because the head part is connected. The optical fiber for transmitting light (1) and the optical fiber for receiving light (2) each use one or more optical fibers or a bundle of optical fibers.Usually, a light transmitting optical fiber consisting of a light emitting diode is used. Light source (
The signal light emitted from the source optical fiber (1) or the optical fiber bundle is made to enter upwardly at one end face of the optical fiber bundle (1).
1) Or, the light emitted from the other end of the optical fiber bundle is projected onto the object to be detected (6), and the reflected light is received by the optical fiber for receiving the principal light (2) or one end of the optical fiber bundle, and the light is received by the optical fiber for light reception. (2) Alternatively, the signal light emitted from the other end of the fiber bundle is detected by a light receiving element (5), typically a photodiode or phototransistor.

By the way, the fifth drawback of the conventional reflective optical sensor head is
As shown in the figure, when a light-reflecting object to be detected comes extremely close to the end face of the optical fiber of the sensor head, the amount of reflected signal light received is extremely reduced, making it impossible to detect the presence of the object. [Object of the Invention] As a result of intensive studies to improve the problems of the conventional reflective optical sensor head described above, the present invention has been developed based on a single optical fiber at the tip of the sensing side that serves both for transmitting and receiving light. By using this method, the above problems were overcome, and the present invention was achieved by discovering a scale that can be detected even when the object to be detected is extremely close. This is a reflective optical sensor head characterized by a sensing device whose distal end is composed of a single optical fiber that serves both for transmitting and receiving light.

Below, the structure of the uninvented optical sensor head is shown in the third section.
This will be explained using the figure.

Signal light emitted from a light transmitting light source (4) consisting of a light emitting diode is emitted through a transmitting optical fiber (1) and a transmitting/receiving optical fiber (3), and is emitted to a light-reflective detection target (6). reach Then, the light reflected by the light-reflective detection object (6) re-enters the optical fiber (3) that serves as a transmitter and receiver as an original signal, and the traveling direction is reversed. (2), it reaches a light receiving element (5), typically a photodiode. In other words, Gengaku Textile, which also serves as the sender and receiver (
3) will be used both as a transmitting optical path and a receiving optical path.

Therefore, even when the sensor end is extremely close to the object, as in the case of distance L1=0 in FIG.
Since the signal light travels back and forth within the light transmitting and receiving optical fiber, it is possible to detect the object (6) to be detected. [Example] The present invention will be explained in more detail with reference to a specific example.

In Fig. 3, plastic optical fibers with a core made of acrylic resin and a sheath made of fluororesin, with an outer diameter of 1 mmφ and a length L3 = 2000 m are used as the sending optical fiber (1) and the receiving optical fiber (2). The above (1) is used as the optical fiber (3) for transmitting and receiving light, using one each.

Plastic optical fiber with the same structure as (2), outer diameter 2
Unfortunately, the length L2 is 10. 20. Six types of 30 m/m were used. In addition, as shown in Figure 4, the joint between the transmitting optical fiber (1), the light receiving optical fiber (2), and the transmitting and receiving optical fiber (3) is a pipe-shaped base made of black polyacecool resin. (7), using optical fiber for light transmission (1
), the light-receiving optical fiber (2) and the light-transmitting/receiving optical fiber (3) were fixed with epoxy adhesive so that they were in close contact with each other. A visible light emitting diode is used as the light source for transmitting light (4), and the light receiving element (
For 5), a photodiode was used. Furthermore, a white business card was used as the detection target (6).

With this configuration, the distance Ll (a) from the tip of the optical sensor to the detection target 1 and the output current value E (
Figure 5 shows the relationship with μA).

As shown in FIG. 5, the uninvented sensor heads, namely those with L2 = 30 mm (A), those with L2 = 20 mm (B), and those with Lz = 101W11 (C), are different from the conventional example (D) ( The output current value is higher than that of the configuration shown in Figure 2), and the distance between the sensor head and the object to be detected (I
It was confirmed that this is an excellent method that can be sufficiently detected even when q) becomes extremely small.

〔Effect of the invention〕

As mentioned above, the uninvented original sensor head has a single optical fiber at the tip on the sensing side that is used for transmitting and receiving light. Even if the object comes extremely close to or comes into contact with the end surface 1c, the reflected light will be reflected in inverse proportion to the distance between the end surface and the object to be detected. It can be detected even in cases such as a reader, and - like a liquid level gauge, the liquid level 1
This has the advantage that it is completely possible to detect the distance at , as an analog quantity. Furthermore, it has the advantage that the absolute value of reflected light weight is higher than that of conventional reflective sensor heads.

[Brief explanation of drawings]

Figures 1 and 2 show conventional original sensor heads; Figure 1 is an explanatory diagram of a transmission type optical sensor, Figure 2 is an explanatory diagram of a reflective type optical sensor, and Figure 6 is an illustration of an uninvented type optical sensor. An explanatory diagram showing the configuration of the original sensor head, FIG. 4 is an enlarged sectional view of the tip of the original sensor head shown in FIG. 3, and FIG. 3 is a graph showing the relationship between output current values of phototeriodes. (1)... Optical fiber for transmitting light (2)... Optical fiber for receiving light (3)... Optical fiber for both transmitting and receiving light (4)... Light source for transmitting light (5)... Light receiving element (6)... Detection target (7)... Base

Claims (1)

[Claims] In a reflective optical sensor head using optical fiber,
A reflective optical sensor head characterized in that the tip on the sensing side is composed of a single optical fiber that serves as both a light source and a light receiver.