Title:
MAGNETIC CODING DEVICE FOR MOVING BODIES SUCH AS CONVEYOR CARRIERS
United States Patent 3735300


Abstract:
A magnetic coding device including a selector mounted on a conveyor carrier and registerable with a code reader mounted along the path of travel of the carrier, the code reader having a group of alternately oppositely polarized reed switches (e.g., ten) spaced around a circumference in code positions. The selector has a pair of oppositely polarized permanent magnets movable to corresponding code positions by a selector dial and shiftable between active and inactive positions relative to the reed switches. In each code position of the selector dial one of the permanent magnets is active relative to one of the reed switches, while the other permanent magnet is inactive and shielded.



Inventors:
Benner, Jean-rene (Seine-et-Marne, FR)
Dop, Pierre (Seine-et-Marne, FR)
Caron, Marcel (Seine-Saint-Denis, FR)
Application Number:
05/252002
Publication Date:
05/22/1973
Filing Date:
05/10/1972
Assignee:
JERVIS B WEBB INT COMP,US
Primary Class:
Other Classes:
335/207, 341/15
International Classes:
B61B10/00; (IPC1-7): H01H41/10
Field of Search:
335/152,153,205,206,207 340
View Patent Images:
US Patent References:
3477046MANUAL CODE PULSING MAGNETIC REED SWITCH1969-11-04Pigeon et al.
3284739Rotary reed switch actuator1966-11-08Olson
3162738Magnetically actuated switching device1964-12-22Abramson et al.



Primary Examiner:
Envall Jr., Roy N.
Claims:
We claim

1. A magnetic coding device for a moving body such as a conveyor carrier, including a selector mounted on the moving body and registerable with a code reader mounted along the path of travel of the moving body;

2. A magnetic coding device according to claim 1 wherein the pair of permanent magnets of the selector are arranged with their poles in opposite relationship.

3. A magnetic coding device according to claim 2 wherein the permanent magnets of the selector are arranged on a circumference corresponding in diameter to that of the circumference on which the reed switches of the code reader are arranged, the permanent magnets being spaced so that in each of said code positions, one of the permanent magnets is in active relationship with one of the reed switches while the other permanent magnet is in inactive relationship with another of the reed switches.

4. A magnetic coding device according to claim 2 wherein the selector includes means responsive to movement of the selector member from one code position to another for shifting the pair of permanent magnets between positions in which one permanent magnet is active and the other is inactive relative to the reed switches of the code reader.

5. A magnetic coding device according to claim 4 wherein the selector further includes means for shielding that permanent magnet which is in said inactive position.

6. A magnetic coding device according to claim 4 wherein the active position of the permanent magnets are located on a circumference corresponding in diameter to that of the circumference on which the reed switches of the code reader are arranged and correspond to the code positions of the reed switches, and said inactive positions of the permanent magnets are located inwardly of this circumference.

7. A magnetic coding device according to claim 4 wherein the means for shifting the pair of permanent magnets of the selector between active and inactive positions includes a rotatable shaft on which the selector member is mounted, a support for the pair of permanent magnets, means connecting the support to the shaft for oscillation about a pivot radially displaced from the axis of the shaft, and cam means for oscillating the support as the shaft is rotated.

8. A magnetic coding device according to claim 7 wherein the selector includes a ratchet device for defining each of said plurality of code positions.

9. A magnetic coding device according to claim 8 wherein the ratchet device defines ten code positions, constituting a selection decade.

10. A magnetic coding device according to claim 9 wherein the code reader comprises a group of ten reed switches for each selection decade on the selector.

Description:
The present invention relates to a magnetic coding device for moving bodies such as conveyor carriers, and includes a selector with variable coding mounted on the moving body and code readers located at points on the path of travel at which it is necessary to know the identity of the moving body or carrier, or the address thereof.

The requirements of conveyor systems for production and distribution necessitate that the moving load carriers must be checked and identified with respect to each other or with respect to addresses located along their travel. This is especially the case with transfer chains, and more particularly for selective conveyors with switching of the "power and free" type. In general, two techniques are employed: one of these is the so-called centralized selection which ensures, by means of a device separate from the conveyor proper, the desired sequence of the moving carriers and the emission of appropriate signals, giving prerecorded orders to the devices to be operated at the proper moment according to the coding operation.

The other technique, of the so-called "escort" type, has settable selectors on the moving carriers. These selectors have the property of being able to receive a given code from amongst a certain number and of keeping the code in memory until a reader arranged along the path of carrier travel and tuned to the same code detects it and emits an electric signal which can be used to control any desired function such as switching, tipping, ejection, stopping, etc. The setting of the code on the selector can be effected by a remote control, acting at the setting station, which transmits the code to the memory of the selector, or by a direct manual action on the selector.

