EP1894303A1

EP1894303A1 - Rotary encoding switch

Info

Publication number: EP1894303A1
Application number: EP05761991A
Authority: EP
Inventors: Siegfried Neumann; Uwe Weiss
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2005-06-20
Filing date: 2005-06-20
Publication date: 2008-03-05
Also published as: US20090135028A1; DE112005003677A5; US7612689B2; CN101208862A; CA2612556A1; WO2006136120A1

Abstract

The invention relates to a rotary encoding switch such as used in the function setting for relays or similar. According to the invention, a particularly secure function setting for relays or similar may be achieved by means of a rotary encoding switch with a number of switch stages with separations between the switch stages which are not constant.

Description

description

rotary coding

The invention relates to a rotary encoder, as used for example for the function setting in relays or the like.

For setting various parameters, such. As current, voltage or time, the use of Widerstandspotentiometern is known. In resistance potentiometers, an analog resistance change is tapped, which can be used directly in analog circuits, for example, to change the gain. In digital circuits, the analog resistance change, for example, read using an analog-to-digital converter and then processed. Although a resistance potentiometer theoretically has an infinitely fine-level setting. In fact, however, due to linearity, mechanical tolerances, reading inaccuracies, etc., it is only possible to set a value with a limited accuracy. As a rule, resistance potentiometers therefore require a complex and expensive adjustment of the adjustment.

An object of the present invention is to enable a particularly secure function adjustment in relays or the like.

This object is achieved by a rotary coding switch according to claim 1 or according to claim 9.

According to the invention, a rotary encoding switch with a number of switching stages is proposed, wherein the distances between the switching stages are not constant.

A basic idea of the ^'invention is using non-constant distances between the setting of the rotary coding the percentage error in the setting of a certain setting value to reduce and thus increase the relative adjustment accuracy. A complex and expensive adjustment is not required. In other words, with such a rotary encoding switch, it is possible for the first time to replace a resistance potentiometer with another technical solution in which a comparable setting accuracy is achieved without a complex adjustment.

Advantageous embodiments of the invention will become apparent from the dependent claims.

It is particularly advantageous if the intervals between the switching stages change continuously, in particular always become smaller. In other words, the distance from one switching stage to the next switching stage is reduced. This makes it possible to achieve a constant percentage error over the entire adjustable scale of the rotary encoder. It is particularly advantageous if the distances between the individual switching stages are reduced logarithmically. In other words, this results in a logarithmic division of the switching stages via the coding of the Drehkodierschalters. It is particularly advantageous if the distances decrease, starting with the switching stages which are assigned to low setting values, to the switching stages which are assigned to high setting values.

With such an embodiment of the switching stages, however, the distances between the switching stages become so small (in particular at higher setting values) that a binary code with "brake before make" can no longer be realized must open closed switch contacts before closing the switch contacts may close. However, for safety reasons, a "brake before make" is necessary to avoid impermissible intermediate positions which can lead to dangerous settings to get stuck unconsciously. This can lead to malfunction. A remedy is provided according to a particularly preferred embodiment of the invention in that a Gray code is used as coding. This results in a change of 1 bit when turning from a position n to a next position n + 1 or n-1, so that no dangerous intermediate positions can occur.

In addition, it is particularly advantageous if a high resolution of the coding is achieved by a high number of switching stages. Particularly advantageous in this context, a rotary encoder with sixty-four switching stages has been found.

If the coding disc is formed as a hub, as provided in a further preferred embodiment of the invention, a nearly continuous adjustment is possible, as is usual with resistance potentiometers. In addition, if fixed mechanical detent positions are dispensed with, a continuous "spin" of the rotary coding switch is made possible, giving the user a feeling that the resistance potentiometer is the same is used to a resist potentiometer.

In a further embodiment of the invention, a rotary encoding switch is proposed, which has a high resolution, for example with sixty-four switching stages, as well as a Gray code as coding and a rotary disc designed as coding disc. With these features, the advantages already described above are achieved. Preferably, this Drehkodierschalter is provided without mechanical detent positions, ie the user can set the desired value "steplessly." Such a rotary encoder combines in itself the most important features to realize a particularly user-friendly operation, but without a special design of the switching stages, such as - example, changing distances between the switching stages to be set.

The invention will be described below with reference to an exemplary embodiment, which will be explained with the aid of the figures. Hereby show:

1 shows a representation of the setting marks as well as the percentage error in a known from the prior art kinking rotary encoder,

2 shows an illustration of the setting marks and the percentage error in a rotary coding switch according to the invention,

3 shows a schematic representation of a coding disc with Gray code,

4 shows a table showing the Gray code for sixty-four levels.

N-stage rotary encoding switches are known from the prior art, for example with n = 16, which are characterized in that the individual switching stages have a constant distance from each other. In the example of the figure shown in Figure 1 is based on such a conventional rotary encoder, wherein already 64 switching stages are used to provide better comparability with the inventive solution. Rotary coding switches with 64 switching stages are not yet known.

