CA2314176A1 - Method and device for obtaining positional information - Google Patents
Method and device for obtaining positional information Download PDFInfo
- Publication number
- CA2314176A1 CA2314176A1 CA002314176A CA2314176A CA2314176A1 CA 2314176 A1 CA2314176 A1 CA 2314176A1 CA 002314176 A CA002314176 A CA 002314176A CA 2314176 A CA2314176 A CA 2314176A CA 2314176 A1 CA2314176 A1 CA 2314176A1
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- Prior art keywords
- signal
- parts
- positional information
- square
- members
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Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
- G01D5/241—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by relative movement of capacitor electrodes
- G01D5/2412—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by relative movement of capacitor electrodes by varying overlap
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Power Engineering (AREA)
- Human Computer Interaction (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
A method of obtaining positional information utilising a device (10) comprising a first member (11) having at least two electrically isolated conducting parts (13-16), and a second electrically conducting member (12) adjacent to and capacitively coupled to the first member (11), the first and second members (11, 12) being relatively movable such that the proportions of the respective parts (13-16) of the first member (11) in overlapping relationship with the second member (12) may be varied, the method comprising the steps of providing a first square waveform signal (26) to one of the parts (13-16) of the first member (11) and a second square waveform signal (27) to the other of the parts (13-16) of the first member (11), analysing a signal arising in the capacitively coupled second member (12) to obtain a device output signal (50) containing information about the relative positions of the first and second members (11, 12).
Description
METHOD AND DEVICE FOR OBTAINING POSITIONAL INFORMATION
Description of Invention This invention relates to a method of and device for obtaining positional information, particularly but not exclusively for providing positional information for a computer, controller, game playing console or the like.
It is known for example from GB-A-872152 to apply sinusoidal voltages of constant magnitude but of differing phasing to two electrically isolated members and to determine positional infor-rnation from an output signal from a relatively movable member ,which output signal varies in phase depending upon the extent of the relative movement.
I have proposed in my previous patent application GB232I 108a device which operates on this principle but is able to provide positional information in two dimensions.
In order to obtain two constant substantially similar sinusoidal signals of different phase, it has been necessary to generate such signals digitally and to filter each of~ the digital signals with respective filters in order to obtain sinusoidal waves. The provision of two filters adds a penalty to the cost of generating the waves and thus to the overall cost of the device.
According to one aspect of the invention l provide a method of obtaining positional information utilising a device comprisinb a first member having at least two electrically isolated conducting parts, and a second elech~ically conducting member adjacent to and capacitively coupled to the first member, the first and second members being relatively movable such that the proportions of the respective parts of the first member in overlapping relationship with the second member may be varied, the method comprising the steps of providing a first sduare wavefor-rn si~:nal to one of the parrts of the first member and a second stluare wavefoim signal to the other of the parts of the first member, analysing a signal arising in the capacitively coupled second member to obtain a device output signal containing information about the relative positions of the first and second members.
Thus utilising the present invention it is unnecessary to provide a filter to filter each of the digitally generated (square) waveforms before applying these to the pans of the first member.
Preferably the first and second square wavefonn signals are of the same frequency but are 90° out of phase with each other and thus may be obtained from a single oscillator.
In one arrangement, the method may comprise filtering the signal arising in the second member so that the signal which is analysed comprises a filtered output signal from the second member which thus may comprise a sine wave.
Thus the phase of the signal arising in the second member may be compared with the phase of one (or both) of the first and second square waves. However this would still require the provision of a filter, albeit a single filter, to filter the output signal from the second member.
It will be appreciated that the signal arising in the second member will comprise a complex wavefonj~, which, assuming the first and second square wavefonn signals are of the same frequency but out of phase with one another, will be of the same frequency as the first and second square wavefonns but having steps either side of a dominant step level. The method may comprise analysing the relative step heights which will vary as the first and second members are relatively moved, to obtain the positional information.
Although simple step height deteunination can be used to determine changes in the relative positions of the first and second membec-s if greater accuracy is required, for example for actually measuring changes in relative position, if desired the method may comprise analysing the difference between at least one of the steps in the complex waveform either side of the dominant step level and the dominant base or peak step level to obtain the positional information.
Thus the method will be substantially self correcting in the event of component drift for example.
In each case no filtering would be required to obtain the positional information. According to a second aspect of the invention I provide a device for obtaining positional information by a method according to the first aspect of the invention the device comprising a first member having at least two electrically isolated conducting parrts, and a second electrically conducting member adjacent to and capacitively coupled to the first member, die f rst and second members being relatively movable such that the proporrtions of the respective parts of the first member in overlapping relationship with the second member may be varied, means to provide a first square waveform signal to one of the parrts of the first member and a second square waveform signal to the second part of the first member, means to analyse a signal arising in the capacitively coupled second member to obtain a device output signal containing information about the relative positions of the first and second members.