The present invention belongs to this latter class of escort selectors with manual indexing control and automatic code reading. However, remote control of the setting of the selector is perfectly well obtainable by known means other than manual, and the invention also extends to automatic control of the selector.

An advantage of manual control resides in the ability to code the moving object by its selector in any desired point of the circuit, whereas remote or automatic control requires one or more control stations which are necessarily costly and often prohibitive if numerous setting stations are necessary.

Many moving selectors of the escort type with manual operation exist at the present time. The qualities required from them vary according to the application; the present invention is essentially directed to the following qualities:

High memory capacity with a small overall size;

Proportioning of this capacity by the adaptation of modular parts (of the decade type for example) without practical limitation;

Ability to be automatically read in motion;

Ability to set the code by manual action;

Ability to clearly read the recorded code, under different angles;

Great reliability of the code readings by elimination of the risks of interference, and complete hermetic closure against dust;

High reliability due to the elimination of mechanical operation between a selector and a reading station;

Low cost price in view of the performances obtained.

According to the invention, a magnetic coding device for a moving body such as a conveyor carrier, includes a selector mounted on the moving body and registerable with a code reader mounted along the path of travel of the moving body. The code reader comprises a group of polarized reed switches arranged in code positions around a circumference with the poles thereof alternately opposite. The selector includes a rotatable dial and a pair of permanent magnets movable therewith into a selected one of a plurality of code positions. In each of the code positions, at least one of the permanent magnets is capable of activating one of the reed switches when the selector is in registry with the code reader; and a synchronizing device carried by the code reader and selector detects such registry therebetween.

In one embodiment of the invention, the pair of permanent magnets of the selector are arranged with their poles in opposite relationship on a circumference corresponding in diameter to that of the circumference on which the reed switches of the code reader are arranged; and, the permanent magnets are spaced from each other so that in each of said code positions, one of the permanent magnets is in active relationship with one of the reed switches while the other permanent magnet is in inactive relationship with another of the reed switches. For example, such an active relationship exists when the adjacent poles of a permanent magnet and a reed switch are similar and complement each other, enabling the reed switch to be activated by the permanent magnet. An inactive relationship exists when the adjacent poles of a permanent magnet and a reed switch are opposite to each other.

In a presently preferred form of the invention, the selector includes means responsive to movement of the selector dial from one code position to another for shifting the pair of permanent magnets between positions in which one permanent magnet is active and the other permanent magnet is inactive relative to the reed switches of the code reader, the inactive magnet being preferably shielded or grounded. Such means may include a rotatable shaft on which the selector dial is mounted, a support for the pair of permanent magnets, means connecting the support to the shaft for oscillation about a pivot radially displaced from the axis of the shaft, and cam means for oscillating the support as the shaft is rotated from one code position to another. The oscillatable support enables the active permanent magnet to be positioned on a circumference corresponding in diameter to that of the diameter of the circumference on which the group of reed switches are arranged, the inactive permanent magnet being moved to a position inwardly of this circumference and preferably being shielded and grounded in this position as mentioned above.

The selector includes a ratchet device for defining each of the code positions, preferably ten, constituting a selection decade, and the code reader has a group of ten reed switches for each selection decade on the selector, it being understood that the selector may incorporate multiple selection dials in order to provide the desired number of codes.

Other features and advantages of the invention will appear from the description to follow of the representative embodiments thereof disclosed in the accompanying drawings, in which:

FIG. 1 is a schematic elevation showing a polarized reed switch and a moving magnet enabling the reed switch to be activated;

FIG. 2 is a schematic plan view of FIG. 1 representing the zone of action of the movable permanent magnet on the reed switch;

FIG. 3 is a schematic representation of a reading station with one decade;

FIG. 4 represents a selector with two permanent magnets N and S registerable with a reading station according to FIG. 3;

FIG. 5 is a schematic diagram representing a known means of synchronizing a moving selector with a stationary code reader;

FIG. 6 is a diagram showing the interaction of the magnets of the device shown in FIG. 5;

FIG. 7 is a plan view of a selector incorporating means for shifting two permanent magnets between active and inactive positions;

FIG. 8 is an elevation, partly in section, of the selector shown in FIG. 7;

FIG. 9 is a plan view of a selector with three selection dials, each with a selection decade;

FIG. 10 is a schematic elevation showing a selector approaching a code reader; and,

FIG. 11 is a sectional elevation of a conveyor track showing a selector on a conveyor carrier in registry with a code reader mounted adjacent the path of carrier travel.

In its principle, the invention utilizes the combined elements of a moving magnetic field generated by the poles of a permanent magnet and of contacts responsive to the action of this magnetic field under well defined conditions.

