U.S. patent application number 17/703675 was filed with the patent office on 2022-07-07 for method of examining the electrical properties of objects using electric fields.
The applicant listed for this patent is Zedsen Limited. Invention is credited to Hrand Mami MAMIGONIANS.
Application Number | 20220214296 17/703675 |
Document ID | / |
Family ID | 1000006215384 |
Filed Date | 2022-07-07 |
United States Patent
Application |
20220214296 |
Kind Code |
A1 |
MAMIGONIANS; Hrand Mami |
July 7, 2022 |
Method of Examining the Electrical Properties of Objects using
Electric Fields
Abstract
The electrical properties of objects are examined, using
electric fields. An object is arranged on an apparatus having a
first electrode (201) and a second electrode (202). The first
electrode is energised during a first strobing operation of a
scanning-cycle and the second electrode is monitored during this
first strobing operation. Thereafter, during a second strobing
operation, the second electrode is energised and the first
electrode is monitored.
Inventors: |
MAMIGONIANS; Hrand Mami;
(Ealing, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zedsen Limited |
London |
|
GB |
|
|
Family ID: |
1000006215384 |
Appl. No.: |
17/703675 |
Filed: |
March 24, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16185447 |
Nov 9, 2018 |
11313823 |
|
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17703675 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 27/226 20130101;
G01N 27/041 20130101; G01N 27/221 20130101 |
International
Class: |
G01N 27/22 20060101
G01N027/22; G01N 27/04 20060101 G01N027/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 11, 2017 |
GB |
1718678.4 |
Claims
1. A method of examining electrical properties of objects, using
electric fields, comprising the steps of: arranging an object on an
apparatus having a first electrode and a second electrode;
energising said first electrode during a first strobing operation
of a scanning cycle; monitoring said second electrode during said
first strobing operation; energising said second electrode during a
second strobing operation of said scanning cycle; and monitoring
said first electrode during said second strobing operation.
2. The method of claim 1, wherein said apparatus includes a
plurality of additional electrodes.
3. The method of claim 2, further comprising the steps of:
sequentially energising each of said additional electrodes during
respective strobing operations of said scanning cycle; and for a
selected energised electrode N, monitoring, when electrode N-1 is
present, electrode N-1, and then monitoring, when electrode N+1 is
present, electrode N+1 during respective strobing operations of
said scanning cycle.
4. The method of claim 1, further comprising the step of analysing
data produced by said monitoring steps after performing a complete
scanning cycle.
5. The method of claim 4, further comprising the steps of:
modifying a scanning characteristic in response to said analysing
step; and conducting a further scanning cycle.
6. The method of claim 5, wherein said modifying step includes
modifying said energising step.
7. The method of claim 1, in which each strobing operation includes
the energising step and the monitoring step, wherein: each said
energising step includes applying an input voltage pulse to a
selected input electrode; and said monitoring step includes
sampling an output voltage received on a selected output
electrode.
8. The method of claim 2, in which each strobing operation includes
the energising step and the monitoring step, wherein: each said
energising step includes applying an input voltage pulse to a
selected input electrode; and said monitoring step includes
sampling an output voltage received on a selected output
electrode.
9. The method of claim 3, in which each strobing operation includes
the energising step and the monitoring step, wherein: each said
energising step includes applying an input voltage pulse to a
selected input electrode; and said monitoring step includes
sampling an output voltage received on a selected output
electrode.
10. The method of claim 5, in which each strobing operation
includes the energising step and the monitoring step, wherein: each
said energising step includes applying an input voltage pulse to a
selected input electrode; and said monitoring step includes
sampling an output voltage received on a selected output
electrode.
11. The method of claim 4, in which each strobing operation
includes the energising step and the monitoring step, wherein: each
said energising step includes applying an input voltage pulse to a
selected input electrode; and said monitoring step includes
sampling an output voltage received on a selected output
electrode.
12. The method of claim 7, wherein: said applying step includes
applying said input voltage pulse via a de-multiplexing process;
and said sampling step includes receiving an output voltage via a
multiplexing process.
13. The method of claim 1, wherein: said electrodes define a
plurality of parallel tracks; and said electric fields extend
between adjacent parallel tracks.
