JP2002517004A - Method and apparatus for remote detection of markers - Google Patents

Abstract

SUMMARY A method and apparatus are provided for remote sensing of markers (10), wherein each marker excites a respective magnetic element (13) to mechanically resonate or a respective magnetic field. At least two magnetic elements (13) arranged in a predetermined relationship for recognizing the marker either by exciting and electrically oscillating an electrical resonant circuit (14) to which the element (13) connects. Is provided. The resonance frequency (fres) of each magnetic element or electrical resonance circuit depends on the applied magnetic field (H) given a changing direction. The corresponding change in the resonance frequency (fres) is monitored and the extreme value of the change (fmin-local) is detected. The instantaneous direction of the magnetic field (αmin-local) is determined in response to the detection of the extremum, and the direction of each element (13) is determined by the instantaneous field direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD The present invention relates to a method and an apparatus (system) for remote detection of a marker, in which each magnetic element is excited to make it mechanically resonate or an electrical connection to which each magnetic element is connected. Each marker comprises at least two magnetic elements recognizing the marker and arranged in a predetermined relationship, either by exciting the resonant circuit and causing it to vibrate electrically, wherein: The resonance frequency of each magnetic element or electrical resonance circuit depends on the applied magnetic field.

Description of the Prior Art Many applications require reliable, non-contact detection of the presence, recognition or positioning of an object. Common examples of such applications are, for example, labeling the price of goods or recognizing the type of object in a production line or recycling plant. The marker or label comprises a number of magnetic sensor elements arranged at a predetermined angular relationship or at a predetermined distance from each other. Such marker detection means are known from WO 88/01427, in which an article detection system excites the magnetic elements and mechanically resonates, and the magnetic signal generated by each resonating magnetic element Is provided. The magnetic element is formed as a magnetostrictive string or ribbon made from an amorphous ferromagnetic material. The resonance frequency of each string depends on the length and mass of the string. In addition, the delta-E effect of amorphous materials
Due to a particular property known as t), the resonance frequency of each element is also
(Longitudinal) direction. This property of the material is used according to WO 88/01427 which allows the simultaneous detection of several identical markers. The coil device has an extraneous magnetic bias.
Different magnetic field strengths are acting on any two markers present simultaneously in the detection area, and thus the markers are also different with respect to the magnetic elements provided by the markers. Indicates the resonance frequency.

[0003] WO 93/14478 discloses a similar system, but wherein the markers comprise one or more electrically resonant circuits, each inductively connected to a respective magnetic sensor element. The relative permeability μ _τ of the magnetic element is heterogeneous (heterogeneo).
us) The resonant frequency of the resonant circuit is affected by a foreign magnetic field due to the inductive connection between the magnetic element and the resonant circuit. WO93 / 14478
Are excited and detected by electromagnetic or magnetic signals.

The magnetic element of each marker is used to identify each marker, the quantity of articles, and the like.
) To indicate the presence of specific information. For markers in which the magnetic elements are arranged in an angular relationship with respect to each other, the information is represented by the respective angle between the pair of magnetic elements and the magnetic elements are arranged parallel to each other and between adjacent elements. For fixed distance markers, the information is displayed by distance.
Other information may be displayed by using different types of elements, for example, different lengths or different masses. One way of forming magnetic sensor elements having different masses and thus eventually different resonance frequencies is known from WO 95/29534.

[0005] A method for detecting several markers simultaneously is known from WO 95/29467. The markers, and the magnetic elements provided therein, are exposed to a sequence of different magnetic field conditions. The resonance frequencies of all elements in the sensing area are detected for all magnetic field conditions, and the element of the magnetic field vector along the length of each element is determined by the corresponding detected resonance frequency. All possible combinations of the angular relationship between the elements of the marker pair have been determined, and for one combination, the resulting magnetic vector is determined using the specific combination of the angular relationships for the particular combination. Calculated by different pairs of determined elements of magnetic field state. Any combinations that do not have the same resulting magnetic vector calculated for different pairs of elements are eliminated and the process is repeated until only those combinations corresponding to the actual element combinations of the markers remain in the detection area. It is.

