JP2770903B2 - Multiple optical sensor position detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting system for a plurality of optical sensors having a plurality of optical sensors for detecting the position of a bit pattern of an encoder plate by using light reflection.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
For example, there are the following techniques. FIG. 4 is a diagram showing a configuration of such a conventional optical sensor position detection system, and FIG. 5 is a diagram showing an upper surface of the encoder plate, showing an example of a configuration in which one sensor is provided.

As shown in these figures, when a moving object 15 is moved by a power source 16, a method of detecting the amount of movement (position) is performed by recognizing a black and white pattern provided on a reflective encoder plate 27. There was a way. The method of recognizing the pattern utilizes the reflection of light emitted from the collimator 26 disposed on the fixed portion 28 on a white pattern of a black and white pattern provided on the reflective encoder plate 27.

By the way, in an aircraft or a plant where it is most necessary to prevent the system from malfunctioning due to noise on the signal due to the influence of electromagnetic interference,
An optical sensor position detecting device having an encoder has evolved into a method using an optical signal without using an electric signal. A block diagram of the optical sensor position detection method will be described with reference to FIG.

The optical sensor position detecting system includes an optical transmitting / receiving section 18, an optical fiber cable 24, an optical sensor position detecting section 2
The optical transmission / reception unit 18 on the system side that performs control includes a control unit 23, a light emitting element 19, a light receiving element 20, an optical coupler (for example, a lens) 21, and an optical splitter / coupler 22. In the sensor position detecting section 25, a collimator 26 (light beam conversion element) is connected to the plurality of optical fiber cables 24, and the collimator 26 provided in the fixing section 28 (see FIG. 4) faces the reflective encoder plate 27. .

[0006] Therefore, in response to a signal from the control unit 23, the optical output of the light emitting element 19 is guided through the optical coupler 21 to one port (a) on the two-port side of the optical branching coupler 22. The light incident on the port (a) side of the optical branching / coupling coupler 22 is further guided to an optical sensor position detecting unit 25 by an optical fiber cable 24. At this time, the optical branching coupler 22
Is not guided to the port (c). The optical sensor position detection unit 25 includes a collimator (light beam conversion element) 26 provided on a fixing unit 28 (see FIG. 4).
And a reflective encoder plate 27.

The light guided from the optical fiber cable 24 is converted into a parallel beam by a collimator 26 and applied to a display pattern having light reflection and light absorption characteristics (white or black) on a reflective encoder plate 27. You. The collimator group is arranged so as to correspond to each of the white or black display pattern positions of the encoder. The display pattern of the reflective encoder plate 27 is, as shown in FIG.
No. forming one code 1 to No. It consists of m m-bit patterns. Of the white and black patterns, white reflects light, whereas black absorbs light, which utilizes the difference in reflectance.

The light reflected by the display pattern of the reflection type encoder plate 27 is collimated by the same collimator 26 as the irradiated optical element.
Then, the light that has passed through the optical fiber cable 24 in the opposite direction to the above and entered the port (b) of the optical branching coupler 22 is guided to the port (c). Further, through the optical coupler 21,
The light enters the light receiving element 20. The light received by the light receiving element 20 is converted by the control unit 23 into “1” or “0” of the electrical data. The reflective encoder plate 27 has an m-bit pattern, and there is a series of systems from the light emitting element 19 to the light receiving element 20 for each bit.

If there are n sensors, (m × n)
It becomes necessary to have individual lines.

[0010]

As described above, in the conventional optical sensor position detecting method, the light emitting element, the light receiving element, the optical fiber cable, the optical fiber, and the light emitting element are equal to the number of bits of the monochrome pattern of the encoder for one sensor. A branch multiplexer, a collimator, and the like are required. Of course, for n sensors, n times more elements are required.

When an encoder of such a system is used for an aircraft or the like, particularly high reliability is required, so that multiplexing of the system is required. For example, if the number of encoder bits is 12 bits and the number of sensors is 10,
A light emitting element, a light receiving element, an optical fiber cable, an optical branching coupler, a collimator, etc., each having 360 (= 12 × 10 ×
3) It is necessary, and there is a problem in terms of space, weight, and economy.

According to the present invention, as described above, when the number of encoder bits or the number of sensors increases, the number of optical components such as a light emitting element, a light receiving element, an optical fiber cable, an optical branching coupler, and a collimator increases. An object of the present invention is to provide an excellent multiple optical sensor position detection method in which the number of optical components does not increase even if the number of encoder bits or the number of sensors increases.