14. The method of claim 2, wherein: said electrodes define a
plurality of parallel tracks; and said electric fields extend
between adjacent parallel tracks.
15. The method of claim 3, wherein: said electrodes define a
plurality of parallel tracks; and said electric fields extend
between adjacent parallel tracks.
16. The method of claim 4, wherein: said electrodes define a
plurality of parallel tracks; and said electric fields extend
between adjacent parallel tracks.
17. The method of claim 1, wherein: said electric fields extend
between electrodes of a first set of substantially parallel tracks
that includes said first electrode and electrodes of a second set
of substantially parallel tracks that includes said second
electrode; and said second set of substantially parallel tracks are
substantially orthogonal to said first set of substantially
parallel tracks.
18. The method of claim 2, wherein: said electric fields extend
between electrodes of a first set of substantially parallel tracks
that includes said first electrode and electrodes of a second set
of substantially parallel tracks that includes said second
electrode; and said second set of substantially parallel tracks are
substantially orthogonal to said first set of substantially
parallel tracks.
19. The method of claim 3, wherein: said electric fields extend
between electrodes of a first set of substantially parallel tracks
that includes said first electrode and electrodes of a second set
of substantially parallel tracks that includes said second
electrode; and said second set of substantially parallel tracks are
substantially orthogonal to said first set of substantially
parallel tracks.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 16/185,447, filed on Nov. 9, 2018, which
claims priority from United Kingdom Patent Application number
1718678.4, filed on Nov. 11, 2017. The whole contents of U.S.
patent application Ser. No. 16/185,447 and United Kingdom Patent
Application number 1718678.4 are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a method of examining
electrical properties of objects using electric fields.
[0003] It is known to examine electrical properties of objects
using electric fields, as described in U.S. Pat. No. 8,994,383,
assigned to the present applicant. Electrodes may be supported by a
dielectric membrane. A strobing voltage may be applied to energise
a first input electrode as a transmitter and an output voltage may
be monitored on an output receiver electrode. An external electric
field is generated that may pass through an object, such that an
output signal will be influenced by electrical properties of the
object, including the permittivity of the object. The output signal
is usually sampled at a sample point during each strobing operation
to facilitate digital processing.
[0004] A problem with known systems is that it can be difficult to
obtain sufficient information to fully identify properties of an
object.
BRIEF SUMMARY OF THE INVENTION
[0005] According to a first aspect of the present invention, there
is provided a method of examining electrical properties of objects,
using electric fields, comprising the steps of: arranging an object
on an apparatus having a first electrode and a second electrode;
energising said first electrode during a first strobing operation
of a scanning cycle; monitoring said second electrode during said
first strobing operation; energising said second electrode during a
second strobing operation of said scanning cycle; and monitoring
said first electrode during said second strobing operation.
[0006] Thus, in this way, the first electrode is not dedicated as a
transmitter electrode and the second electrode is not dedicated as
a receiver electrode. Each of these electrodes can perform both
functions, thereby enhancing the amount of information that can be
derived from the apparatus, without making significant
modifications to the apparatus itself.
[0007] In an embodiment, additional electrodes are provided. The
method may then further comprise the steps of energising all of the
additional electrodes during respective strobing operations of the
scanning cycle; and monitoring all of said additional electrodes at
appropriate strobing operations of the scanning cycle.
[0008] Embodiments of the invention will be described, by way of
example only, with reference to the accompanying drawings. The
detailed embodiments show the best mode known to the inventor and
provide support for the invention as claimed. However, they are
only exemplary and should not be used to interpret or limit the
scope of the claims. Their purpose is to provide a teaching to
those skilled in the art.
[0009] Components and processes distinguished by ordinal phrases
such as "first" and "second" do not necessarily define an order or
ranking of any sort.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0010] FIG. 1 shows an environment in which an examination
apparatus is deployed;
[0011] FIG. 2 details the examination apparatus identified in FIG.
