JPS62276402A - Linear output type position sensor - Google Patents

Abstract

PURPOSE:To obtain the linear positional output of an object to be detected, by integrally fixing a tapered approaching body to the object to be detected and linearly displacing the approaching body in a hollow oscillation coil along the axial direction of said coil. CONSTITUTION:A cylindrical projection 13 is fixed to an object 12 to be detected positionally and an approach body 14 is connected to the leading end of said projection 13. The object 12 to be detected takes linear motion left and right, and the approach body 14 and a hollow oscillation coil 11 are held apart from the inner wall of a coil bobbin 10 so that the approach body 14 takes linear motion along the center axis of the oscillation coil 11 with the linear motion of said matter 12. A resonance condenser 15 is connected to the oscillation coil 11 thus formed to constitute a resonance circuit, and an oscillation circuit 16, a detection circuit 17 and an output circuit 18 are operated. By this constitution, output difference corresponding to the tapered shape of the approaching body 14 is obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of the Invention] The present invention relates to a linear output type position sensor that obtains a linear output corresponding to the position of an object.

[Summary of the invention]

The linear output type position sensor according to the present invention configures an oscillation circuit using a hollow coil as an oscillation coil, and has a tapered proximal body that protrudes from the object to be detected and is attached integrally, so that the inside of the oscillation coil is moved in the axial direction. The sensor is configured so that it can be displaced over a predetermined interval along the object, and can linearly output the position of the object to be detected based on the output of the oscillation circuit corresponding to the position of the nearby object. .

[Prior art and its problems]

(Prior art) As shown in Fig. 5, a conventional linear output type position sensor uses a high frequency oscillation type proximity switch.
A near output type proximity sensor is known that detects the distance from the oscillation coil 2 to the oscillation coil 2 based on changes in the oscillation level and oscillation frequency. Such a proximity sensor is provided with an oscillation coil 2 facing the object to be detected 1 and an oscillation circuit 3 that oscillates at the resonance frequency of the resonance circuit including the oscillation coil 2.

The oscillation output is detected by the next-stage detection circuit 4, and a signal corresponding to the position of the detected object is obtained based on the change in the oscillation amplitude. However, since the oscillation amplitude or oscillation frequency does not change linearly in response to changes in the distance from the oscillation coil 2 to the object, the detection circuit 4 and the output A linearizer circuit 5 is required between the circuit 6 and the circuit 6.

(Problems to be Solved by the Invention) However, such a conventional linear output type proximity sensor has a problem in that the circuit configuration of the linearizer circuit 5 is complicated and adjustment is difficult. In addition, since the active area of the oscillation circuit 3 is narrow, the distance detection range from the oscillation coil 2 to the detected object 1 is narrow (there was a problem that it was difficult to use).Furthermore, in order to expand the distance detection range, a ferrite was used in the oscillation coil 2. When using cores, etc., temperature changes have a large effect on the output.
There was also the problem that the temperature characteristics deteriorated if left as is.

[Purpose of the invention]

The present invention has been made in view of the problems of conventional linear output type proximity sensors, and it is possible to make the oscillation output directly linearized with respect to distance without using a linearizer circuit. The technical challenge is to do so.

[Structure and effects of the invention]

(Structure) The present invention is a linear output type position sensor that detects the position of an object, and as shown in Fig. 1.3, uses a hollow oscillation coil formed over a predetermined length and an oscillation coil. Based on the oscillation output of the oscillation circuit, an oscillation circuit configured, a proximal body formed in a tapered shape that is attached to protrude integrally with the object to be detected and linearly displaced within the oscillation coil along its central axis, and an oscillation output of the oscillation circuit. The present invention is characterized by comprising a detection circuit that obtains a position output with respect to a nearby object.

(Function) According to the present invention having such features, a tapered proximal body is integrally fixed to the object to be detected, and the proximate body is linearly displaced within the hollow oscillation coil along the axial direction of the coil. That's what I do. The coil is used as an oscillation coil to constitute an oscillation circuit, and a linear position output of the detected object is obtained based on the oscillation output.

(Effect) Therefore, according to the present invention, by selecting the tapered shape of the proximate object, a linear position output corresponding to the position of the detected object can be obtained in a predetermined range within the oscillation coil without using a special linearizer circuit. It can be a linear output type position sensor. Since the detection distance can be approximately half the length of the oscillation coil, the range in which the object to be detected can be detected can be expanded by appropriately selecting the length of the oscillation coil and increasing it as necessary. Therefore, unlike conventional proximity sensors, there is no need to use a ferrite core to increase the detection distance, and the temperature characteristics of the oscillation circuit section can be improved.

