GB2116717A - Indicator instruments - Google Patents

Abstract

A depth meter or other indicator instrument has a pointer (10) or a series of sequentially energisable light emitting elements that is rotatable around a circular scale (2) calibrated in metres, upon change in depth. At five metres intervals there are small display regions (11 to 20) that are energised to produce numbers '0' to '45' representative of the depths associated with respective points of the scale. The number in each display region (11 to 20) remains constant until the pointer (10) moves past the region (16) showing the number '25', when the opposite display region (11) changes the number displayed from '0' to '50'. As depth increases further, the instrument changes successive display regions (12, 13 and so on) opposite the pointer (10) to read '55', '60' and so on. At depths greater than 50 metres the point (10) is rotated through more than 360 DEG until it passes the region (16) representing 75 metres when the opposite region (11) changes from '50' to '00' (representing 100 metres). Further increase in depth rotates the pointer (10) but does not change the numbers displayed by the regions (11 to 20). <IMAGE>

Description

SPECIFICATION Indicator instruments This invention relates to indicator instruments.

The invention is more particularly concerned with indicator instruments in which the position of a pointer around a scale provides an indication of the value of an input variable.

Conventional pointer indicator instruments have the disadvantage that, if the instrument is to be used to indicate a wide range of values, the resolution to which the instrument can be read is correspondingly reduced. This can be a severe detriment in some circumstances. For example, in a submarine, it may be necessary to be able to read the value of depth to within a quarter of a metre over a range of zero to one hundred metres; to do this with a conventional pointer indicator instrument would require a very large scale.

Various alternative instruments have been proposed but these generally employ digital displays or two indicators, respectively for coarse and fine measurements, such as two pointer hands.

Whilst these alternative instruments can be satisfactory in some circumstances, they lack the advantages of conventional single pointer instruments, such as the ease and speed with which they can be read and the provision of an analogue presentation which enables trends to be readily recognised.

It is an object of the present invention to provide an indicator instrument that avoids to a substantial extent the above-mentioned disadvantages.

According to one aspect of the present invention there is provided an indicator instrument having a dial face and a pointer that is moveable around said face such that the position of said pointer around said face is indicative of the value of an input variable, wherein said instrument has a plurality of electrically-energisable digital display regions spaced around said face, wherein said instrument includes means for energising said regions such that some at least display a series of respective numbers defining a scale against which said pointer is to be read, and wherein the energisation means is arranged such that, for some at least of the values of the input variable, as its value increases and the pointer is correspondingly displaced to higher values along said scale, the region formerly displaying the lowest number in the series is changed to display the next number in the series above that of what was formerly the highest number displayed, and that, for some at least of the values of the input variable, as its value decreases and the pointer is correspondingly displaced to lower values along said scale, the region formerly displaying the highest number in the series is changed to display the next number in the series below that of what was formerly the lowest number displayed.

The instrument can thereby be arranged to display only a portion of the actual range, the diplayed range being altered as the value of the input variable changes. In this way, the displayed range is expanded and can be read with greater resolution than would otherwise be the case.

The digital display region that is changed on movement of said pointer may be substantially opposite said pointer. When the lowest value part of the scale is represented by said instrument, the said digital display regions may be arranged not to be changed by any displacement of said pointer in the lower value half of the scale represented by said instrument. Similarly, when the highest value part of the scale is represented by said instrument, the said digital regions are not changed by any displacement of said pointer in the higher value half of the scale represented by said instrument. The digital display region that is changed in value upon displacement of said pointer may be first arranged such that no number is represented in said region.

According to another aspect of the present invention there is provided a method of providing an indication of the value of an input variable on an indicator instrument having a pointer that is moveable around a dial face, and a plurality of electricallyenergisable digital display regions spaced around said face, said display regions being energised such that some at least of said regions display a series of respective numbers defining a scale against which said pointer is to be read, wherein for some at least of the values of the input variable, as its value increases the pointer is corresponding displaced to higher values along said scale, and the region formerly displaying the lowest number in the series is changed to display the next number in the series above that of what was formerly the highest number displayed, and for some at least of the values of the input variable, as its value decreases the pointer is correspondingly displaced to lower values along said scale, and the region formerly displaying the highest number in the series is changed to display the next number in the series below that of what was formerly the lowest number displayed.

A depth meter for a submarine, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 to 8 show the face of the instrument indicating different values; and Figure 9 illustrates schematically the construction of the instrument.

With reference to Figure 1, the dial face 1 of the depth meter instrument is of circular shape and is printed with a scale 2 around its edge. The scale 2 has fifty equally-spaced indicia 3, every fifth indicia being longer than the others. A pointer 10 in the form of a radially-extending hand can be rotated about the centre of the face 1 around the scale 2.