1;
[0012] FIG. 3 shows a schematic representation of the functionality
of the apparatus shown in FIG. 2;
[0013] FIG. 4 illustrates the generation of electric fields;
[0014] FIG. 5 shows an alternative configuration of the apparatus
shown in FIG. 3;
[0015] FIG. 6 illustrates electric fields generated in response to
the configuration of FIG. 5;
[0016] FIG. 7 shows an alternative configuration of the apparatus
shown in FIG. 3 and FIG. 5;
[0017] FIG. 8 shows resulting electric fields from the
configuration of FIG. 7;
[0018] FIG. 9 illustrates an examination period;
[0019] FIG. 10 shows a schematic representation of the examination
apparatus shown in FIG. 2;
[0020] FIG. 11 shows a schematic representation of a strobing
circuit of the type identified in FIG. 9;
[0021] FIG. 12 shows an example of a multiplexing environment of
the type identified in FIG. 10;
[0022] FIG. 13 shows an example of a monitoring circuit of the type
identified in FIG. 10;
[0023] FIG. 14 shows an overview of procedures performed by the
processor identified in FIG. 10;
[0024] FIG. 15 details procedures for scanning electrodes
identified in FIG. 14; and
[0025] FIG. 16 shows an alternative examination apparatus.
DETAILED DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0026] FIG. 1
[0027] An examination apparatus 101 is shown in FIG. 1 for
examining electrical properties of objects, using electric fields.
The examination apparatus 101 communicates with a data processing
system 102 via a data communication cable 103, possibly designed in
accordance with established USB protocols.
[0028] FIG. 2
[0029] The examination apparatus 101 is shown in greater detail in
FIG. 2. It includes a plurality of parallel electrodes, including a
first electrode 201 and a second electrode 202, along with a
plurality of additional electrodes 203. Electrodes 201 to 203 are
supported by a dielectric insulating membrane 204 and the
electrodes are then covered by an insulating material to ensure
that the surface of the examination apparatus is
non-conductive.
[0030] The examination apparatus 101 is arranged to examine the
electrical properties of entities, such as an object 205. In known
systems of the type illustrated in FIG. 2, electrodes have
dedicated functionality; in that they are either energised, to
provide a transmitter electrode, or monitored to provide a receiver
electrode. Thus, in known systems, each electrode is identified
exclusively as a dedicated input electrode or a dedicated output
electrode.
[0031] The present embodiment provides an apparatus in which a
first electrode 201 is configured to be energised during a first
strobing operation of a scanning cycle and a second electrode 202
is configured to be monitored during this first strobing operation.
Thus, in conventional systems, the first electrode 201 would be
dedicated as a transmitter electrode and the second electrode 202
would be dedicated as a receiver electrode. However, in accordance
with the present invention, during part of the same scanning cycle,
the second electrode 202 is configured to be energised during a
second strobing operation and the first electrode 201 is configured
to be monitored during this second strobing operation. Thus, within
the same overall scanning cycle, data is obtained by using the
first electrode 201 as a transmitter and the second electrode 202
as a receiver. Subsequently, these roles are reversed, such that
additional data is received by energising the second electrode 202
as the transmitter, with the first electrode 201 being scanned as a
receiver. To achieve this, additional electronics are required and
operations performed by a microcontroller must ensure that any one
electrode is not energised and scanned simultaneously as part of
the same strobing operation.
[0032] In an embodiment, as illustrated in FIG. 2, the additional
electrodes 203 are also configured to be energised during
respective strobing operations, such that the first electrode 201,
the second electrode 202 and the additional electrodes are all
configured to be monitored at appropriate strobing operations of a
scanning cycle.
[0033] FIG. 3
[0034] In the embodiment of FIG. 2, the first electrode 201, the
second electrode 202 and the plurality of additional electrodes 203
define substantially parallel tracks, as shown schematically in
FIG. 3. Electric fields are generated between adjacent ones of said
tracks, as will be described with reference to FIG. 4. Alternative
arrangements of tracks are possible, an example of which will be
described with reference to FIG. 16.
[0035] As used herein, a scanning cycle consists of unique
sequential strobing operations performed in a particular order.