Both of these elements are well known and have already been employed for proximity detection. The contacts responsive to a magnetic field are commonly known as "reed switches".

In the present invention, a reed switch 1 shown in FIG. 1 is polarized by a permanent magnet 2 bonded to the wall of a protective casing 3 which preferably encloses the whole unit.

This polarizing magnet 2 has a field insufficient to close the reed switch 1 or to hold it closed.

The closure of the reed switch 1 is effected by the passage of a moving permanent magnet 4 with its polarity N-S orientated as shown in FIG. 1. The field of this magnet 4 is additive to the field produced by the polarizing magnet 2 and causes the closure of the reed switch 1, as long as the magnet 4 is located in a well-defined zone, as a function of the relative ampere-turns of the magnets 2 and 4 and of the sensitivity of the reed switch 1. The contour of this zone is represented at 5 in FIG. 2. Any magnet 4 outside this contour 5 cannot close the reed switch 1, whereas any magnet 4 located inside the contour 5 holds the reed switch closed.

It will be understood that a moving magnet orientated in the direction opposite to the magnet 4 cannot in any case actuate the reed switch 1 as long as the field resulting from this moving magnet and the polarizing magnet 2 is less than the closure field of the reed switch 1. The reed switches employed are constructed in such manner that the differential: closure ampere-turns -- opening ampere-turns is small, so that for a direction of movement of the moving magnet from the left towards the right, the contour of the operating zone 6 of the reed switch differs very little from the contour 5. This particular feature of construction is covered by the invention and permits at the same time a small overall size of the device and an increased reliability of the reading, as will be explained below.

FIG. 3 represents a code reader with one decade, permitting a moving selector to be read in the decimal code, which may be a number comprised between 0 and 9. Ten polarized reed switches 7 are arranged on a circumference 8 with the poles thereof alternately opposite, or in such a manner that any two adjacent reed switches are actuatable by moving magnets of inverse polarity. Thus, the reed switch reading the code 1 is known as "South" and is closed by the passage of a moving magnet, the South pole of which is facing this reed switch; and, the reed switch reading the code 6 is known as "North" and is actuatable by a moving magnet having its North pole facing this reed switch. It will be understood that to achieve this, the two reed switches have polarizing magnets with oppositely arranged fields.

FIG. 4 shows an arrangement of two permanent magnets N and S of a selector employable with the code reader described above. The reed switches 7 of the code reader of FIG. 3 are separated from each other by an angular distance of 36°, while the North and South permanent magnets 9 and 10 of the selector are separated by an angular distance of 144° and are located on a circumference 11 of the same diameter as that of the circumference 8. Thus, when the code reader and selector are exactly superimposed or registered with each other, if the North magnet 9 sees a reed switch 7 with North polarization, the South magnet 10 will see a reed switch 7 with North polarization. This arrangement is thus such that one magnet and one magnet only of the selector is active in each code position.

However, in the displacement of the selector from left to right towards the code reader, it will be understood that the North magnet 9 will successively actuate the code reed switches 8 and 0 and that the South magnet 10 will successively actuate the code reed switches 3 and then 1. In the respective arrangement of the reading elements of FIG. 3 and of the selector of FIG. 4, the code to be read is the code 2 when the code reader and selector are in registry.

In order not to take into account any parasitic readings, a synchronization device shown in FIG. 5 is employed to detect such proper registration and permits only the reading corresponding to the superimposition of the reading station and the selector to be taken into consideration. This well-known device utilizes two reed switches 12 and 13 fixed at the reading station and two permanent magnets 14 and 15 fixed on the selector.

The two reed switches 12 and 13 are preferably of the polarized type in order to have greater precision in the closure and opening synchronizing pulses, and the two moving magnets have a distance between their axes slightly less than that of the two synchronizing reed switches 12 and 13. In this such manner, the reading information is only taken into account in a zone which is geographically limited at will by the displacement of the distance between centers of the magnets 14 and 15 with respect to the distance between axis of the reed switches 12 and 13. As indicated in FIG. 6, the line 16 represents the axis of the centers of the two circumferences 8 and 11 (FIGS. 3 and 4) when the code reader and selector are superimposed, the line 17 indicates the zone of action of the magnet 14 on the reed switch 12, the line 18 indicates the zone of action of the magnet 15 on the reed switch 13, and the line 19 indicates the smaller zone of action during which the reed switches 12 and 13 in series enable account to be taken of the reading of the code

The arrangement of the various elements described above and the use of a synchronization device make it possible to avoid interference between two codes during a synchronizing pulse for a smaller overall size of the selection device.

