GB2119091A - Gas-discharge scale for a measuring instrument - Google Patents

Abstract

The gas-discharge scale comprises a front plate (1) having a transparent anode (2) a hermetically sealed to a base plate (3) having at least one row of cathodes (4) serving as the calibration marks of the scale. The cathodes (4) are arranged so that their ends belong to at least four smoothly curved portions (5), the curvature radii of these portions being at least one order of magnitude smaller than the curvature radius of a line 6 interconnecting the termination or endmost points of these portions (5). The endmost calibration marks belonging to the adjacent ones of the portions (5) of a smooth curve receive therebetween a means (7) for transfer of discharge between their cathodes (4). <IMAGE>

Description

SPECIFICATION Gas-discharge scale for a measuring instrument Gas-discharge scales are used predominantly in electric meters operated for measuring electric current, voltages, and other electric variables in monitoring and control systems.

The present invention resides in a gas-discharge scale for a measuring instrument, comprising a hermetically sealed connection of a front plate with a transparent anode and a base plate with at least one row of cathodes serving as the calibration or indication marks of the scale, adapted to perform the transfer of the discharge from one cathode to the successive one to indicate the value of the variable being measured, in which scale the cathodes are arranged so that their ends belong to at least four lengths or portions of a smooth curve, the curvature radii of these portions being by at least one order of magnitude smaller than the curvature radius of a line interconnecting the extreme of termination points of these portions, the endmost cathodes belonging to the adjacent portions of the smooth curve having provided therebetween a discharge transfer means providing for the ignition of the frontmost cathode of the successive portion of the scale from the preceding cathode.

It is expedient for the discharge transfer means to be in the form of a cathode shaped as a triangle, with the lateral sides of this triangle directly adjoining the respective indication marks of the adjacent portions.

It is expedient for the ends of the cathodes to belong to the portions of a curve which is a single-side convex one.

The scale offers high ergonomic ratings and enables an operator to completely avoid errors in taking the readings. Each indication mark differs from the adjacent one by its individual position on the length or portion of the smooth curve. Furthermore, the groups of the marks within individual portions are readily distinguished and easily counted owing to the significant curvature of these lengths or portions. The operator sees the line of taking and counting the readings as a strip with repetitive curves, with each indication mark in a group belonging to the respective one of diverging rays or beams whose inclination relative to a vertical line is within a predetermined angle. The extent of the arc of the circle of each such length or portion is preferably 80 , and the arcs are arranged in succession along a horizontal line.In this embodiment of the invention, the minimum reading error is defined by the fact that the maximum angle of the inclination of the rays to which the indication mark belong is not in excess of 40".

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front view of a gas-discharge scale of a measuring instrument; Figure2 is a section on line ll-ll of Figure 1; and Figure 3 shows on an enlarged scale a modification of the gas-discharge transfer means.

The gas-discharge scale illustrated comprises a front plate or panel 1 (Figures 1 and 2) of glass, having a transparent anode 2 applied to the inner surface thereof, and a base plate 3. The base plate 3 accommodates a row (or rows) of cathodes 4 in the form of thin metal plates or films applied to a dielectric or non-conductive layer (not shown) secured to the base plate 3 or integral with it.

The cathodes 4 constitute the calibration or indication marks of the scale, the ends of the marks belonging to a curve. The curve is made up of at least four smoothly curved lengths or portions, the actual number of these lengths or portions being defined by the amount of the indication marks required. The required amount of the indication marks, in its turn, depends on the accuracy class of the measuring instrument.

The curvature radii of the portions 5 are at least one order of magnitude smaller than the curvature radius of a line 6 interconnecting the terminal points of these portions 5, with the marks being arranged in groups over the individual portions 5. In the embodiment being described, each portion 5 has its shape close to that of an arc of a circle, whose extent is in the range from 30 to 80". This extent of the arc provides for clearly distinguishing between the adjacent portions 5 and, consequently, between the adjacent groups of the marks, which, in its turn, enhances the accuracy of taking the readings by the operator.

Arranged between the mark belonging to adjacent portions 5 is a discharge transfer means 7 providing for igniting the first orfrontmost cathode 4 belonging to the successive portion 5 of the scale from the last cathode 4 of the preceding portion 5.