During an examination, the scanning cycle may be repeated and
characteristics of the scanning cycle may be adjusted. However,
without making any adjustments of this type, the cycle is repeated
periodically at a rate primarily determined by electrical
characteristics of the examination apparatus 101, clock speed and
the number of strobing operations performed within each cycle. In
this embodiment, a strobing operation consists of energising a
selected electrode to generate an electric field. This in turn
capacitively couples to other electrodes; such that the scanning
operation is completed by selecting an adjacent electrode to be
monitored. This provides an output signal that is sampled and then
processed within the digital domain.
[0036] As previously stated, known apparatus dedicate each
electrode to being either an input (transmitter) electrode or an
output (receiver) electrode. In accordance with an embodiment of
the present invention, any electrode 201 to 203 can be selected to
receive an energising signal or can be selected to be monitored and
thereby produce an output signal.
[0037] A schematic representation for achieving this functionality
is illustrated by a switching device 301. The switching device 301
receives input energising signals on an input line 302. Similarly,
the switching device 301 provides output signals on an output line
303.
[0038] The first electrode 201 is connected to a first switch 304
within the switching device 301. Similarly, the second electrode
202 is connected to a second switch 305. In this embodiment, a
third electrode 306, of the additional electrodes 203, is connected
to a third switch 307. A fourth electrode 308 is connected to a
fourth switch 309. A fifth electrode 310 is connected to a fifth
switch 311 and a sixth electrode 312 is connected to a sixth switch
313. Similarly, a seventh switch 314 connects to a seventh
electrode 315, with an eighth electrode 316 being connected to an
eighth switch 317.
[0039] Each of switches 304, 305, 307, 309, 311, 313, 314 and 317
includes a first contact 318, a second contact 319 and a third
contact 320. For each of the switches, the first contact 318 is
connected to the input line 302. Similarly, the third contact 320
is connected to the output line 303. The second contact 319,
positioned between the first contact 318 and the third contact 320,
does not provide a connection at all and, in this embodiment,
presents an open circuit to its respective electrode such that, in
the terminology of the art, the electrode is left floating when
connected to the second contact 319. In an alternative embodiment,
the second contact 319 may be connected to ground.
[0040] In the configuration shown in FIG. 3, the first switch 304
connects the input line 302 to the first electrode 201 such that,
during the next strobing operation, the first electrode 201 will be
energised. Furthermore, in the configuration of FIG. 3, the third
contact 320 of the second switch 305 connects the second electrode
202 to the output line 303. Thus, during a strobing operation
identified above, the second electrode 202 will be monitored while
the first electrode 201 is energised. A schematic representation of
this strobing operation, when viewed in the direction of arrow 400,
is illustrated in FIG. 4.
[0041] FIG. 4
[0042] A cross-sectional view of the examination apparatus of FIG.
2 is illustrated in FIG. 4, when viewed in the direction of arrow
400 (of FIG. 3). The object 205 has been placed on the examination
apparatus 101. The first electrode 201 is shown in cross-section,
along with the second electrode 202, the third electrode 306, the
fourth electrode 309 and the fifth electrode 311. In the
embodiment, the apparatus extends to the right to include
electrodes 313, 314 and 317. The first electrode 201, the second
electrode 202 and the additional electrodes are supported by the
dielectric membrane 204. This is in turn covered by an insulating
coating 401, thereby insulating the electrodes 201, 202 etc. from
the object 205.
[0043] A conducting ground plane 402 is provided to shield the
apparatus from external electrical noise. An intermediate layer 403
is also provided between the dielectric membrane 204 and the ground
plane 402 that, in an embodiment, may include response enhancement
properties.
[0044] During a strobing operation, an electric field is produced
between the first electrode 201 and the second electrode 202, as
illustrated by electric field lines 404. These represent capacitive
coupling, that occurs given that the first electrode 201 is
providing the functionality of a transmitter electrode and the
second electrode 202 is providing the functionality of a receiver
electrode. During a strobing cycle, the first electrode 201 is
energised and the second electrode 202 is monitored.
[0045] The electric field lines 402 show that the electric field
penetrates the object 205. A useful depth of penetration is
indicated at 405. The distance between the electrodes is indicated
at 406. Experiments conducted by the inventor suggest that the
useful depth of penetration 405 is approximately half of the
distance 406 between the electrodes.