However, in order to be able to reduce still further the diameter of the circumferences 8 and 11 of FIGS. 3 and 4, which implies the necessity of bringing the ten reed switches 7 still closer together, a preferred form of selector of the present invention includes the improvement of bringing the non-active magnet of the selector closer to the center of the circumference 11, only keeping the active magnet on the periphery of the circumference 11. An example of a mechanical solution of the retraction of one magnet in two is shown diagrammatically in FIG. 7, by way of non-limitative example, and will be described below.

The selector of FIGS. 7 and 8, is built around a commercial ratchet device 20b having a shaft 20a and ten equidistant code positions.

The shaft 20a of the ratchet is equipped with an operating member or dial B, preferably fitted with an inclined and engraved base 29. The various graduations are marked in the increasing direction from zero to nine, and their orientation is a function of the geometric position of the code carrier on each installation. Each of the ten code positions is indicated by a fixed index 30.

Two cylindrical magnets 21 and 22 are so directed that one North-South magnet 21 has its North pole facing the reed-switches of a reader while the other South-North magnet 22 has its South pole facing such reed switches. In addition, these two magnets 21 and 22 are arranged in such manner that when one magnet is active, that is to say it is located on the circumference 8 (FIG. 3), the other is passive, that is to say it is located inside of this circumference and outside the zone of action of the reed switches.

In the angular position of FIG. 7, the magnet 21 is active and the magnet 22, displaced towards the center, has its poles shielded by two pole-pieces 23, thus closing its lines of force through the ratchet shaft 20a on which the pole pieces 23 are mounted.

The two magnets 21 and 22 are carried by an oscillatable support 24 driven by the ratchet shaft 20a through the intermediary of two arms 25 mounted on the shaft and to which the support 24 is connected by a pivot radially displaced from the axis of the shaft. An oblong slot L permits the free passage of the ratchet shaft through the oscillatable support 24.

In order that, at each of the ten possible angular positions of the device, each of the magnets is alternately presented on the active circumference 8 (see FIG. 3), two star-shaped cams 27 and 28, each having five points, form a guiding track for a follower 26 rigidly fixed to the oscillating support 24.

A particular feature resides in the alternate formation of a curvilinear guiding zone on the cam surface of the outer cam 28 in order to permit the same possibility and smoothness of operation in both directions of rotation of the operating member B. The angular positions of the ratchet system are also reinforced by the relative attraction between the inactive magnet and the two pole-pieces 23.

Hence it will be seen that the selector of FIGS. 7 and 8 includes means responsive to movement of the operating member or knob B from one code position to another for shifting the pair of permanent magnets 21 and 22 between active and inactive positions relative to the reed switches 7 of the code reader, one of the permanent magnets being active and the other being inactive in each code position; and, the inactive permanent magnet being shielded or grounded.

The selector mechanism is attached to a support 31 by means of a threaded socket and a nut.

A closure plate 32 located on the active face side of the device retains the moving assembly formed by the parts 21, 22, 23, 24 and 25.

All the parts with the exception of the parts 20a, and 23 must be made of a non-magnetizable material.

The angular combination of the above selector mechanism and the code reader shown diagrammatically in FIG. 3 is such that:

The North magnet 21 is active at the five even-numbered positions 0, 2, 4, 6, 8;

The South magnet is active at the five odd-numbered positions 1, 3, 5, 7, 9,

In the above description, given by way of example and without limitation, mention has only been made of one decade. It will be understood that it is quite possible to associate a plurality of decades, for example three, which will permit the reading of 999 codes, the first decade serving to read the units, the second for reading the tens and the third for reading the hundreds. As a function of the number of reed switches employed and of the electrical circuit adopted, it will be possible to read one or a plurality of codes from a single reading station.

A possible example of an embodiment with three decades used with a conveyor is illustrated in FIGS. 9, 10 and 11.

FIG. 9 shows diagrammatically a selector including the support 31, three operating knobs 29 and three code position validation pointers 30.

FIG. 10 is a diagrammatic view of the selector approaching a code reader 34. In this embodiment, the closure plate 32 projects slightly from the support 31 in order to serve as a guiding member.

During the operation of bringing the selector into registry with the reader, this plate 32 first encounters two guides 37 which ensure the horizontal centering of the code reader with respect to the selector. As the movement of the selector then continues, this same plate 32 encounters a portion 38 which then ensures vertical centering by raising the code reader 34. A suspension of the code reader by two rods 35 with oval slots permits this slight movement.

FIG. 11 completes this description by showing diagrammatically the end view (known as the running section) of an installation on the track V of a conveyor. A support 36 holds the code reader 34 at a suitable height and distance with respect to the axis 33 of the track V.

The advantages of a system of this kind include the utilization (not limitative furthermore) of the decimal system, and the ability to visually read the code of the moving body by the particular arrangement of the operating members of the selector.