Displacement of the pointer 10 between any two adjacent indicia 3 is representative of a change of depth of one metre. The spacing between the indicia is sufficient to enable the depth to be read to a resolution of about a quarter of a metre. It will be appreciated that in a conventional instrument with a similarly-marked face this would only give the instrument a range of fifty metres.

In the present invention an individual display region 11 to 20 is provided alongside and radiallyinwards of each fifth indicia 3, making ten display regions in all. Each region 11 to 20 is capable of providing a display of any two-digit number according to the manner in which it is energised. The display regions 11 to 20 may be provided by light-emitting diodes or other light-emitting, -reflecting, or -absorbing elements and they may each be arranged in a known, seven-segment configuration or as a matrix array.

The display regions 11 to 20 are energised so that they display a series of numbers that increase by steps of five and that are each a multiple of five. For the value represented in Figure 1, in which the pointer 10 indicates the value "3" metres, the region 11 shows "0", the adjacent clockwise region 12 shows "5" and so on around the scale until the region 20, adjacent the region 11 on its other side, shows the value "45".

Any change in depth between 0 metres and 25 metres, that is, around the first half of the scale (as shown in Figures 1 and 2) will cause rotation of the pointer 10 but no change in the numbers represented in the region 11 to 20. For this range of depths, therefore, the instrument resembles in operation and appearance a conventional pointer instrument.

When, however, the depth increases beyond 25 metres, such as to 28 metres (shown in Figure 3) and the pointer 10 moves into the second half of the scale, passing the lower-most region 16, the number represented in that region 11 directly opposite the pointer is increased to "50". The upper-most region 11 which formerly represented the lowest number in the series ("0") now therefore displays the next, highest number in the series above that of the adjacent, anti-clockwise region 20, which formerly represented the highest number in the series. The range covered by the instrument is now, effectively 5 metres to 55 metres.

A further change in the value of the input variable between 25 metres and 30 metres does not result in any change in the numbers represented by the regions 11 to 20. As soon as the value rises above a multiple of five, however, the region opposite the pointer 10 changes to display the next, highest number in the series. Figure 4 shows the value 37 metres and it can be seen that the regions 12 and 13 have changed to read "55" and "60" respectively.

Thus, as the value of the input variable increases, the displayed range is correspondingly shifted up the actual range by changing the numbers represented by the regions 11 to 20, one at a time.

This continues until the input rises above a value indicative of 70 metres, such as to 71 metres shown in Figure 5. Between the values 70 and 75 metres the regions 11 to 20 represent the numbers "50" to "95" respectively. When, however, the value indicated exceeds 75 metres (Figure 6) the upper-most region 11 changes from the number "50" to "00" (to represent the value 100). Any further increase in value above 75 metres causes the pointer 10 to move around the scale in the usual way but with the regions 11 to 20 remaining with the values "0" to "95". This is illustrated in Figure 7 which shows the instrument indicating a depth of 93 metres.

When the value of the input variable falls, the instrument behaves in the opposite sense. Thus, a fall in value would produce a corresponding deflection of the pointer 10 but providing this remains above 75 metres it does not produce any change in the numbers represented by the regions 11 to 20. As soon, however, as the value falls below 75 metres the number represented by the upper-most region 11 will change from "0" to "50" that is, to the next lowest number in the series below that of the adjacent, clockwise region 12 which was formerly representing the lowest number in the series. Similarly, each time the value falls below a multiple of five, the region opposite the pointer will change the number displayed from being the highest number in the displayed series to being the next lowest number.In this way, as the value falls the displayed range is shifted gradually down the actual range.

This continues until the indicated value falls below 25 metres (as shown in Figure 8) when the regions 11 to 20 will again be representing the numbers of the series "0" to "45" respectively. A further fall in the value of depth will not produce any change in the numbers represented by the regions 11 to 20, the displayed range being fixed for these low values.

It can be seen therefore that the instrument enables a range of depths between 0 metres and 100 metres to be measured and that, because the instrument scale represents only a part of the actual range at any time, the displayed range can be significantly expanded. In practice this enables the depth to be read to a resolution of about a quarter of a metre.

The construction of the instrument is shown in Figure 9. The instrument includes a processing unit 50 which receives input signals on line 51 from an external depth sensor 52. The processing unit 50 supplies a suitable analogue signal on line 53 to a servo motor 54. The motor drive shaft is coupled to a spindle 55 that extends through an aperture in the centre of the instrument dial face 1, the motor 54 being arranged to rotate the pointer 10 about the face, through at least two revolutions, in accordance with the value of the depth signal.