[0046] FIG. 5
[0047] In this embodiment, for the next strobing operation of the
scanning cycle, the first switch 304 is activated to connect the
third contact 320 to the first electrode 201. Similarly, the second
switch 305 is activated to connect the second electrode 202 to a
second first contact 501. Thus, in this configuration, electrode
202 now performs a transmitter function, with the first electrode
201 performing a receiver function.
[0048] FIG. 6
[0049] The result of this switching operation, from the
configuration of FIG. 3 to the configuration of FIG. 5, results in
a reversal of functionality, such that the second electrode 202
becomes a transmitter and the first electrode 201 becomes a
receiver.
[0050] Thus, as illustrated in FIG. 6, the direction of the
electric field lines 404 has reversed.
[0051] FIG. 7
[0052] In this embodiment, for the next strobing operation, the
first switch 304 is activated, the second switch 305 is activated
and the third switch 307 is activated. The first switch 304
connects the first electrode 201 to the second contact 319, such
that the first electrode 201 will not contribute to the next
strobing operation. Switch 305 remains in position, connected to
the second first contact 501, such that, again, the second
electrode 202 will provide the functionality of a transmitter.
However, on this strobing operation, the third switch 307 has been
activated to connect a third electrode 701 to the output line 303,
thereby causing the third electrode 306 to provide the
functionality of a receiver.
[0053] FIG. 8
[0054] Upon initiating a strobing operation for the configuration
described with reference to FIG. 7, an electric field 801 is
generated, as illustrated in FIG. 8. Thus, the second electrode 202
provides transmitter functionality and the third electrode 306
provides receiver functionality.
[0055] Thus, in this embodiment, each electrode sequentially adopts
the functionality of a transmitter. When given this functionality,
a first strobing operation monitors an electrode immediately to the
left, followed by a second strobing operation that monitors the
electrode immediately to the right. The sequencing then advances
and the roles of the electrodes are changed.
[0056] FIG. 9
[0057] During a working period, many objects may be examined. The
duration of an examination is illustrated in FIG. 9. Similar
procedures are performed for each object and a particular
examination of an object starts by arranging the object on the
apparatus, as described with reference to FIG. 2.
[0058] During an examination process 901, electrodes are energised
sequentially and the procedure may be referred to informally as
"scanning". As used herein, a complete scan cycle is performed when
all unique combinations of transmitters and receivers have been
exercised. Thus, during the examination 901, many scan cycles may
be performed. For the purposes of this illustration, during
examination procedure 901, a first scan cycle 902 is performed,
followed by a similar second scan cycle 903 and a similar third
scan cycle 904.
[0059] During each scan cycle, such as scan cycle 902, many
strobing operations are performed, including a first strobing
operation 905, a second strobing operation 906, and a third
strobing operation 907 etc. Each strobing operation is unique, in
terms of the particular electrode selected as the transmitter in
combination with the particular electrode selected as the receiver.
Each strobing operation consists of energising the selected
transmitter electrode and monitoring the selected receiver
electrode.
[0060] Due to capacitive coupling, each monitoring process monitors
a voltage at the receiver electrode. To determine electrical
properties of objects, a measurement is required. In a preferred
embodiment, this measurement is achieved by performing a process of
analog to digital conversion, thereby allowing the result of this
conversion to be processed within the digital domain.
[0061] In FIG. 9, strobing operation 905 takes place within a
monitored duration 908. Within the monitored duration 908, a
sampling instant 909 occurs, representing an instant within the
monitored duration at which an output voltage is sampled.
[0062] In order to optimise results received from the examination
process, the sampling instant does not occur immediately following
the generation of an input strobing signal. Although, in an
embodiment, a sharp, rapidly-rising strobing input signal is
supplied to the transmitters, the shape of resulting output signals
will not rise so steeply; as a result of the electrical properties
of the device and the electrical properties of the objects. Thus,
to optimise the value of the information derived from the
procedure, the sampling instant 909 is delayed by a predetermined
delay period 910.