The first member of the device may comprise nvo electrically isolated parts relative to which the second member moves whereby the device is able to obtain positional information about relative movement in a single linear direction, or the first member may comprise more than two electrically isolated parts relative to which the second member may move, square waveform signals being applied to each of the plurality of harts whereby the device is able to obtain positional information about relative movement bem~een the first and second member in two dimensions.
The invention will now be described with reference to the accompanying drawings in which:
FIGURE 1 is an illustrative plan view of part of a device in accordance with the invention;
Description of Invention This invention relates to a method of and device for obtaining positional information, particularly but not exclusively for providing positional information for a computer, controller, game playing console or the like.
It is known for example from GB-A-872152 to apply sinusoidal voltages of constant magnitude but of differing phasing to two electrically isolated members and to determine positional infor-rnation from an output signal from a relatively movable member ,which output signal varies in phase depending upon the extent of the relative movement.
I have proposed in my previous patent application GB232I 108a device which operates on this principle but is able to provide positional information in two dimensions.
In order to obtain two constant substantially similar sinusoidal signals of different phase, it has been necessary to generate such signals digitally and to filter each of~ the digital signals with respective filters in order to obtain sinusoidal waves. The provision of two filters adds a penalty to the cost of generating the waves and thus to the overall cost of the device.
According to one aspect of the invention l provide a method of obtaining positional information utilising a device comprisinb a first member having at least two electrically isolated conducting parts, and a second elech~ically conducting member adjacent to and capacitively coupled to the first member, the first and second members being relatively movable such that the proportions of the respective parts of the first member in overlapping relationship with the second member may be varied, the method comprising the steps of providing a first sduare wavefor-rn si~:nal to one of the parrts of the first member and a second stluare wavefoim signal to the other of the parts of the first member, analysing a signal arising in the capacitively coupled second member to obtain a device output signal containing information about the relative positions of the first and second members.
Thus utilising the present invention it is unnecessary to provide a filter to filter each of the digitally generated (square) waveforms before applying these to the pans of the first member.
Preferably the first and second square wavefonn signals are of the same frequency but are 90° out of phase with each other and thus may be obtained from a single oscillator.
In one arrangement, the method may comprise filtering the signal arising in the second member so that the signal which is analysed comprises a filtered output signal from the second member which thus may comprise a sine wave.
Thus the phase of the signal arising in the second member may be compared with the phase of one (or both) of the first and second square waves. However this would still require the provision of a filter, albeit a single filter, to filter the output signal from the second member.
It will be appreciated that the signal arising in the second member will comprise a complex wavefonj~, which, assuming the first and second square wavefonn signals are of the same frequency but out of phase with one another, will be of the same frequency as the first and second square wavefonns but having steps either side of a dominant step level. The method may comprise analysing the relative step heights which will vary as the first and second members are relatively moved, to obtain the positional information.
Although simple step height deteunination can be used to determine changes in the relative positions of the first and second membec-s if greater accuracy is required, for example for actually measuring changes in relative position, if desired the method may comprise analysing the difference between at least one of the steps in the complex waveform either side of the dominant step level and the dominant base or peak step level to obtain the positional information.
Thus the method will be substantially self correcting in the event of component drift for example.
In each case no filtering would be required to obtain the positional information. According to a second aspect of the invention I provide a device for obtaining positional information by a method according to the first aspect of the invention the device comprising a first member having at least two electrically isolated conducting parrts, and a second electrically conducting member adjacent to and capacitively coupled to the first member, die f rst and second members being relatively movable such that the proporrtions of the respective parts of the first member in overlapping relationship with the second member may be varied, means to provide a first square waveform signal to one of the parrts of the first member and a second square waveform signal to the second part of the first member, means to analyse a signal arising in the capacitively coupled second member to obtain a device output signal containing information about the relative positions of the first and second members.
The first member of the device may comprise nvo electrically isolated parts relative to which the second member moves whereby the device is able to obtain positional information about relative movement in a single linear direction, or the first member may comprise more than two electrically isolated parts relative to which the second member may move, square waveform signals being applied to each of the plurality of harts whereby the device is able to obtain positional information about relative movement bem~een the first and second member in two dimensions.
The invention will now be described with reference to the accompanying drawings in which:
FIGURE 1 is an illustrative plan view of part of a device in accordance with the invention;
FIGURE 2 is~an illustrative end view of the paa of the device of figure 1;
FIGURE 3 is a diayam illush~ating a possible elech~onic circuit for the device of figures 1 and 2.
