JPH03235020A - Adjusting method of gap of encoder - Google Patents

Abstract

PURPOSE:To easily and correctly adjust the gap between a magnetric drum and a magnetoresistance element by a method wherein a shrinking tube of a predetermined thickness corresponding to the gap is applied on the circumferential surface of the drum, and the detecting element is fixed in contact with the tube, and then the tube is peeled off. CONSTITUTION:A shrinking tube 2 is applied on a circumferential surface 1' of a magnetic drum 1 and heated to shrink. The tube 2 has perforations or a partially thin part to be easily broken. After a magnetoresistance element 4 is fixed in contact with the circumferential surface 1' of the drum 1 to confront it, the tube 2 is peeled off at the perforations or the thin part, whereby a correct gap of a hundred and several tens mum is formed. Such a tube 2 should be selected that the thickness thereof after shrinking by heat agrees with the necessary size of the gap.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an encoder, and more particularly to a gap adjustment method for an encoder used in detecting the rotational position and speed of an FM device, an OM device, or the like.

BACKGROUND OF THE INVENTION In recent years, non-contact measurements have become mainstream for detecting the rotational position and rotational speed of objects, and magnetic encoders are also widely used as one of them.

Conventionally, taking a magnetic encoder as an example, the arrangement and fixation of the magnetoresistive element facing each other is done by mounting the magnetoresistive element 4 on the holder 5 as shown in FIG. It was fixed with screws 8 or by adhesive. At this time, the gap between the magnetic drum 1 and the magnetoresistive element 4 is as follows.

Adjustments were made using a gap gauge 7. For example, JP-A-63
An example is shown in Japanese Patent No.-317719.

Problems to be Solved by the Invention However, in the above-described gap adjustment method, it is necessary to be careful when handling the magnetic drum 1 and the magnetic resistance element 4 during assembly and adjustment work so as not to damage the magnetic drum 1 and the magnetic resistance element 4. There is a problem in that the size of the gap varies between the resistance element 4 and the parallelism or azimuth angle of the gap.

The present invention is intended to solve these problems,
It is an object of the present invention to provide a gap adjustment method for an encoder that can easily and accurately adjust the gap between a magnetic drum and a magnetoresistive element.

Means for Solving the Problems In order to solve the above problems, the present invention covers the circumferential surface of the drum with a shrinkable tube having a constant thickness corresponding to the gap between the drum and the detection element, and the detection element is placed on the shrink tube. The gap can be adjusted by fixing the tube in contact with the tube and peeling off the shrink tube.

Function The present invention allows the gap between the drum and the detection element to be easily adjusted by the above-described method, and eliminates variations in the size of the gap and deviations in the parallelism and azimuth angle of the gap.

Embodiment FIG. 1 is a perspective view of a shrinkable tube attached to the circumferential surface of a magnetic drum according to an embodiment of the present invention, and FIG. 2 is a perspective view of a magnetic drum in which a magnetic resistance element (detection element) is fixed in contact with the magnetic drum. It is a diagram. The structure and operation will be explained below with reference to the drawings. As shown in FIG. There is. A shrink tube 2 (for example, having a thickness of 100-odd μm) is attached to the circumferential surface 1 of the magnetic drum 1, and the tube is heated and shrunk. The shrink tube 2 is provided in advance with a part that can be easily broken, such as a perforation or a partially thin part.

In FIG. 2, the magnetoresistive element 4 is housed in a holder 5, and the holder 5 is screwed to a fixing base 6 with a holder set screw 8.

After the magnetoresistive element 4 is fixed in contact with the circumferential surface 1' of the magnetic drum 1 covered with the shrink tube 2, the shrink tube 2 is peeled off from the perforation or the thin part and removed. Accurate gaps can be created.

Note that the heat-shrinkable tube 2 may be selected so that its thickness after heat-shrinking matches the required gap.

In addition, although this example was explained as an example of gap adjustment between a magnetic drum and a magnetoresistive element, other principles such as an optical encoder can be used to adjust the gap between the drum and the magnetoresistive element.

It can also be applied to devices that require a certain gap between the detection element and the opposing detection element.

Effects of the Invention As described above, according to the present invention, the gap between the drum and the detection element can be adjusted in an extremely simple manner, and an accurate gap without variation can be obtained. It is practical and useful as there is no risk of damaging the detection element.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a magnetic drum covered with a shrinkable tube according to an embodiment of the present invention, Fig. 2 is a side view of a magnetic drum in which a magnetic resistance element is fixed in contact with the magnetic drum, and Fig. 3 is a gap gauge of a conventional example. FIG. 1... Magnetic drum, 1'... Circumferential surface of magnetic drum, 2... Heat shrink tube, 4...
... Magnetoresistive element (detection element).

Claims (3)

[Claims] (1) In an encoder having a structure in which a detecting element faces the circumferential surface of a drum across a narrow gap, the detecting element is brought into contact with and fixed to the drum, which is covered with a heat shrink tube in advance, and then the heat shrink How to adjust the encoder gap by removing the tube. (2) The encoder gap adjustment method according to claim 1, wherein the heat-shrinkable tube is provided with perforations or easily breakable parts in advance. (3) The encoder gap adjustment method according to claim 1, wherein the thickness of the heat-shrinkable tube after shrinkage is the same as the gap required between the drum and the detection element.