[0063] FIG. 10
[0064] A schematic representation of the examination apparatus 101
is illustrated in FIG. 10. This provides an apparatus for examining
electrical properties of objects, using electric fields. A number
of substantially parallel electrodes are supported on a dielectric
membrane, as described with reference to FIG. 2. In the
representation of FIG. 10, the dielectric membrane, with parallel
electrodes, is included within a multiplexing environment 1001. In
addition to the dielectric membrane, the multiplexing environment
1001 includes a de-multiplexer for selectively de-multiplexing
multiplexed energising input voltage pulses for application to each
of the electrodes, along with a multiplexer for selectively
multiplexing output signals monitored from each of the electrodes,
as described with reference to FIG. 12.
[0065] A processor 1002, implemented as a microcontroller, controls
the de-multiplexer and the multiplexer to ensure that the same
electrode cannot both be energised and monitored during a strobing
operation.
[0066] An energising circuit 1003 is energised by a power supply
1004 that in turn may receive power from an external source via a
power input connector 1005. A voltage control line 1006 from (a
digital to analog convertor within) the processor 1002 to the
energising circuit 1003 allows the processor 1002 to control the
voltage (and hence energy) of energising signals supplied to the
multiplexing environment 1001, via a strobing line 1007. The timing
of each strobing signal is controlled by the microcontroller 1002
via a trigger signal line 1008.
[0067] An output from the multiplexing environment 1001 is supplied
to an analog processing circuit 1009 over a first analog line 1010.
A conditioning operation is performed by the analog processing
circuit 1009, allowing analog output signals to be supplied to the
microcontroller 1002 via a second monitoring line 1011. The
processor 1002 also communicates with a two way data communication
circuit 1012, thereby allowing a data interface 1013 to connect
with the data communication cable 103.
[0068] In operation, the processor 1002 supplies addresses over
address busses 1014 to the multiplexing environment 1001 in order
to achieve the functionality described with reference to FIGS. 3 to
8. Thus, having supplied addresses to the multiplexing environment
1001, a strobing voltage is supplied via strobing line 1007,
resulting in an output signal being supplied to the processor 1002.
At the processor 1002, an analog input signal is sampled to produce
a digital representation and, in an embodiment, this digital data
is uploaded to the data processing system 102 via the data
interface 1013.
[0069] FIG. 11
[0070] An example of the energising circuit 1003 is shown in FIG.
11. The energising circuit 1003 consists of a voltage control
circuit 1101 connected to a strobing circuit 1102 via a current
limiting resistor 1103.
[0071] A voltage input line 1104 receives energising power from the
power supply 1004 to energise an operational amplifier 1105. The
operational amplifier 1105 is configured as a comparator and
receives a reference voltage via feedback resistor 1106. This is
compared against a voltage control signal, received on the voltage
control line 1006, to produce an input voltage for the strobing
circuit 1102.
[0072] In the embodiment of FIG. 11, the strobing circuit 1102
includes two bipolar transistors configured as a Darlington pair,
in combination with a MOSFET. This creates strobing pulses with
sharp rising edges and sharp falling edges that are conveyed to the
strobing line 1008.
[0073] FIG. 12
[0074] An example of a multiplexing environment 1001 is detailed in
FIG. 12. The switching functionality, described with reference to
FIG. 3, is achieved by the provision of a first multiplexing device
1201 and a second multiplexing device 1202. In this alternative
embodiment, a dielectric membrane 1203 supports sixteen parallel
electrodes 1204.
[0075] The address busses 1014 include an input address bus 1205
and an output address bus 1206, for addressing the first
multiplexing device 1201 and the second multiplexing device 1202
respectively. The addressing space for the input address bus 1205
and the output address bus 1206 may be similar, which may assist in
terms of ensuring that the same address cannot be supplied
simultaneously to both the input address bus 1205 and the output
address bus 1206.
[0076] The first multiplexing device 1201 also includes a first
enabling line 1207. Similarly, the second multiplexing device 1202
includes a second enabling line 1208. In operation, addresses are
supplied to the input address bus 1205 and to the output address
bus 1206 but line selection does not actually occur until the
multiplexing devices receive a respective enabling signal.