FIGURE 4 is an illusri~ation slowing first and second square waveform inputs for the device of figures 1 and 2 and a resultant output signal containing positional infoi~rnation.
Refewing to the drawings an input device IO for inputting positional information into a computer', controller, game playing console or the like comprises a first member l 1, and a relatively moveable second member 12. The first member I1 comprises in this example, four isolated elechically conducting generally flat parts 13, 14, 15 and 1G an~anged in a generally rectangular away such that the parts 13 to 16 are isolated fi-om one another by a generally cross shaped isolating element indicated at 17.
In this example, the second pact 12 is moveable over the fu-st part 1 I by means hereinafter explained. The total area of the first part i 1 is at least four times that of the area of the second member 12 in this example.
Conveniently the first member 11 is made fi-orn single sided printed circuit board material or is otherwise a mixed consrivction of conducting and insulating pans. The first pact 1 I may comprise a discrete member, or may comprise pau of or an extension to an existing painted circuit board.
Each of the pans 13 to 1 G of the first member 11 is provided with a connection 20 to 23 respectively.
The device 10 further comprises ~an oscillator signal source 25 which produces two substantially identical square wavefonn output signals 26,27 which are however 90" out of phase with one another.
One of the signals, namely the signal indicated at ?G, is connected via a conductor 30 to the terminal 20 of the first pan 1 ~ of the first member 11.
The sigmal 2G may, in dependence upon the condition of an elecn~onic switch 31, simultaneously be connected via a conductor 32 either to the second pair 14 of the first member 11, or the fourth part 1 G of the first member i 1 depending upon whether the device 10 is operating to provide positional information along an X
axis indicated at 33, or a Y axis indicated at 34. The second signal 27 is connected via a conductor 3G to terminal 22 of the tlrird pain IS of the first member i 1, and depending upon the condition of the elech~onic switch 31, may simultaneously be connected either to terminal 21 of the second part of 14 of the first member 11, or to terminal 23 of the fourrth pact 1 G of the first member I 1.
The device 10 further comprises a signal analyser means indicated at 40 which has a first input connected to conductor 30 carrying the first signal 26 from the oscillator signal source 25 to the first member 1 l, and a second input 42 connected, in this example via a flexible wire 43, to the second member 12.
The signal analyser means 40 provides an output signal ~0 indicative of the relative position of the second member 12 to the f rst member I 1.
Of course, the second member 12 may be connected by any other desired kind of conductor to the input 42, such as conductor incorporating one or more wiping contacts or the like.
The second member 12 may also comprise a printed circuit board and is positioned adjacent to the first member 1 1 with there bein~~ an air gap 46 between the first 11 and second 12 members.
The second member 12 may be constt~ained by any desired known means to move relative to the first rnernber I 1 sucli that distance d between the first I 1 and second 12 menabers remains substantially constant and the first member and second member 12 remain substantially parallel.
It will be appreciated therefore that as the second Illeillbei' 12 is moved over the first member that the proportions of the respective parts 13-1G of the first member 11 in overlapping relationship with the second member 12 will be varied.
G
The air in the'air gap 4G between the f rst 11 and second 12 members is a di-electric and as such, the first and second membem 11, 12 will be capacitively coupled.
Of course, if desired, instead of providing an air gap 46 between the first 11 and second 12 members, an insulating material may be provided. In one example, a polythene or other thin membrane may be placed on the first member 11, and the second member ( 12) may carry a conductive foam robber which is moved over the fimt member 11 as the second member 12 moves. In that way, the spacing D between the first and second members 1 l, I 2 would remain constant during movement of tle second member i 2. Other arrangements aue no doubt possible.
When the elech~onic switch 31 is in a condition such that the first signal 26 is connected to the two pants 13 and 1 G and the second signal 27 is connected to the second and third pans 14, I5, movement of the second member I2 relative to the Y axis 34 (i.e. along the X axis 33} will thus change the waveform of the signal arising in the second member 12 by virtue of its capacitive coupling to the first member 1 1. The foam of the signal arising will depend upon the relative extents of overlap of the second member 12 and the parts i3,1G and 14,1 S of the first member 11.
The signal from the second member 12 may according to the invention, be analysed in at least the following two alternative ways.