The discharge transfer means 7 in one embodiment of the scale (Figure 1) is a cathode shaped as a triangle whose lateral sides directly adjoin the adjacent indication marks. In another embodiment (Figure 3) the endmost cathodes 4 of adjacent groups are provided with branches 8 directly adjoining each other and thus defining the discharge transfer means 7.

The curve made up of the lengths or portions 5 (Figure 1 ) to which the ends of the indication marks belong is a one-sided convex one.

The scale further includes an auxiliary cathode 9 intended for igniting a discharge at the adjoining frontmost or first one of the cathodes 4 of the scale, when the indication begins.

The cathodes 4 of the scale are electrically interconnected into three individual circuits connected to a power supply source (not shown), so that the first, fourth, seventh, etc. cathodes 4 are interconnected into the first circuit, the second, fifth, eight, etc. ones are interconnected into the second circuit, and the third, sixth, ninth, etc. cathodes are interconnected into the third circuit.

The scale further comprises accentuated indication marks which in the presently described embodiment are the cathodes defining the dischargetransfer means 7. Providing numerals at the successive calibrations of the herein disclosed scale is not obligatory; however, this should be considered expedient to facilitate taking the readings, such numerals may be printed or otherwise marked on the front plate or panel 1, next to the accentuated marks.

The sequential number of each indication mark is defined by its respective geometric group and its position in this group, with the angle formed by the respective radius or ray to which any one of the marks belongs and a vertical line not exceeding 40 , which allows for a high accuracy of taking the readings.

The operation of the above-described gasdischarge scale is as follows.

Readings of the measuring instrument are taken with the scale in the operating state which begins with feeding voltage to the anode 2 (Figure 1) and igniting the auxiliary cathode 9. Then the first cathode 4 is energized, and a discharge is ignited at this cathode 4 owing to the connection with the discharge area of the auxiliary cathode 9. The discharge appearing at the first cathode 4 is maintained for a time satisfying the conditions of the predetermined speed of response of the scale and of normal discharge duty setting in whereafter the circuit of the first cathode 4 is de-energized, and at the same time the circuit including the second cathode 4 is energized. The discharge now glows exclusively at this second cathode 4, which is due to its being close to the discharge area of the first cathode 4.

The third cathode 4 is energized in a similar manner when the second cathode 4 is de-energized, and this sequence takes place up to the moment when that one of the cathodes 4 is ignited, whose sequential number indicates the value of the variable being measured. Thus, the number of the glowing marks is made to correspond to the indicated value, and the operator sees them as a continuously glowing sinuous strip.

With the accentuated indication marks having shapes resembling by their outline a triangle, it is much easierto distinguish between the groups and to keep track of the numerals accompanying these marks, while the fact that the sides of these accentuated marks extend similarly with their adjoining marks offers the best possible situation for the transfer of the discharge between the groups of the marks.

The above-described structure of the scale provides optimized conditions for taking the readings not only in embodiments where the indication or calibration marks are arranged on curved portions having their centres of curvature to one side of the curve, but also in embodiments where some of the marks are arranged on portions of a periodic curve whose centres of curvature are to both sides of the curve.

When comparative tests were conducted, including taking readings off the above-described scale and the scale of an indicator of the prior art, it was found that as 700 readings were taken of values uniformly distributed over the entire extent of the scale, the relative reading error amounted to 0.54 percent for the scale of the indicator of the prior art and 0.06 percent for the above-described scale.

Claims (4)

1. A gas-discharge scale for a measuring instrument, comprising a front plate with a transparent anode hermetically sealed with a base plate accommodating at least one row of cathodes serving as the calibration marks of the scale, the cathodes being so arranged that their ends belong to at least four smoothly curved portions, the curvature radii of these portions being at least one order of magnitude smaller than the curvature radius of a line interconnecting the termination points of these portions, discharge transfer means being provided between adjacent portions in order to ignite the first cathode of a succeeding portion from the last cathode of the preceding portion.

2. A gas-discharge scale as claimed in claim 1, in which the discharge transfer means comprises a cathode shaped as a triangle, with its lateral sides adjoining adjacent calibration marks belonging to the adjacent portions.

3. A gas-discharge scale as claimed in claim 1 or 2, in which the ends of the cathodes belong to the portions of a curve which is a one-sided convex one.

4. A gas-discharge scale for a measuring instrument, substantially as described with reference to, and as shown in, Figures 1 and 2 or Figure 3 of the accompanying drawings.