In order to achieve the above object, the present invention provides a multi-optical sensor position detecting system having a plurality of optical sensors for detecting a reading position of a bit pattern of an encoder plate using light, the control unit comprising: A broadband wavelength light source connected to the control unit, an optical coupling element connected to the broadband wavelength light source, an optical branching coupler connected to the optical coupling element, and one of the optical branching couplers connected to the optical branching coupler. Fiber optic cable and light from this fiber optic cable for each wavelength
The light is demultiplexed and guided to each of a plurality of optical sensors, and is distributed for each wavelength.
Light is different for each of the multiple bits of each light sensor.
An optical multiplexer / demultiplexer further distributed to optical delay means having a length of
The optical splitter / coupler to which the output signal from the optical multiplexer / demultiplexer is transmitted, the optical multiplexer / demultiplexer connected to the optical splitter / coupler, and each signal demultiplexed by the optical multiplexer / demultiplexer is connected. Each of the optical coupling elements, and a light receiving element that is input to the optical coupling element and whose output is connected to the control unit, are configured to simultaneously use the wavelength division multiplexing method and the pulse delay method.

[0014]

According to the present invention, as described above, the optical spectrum of a broadband wavelength light source having a broadband wavelength spectrum is divided into a number corresponding to a plurality of sensors by an optical multiplexer / demultiplexer. By dividing the light into the number of white and black pattern bits on the encoder plate and simultaneously irradiating the encoder plate with light by giving different delays to each, a plurality of optical sensor information can be obtained without increasing the number of optical components. Are collected at the same time.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a position detection system having a plurality of optical sensors according to an embodiment of the present invention.
FIG. 3 is a configuration diagram of the optical multiplexer / demultiplexer of the optical sensor position detection method, and FIG. 3 is a diagram showing a signal waveform of the optical sensor position detection method.

First, when a modulation signal having a short pulse width (see FIG. 3A) is applied from the control section 1 to the broadband wavelength light source 2, the light source having a wide wavelength spectrum is optically turned on.
/ OFF is repeated, and an optical pulse (see FIG. 3B) is output. Here, for example, when the optical fiber amplification (EDFA: erbium-doped fiber amplifier) system is adopted as the broadband wavelength light source 2, the emission center wavelength is 1.55 μm, the wavelength bandwidth is 35 nm, and
The division width at the time of division into two is 3 nm, and the light emission level is 6 to 8 dBm.
Can be obtained.

When the broadband wavelength light source 2 is of a semiconductor amplifier type, and its emission center wavelength is 1.3 μm,
The wavelength bandwidth is 60 nm, the division width at the time of division into 12 is 5 nm,
When the emission level is −5 to 0 dBm and the emission center wavelength is 1.5 μm, the wavelength bandwidth is 80 nm, the division width in 12 divisions is 5 nm, and the emission level is −5 to 0 dBm.

This optical pulse signal is applied to the port (a) of the optical branching coupler 4 via the optical coupling element (lens system) 3. Due to the characteristics of the optical branching coupler 4, the optical signal from the port (a) is coupled to the port (b) with low loss and coupled to the optical fiber cable 8. At this time, the optical branching coupler 4
The optical signal from the port (a) is attenuated due to the characteristics of the optical branching coupler, and is not coupled to the port (c).

Then, the optical signal having a wide band wavelength from the port (b) of the optical branching / combining device 4 is guided to the optical multiplexer / demultiplexer 9. The light having the broadband wavelength spectrum that has reached the optical multiplexer / demultiplexer 9 is wavelength-divided on the output side, and narrow wavelength spectrum lights respectively appear at the ports (a), (b),.

Here, as the optical multiplexer / demultiplexer 9, an interference filter is used. For example, as shown in FIG. 2, the light reaches from the optical fiber cable 8 to the incident portion 9A, the light is irradiated from the spherical lens 9A-1 of the incident portion 9A, and the light passes through the interference filters 9B arranged in multiple stages. Each port (a), (b), is guided to each collimator 9C having the 9C-1.
... (f) from the wavelength λ _1, λ _2, is demultiplexed to ... λ _n.

Further, each of these ports (a), (b),...
(F) corresponds to each optical sensor. The light emitted from each port is split into light according to the number of bits of the encoder,
Further, the split light is delayed by the optical delay unit 10 having a different delay amount (here, the length of the optical fiber cable is changed to make the light propagation time different). As shown in FIGS. 3C, 3D, and 3E, in the optical sensor n, as shown in FIGS.
Reach the upper white / black pattern.

That is, at this stage, the single-pulse light from each of the ports (a), (b),. Is emitted from the collimator 11. Then, the light reflected or absorbed by the white / black pattern on the encoder plate 12 passes through the reverse path and reaches the optical branching / combining device 4, where it goes to the port (c) of the optical branching / combining device 4. As shown in FIG. 3I, the wavelength is propagated, and separated by the optical multiplexer / demultiplexer 5 for each wavelength, that is, for each port, as shown in J, K, and L in FIG. And
The light reaches the light receiving element 7 through the optical coupling element 6.

Therefore, the position information from each optical sensor is converted into a time-series pulse pattern to each port of the optical multiplexer / demultiplexer 5, and this pattern is subjected to electrical signal processing by the control unit 1 and the intended signal is processed. Optical sensor position information can be obtained. That is, in the present invention, each wavelength-divided wavelength is made to correspond to each sensor, and the pulse delay is made to correspond to the displacement of each sensor.