First, refen-ing to figure 4, it will be appreciated that the signal 52 arising in the second member 12 by virtue of its capacitive coupling to the first member 11 will comprise a complex waveform 5? comprising dominant base ~5 and peak SG step levels, with steps 57,58 between the dominant base and peak levels SS,SG. As the proportion of overlap of the second member I2 with the respective pans 13, I G and 14,15 of the first member 11 is changed, this will affect the levels of the steps 57,58 above and below the base and peak levels ~a,SG respectively . For example as the second member 12 is moved so that a greater proportion of the parts I 4 and 15 of the f rst member 11 are overlapped, the height of step 58 above the base level 55 may rise whilst the height of the step 57 above the base level 55 may fall.
Thus the steps 57,58 heights will be indicative of the position of the second member I2 relative to the first member 11 along the X axis 33 and so by analysing the signal output from the second member 12 to sense the step 57,58 heights information concerning the relative position of the second member 12 to the first member 1 I along the X axis may be determined.
When the electronic switch 31 is in a condition such that fast signal 26 from the oscillating signal source 35 is connected to parts I3 and 14 of the first member 11, and the second signal 27 is connected to third and fourth parrts 15 and 16 of the first member 11, then the output siln~al 50 from the analyser means will be indicative of the relative position of t1e second part I 2 relative to the X axis 34 i.e. along the Y axis 34.
In each case, the frequency of the signal 52 arising in the second member 12, which is analysed will be nominally the same as the frequency of the first and second square waveform signals 26,27.
In a practical ar-rangernent because the levels of both of the steps 57 and 58 in the signal 52 will vary as the second member 12 is rpoved relative to the first member I I, the level of only one of the steps 57,58 may be determined.
However it will be appreciated that in a practical ar~l~angement the resultant wavefonn signal 52 arising in the second member 12 may not remain constant due to, for example only, component drift, which may affect the accuracy of the square wavefonns 26,27 provided to the first member 11. Hence preferably the signal ~2 is analysed by compacin~; the level of step ~7 or 58 with the base 55 or peak 52 dominant step levels so that any variations in the sduare wavefonn signals 26,27 do not affect tile accuracy of the positional lIlfol'Itlatroll. It will be appreciated that there will be a ratiornetric relationship between the base 55 and' peal: 52 dominant step levels and the step levels of the steps 57,58 to either side in the complex waveform.
Analysing the signal 52 arisinb in the second member 12 in this way, it is envisaged that the method and device described may subject to calibration, be sufficiently accurate to be used for measurement.
When the device 10 is operating such that the device output signal 50 is indicative of the position of the second member 12 relative to the X axis 33, it will be appreciated that movement of the second member 12 relative to the Y
axis, i.e. along X axis 33 will not affect the signal 52 arising in the second member 12 by virtue of its capacitive coupling to the first member 11, and conversely, when the output signal 50 is indicative of the position of the second member 12 relative to the Y axis 34, movement of the second member 12 relative to the X axis 33 i.e. along the Y axis 34,wi11 not affect the signal ausing in the second member 12:
The output signal 50 from the analyser means 40 thus may, depending on the condition of the electronic switch 31, be indicative of the position of the second member along the X or Y axes 33,34.
A second way of analysing the waveform arising in the second member 12 is to filter har-rnonics from the complex waveform 5? in order to obtain a simple sinusoidal waveform. In fil;ure 4 the resultant filtered sinusoidal wavefonn is indicated in dotted lines at S. This waveforrn S will still be of the same frequency as the two square wavefonns 26,27 which are provided to the parts 13-IG of the first member 11 althoul;h the phase of the filtered signal will vary depending on the relative position of the second member 12 to the first member 11 i.e. the proportion of overlap of the second member 12 to the respective hvo parts 13,14 to 15, I G or 1 3,1 G to i 4, l5of the first member 11.
Thus the analyser means 40 may comprise a phase comparator to compare the phase of the filtered signal GO derived from the output signal arising the second member 12, with the phase of one or both of the square waveform signals 26,27 provided to the first member i 1.
The phase comparator 40 relay compare the relative phases of the signals at the two inputs 41 and 42 by any applicable means such as a (software) timing loop or (hardware) ASIC counter or the like.
In all cases the electronic switch 31 may be manually controlled but most conveniently, the electronic switch 31 is arranged to provide the respective first and second squam waveforn signals 26, 27 to the different parrts I3 - 16 of the first member 11 automatically and in sequence. A rnultiplexer or like arrangement may therefore be provided as the electronic switch 31 and it will be appreciated that the device output signal 50 may need appropriately to be switched to different inputs of a computer controller, game console or the like, which may thus utilise the device output signal 50 appropriately to determine X-Y axis positional information in real time.
It will appreciated that in many items of elech~orzic equipment or other apparatus which contain electronic control means, there will be an existing microcontr-oller or ASIC, and that the existing microcontroller or ASIC may be utilised both to obtain one or- more square waveforn si~mals such as signals 26 and 27 for use in the device 10, and that the rmicrocontroller or ASIC may also comprise the means necessary for step level determination and/or phase comparison.