[Explanation of Examples]

FIG. 1 is a diagram showing an oscillation coil of a linear output type position sensor according to an embodiment of the present invention. In the present invention, as the oscillation coil, a hollow oscillation coil 11 wound around a coil pobin 10 is used as the oscillation coil.

Then, as shown in the figure, a cylindrical projection 13 is fixed to the detected object 12 whose position is to be detected, and a proximal body 14 is connected to the tip thereof. FIG. 2 is a perspective view showing an example of the proximate body 14, which is configured to have a tapered shape as shown.

The object to be detected 12 moves linearly from side to side, and the object 14 and the hollow oscillation coil 11 are held apart from the inner wall of the coil bobbin 10 so that the object 14 to be detected moves linearly along the central axis of the oscillation coil 11. I'll keep it. Now, as shown in FIG. 3, a resonant capacitor 15 is connected in parallel to the oscillation coil 11 thus formed to form a resonant circuit, and an oscillation circuit 16 is connected thereto. The oscillation circuit 16 is a high frequency oscillation circuit that oscillates at this resonant frequency, and its output is sent to the detection circuit 1.
7 is given.

The detection circuit 17 outputs a level signal corresponding to the amplitude of the oscillation circuit, and supplies the output to the output circuit 18.

With this configuration, different outputs can be obtained depending on the shape of the taber of the proximate body 14. For example, Fig. 4 is a diagram showing the change in output with respect to distance when the length of the oscillation coil 11 is 40 mm, the proximity body 14 is made of stainless steel, and the length l is 25 mm, and the taber size is varied. It is. In Figure 4, curve A has diameters a and b at both ends of 10 mm,
Output characteristics of the proximal body 14a with a thickness of 8 mm, curve B in the same figure.
is the diameter a at both ends.

Proximate body 14b when b is lQmm and 4m, respectively
Curve C in the same figure has diameters a and b at both ends of 101111. 21111 is a curve showing the output characteristics of the proximate body 14c. By changing the size of the taber in this way, the output characteristics vary. Therefore, when using the proximal body 14b having the taper shown by the curve B in FIG. 4, it is possible to obtain substantially linear output characteristics in the range of, for example, 4 to 20 fins. Note that when the proximal body 14 is inserted beyond the center of the oscillation coil 11 shown by the two-dot chain line in FIG. 1, the output that has once decreased will increase again. Therefore, the range of linearity is limited to approximately A or less of the oscillation coil 11.

As described above, according to the present invention, by adjusting the taber of the proximate object, it is possible to obtain a position sensor having an output linearized with respect to distance from a detection circuit without using a linearizer circuit.

Although this embodiment detects the output of the oscillation circuit and detects the position of the object to be detected based on the amplitude of the oscillation output, it is also possible to detect the position of the object to be detected based on the oscillation frequency of the oscillation circuit. You can also do it. In this case as well, by appropriately selecting the tapered shape of the proximate object, it is possible to obtain a linear output type position sensor having high linearity within a predetermined range.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an oscillation coil used in a linear output type position sensor according to an embodiment of the present invention, FIG. 2 is a perspective view showing the structure of a proximal body inserted into the oscillation coil, and FIG.
Figure 4 is a block diagram showing the circuit configuration of this embodiment, Figure 4 is a graph showing the output characteristics of a linear output type position sensor for different shapes of proximate objects, and Figure 5 shows the configuration of a conventional linear output type proximity sensor. FIG. 1, 12-----One object to be detected 1 (1-
------Coil bobbin 2. 11-----Oscillation coil 13-------Protrusion 14--One neighbor 15-----Resonance capacitor 16----
--Oscillation circuit 17--Detection circuit 18--
---- Output circuit patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Kanki Okamoto (and 1 other person) 13-・-Protrusion 1'1-----4 Aspiration and withdrawal Fig. 2 ← Doo Fig. 3 Fig. 5 Fig. 4

Claims (3)

[Claims] (1) A hollow oscillation coil formed over a predetermined length, an oscillation circuit configured using the oscillation coil, and an oscillation circuit configured by using the oscillation coil, which is attached so as to protrude integrally with the object to be detected, and whose central axis extends inside the oscillation coil. A linear output type position sensor comprising: a proximal body formed in a tapered shape that is linearly displaced along the oscillation circuit; and a detection circuit that obtains a position output with respect to the proximal body based on an oscillation output of the oscillation circuit. . (2) The linear output type position sensor according to claim 1, wherein the detection circuit is a detection circuit that detects the oscillation output of the oscillation circuit and provides an output corresponding to the amplitude thereof. (3) The linear output type position sensor according to claim 1, wherein the detection circuit is a frequency detection circuit that provides an output corresponding to the oscillation frequency of the oscillation circuit.