[0006] The method of WO 95/29467 is advantageous because it is possible to process and recognize several identical markers that are simultaneously present in the detection area. However, if the total number of possible code values (the number of element configurations at different angles) is large, the total number of calculations that must be performed will be extremely large, and the recognition process will take May need to continue for a significant amount of time before the element is correctly recognized. Therefore, there is a need for a faster detection method and system (device) that can recognize markers more quickly.

SUMMARY OF THE INVENTION It is an object of the present invention to provide faster detection of a marker for remote detection of an object. The object is achieved by a method and a device according to the appended independent claims. Basically, the purpose is to apply a rotating magnetic field to the marker, and the magnetic field vector of the magnetic field is rotated 360 degrees, while continuously monitoring the change of the resonance frequency generated by each magnetic element. This is realized by understanding that the detection of the moment when the change in the resonance frequency reaches an extreme value such as the minimum value can be performed very quickly. The actual direction of the magnetic field vector is recorded at the moment when this extremum is detected, and the direction of each magnetic element is determined by the direction of the instantaneous magnetic field.

In summary, as the magnetic field vector rotates 360 degrees, the field vector becomes increasingly aligned with the first element of the marker and becomes substantially parallel to this element, in which case The extreme value is detected and the direction of the first element is determined. As the field vector rotates further, it becomes less and less aligned with the first magnetic element, but instead becomes more and more aligned with the second magnetic element. The orientation of the second magnetic element is determined when the magnetic field vector aligns with the second element, and the process is repeated for the remaining elements of the marker. Once the correct element orientation is determined, the type of each element may be determined in a second step according to a preferred embodiment, in which case a magnetic field having a varying field strength is determined for each determination. By applying along the direction of the elements that have been sensed, detecting the global minimum / maximum resonance frequency of each element and comparing this resonance frequency to a set of pre-stored data,
Determine its type.

[0009] Further objects, features and advantages of the invention will become apparent from the following detailed description, drawings and dependent claims. The present invention will be described in further detail with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates a sensing device (system) according to an exemplary embodiment of the present invention. The detection device comprises an excitation means 15 and a detection means 16, both of which are operatively connected to a system controller 17 and furthermore a magnetic field generation means 1.
8 is provided. The marker 10 comprises four magnetic sensor elements 13 arranged at an angle. In the illustrated embodiment, these magnetic elements may be any known magnetoelastic (magneto) formed, for example, as thin strings, ribbons or wires made of an amorphous alloy having specific magnetic properties.
elastic (magnetostrictive) type. However, the invention is equally applicable to markers having an electrical resonance circuit to which each magnetic element 13 connects. These two types of markers are described, for example, in WO 88/01427.
And WO 93/14478, which have been described above and are hereby incorporated by reference.

The individual magnetic elements 13a-d (FIG. 2) are of different types and present different resonance frequencies. Different types may be selected between elements of different lengths and / or elements of different mass, shape, etc.

The excitation means is configured to generate a magnetic or electromagnetic excitation signal that forces the magnetic element 13 into a mechanical resonance. The magnetic signal generated by the resonating magnetic element 13 is detected by the detecting means 16 and transmitted to the system controller 17. Further, the magnetic field generating means 18 is configured to generate a changing magnetic field H,
It is described in more detail below. The magnetic element 1 corresponding to the change of the magnetic field H
The material properties of 3 cause a corresponding change in the resonance frequency fres of each element 13.

