JPH0244003B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plunger-type length measuring instrument comprising a scale housed in a case, a detection head movable along the scale, and a measuring plunger slidably protruding from the case. In particular, the present invention relates to a plunger-type length measuring device in which a flexible signal cable connecting the detection head and a signal shaping processing circuit provided in a case is provided with sufficient strength.

Conventionally, when measuring the distance between two points, for example, the distance or position of a movable member with respect to a stationary member, a scale is fixed to the movable member to be measured, a detection head is attached to a base, which is a stationary member, and the movable member is measured. That is, a length measuring device is used to measure the amount of movement of the scale, but this conventional technology has the disadvantage that oil droplets and dust tend to adhere to the scale, causing measurement errors due to the influence of the environment. . Also,
Another drawback was that it was inconvenient to attach the scale to some of the movable members.

In order to solve the above problems, plunger-type length measuring instruments have recently been developed in which the scale and detection head are sealed inside a case and a measuring plunger that protrudes from the case is connected to a movable member to be measured. , has started to be adopted.

Fig. 1 schematically shows a plunger-type length measuring instrument, in which a scale 2 with an optical grating on its surface is installed inside a closed case 1.
A detection head 3 is movably supported along the scale 2, and a light projecting section and a receiving section are disposed facing each other on the detection head 3 with the scale 2 in between. One end of a measuring plunger 5 is connected to the detection head 3 via a connecting rod 4, and the other end of the plunger 5 protrudes from one end of the case 1 so as to be slidable relative to the case. 5a is attached to a movable member to be measured. A cable clamp 7 is attached to the other end of the measurement plunger 5 via a support member 6, and a flexible signal cable 8 is connected thereto. The other end of the signal cable 8 is connected to a signal shaping processing circuit section 9 fixedly provided within the case 1. The detection head 3 and the flexible signal cable 8 are connected to the signal line 1.
Connected by 0.

In the above configuration, when the tip 5a of the measurement plunger 5 is attached to the movable member to be measured, the measurement plunger 5 moves freely in and out as the movable member moves, and the detection head 3 is integrated with the plunger 5 into the scale. 2 Move above. At this time,
A measurement pulse is generated each time it passes through the graduation grating on the scale 2, and the measurement pulse is sent to the signal shaping processing circuit section 9 via the signal line 10 and the flexible signal cable 8, where it is counted and moved. The amount of movement of the member is measured.

However, the flexible signal cable 8 is
Generally, a strip-shaped cable substrate made of Mylar or synthetic resin with copper foil vapor-deposited in a wire is used. Clamp 7 and
The signals are connected along a curved path to the signal shaping processing circuit section 9 on the fixed side and stored in a loop shape.

However, in such a flexible signal cable 8, during measurement work, due to the movement of the cable clamp 7 accompanying the movement of the measurement plunger 5,
As shown in FIG. 3, a buckling phenomenon 8a often occurs along the way, especially near the connecting portion with the cable clamp 7, accompanied by arm bending with an extremely small radius of curvature. Furthermore, as shown in FIG. 4, a winding phenomenon 8b occurs in which the cable is bent backward beyond the cable clamp 7.

Incidentally, in order to avoid breakage due to repeated stress, it is preferable that the flexible signal cable 8 has a radius of curvature R as large as possible to form a loop shape. Since it is much smaller than the radius R, stress concentration occurs in this portion, and the flexible signal cable 8 frequently breaks, resulting in a drawback that it cannot withstand long-term use.

The purpose of the present invention is to solve problems such as breakage of flexible signal cables due to structural limitations of plunger type length measuring instruments based on the above-mentioned prior art. By adopting a structure in which reinforcing material is attached, the above-mentioned drawbacks are eliminated, and the flexible signal cable does not buckle during operation, thus allowing long-term use without breakage. The purpose is to provide an excellent plunger-type length measuring instrument that is durable.

In accordance with the above object, the present invention has a structure in which a reinforcing member having an arc-shaped arm bent in the cross-sectional direction with a constant radius of curvature is attached to the back side of a band-shaped flexible signal cable, and the flexible signal cable is traversed. By keeping the arm bent in the plane direction, it is possible to make it easy to bend only at a certain radius of curvature, and to make it difficult to bend at other radii of curvature, thereby preventing the occurrence of buckling. The main points are as follows.