It will be appreciated that the oscillator signal source 25 may provide appropriate signal waveform signals to a plurality of position sensing;
devices.
Thus for example in a graphic equalizer which may have a substantial number of individual channels, thirty say, only one oscillator signal source '?5 would be required. A dedicated anal~-ser means 40 rn~y be provided for each positional sensor, or usin,~ a multiplexing type ar-angernent, a single analyser means 40 may be used for each of the plurality of positional sensing devices.
Various modifications may be made without departing from the scope of the invention.
In particular, the present invention has been described in the embodiment above with reference to a device for obtaining positional information along mutually generally orthogonal X and Y axis 33 and ~4. The invention may be utilised to obtain omnidirectional information only, and that direction may be linear or otherwise. For example, a conventional slider type conh~ol having wiping contacts may be replaced by a device in accordance with the invention in which the first member has only two pairs which are isolated electrically conducting parts.
Alternatively, the device rnay provide positional ilfonnation relative to tlwee axes at 120° to one another in which case the fit~st member may comprise tlwee isolated electrically conducted pacts in a suitably an-ay.
It is envisaged that a device in accordance with figures 1 to 3 may' be constructed in which the first member 1 I has an area of about 25 x 20 mm. The oscillator signal source 25 may generate a sduare wave signial at a frequency of about 10 kHz. Stability of fi~eduency is not critical but should remain stable whilst positional movement of the second member 12 relative to the first member is performed. The oscillator sigmal source 25 may generate the square waveform signal or signials 26, 27 digitally or otherwise.
VVhereas it is preferred for the distance d between the moving member 12 and the fixed member I1 to remain gener~clly constant. slight variations in distance d during second member movement need not have a severe effect on the positional movement determined provided that the air gap 4G is sufficiently great.
In Figure 3 it can be seen that there is an input 41 to the analyser means 40 from the conductor 30. This is used to facilitate tuning in the analyser means 40 but is not essential. A timing pulse rnay be provided direct from oscillator means 25 if desired.
The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific f0r711S Or' in terms - WO 99/32853 PCTlGB98I03731 of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse foams thereof.
FIGURE 3 is a diayam illush~ating a possible elech~onic circuit for the device of figures 1 and 2.
FIGURE 4 is an illusri~ation slowing first and second square waveform inputs for the device of figures 1 and 2 and a resultant output signal containing positional infoi~rnation.
Refewing to the drawings an input device IO for inputting positional information into a computer', controller, game playing console or the like comprises a first member l 1, and a relatively moveable second member 12. The first member I1 comprises in this example, four isolated elechically conducting generally flat parts 13, 14, 15 and 1G an~anged in a generally rectangular away such that the parts 13 to 16 are isolated fi-om one another by a generally cross shaped isolating element indicated at 17.
In this example, the second pact 12 is moveable over the fu-st part 1 I by means hereinafter explained. The total area of the first part i 1 is at least four times that of the area of the second member 12 in this example.
Conveniently the first member 11 is made fi-orn single sided printed circuit board material or is otherwise a mixed consrivction of conducting and insulating pans. The first pact 1 I may comprise a discrete member, or may comprise pau of or an extension to an existing painted circuit board.
Each of the pans 13 to 1 G of the first member 11 is provided with a connection 20 to 23 respectively.
The device 10 further comprises ~an oscillator signal source 25 which produces two substantially identical square wavefonn output signals 26,27 which are however 90" out of phase with one another.
One of the signals, namely the signal indicated at ?G, is connected via a conductor 30 to the terminal 20 of the first pan 1 ~ of the first member 11.
The sigmal 2G may, in dependence upon the condition of an elecn~onic switch 31, simultaneously be connected via a conductor 32 either to the second pair 14 of the first member 11, or the fourth part 1 G of the first member i 1 depending upon whether the device 10 is operating to provide positional information along an X
axis indicated at 33, or a Y axis indicated at 34. The second signal 27 is connected via a conductor 3G to terminal 22 of the tlrird pain IS of the first member i 1, and depending upon the condition of the elech~onic switch 31, may simultaneously be connected either to terminal 21 of the second part of 14 of the first member 11, or to terminal 23 of the fourrth pact 1 G of the first member I 1.
The device 10 further comprises a signal analyser means indicated at 40 which has a first input connected to conductor 30 carrying the first signal 26 from the oscillator signal source 25 to the first member 1 l, and a second input 42 connected, in this example via a flexible wire 43, to the second member 12.