The system controller 17 is configured to drive the magnetic field generation means 18 and generates a magnetic field having a rotating field vector. The field vector preferably rotates 360 degrees. The rotation of the magnetic field vector is illustrated in FIG. 2 and the oscillations of each magnetic element 13 occurring at the resonance frequency fres are illustrated in FIG. Magnetic field H
When the field vector starts to rotate from 0 degrees to 360 degrees, the field vector first becomes gradually aligned with the first magnetic element 13 a of the marker 10. As the field vector H becomes increasingly aligned with this magnetic element, its resonant frequency fres decreases in value (illustrated by the arrow I in FIG. 3), but it is determined by the first magnetic element 13a. Projection of the magnetic field vector H along the longitudinal direction
Is gradually increased. At a particular angle of rotation αmin-local, the projection of the field vector H is maximal (ideally, perfectly parallel to the first magnetic element 13a).
, In which case the resonance frequency fres reaches the minimum value fmin-local.
As the field vector H rotates further, its alignment with the first element 13a becomes less perfect, in which case the resonance frequency fres begins to increase as illustrated by the arrow II in FIG. . At the moment when the resonance frequency reaches its local minimum point fmin-local, the instantaneous angular rotation αmin-local of the field vector H is recorded. Since the local minimum resonance frequency occurs when the field vector H and the first magnetic element 13a are parallel, the direction in which the element 13a faces is the instantaneous direction of the field vector H, that is, αmin-local. Directly obtained from

As the field vector H rotates continuously, it gradually becomes out of alignment with the first element 13a but becomes increasingly aligned with the second element 13b. At a particular angular rotation, the field vector H becomes parallel to the second magnetic element 13b, in which case its direction is determined as described above. Subsequently, the corresponding decisions are made in the third and fourth
In the directions of the magnetic elements 13c and 13d.

In a preferred embodiment of the invention, the marker 10 is a magnetic element 13 exhibiting a resonance frequency of a different type, ie within a different (but partially overlapping) frequency range.
a-d. For such markers, once each element 13a-d
Is determined as set above, the type of each magnetic element 13a-d is determined as follows. For each element direction determined above, the system controller 17 operates the generating means 18 to generate a magnetic field H of varying intensity along each direction, as illustrated in FIGS. . Each magnetic element 1
As the magnetic field strength changes along the longitudinal direction of 3a-d, its resonance frequency decreases and eventually reaches the overall minimum fmin-global in the magnetic field strength Hfmin-global. The overall minimum resonance frequency is directly related to each element type, and the mapping between the overall minimum resonance frequency and the particular element type is a storage operatively connected to the system controller 17. Indicated by a set of reference data previously stored in the device. Once the entire minimum resonance frequency fmin-gl
Once the obal is determined, the controller 17 compares this value to a set of previously stored reference data to determine the type of a particular element whose corresponding frequency value or range is compatible with the detected overall minimum resonance frequency. select. For some marker types, it may be possible to detect the global maximum of the resonance frequency instead of the global minimum.

According to the invention, markers representing each code value among a very large number of possible code values can be detected accurately and quickly. For example, for a marker similar to the example shown in the figures, it comprises four different magnetic elements, each of which is selected between four different types and arranged at any of fifteen possible angles. And the total number of different code values is 327,600. If the four elements are 1
If selected between zero different types of sums, each marker can display one of 13,628,160 different code values for the same number of different angular positions.

It is possible to detect more than one marker simultaneously within the scope of the present invention, even if the elements face the same direction on the markers. For simultaneous detection, for example, with respect to two markers, one is rotated at a specific angle with respect to the other, and the sequence of absolute angular position values (order) obtained for all elements of the two markers. , It is possible to identify the two markers. The first element of each of the two markers has a 0 degree direction with respect to the given reference direction, while the second element has a 10 degree direction and the third element has a 2 degree direction.
Assuming a 5 degree direction, this typical sequence of absolute angular position values may be recognized at a rotation of the magnetic field {0, 7, 10, 17, 25, 32 degrees, etc.}. .

It can be concluded from the above sequence that all second values deviate by 7 degrees from the previous value. This means that one of the markers is displaced at 7 degrees with respect to the other, thereby making the two markers distinguishable with respect to each other.

If, on the other hand, the two markers were quite parallel, they could nonetheless be individually identified by applying a gradient of the field to the rotating magnetic field. Will. Thus, the rotating field vector is not uniformly strong, but its magnitude is increasing, where the two markers present different changes in resonance frequency when a rotating magnetic field acts. .

While the present invention has been described above with reference to illustrative embodiments shown for purposes of illustration, and not limitation. As will be immediately recognized by those skilled in the art,
Embodiments other than those disclosed herein are possible within the scope of the invention as limited by the independent claims set forth.