For a 64-step rotary encoder with circular scoring disc, the constant distance is between each

Switching stage about 5.63 °. If such a rotary coding switch is used as a current setting element in an overload relay, a scale with current marks and an adjustment arrow is required. The application of the scale and the adjustment arrow on the Drehkodierschalter is always associated with manufacturing tolerances. These are according to experience in the range up to +/- In the example case (see FIG. 1), an overload relay has a setting range of 25A to 100A. The bias current would then increase from (1) step to step (100A-25A) / (64-1) = 1.19A. If the user wants to set the overload relay to 25A, it is conceivable that the 25A mark will not be set but that the user will adjust to the (25A-1, 19A) mark. In other words, a setting error of 1.19A at a set value of 25A (lower setting mark) corresponds to a percentage error of 1.19A / 25A * 100% = 4.8%. However, at the upper setting mark (100A), the error is only 1, 19A / 100A * 100% = 1.19%. The constant distance between the switching stages thus has the disadvantage that, due to the setting accuracy of +/- 4 ° at the lower setting mark (25A), a large percentage error occurs, while at the upper setting mark (100A) the percentage error is very small.

The invention therefore proposes a rotary coding switch which has a constant percentage error over the entire scale. This is achieved in that the distances of the switching stages at the lower setting mark (25A) are greater than the intervals of the switching stages at the upper setting mark (100A), where one can allow a larger Einstellwinkelfehler. In particular, the distances between the individual switching stages from the lower switching stage to the upper switching stage logarithmically smaller. As shown in FIG. 2, the percentage error at the lower index mark (25A) is 0% for such a rotary encoder and 2.4% at the upper index. The largest error percentage is when the distance between one switching stage and the next switching stage is greater than 8 ° for the first time. In the example chosen, this would be the case at 42, 9A. Here, the percentage error (42, 9A / 41, 7A-1) is * 100% = 2, 9%.

Due to the logarithmic decreasing distance between the switching stages can be compared to a rotary coding with a constant distance between the switching stages of the maximum percentage errors are reduced according to the invention from 4.8% to 2.9%.

As encoder a turntable is used, which has a tap. In contrast to conventional resistance potentiometers, however, it is not resistance values but digital signals that are tapped. The coding of the coding disc is effected by the use of conductive and non-conductive surfaces (shown in FIG. 3 as black and white bars), which are scanned with a corresponding number of sensors. In this case, a conductive area stands for the digital value "1 ^λ" and a non-conductive area for the digital value "0".

For the coding of the coding disc, a Gray code is used, cf. FIG. 3. The Gray code is a coding method for the robust transmission of digital quantities. Its essential feature is that the Graycodes for two adjacent segments only differ by 1 bit. This reduces the maximum possible setting error. The Gray code is suitable in particular for a circular arrangement as on the coding disk shown in FIG. 3, since only one point changes during the transition from the highest number to 0. A table representing the Gray code for 64 switching stages is shown in FIG. 4.

As illustrated in FIG. 3, the distance between the individual switching stages, for example, changes on the encoder disk. logarithmic. In other words, the conductive and non-conductive areas at the lower switching stages (for example, at the switching stages 0, 1, 2, etc.) are wider than the areas at the upper switching stages 61, 62, 63. This means at the same time that the distances change between the switching stages. Starting from the low switching stages to the higher switching stages, the distances between the individual switching stages are reduced.

In general, a coding disk with n segments applies here: HI

360 ° =] T a _o av = 0

where CC _{0 is} the angle of the segment "0" and a is the basis for the angle ^calculation For the angle of the segment "v ^{λλ the} following applies:

a _v = CC ₀ Ci

for n = [0 .... (n-1)]. In addition, for segment "v ^v

For the example shown in FIG. 3, n = 64, αo = 2 °, a = 1, 0289.

The use of a rotary coding switch without latching hooks or other mechanical locking elements makes it possible to operate the rotary coding switch, which corresponds to that of a resistance potentiometer. Due to the logarithmic division of the switching stages, the setting error is simultaneously kept so low that a high setting accuracy is made possible. However, since only digital signals are tapped, an adjustment, as it is required in a resistance Potentiometer, is not necessary.

In other words, it is achieved by the invention that a Drehkodierschalter can take over the function of a Widerstandspotentiometers, while maintaining the positive characteristics of the Widerstandspotentiometers (continuous rotation, relative adjustment accuracy), but without having to perform an expensive and complex adjustment.

Alternatively, it is of course possible to provide the rotary encoder switch with detent positions. This is particularly useful if the rotary encoder switch is shock- In this case, the detents serve to prevent unintentional misalignment.

Claims

claims

1. rotary encoder with a number of switching stages, characterized in that the distances between the switching stages are not constant.

2. Rotary encoding switch according to claim 1, characterized in that the distances between the switching stages change continuously.

3. Drehcodierschalter according to claim 2, characterized in that change the intervals between the switching stages logarithmically or logarithmically similar.

4. Drehcodierschalter according to claim 2 or 3, characterized in that reduce the intervals between the switching stages, starting from the switching stages, which are assigned low setting values, to the switching stages, which are assigned high setting values.

5. Drehkoder switch according to one of claims 1 to 4, characterized by a Gray code as coding.

6. Rotary encoder switch according to one of claims 1 to 5, characterized by sixty-four switching stages.

7. Drehkoder switch according to one of claims 1 to 6, characterized by a trained as a turntable encoder.

8. Drehkoder switch according to one of claims 1 to 7, characterized by the absence of mechanical RastStellungen.

9. rotary coding switch - with a high resolution, for example with sixty-four switching steps,

- with a Gray code as coding and

- With a trained as a turntable encoder.

10. Drehkodierschalter according to claim 9, without mechanical RastStellungen.