The signal analyser means 40 provides an output signal ~0 indicative of the relative position of the second member 12 to the f rst member I 1.
Of course, the second member 12 may be connected by any other desired kind of conductor to the input 42, such as conductor incorporating one or more wiping contacts or the like.
The second member 12 may also comprise a printed circuit board and is positioned adjacent to the first member 1 1 with there bein~~ an air gap 46 between the first 11 and second 12 members.
The second member 12 may be constt~ained by any desired known means to move relative to the first rnernber I 1 sucli that distance d between the first I 1 and second 12 menabers remains substantially constant and the first member and second member 12 remain substantially parallel.
It will be appreciated therefore that as the second Illeillbei' 12 is moved over the first member that the proportions of the respective parts 13-1G of the first member 11 in overlapping relationship with the second member 12 will be varied.
G
The air in the'air gap 4G between the f rst 11 and second 12 members is a di-electric and as such, the first and second membem 11, 12 will be capacitively coupled.
Of course, if desired, instead of providing an air gap 46 between the first 11 and second 12 members, an insulating material may be provided. In one example, a polythene or other thin membrane may be placed on the first member 11, and the second member ( 12) may carry a conductive foam robber which is moved over the fimt member 11 as the second member 12 moves. In that way, the spacing D between the first and second members 1 l, I 2 would remain constant during movement of tle second member i 2. Other arrangements aue no doubt possible.
When the elech~onic switch 31 is in a condition such that the first signal 26 is connected to the two pants 13 and 1 G and the second signal 27 is connected to the second and third pans 14, I5, movement of the second member I2 relative to the Y axis 34 (i.e. along the X axis 33} will thus change the waveform of the signal arising in the second member 12 by virtue of its capacitive coupling to the first member 1 1. The foam of the signal arising will depend upon the relative extents of overlap of the second member 12 and the parts i3,1G and 14,1 S of the first member 11.
The signal from the second member 12 may according to the invention, be analysed in at least the following two alternative ways.
First, refen-ing to figure 4, it will be appreciated that the signal 52 arising in the second member 12 by virtue of its capacitive coupling to the first member 11 will comprise a complex waveform 5? comprising dominant base ~5 and peak SG step levels, with steps 57,58 between the dominant base and peak levels SS,SG. As the proportion of overlap of the second member I2 with the respective pans 13, I G and 14,15 of the first member 11 is changed, this will affect the levels of the steps 57,58 above and below the base and peak levels ~a,SG respectively . For example as the second member 12 is moved so that a greater proportion of the parts I 4 and 15 of the f rst member 11 are overlapped, the height of step 58 above the base level 55 may rise whilst the height of the step 57 above the base level 55 may fall.
Thus the steps 57,58 heights will be indicative of the position of the second member I2 relative to the first member 11 along the X axis 33 and so by analysing the signal output from the second member 12 to sense the step 57,58 heights information concerning the relative position of the second member 12 to the first member 1 I along the X axis may be determined.
When the electronic switch 31 is in a condition such that fast signal 26 from the oscillating signal source 35 is connected to parts I3 and 14 of the first member 11, and the second signal 27 is connected to third and fourth parrts 15 and 16 of the first member 11, then the output siln~al 50 from the analyser means will be indicative of the relative position of t1e second part I 2 relative to the X axis 34 i.e. along the Y axis 34.
In each case, the frequency of the signal 52 arising in the second member 12, which is analysed will be nominally the same as the frequency of the first and second square waveform signals 26,27.
In a practical ar-rangernent because the levels of both of the steps 57 and 58 in the signal 52 will vary as the second member 12 is rpoved relative to the first member I I, the level of only one of the steps 57,58 may be determined.
However it will be appreciated that in a practical ar~l~angement the resultant wavefonn signal 52 arising in the second member 12 may not remain constant due to, for example only, component drift, which may affect the accuracy of the square wavefonns 26,27 provided to the first member 11. Hence preferably the signal ~2 is analysed by compacin~; the level of step ~7 or 58 with the base 55 or peak 52 dominant step levels so that any variations in the sduare wavefonn signals 26,27 do not affect tile accuracy of the positional lIlfol'Itlatroll. It will be appreciated that there will be a ratiornetric relationship between the base 55 and' peal: 52 dominant step levels and the step levels of the steps 57,58 to either side in the complex waveform.
Analysing the signal 52 arisinb in the second member 12 in this way, it is envisaged that the method and device described may subject to calibration, be sufficiently accurate to be used for measurement.