[0077] The first multiplexing device 1201 receives an input pulse
from the energising circuit 1003 via the strobing line 1008.
Multiple strobing operations are performed, such that an input
energising voltage is supplied sequentially to electrodes
performing a transmitter function. Strobing signals are distributed
to multiple inputs; therefore, the first multiplexing device 1201
should be seen as performing a de-multiplexing operation.
[0078] The second multiplexing device 1202 performs a multiplexing
operation, in that multiple output signals are selected
sequentially and then combined onto the first monitoring line 1010
for reception by the monitoring circuit 1009. Thus, in this
embodiment, the multiplexing environment is established by a single
first multiplexing device for input signals and a single second
multiplexing device for output signals, both of which are connected
to all sixteen of the available electrodes. Furthermore, if a
greater number of electrodes are present upon a dielectric
membrane, it is possible for additional multiplexing devices to be
provided such that, for example, a pair of multiplexing devices may
provide the input de-multiplexing function and a further pair of
multiplexing devices may provide the multiplexing output function;
provided that an appropriate addressing space has been
established.
[0079] During a strobing operation, an input address is supplied on
the input address bus 1205 and an output address is supplied on the
output address bus 1206. The addresses are enabled such that, at a
particular point in time, the output multiplexer 1202 is enabled
and as such is then configured to monitor output signals on the
addressed output electrodes. The selected input electrode is then
energised by the application of a strobing pulse, which may be
considered to occur at the start of arrow 910 shown in FIG. 9.
[0080] A short, predetermined delay, for the duration of arrow 910,
occurs before the sampling instant 909 occurs; taking a sample of
the voltage monitored on the output electrode. In this embodiment,
the first monitoring line 1010 applies an output analog voltage to
the analog processing circuit 1009 for the duration of the strobing
operation, such as strobing operation 905. The analog voltage is
conditioned by the analog processing circuit 1009, which in turn
supplies a conditioned voltage to the processor 1002 via the second
monitoring line 1011. Digital-to-analog conversion then takes place
within the processor 1002, such that the point at which the
sampling instant 909 occurs is determined by the processor.
[0081] FIG. 13
[0082] An example of an analog processing circuit 909 is
illustrated in FIG. 13. Signals received on the first monitoring
line 1010 are supplied to a buffering amplifier 1301 via a
decoupling capacitor 1302. During an initial set-up procedure, a
variable feedback resistor 1303 is trimmed to optimise the level of
monitored signals supplied to the processor 1002 via the second
monitoring line 1011. A Zener diode 1304 prevents excessive
voltages being supplied to the processor 1002.
[0083] FIG. 14
[0084] An overview of procedures performed by the processor 1002 is
illustrated in FIG. 14. After an initial switch-on, possibly
initiated by the data processing system 102, the sensor array is
calibrated at step 1401. This enables a reference level to be
established, prior to the application of an object, such as object
205.
[0085] After the application of an object, the electrodes are
scanned at step 1402. As previously described, each scan consists
of a plurality of strobing operations with each strobing operation
consisting of a unique combination of transmitter electrode and
receiver electrode.
[0086] At step 1403, data is processed and the degree of local data
processing will depend upon the processing capabilities provided by
the processor 1002.
[0087] In an embodiment, the level of received monitored signals
may be compared against a reference and, where appropriate, a
control voltage on the voltage control line 906 may be
adjusted.
[0088] More sophisticated processing may be achieved by the data
processing system 102, therefore the data is supplied as an output
to the data processing system 102 at step 1404. Thereafter, further
scanning is performed at step 1402 and the procedures are repeated
until a de-energisation command is received.
[0089] FIG. 15
[0090] Procedures 1402 for scanning the electrodes are detailed in
FIG. 15. At step 1501, an input electrode is selected; which would
be the first electrode 201 on the first iteration. At step 1502 a
question is asked as to whether there is an N minus one (N-1)
electrode which, if present, is selected at step 1503. Thereafter,
the input electrode N selected at step 1501 is energised and the
electrode before it, N minus one, is monitored at step 1504.
[0091] On a first iteration, the first electrode will have been
selected; therefore, an N minus one electrode does not exist.