The processing unit 50 also has a digital output which is supplied on line 56 to the input of a scale switching unit 57. The scale switching unit 57 is programmed to set the numbers to be represented by each of the display regions 11 to 20. In this respect, the unit 57 compares the input on line 56 with a set of stored values and produces output signals on ten output lines 60 to 69 which are supplied to respective display driving units 70 to 79 of conventional construction. These in turn control energisation of the respective display regions 11 to 20 so that they provide a display representation of the number set by the scale switching unit 57. Thus, for example, if the input to the unit 57, on line 56, is below that representative of 25 metres, the switching unit supplies output signals on lines 60 to 69 indicative of the values "0", "5", "10", "15", "20", "25", "30", "35", "40" and "45" respectively. If the depth changes to 37 metres (as shown in Figure 4) the switching unit 57 determines that this value is between 35 metres and 40 metres and accordingly produces outputs on lines 60 to 69 indicative of the values "50", "55", "60", "15", "20", "25", "30", "35", "40" and "45" respectively.

It will be appreciated that, if the display regions were each capable of representing three of more digits, the actual range of the instrument could be correspondingly expanded. The instrument could also be modified for indicating the values of various alternative variables. Instead of having energisable display regions for every five units, they could be provided at other intervals, for example, every ten units. Various other possible modifications of the instrument will be readily apparent.

It is not essential for every display region of the instrument to display a number. In some cases it may be advantageous to blank out a region prior to any change of the number which it is displaying. So, in Figure 4, for example, the regions 13 and 14 could be blanked out so that neither displays a number until the input variable changes in value, at which time different regions are blanked out. In this way the instrument can avoid the distracting uncertainty which would be caused as a display region changes alternately between the highest and lowest numbers when the input variable is oscillating - instead, the display regions adjacent the blanked out region are merely turned on or off, without change in the value of the displayed number, until the input variable changes by a greater amount.

The pointer (10) need not be a rotatable hand but could instead be some other form of marker, such as could be formed by energising selected ones of a series of light-emitting elements arranged around the scale (2).

Claims (12)

1. An indicator instrument having a dial face and a pointer that is moveable around said face such that the position of said pointer around said face is indicative of the value of an input variable, wherein said instrument has a plurality of electricallyenergisable digital display regions spaced around said face, wherein said instrument includes means for energising said regions such that some at least display a series of respective numbers defining a scale againstwhich said pointer is to be read, and wherein the energisation means is arranged such that, for some at least of the values of the input variable, as its value increases and the pointer is correspondingly displaced to higher values along said scale, the region formerly displaying the lowest number in the series is changed to display the next number in the series above that of what was formerly the highest number displayed, and that, for some at least of the values of the input variable, as its value decreases and the pointer is correspondingly displaced to lower values along said scale, the region formerly displaying the highest number in the series is changed to display the next number in the series below that of what was formerly the lowest number displayed.

2. An indicator instrument according to Claim 1, wherein the said digital display region that is changed on movement of said pointer is substantially opposite said pointer.

3. An indicator instrument according to Claim 1 or 2, wherein, when the lowest value part of the scale is represented by said instrument, the said digital display regions are not changed by any displace mentofsaid pointer in the lower value half of the scale represented by said instrument.

4. An indicator instrument according to any one of the preceding claims, wherein, when the highest value part of the scale is represented by said instrument, the said digital display regions are not changed by any displacement of said pointer in the higher value half of the scale represented by said instrument.

5. An indicator instrument according to any one of the preceding claims, wherein the said digital display region that is changed in value upon displacement of said pointer is first arranged such that no number is represented in said region.

6. An indicator instrument according to Claim 5, wherein said instrument is arranged such that no number is represented in the region or regions substantially opposite said pointer.

7. An indicator instrument according to any one of the preceding claims, wherein the full scale of said instrument is twice the scale which can be represented by said instrument at any one time.

8. An indicator instrument according to any one of the preceding claims, wherein said digital display regions are capable of representing a plural digit number.

9. An indicator instrument according to any one of the preceding claims for providing an indication of depth, wherein said input variable is representative of depth, and wherein said pointer is displaced in accordance with change of depth.

10. A method of providing an indication of the value of an input variable on an indicator instrument having a pointer that is moveable around a dial face, and a plurality of electrically-energisable digital display regions spaced around said face, wherein said display regions are energised such that some at least of said regions display a series of respective numbers defining a scale against which said pointer is to be read, wherein for some at least of the values of the input variable, as its value.increases the pointer is corresponding displaced to higher values along said scale, and the region formerly displaying the lowest number in the series is changed to display the next number in the series above that of what was formerly the highest number displayed, and for some at least of the values of the input variable, as its value decreases the pointer is correspondingly displaced to lower values along said scale, and the region formerly displaying the highest number in the series is changed to display the next number in the series below that of what was formerly the lowest number displayed.

11. An indicator instrument substantially as herein before described with reference to the accompanying drawings.

12. A method substantially as hereinbefore described with reference to the accompanying drawings.