When the device 10 is operating such that the device output signal 50 is indicative of the position of the second member 12 relative to the X axis 33, it will be appreciated that movement of the second member 12 relative to the Y
axis, i.e. along X axis 33 will not affect the signal 52 arising in the second member 12 by virtue of its capacitive coupling to the first member 11, and conversely, when the output signal 50 is indicative of the position of the second member 12 relative to the Y axis 34, movement of the second member 12 relative to the X axis 33 i.e. along the Y axis 34,wi11 not affect the signal ausing in the second member 12:
The output signal 50 from the analyser means 40 thus may, depending on the condition of the electronic switch 31, be indicative of the position of the second member along the X or Y axes 33,34.
A second way of analysing the waveform arising in the second member 12 is to filter har-rnonics from the complex waveform 5? in order to obtain a simple sinusoidal waveform. In fil;ure 4 the resultant filtered sinusoidal wavefonn is indicated in dotted lines at S. This waveforrn S will still be of the same frequency as the two square wavefonns 26,27 which are provided to the parts 13-IG of the first member 11 althoul;h the phase of the filtered signal will vary depending on the relative position of the second member 12 to the first member 11 i.e. the proportion of overlap of the second member 12 to the respective hvo parts 13,14 to 15, I G or 1 3,1 G to i 4, l5of the first member 11.
Thus the analyser means 40 may comprise a phase comparator to compare the phase of the filtered signal GO derived from the output signal arising the second member 12, with the phase of one or both of the square waveform signals 26,27 provided to the first member i 1.
The phase comparator 40 relay compare the relative phases of the signals at the two inputs 41 and 42 by any applicable means such as a (software) timing loop or (hardware) ASIC counter or the like.
In all cases the electronic switch 31 may be manually controlled but most conveniently, the electronic switch 31 is arranged to provide the respective first and second squam waveforn signals 26, 27 to the different parrts I3 - 16 of the first member 11 automatically and in sequence. A rnultiplexer or like arrangement may therefore be provided as the electronic switch 31 and it will be appreciated that the device output signal 50 may need appropriately to be switched to different inputs of a computer controller, game console or the like, which may thus utilise the device output signal 50 appropriately to determine X-Y axis positional information in real time.
It will appreciated that in many items of elech~orzic equipment or other apparatus which contain electronic control means, there will be an existing microcontr-oller or ASIC, and that the existing microcontroller or ASIC may be utilised both to obtain one or- more square waveforn si~mals such as signals 26 and 27 for use in the device 10, and that the rmicrocontroller or ASIC may also comprise the means necessary for step level determination and/or phase comparison.
It will be appreciated that the oscillator signal source 25 may provide appropriate signal waveform signals to a plurality of position sensing;
devices.
Thus for example in a graphic equalizer which may have a substantial number of individual channels, thirty say, only one oscillator signal source '?5 would be required. A dedicated anal~-ser means 40 rn~y be provided for each positional sensor, or usin,~ a multiplexing type ar-angernent, a single analyser means 40 may be used for each of the plurality of positional sensing devices.
Various modifications may be made without departing from the scope of the invention.
In particular, the present invention has been described in the embodiment above with reference to a device for obtaining positional information along mutually generally orthogonal X and Y axis 33 and ~4. The invention may be utilised to obtain omnidirectional information only, and that direction may be linear or otherwise. For example, a conventional slider type conh~ol having wiping contacts may be replaced by a device in accordance with the invention in which the first member has only two pairs which are isolated electrically conducting parts.
Alternatively, the device rnay provide positional ilfonnation relative to tlwee axes at 120° to one another in which case the fit~st member may comprise tlwee isolated electrically conducted pacts in a suitably an-ay.
It is envisaged that a device in accordance with figures 1 to 3 may' be constructed in which the first member 1 I has an area of about 25 x 20 mm. The oscillator signal source 25 may generate a sduare wave signial at a frequency of about 10 kHz. Stability of fi~eduency is not critical but should remain stable whilst positional movement of the second member 12 relative to the first member is performed. The oscillator sigmal source 25 may generate the square waveform signal or signials 26, 27 digitally or otherwise.
VVhereas it is preferred for the distance d between the moving member 12 and the fixed member I1 to remain gener~clly constant. slight variations in distance d during second member movement need not have a severe effect on the positional movement determined provided that the air gap 4G is sufficiently great.
In Figure 3 it can be seen that there is an input 41 to the analyser means 40 from the conductor 30. This is used to facilitate tuning in the analyser means 40 but is not essential. A timing pulse rnay be provided direct from oscillator means 25 if desired.
The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific f0r711S Or' in terms - WO 99/32853 PCTlGB98I03731 of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse foams thereof.