As described above, the optical multiplexer / demultiplexer 9 includes:
Although an interference filter has been described as an example, it may be configured as a grating type as shown in FIGS. As shown in FIG. 7, the principle of the grating type is that α is the angle between the grating plane and the incident light, β is the angle between the grating plane and the outgoing light, and m = 0, ± 1,
When ± 2,... (Spectral order) and θ are the blaze angles, the following equation is established. In addition, 13 is a lattice.

Sin α + sin β = mλ / d That is, when the angle (α) of the incident light is constant, the angle (β) of the outgoing light differs depending on the wavelength, and an angle dispersion effect on the angle of the incident light occurs. FIG. 8 shows an example of demultiplexing using this principle. As shown in this figure, from the μ lens 31, the light is irradiated by the first lens 32, collimated beam by the grating 13, the wavelength lambda _1, lambda _2, lambda _3, are demultiplexed to ... lambda _n, the become parallel beams by first lens 32, through the second lens 33, the wavelength lambda _1, lambda _2, lambda _3, by ... lambda _n, reads the pattern of the encoder plate 34.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0027]

As described above, according to the present invention, the following effects can be obtained. (1) The optical spectrum of a broadband wavelength light source having a broadband wavelength spectrum is divided by an optical multiplexer / demultiplexer into a number corresponding to the number of each of a plurality of sensors, and the wavelength-divided light is divided into white and black on an encoder plate. By irradiating the encoder plate with light while dividing it into the number of pattern bits and giving each with a different delay, it is possible to collect a plurality of pieces of optical sensor information at the same time without increasing the number of optical components.

(2) For a plurality of optical sensors, the number of light sources, the number of optical branching couplers, and the number of transmission optical fiber cables can be reduced to one. Therefore, it is possible to provide a multiple-optical-sensor position detection method that can improve reliability, reduce cost, and reduce space. (3) The number of light receiving elements may be the same as the number of sensors.

(4) A plurality of optical sensors can be driven and measured simultaneously.

[Brief description of the drawings]

FIG. 1 is a block diagram of a position detection method having a plurality of optical sensors according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical multiplexer / demultiplexer of an optical sensor position detection type showing an embodiment of the present invention.

FIG. 3 is a waveform diagram of a signal of an optical sensor position detection method according to the embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional optical sensor position detection method.

FIG. 5 is a top view of the optical sensor position detection type encoder plate of FIG. 4;

FIG. 6 is a block diagram of a conventional position detection method having a plurality of optical sensors.

FIG. 7 is a principle diagram of another optical multiplexer / demultiplexer showing an optical sensor position detection system according to an embodiment of the present invention.

FIG. 8 is a configuration diagram of another optical multiplexer / demultiplexer that detects an optical sensor position according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Control part 2 Broadband wavelength light source 3, 6 Optical coupling element 4 Optical branching coupler 5, 9 Optical multiplexer / demultiplexer 7 Light receiving element 8 Optical fiber cable 9A Incident part 9A-1, 9C-1 Spherical lens 9B Interference filter 9C, 11 the collimator 10 optical delay means 12, 34 encoder plate 13 grid 31 mu lens 32 first lens 33 and the second lens _{λ 1, λ 2, ... λ} n wavelength

Continued on the front page (72) Inventor Hiroshi Nakazawa 1-39-2-2-305, Kuboyama-cho, Hachioji-shi, Tokyo (72) Inventor Shinichiro Ina 67-10 Shimo-Otsuki, Hadano-shi, Kanagawa Prefecture (72) Inventor Yasuaki Tamura Tokyo 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor ▲ Shin Kunihiko No. 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Fumio Nakamura 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. Yoshiji Gifu Prefecture 1 Kawasaki-cho, Kakamigahara-shi Kawasaki Heavy Industries, Ltd. Gifu Factory (56) References JP-A-5-10784 (JP, A) Japanese Utility Model 1983-36494 (JP, U) (58) Fields surveyed (Int.Cl. ⁶ , DB name) G01J 9/00 G01D 5/00

Claims (1)

(57) [Claims] 1. A plurality of optical sensor position detection systems having a plurality of optical sensors for detecting a reading position of a bit pattern of an encoder plate using light, wherein: (a) a control unit; and (b) a connection to the control unit. (C) an optical coupling device connected to the broadband wavelength light source, (d) an optical branching coupler connected to the optical coupling device, and (e) connecting to the optical branching coupler. And (f) demultiplexing the light from the optical fiber cable for each wavelength.
The light distributed to each of the plurality of optical sensors
Is a different length for each of the multiple bits of each light sensor
An optical multiplexer / demultiplexer further distributed to the optical delay means , ( g ) the optical branch / coupler to which an output signal from the optical multiplexer / demultiplexer is transmitted, and ( h ) an optical multiplexer / demultiplexer connected to the optical multiplexer / demultiplexer. an optical demultiplexer, and the optical coupling device each signal is connected, which is demultiplexed by (i) the light demultiplexer, are input to the (j) optical coupling element, connected the output thereof to the control unit ( K ) a plurality of optical sensor position detection systems, wherein a wavelength division multiplexing system and a pulse delay system are simultaneously used.