Next, an embodiment of the present invention will be described below based on FIGS. 5 and 6.

In the figure, a reinforcing agent 11 is attached to the back surface of the band-shaped flexible signal cable 8 with an adhesive or the like, and the reinforcing agent 11 is formed into an arc shape by bending its arms with a constant radius of curvature r in the cross section. ing. The reinforcing material 11 is made of stainless steel, for example, and is formed into an arm shape in the cross-sectional direction using a rolling roll, and then subjected to a heat treatment. By doing so, the flexible signal cable 8 is maintained in a bent state with a constant radius of curvature r in the cross-sectional direction. Due to the arm bending in the cross-sectional direction, the flexible signal cable 8 becomes easy to bend in the longitudinal direction for a certain radius of curvature R, and has a very low resistance to bending for other radii of curvature. It will become larger.

Note that the reinforcing agent 11 is applied to the flexible signal cable 8.
It is preferable to make the width smaller than the width of the reinforcing material 11 to prevent the reinforcing material 11 from damaging other members.Furthermore, the edge 11a of the reinforcing material 11 should be sufficiently polished to prevent cracking. is desirable.

Here, the relationship between the radius of curvature r of the reinforcing agent 11 and the radius of curvature R of the inherent longitudinal bending of the flexible signal cable 8, which is selectively determined thereby, is as follows.

Flexible signal cable 8 with a thickness of 135μ (75μ base layer made of polyimide, conductor layer made of copper foil)
35μ, on the back side of the reversible layer (25μ) made of polyimide,
Made of stainless steel with a thickness of 80μ, curve radius r = 8
When the reinforcing agent 11 with an arm bend of mm is attached, the selectively determined specific radius of curvature R in the longitudinal direction of the flexible signal cable 8 is 10 mm.

As described above, according to the present invention, the detection head 3 moves integrally with the measuring plunger 5 along the scale 2 and is fixedly provided with respect to the case 1 and moves relative to the case 1. A flexible signal cable 8 connected along a curved path to the signal shaping processing circuit section 9 and stored in a loop shape.
A reinforcing material 11 curved with a constant radius of curvature with respect to the cross section is attached to the flexible signal cable 8 to maintain the shape of the flexible signal cable 8 curved with a constant radius of curvature with respect to the cross section. In the longitudinal direction of the cable 8, the signal cable 8 is given a property of being easily bent only at a certain radius of curvature, and the radius of curvature of the curve in such longitudinal direction is the same as that of the signal cable 8.
can be selectively determined depending on the radius of curvature of the cross section of the reinforcing material 11 attached to the reinforcing material 11. Therefore, it becomes extremely difficult to bend with a radius of curvature other than the specific radius of curvature selected in this case, and as a result, it becomes extremely difficult to bend. This has the excellent effect of reliably preventing the occurrence of buckling or entrainment that would be caused by curvature with a small radius of curvature.

Moreover, its structure is simple, consisting of pasting a reinforcing agent with bent arms on the conventional flexible signal cable, which has the practical benefit of requiring only minimal modification of the conventional product. Since there is no breakage, long-term use is possible and it is advantageous in terms of cost.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a general plunger type length measuring device, Figs. 2, 3, and 4 are illustrations of its operation, and Figs. 5 and 6 are related to embodiments of the present invention. FIG. 5 is a side view extracting the cable clamp 7 and the flexible signal cable 8, and FIG.
The figure is a sectional view taken along line AA in FIG. DESCRIPTION OF SYMBOLS 1... Case, 2... Scale, 3... Detection head, 5... Measurement plunger, 8... Flexible signal cable, 9... Signal shaping processing circuit section, 11...
...Reinforcement material.

Claims (1)

[Claims] 1. A scale 2 housed in a case 1; a detection head 3 movably supported along the scale 2; one end of which is connected to the detection head 3, and the other end connected to one end of the case 1. The measurement plunger 5 projects slidably relative to the case, the signal shaping processing circuit section 9 is fixedly provided within the case 1, and the signal shaping processing circuit section 9 and the detection head 3 or the measurement plunger In a plunger-type length measuring device, a flexible signal cable 8 is connected along a curved path between one end of the detection head 3 of the signal cable 8 and stored in a loop. A plunger type length measuring instrument characterized in that a reinforcing material 11 which is curved and formed into an arc shape in cross section is attached.