SE422999B - FIBEROPTIC SENSOR - Google Patents

Description

15 20 25 50 3006155-6 The light guide can consist of several conductors, however conducting collecting signal, and you can also use different conductors for different measuring signals.

The invention thus relates. an incremental encoder, consisting of an optical-mechanical part and an electrical part. The design "makes a small pulse unit and the advantages from a disturbance point of view, which characterize an optical transmission. The interface between optics and electronics can be placed close to the pulse unit or on. hundreds of meters distance from aem (compare when the fly technology). vu een m placed is a disturbance ooh / or economic issue. With the gradually falling prices of. cable with optical fiber, it can be economical within a few years to lay the cut where the control electronics for the plant are located. An advantage of the invention is also that the pulse unit only has optical supply and that only one optical light guide can be used for each measuring channel. In this fiber optic conductor, light is supplied to the pulse horse at the same time as the pulsed signal is transmitted from it to the electronics part.

The invention is further exemplified in the accompanying figures, of which Figure 1 shows a principle element of the invention, Figures 2-6 exemplify pulse units (puleglvazeywsa invention.

Figure 1 shows how from a light emitter (LED) 1 continuous light (frequency> 101232, visible and / or invisible light) is transmitted via a fiber optic conductor 2, a fiber branch 5 and a common fiber optic conductor 4 towards a pulse unit S, e.g. containing a pulse disk 6. The number of conductors for the same signal may be one or more, and the same conductor is used for the reflected signal.

When the pulse disk 6 is rotated, for example together with the machine, verse speed is to be measured, ae fl a light is "chopped" (see pointer below), een ae: the light is returned via the light guide ß .ooh the branch 3 and a special light guide 7 to electronics unit 8 photodetector 9.

In the electronics unit its light pulses are converted into electrical pulses, or velocity values in parallel or series form and these signals can be taken at 10. For direction determination and / or increased pin speed per revolution for the disc, several light conductors or electronics units can be connected to true pulse unit along the periphery of the pulse disc 6. A serial code signal can also be extracted at 11 from the electronics unit 8.

The pulse disc 6 can be made with mechanical or only optical ignition (trans- 15 20 25 30 8006133-6 parent disc material). Figures 2 and 3 show in principle how the optical light guide can be connected to the heart rate monitor.

Figure 2 shows a encoder with special light guide 12, here a channel. The disc 14 is toothed with light-absorbing material, but light is transmitted in the loops between these teeth through to a reflector (mirror) 15 and is reflected back into the fiber. The disc 14 is rotated synchronously with the machine whose rotational speed is to be measured.

Figure 3 shows a pulse sensor with radial light guide 15 with a disc so. performed that the sigwl is chopped, and the pulse is reflected back into the light guide 15.

The principle of the design and function of the rotating pulse disc is shown in Figure 4-6.

The light emitted from light emitter 1 (figure 1) in figure 1 will be fully or partially reflected back to the fiber 4 if one of the pins of the pulse disk is completely or partially in front of the end of a light guide. Figure 4 shows a disc 16 with tongues 17. When the light guide 18 'is between the tongues 17, no light is reflected back to the light guide reindeer 18, but the light is refracted or reflected away, for example at the inclined mirror 19 or dimmed directly in a light-dimming material. The tongues 17 reflect light back to the conductor 18, and a pulsed light signal is transmitted at the rotation of the disk 16 back to the electronics unit 8.

To increase the possible pulse rate per revolution of the pulse disk, a diaphragm can be inserted between the light guide and the pulse disk. In this way, the resolution can be increased and the possibility of increased pulse rate is obtained. The aperture 20 (Figure 5) can be light absorbing or designed so that shielded light is reflected off. _ You can according to figure 5 to get. a good signal-to-noise ratio arranges a parabolic mirror 21 which reflects the desired signal light pulses back into the light guide 18. The mirror 21 is optically adapted to the numerical aperture of the light guide 18. In the case according to Figure 5, reflection of light is obtained in the opening between the pins 23 of the pulse disk 22. The pins 23 can in this case be made with light-absorbing surface or with inclined reflecting surfaces, which gives the light an angle unacceptable to the fiber, i.e. 18. A pulse disk according to Figure 6 provides the possibility of radial connection of the light guide 24 (see also Figure 3) to the edge of the disk 25. (The right part of Figure 6 is a section A-A in the left). This can be

Claims (7)

10 15 '8006133-.6 Å i rymneeeynpnnkt vara. An advantage. In this embodiment, the surface 27 is angular and reflective between the reflective surfaces. The surface 28 is directly reflective. Here, some embodiments of fiber optic pool sensors have been described. Many other. There are possibilities, such as a radial insertion of the fiber, which can be used with an angled disc by means of an angled ablation or curvature. those described for exial sensing. Which version is chosen is often. depending on the cost and necessary measures for a good enough. signal-to-noise ratio. The discs can be arranged inside an enclosure or in a machine, through either wall one or more. light guides are led. In or near the pulse unit, a light reading envelope can be arranged with one or more light guide channels, mutually offset so that they have different phase positions, whereby a doubling or multiplication of the pulse number is obtained with increased resolution and the possibility of sensing the direction of rotation of the disc. The positions of the pulses can also depend on a network dryness, which on aim »: att can inaikem. The devices as above can be varied on. manifold. within the scope of the following claims. PATENTIEAV Fiber optic pulse sensor for measuring speed, position Sto, Vä-I-'Viä G21 15115- signal, visible ooh / or invisible, arranged to be guided via at least one optical light guide (4) to a pulse unit (5), and i. this in pulsfom is reflected lill-Dale into sme. light layer (4), 1: characterized in that the pulse unit contains a pulse disk (6) with light-reflecting surfaces with varying reflection direction (27, 28), which reflects the light back to, respectively away from the light guide, whereby a pulsed light signal is obtained therein. ., and which is led therefrom to an electronics unit (8) for pulse shaping and / or pulse position measurement, selection via the electronics unit (a) uisignil (10) becomes dependent on the pulse disk speed, the positions of the pulses, etc. Fiber optic encoder according to claim 1, characterized in that the pulse disk (6) contains reflective tongues or surfaces (117) for pulsed reflection of light back into the light guide / -leäßrnß- 8006133-6 Fiber optic encoder according to claims 1-2, characterized in that between the tongues (17) the disc (6) is optically transparent. 4. A fiber optic encoder according to claim 1, characterized in that the pulse disc contains tongues (25) with light-absorbing material, incident light being attenuated therewith, and that the pulse unit contains one or more mirrors (13) or liknarxde for pulsed reflection of incident light. Fiber optic encoder according to one or more of the preceding claims, characterized in that a diaphragm (20) is arranged between the pulse unit and the light guide, which can be light-absorbing or designed in such a way that shielded light is reflected off. 6. A fiber optic encoder according to claim 1, characterized in that the disc is arranged to be rotated inside a capsule or in a machine, through which wall one or more light guides are passed. Fiber optic encoder according to one or more of the preceding patents, characterized in that at or in the pulse unit at least one reading head is arranged with one or more fiber casings, mutually offset so that they have different phase positions, wherein a doubling or multiplication of the pulse number is obtained together with increased resolution and possible possibility of sensing the direction of rotation of the disc.