For example, exposing the marker to two or more sequences of different rotating magnetic fields, with the plane in which the direction in which the marker element points lies is substantially different from the plane of rotation of the magnetic field. May be advisable, and the plane of rotation is not parallel (preferably orthogonal), so that the orientation of the elements can be reliably determined with accuracy.

[Brief description of the drawings]

FIG. 1 is an illustrative view of a remote detection device according to the present invention.

FIG. 2 is a schematic illustration of the method according to the invention.

FIG. 3 is a frequency diagram illustrating the method according to the invention.

FIG. 4 shows a second step of the method according to a preferred embodiment of the present invention.

FIG. 5 is a frequency diagram illustrating a second procedure of FIG. 4;

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] March 25, 2000 (2000.3.25)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2F063 AA37 BA30 BB03 BB10 BC08 CA11 DA01 DA05 GA00 LA04 LA30 2F077 AA49 CC02 JJ00 TT02 TT07 TT35 TT58 TT82 5B072 CC27 DD04 5C084 AA03 AA09 AA16 BB40 DD21 CC36 DD

Claims (11)

[Claims] 1. A method for remote sensing of markers (10), wherein each marker excites a respective magnetic element (13) to mechanically resonate or a respective magnetic element (13) connects. Comprising at least two magnetic elements (13) that identify the markers and are arranged in a predetermined relationship by either exciting and electrically oscillating an electrical resonant circuit. And a method for remote sensing of the marker (10), wherein the resonance frequency (res) of each magnetic element or electrical resonance circuit is dependent on the applied magnetic field (H), wherein the magnetic field (H) is Given the direction of change, the corresponding change in the resonance frequency (fres) is monitored, the extreme value of the change (fmin-local) is detected, and the instantaneous Direction (αmin-local) is determined in response to the detection of the extremum, and the direction of each element (13) is determined by the instantaneous field direction. Way for. 2. The method according to claim 1, wherein the direction of the instantaneous field is essentially parallel to the longitudinal axis of the respective magnetic element. 3. The method according to claim 1, wherein the direction of each element is determined as being essentially parallel to the determined instantaneous field direction. 4. The method according to claim 1, wherein the extreme value is a maximum value or a minimum value. 5. After determining the direction of each element, each element (13)
Further comprising a procedure for determining the type, the procedure comprising a magnetic field (H) having a field strength that varies along the direction of each determined element.
), Detecting the maximum or minimum value of the resonance frequency of each element (13), and determining the maximum or minimum value of the detected resonance frequency for each element type. A set of stored values related to frequency values or ranges
Comparing to reference data, selecting a particular one of the types of stored elements whose associated stored frequency value or range matches the minimum or maximum value of the detected resonance frequency; The method according to any one of claims 1 to 4, comprising: 6. The method according to claim 1, wherein the magnetic element comprises an amorphous alloy. 7. The method according to claim 1, wherein the magnetic element (13) is formed as a string, ribbon or wire or the like. 8. The method according to claim 1, wherein the at least two magnetic elements are arranged in an angular relationship with respect to each other with respect to a longitudinal direction of the elements. . 9. The method according to claim 1, wherein the at least two magnetic elements are arranged in a distance relationship with respect to one another. 10. An apparatus (system) for remote sensing of markers (10), wherein each marker comprises at least two magnetic elements (13) arranged in a predetermined relationship.
The apparatus comprises: excitation means (15, 17), detection means (16, 17), magnetic field generation means (18), and further associated with each magnetic element. And the magnetic field (H
) Dependent on a marker (10) arranged to detect a resonance frequency (fres)
), Wherein the magnetic field generating means (18) is configured to generate a rotating magnetic field (H), and the detecting means (16, 17) is configured to rotate the rotating magnetic field (H). Resonance frequency (f
res) is configured to detect the extreme value (fmin-local) of the change, and the direction of each magnetic element (13) is determined by the instantaneous direction (αmin-local) of the rotating magnetic field (H). A device for remote detection of a marker, characterized in that it is arranged to determine. 11. The magnetic field generating means (18) is further configured to generate a magnetic field having a varying field strength to determine a respective type of a respective magnetic element (13). An apparatus according to claim 1.