Consequently, the question asked at step 1502 will be answered in
the negative.
[0092] At step 1505 a question is asked as to whether there is an N
plus one electrode (N+1) which, when answered in the affirmative,
results in a selection of this electrodes as a monitoring electrode
at step 1506. Thus, at step 1507 electrode N is energised and
electrode N plus one (N+1) is monitored. On the first iteration, an
N plus one electrode is present, therefore the energisation at step
1507 is as illustrated in FIG. 4, with the first electrode 201
being a transmitter and the second electrodes 202 being a receiver.
Thus, output data is generated.
[0093] Thereafter, a question is asked at step 1508 as to whether
another input electrode is present which, when answered in the
affirmative, results in the next input being selected at step 1501.
In this example, this will result in the second electrode 202 being
selected at step 1501 and the question then asked at step 1502 will
be answered in the affirmative, given that the first electrode 201
will now be selected as the N minus one (N-1) electrode.
Consequently, the second electrode 202 is energised and the first
electrode 201 is monitored, as illustrated in FIG. 6.
[0094] Thereafter, at step 1505 a question is asked as to whether
there is an N plus one (N+1) electrode, which would be answered in
the affirmative; resulting in the third electrode 306 being
selected at step 1506. Consequently, at step 1507, the second
electrode 202 will be energised and the third electrode 306 will be
monitored, as illustrated in FIG. 8. Thereafter, the question asked
at step 1508 will be answered in the affirmative and the process
will be repeated, this time with the third electrode 306 being the
energised transmitter electrode N.
[0095] Thus, the question asked at step 1508 will continue to be
answered in the affirmative until all of the electrodes have been
selected. This will result in the establishment of a complete cycle
such that, at step 1509, a question is asked as to whether the
cycle is to repeat. When answered in the affirmative, the first
electrode is selected again at step 1501.
[0096] The procedure provides a method of examining electrical
properties of objects, using electric fields. An object is arranged
on an apparatus having a first electrode and a second electrode, as
described with reference to FIG. 2. The first electrode is
energised during a first strobing operation of a scanning cycle and
a second electrode is monitored during this first strobing
operation. Usually, this would establish electrodes as being
specifically dedicated for a transmitting operation or a reception
operation. However, by providing a sophisticated multiplexing
environment, as described with reference to FIG. 12, it is possible
to then energise the second electrode during a second strobing
operation, while monitoring the first electrode during this second
strobing operation; as part of the same scanning cycle.
[0097] FIG. 16
[0098] An alternative examination apparatus 1601 is shown in FIG.
16. A first electrode 1602 and a first plurality of additional
electrodes provide a first set of substantially parallel tracks;
substantially similar to the arrangement described with respect to
FIG. 12. However, the second electrode 1603 and a second plurality
of electrodes provide a second set of substantially parallel
tracks; where both sets of tracks are mounted on opposite sides of
a dual-sided membrane 1604.
[0099] The second set of electrodes, including second electrode
1603, is substantially orthogonal to the first set of electrodes,
including the first electrode 1602, and electrically insulated
therefrom. The first electrode and the first plurality of
electrodes are energised (sequentially) while the second electrode
and the second plurality of electrodes are sequentially monitored.
Thereafter, the second electrode and the second plurality of
electrodes are energised while the first electrode and the first
plurality of electrodes are monitored.
[0100] A first alternative multiplexing device 1605 supplies
energising signals to the first set of electrodes. A second
alterative multiplexing device 1606 receives output signals from
the first set of electrodes. Similarly, a third alterative
multiplexing device 1607 supplies energising signals to the second
set of electrodes and a fourth alternative multiplexing device 1608
receives output signals from the second set of electrodes.
[0101] During a scanning cycle, the first alterative multiplexing
device 1605 is operative, in combination with the fourth
alternative multiplexing device 1608, such that, for part of the
cycle, the first set of electrodes are energised and the second set
of electrodes are scanned. Thereafter, as part of the same cycle,
the third alternative multiplexing device 1607 is energised;
thereby energising the second set of electrodes and the second
alternative multiplexing device 1606 is addressed.
* * * * *