Claims (11)
1. A method of obtaining positional information utilising a device comprising a first member having at least two electrically isolated conducting parts, and a second electrically conducting member adjacent to and capacitively coupled to the first member, the first and second members being relatively movable such that the proportions of the respective parts of the first member in overlapping relationship with the second member may be varied, the method comprising the steps of providing a first square waveform signal to one of the parts of the first member and a second square waveform signal to the other of the parts of the first member, analysing a signal arising in the capacitively coupled second member to obtain a device output signal containing information about the relative positions of the first and second members.
2. A method according to claim 1 wherein the first and second square waveform signals are of the same frequency but are 90° out of phase with each other.
3. A method according to claim 1 or claim 2 wherein the signal which is analysed comprises a filtered output from signal arising in the second member.
4. A method according to claim 3 wherein the filtered output signal comprises a sine wave the phase of which is compared with the phase of one of the first and second square waves.
5. A method according to claim 1 or claim 2 wherein the output signal from the second member is a complex waveform of the same frequency as the first and second square waveforms having steps either side of a dominant step level, the method comprising analysing at least one of the step heights to obtain the positional information.
6. A method according to claim 1 or claim 2 wherein the output signal from the second member is a complex waveform of the same frequency as the first and second square waveforms having steps either side of a dominant step level, the method comprising analysing the difference between at least one of the steps and the dominant base or peak step level to obtain the positional information.
7. A method of obtaining positional information substantially as herinbefore described with reference to the accompanying drawings.
8. A device for obtaining positional information by a method according to any one of the preceding claims the device comprising a first member having at least two electrically isolated conducting parts, and a second electrically conducting member adjacent to and capacitively coupled to the first member, the first and second members being relatively movable such that the proportions of the respective parts of the first member in overlapping relationship with the second member play be varied, means to provide a first square waveform signal to one of the parts of the first member and a second square waveform signal to the second pert of the first member, means to analyse a signal arising in the capacitively coupled second member to obtain a device output signal containing information about the relative positions of the first and second members.
9. A device according to claim 8 wherein the first member of the device comprises more than two electrically isolated parts relative to which the second member may move, square waveform signals being applied to each of the plurality of parts whereby the device is able to obtain positional information about relative movement between the first and second member in two dimensions.
10. A device for obtaining positional information substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
11. Any novel feature or novel combination of features described herein and/or shown in the accompanying drawings.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9726640.7 | 1997-12-18 | ||
| GBGB9726640.7A GB9726640D0 (en) | 1997-12-18 | 1997-12-18 | Method of obtaining positional information |
| PCT/GB1998/003731 WO1999032853A1 (en) | 1997-12-18 | 1998-12-11 | Method and device for obtaining positional information |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2314176A1 true CA2314176A1 (en) | 1999-07-01 |
Family
ID=10823746
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002314176A Abandoned CA2314176A1 (en) | 1997-12-18 | 1998-12-11 | Method and device for obtaining positional information |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP1040318A1 (en) |
| AU (1) | AU1499199A (en) |
| CA (1) | CA2314176A1 (en) |
| GB (1) | GB9726640D0 (en) |
| WO (1) | WO1999032853A1 (en) |
| ZA (1) | ZA9811622B (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2931489C2 (en) * | 1979-08-03 | 1987-07-09 | Jungheinrich Unternehmensverwaltung Kg, 2000 Hamburg | Control lever switch |
| DE3411979A1 (en) * | 1983-03-30 | 1984-10-04 | Siemens AG, 1000 Berlin und 8000 München | Angle resolver |
| DE4410918A1 (en) * | 1994-03-29 | 1995-10-05 | R & R Ges Fuer Rationalisierun | Capacitive device for rotational distance and/or position measurement around axis |
| GB2321108A (en) * | 1997-01-08 | 1998-07-15 | David Alan Woodfield | Input device for inputting positional information |
-
1997
- 1997-12-18 GB GBGB9726640.7A patent/GB9726640D0/en not_active Ceased
-
1998
- 1998-12-11 WO PCT/GB1998/003731 patent/WO1999032853A1/en not_active Application Discontinuation
- 1998-12-11 AU AU14991/99A patent/AU1499199A/en not_active Abandoned
- 1998-12-11 CA CA002314176A patent/CA2314176A1/en not_active Abandoned
- 1998-12-11 EP EP98959063A patent/EP1040318A1/en not_active Withdrawn
- 1998-12-18 ZA ZA9811622A patent/ZA9811622B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| WO1999032853A1 (en) | 1999-07-01 |
| ZA9811622B (en) | 1999-06-23 |
| GB9726640D0 (en) | 1998-02-18 |
| EP1040318A1 (en) | 2000-10-04 |
| AU1499199A (en) | 1999-07-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |