What is claimed is
1. An apparatus for magnetically identifying a material unit at a predetermined location in a system having a conveying medium and a second medium, the conveying medium moving relative to said second medium along a path, one of said media supporting a material unit, said apparatus comprising a magnetic memory plate device associated with the material unit, a magnetic head device, means for supporting said magnetic memory plate device in a predetermined relation to said material unit on the medium supporting said material unit, means for supporting said magnetic head device on the other medium, one of said magnetic devices and its associated supporting means being adapted to be moved by said conveying medium relative to the other device generally along the conveying path, guide means associated with one of said magnetic devices for aligning both of said devices for magnetic coupling independently of ordinarily expected deviance of the supporting means associated with said one magnetic device moved by said conveying medium transverse to said path, one of said device supporting means supporting its associated device for resilient movement transverse to said path towards the other device at said predetermined location.
2. An apparatus as set forth in claim 1 wherein said guide means comprises a pair of opposed surfaces having portions extending transversely to said path.
3. An apparatus as set forth in claim 2 wherein said guide means is associated with said magnetic head and other portions of said opposed surfaces are spaced apart a distance slightly greater than the thickness of said memory plate.
4. An apparatus as set forth in claim 3 wherein a pair of plates provide said opposed surfaces and each of said plates is flared outwardly to provide said transversely extending portions.
5. An apparatus as set forth in claim 3 wherein the magnetic head device supporting means includes said guide means.
6. An apparatus as set forth in claim 5 wherein said magnetic head device supporting means also includes an elastic member fixed to the medium associated with said magnetic head device and permitting resilient movement of said head transverse to said path.
7. An apparatus as set forth in claim 1 wherein each of said device supporting means supports its associated magnetic device for movement relative to the associated medium transverse to said path, said guides means causing both of said devices to move laterally together at said predetermined locations.
8. An apparatus as set forth in claim 7 wherein each of said device supporting means supports its associated magnetic device for pivotal movement.
9. An apparatus as set forth in claim 1 wherein said guide means includes a pair of opposed surfaces associated with one of said magnetic devices having a predetermined spacing transverse to said path, the other of said magnetic devices including a portion having a width transverse to said path smaller than said predetermined spacing to thereby allow said portion to freely pass between said opposed surfaces at relatively high speed.
10. A system containing a succession of material units, a conveying medium, a second medium, the conveying medium moving relative to the second medium along the path, one of said media supporting said succession of material units, and apparatus for magnetically identifying each material unit including a magnetic head, means for supporting the magnetic head on the other of said media, a flexible magnetic memory plate associated with each material unit, means for supporting each memory plate in a predetermined relation to its associated material unit, the conveying medium causing relative transverse deviation between said magnetic head and said magnetic memory plates, guide means associated with said magnetic head including guide surfaces extending transversely to said path, said flexible magnetic plates being deflected by said guide surfaces into alignment with said magnetic head independently of said relative transverse deviation between said magnetic head and said magnetic plate.
11. A materials handling system comprising a conveyor carrying a succession of material units along a path, a stationary material unit identification station, a magnetic memory plate associated with each material unit and moving with said conveyor past said identification station, said identification station including a magnetic head, opposed guide plates for guiding said magnetic memory plates into alignment with said magnetic head, said opposed guide plates having flared portions extending transversely to said path, a spacer element maintaining other portions of said plates apart a distance slightly greater than the thickness of said magnetic plates, said magnetic head being supported on one of said opposed plates, elastic means supporting said guide plates for pivotal movement transverse to said path, said magnetic memory plates being mounted for pivotal movement relative to said conveying medium and transverse to said path, engagement between a magnetic memory plate and a flared portion of a guide plate causing pivotal movement of the memory plate and said guide plate towards each other to align said memory plate and said magnetic head independently of side sway of said conveyor.
BACKGROUND OF THE INVENTION
This invention relates to an improvement in apparatus for magnetically identifying material units. More specifically it relates to apparatus for scanning a succession of material units with a magnetic device for identification purposes.
The term "material unit" is intended to include any material or product, or quantity or group thereof, which is segregated or capable of being segregated from similar or dissimilar materials or products. Thus, material units may comprise such various commodities as appliances, tools, packaged or bottled goods, and loose materials on a tray or conveyor.
The invention may be employed where it is desirable to identify such material units in industrial or commercial systems. Typical systems in which this invention may be employed include automatic warehousing, inventory control, material handling, conveyor sorting, stacking, baggage handling, mass transit, process control and automatic machines such as transfer devices and numerically controlled machine tools.
Magnetic devices are particularly suited for sensing or switching signals since they do not require mechanical contact or movement and are therefore not subject to wear and eventual failure. For these reasons, it has been previously proposed to use magnetic recording and reading devices for identifying material units in the above type of systems. Various such systems have been disclosed, for example, in U.S. Pat. Nos. 3,075,653, to D. A. Wales et al. and 3,214,003, to W. E. Wilson.
In a typical system, such as a materials handling system, a succession of material units may be carried on a conveyor through various sorting or processing stations where each material unit may be diverted, altered, or counted, or the like. A magnetic plate, identifying a particular material unit, may be secured to the unit itself or a component of the conveyor and the magnetic plate may be magnetized or sensed by a stationary magnetic head.
Ordinarily the material units are not uniformly deposited on the conveyor and the conveyor will exhibit random side sway motion transverse to the conveying direction due to tolerances in the conveyor guides. Since physical contact between the magnetic devices is not necessary for their operation, it has been customary in the past to separate the stationary magnetic device from the nominal or theoretical path of the moving device by a distance greater than the expected deviation or side sway of the moving device from its nominal path. Such an arrangement avoids the risk of physical interference between the magnetic devices in a simple manner but may be unsatisfactory in some instances.
The performance of the magnetic devices will be unreliable when the displacement of the moving device from its nominal path is relatively large in comparison to the maximum allowable spacing between the magnetic devices. It may be appreciated that the side sway of a conveyor will increase, due to acceleration forces, when conveyor speed is increased. Substantial side sway motion and vibration may cause weak magnetic signals and may introduce error signals. For these reasons magnetic identification apparatus previously available has been somewhat limited in certain applications particularly where high speed is involved.
SUMMARY OF THE INVENTION
The invention provides an apparatus for aligning a magnetic identification or memory plate and a magnetic head for detecting or recording magnetic signals on the memory plate. Mounting structures are provided at both the magnetic head and the plate to permit these devices to move into alignment as one is conveyed past or scans the other. Guide surfaces are also provided to bring the magnetic devices into alignment and to maintain alignment while the devices are in communication. The mounting arrangement and guides permit uniform alignment of the magnetic devices regardless of the relative positions of their supporting media for near perfect signal recording or detection.
With the magnetic memory plate accurately positioned relative to the magnetic head signal errors due to secondary motion of the conveying medium are eliminated. Thus, the invention is particularly suited for high-speed conveying or scanning. Further, the apparatus simplifies initial installation because the normal or ideal position of the devices is not critical due to the self-aligning nature of the apparatus. Additionally, the apparatus eliminates the risk of physical interference and collision between components.
An additional feature of this invention is a flexible magnetic memory plate which improves the operation of apparatus. Flexibility permits the memory plate to adjust itself relative to the magnetic head and minimizes any impact forces between it and other components of the apparatus. Flexibility also permits the plate to be used in conveying systems having relatively tight turns or corners since the plate may be made to flex around such corners.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary perspective view of a somewhat schematic conveying system employing the apparatus of this invention.
FIG. 2 is an elevational view of the apparatus with the magnetic memory plate in cross section as indicated by the lines 2--2 in FIG. 1.
FIG. 3 is a view similar to FIG. 2 showing the magnetic memory plate support misaligned with the magnetic head support.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A materials handling system 10 is shown in the figures and described below to explain the operation of the apparatus embodying this invention with a typical system. The material handling system includes a conveyor car 11, a main track 12, and a secondary or diversion track 13. The conveyor car 11 carries a material unit or package 14 through the system 10. It should be understood that the system 10 would include other conveyor cars and possibly other diversion tracks but they need not be shown for the purposes of this description. While the illustrated embodiment employs mechanical tracks or guideways, the present invention is adaptable to trackless trolley systems where conveyor cars or trolleys are guided by other means, e.g., optically or by radio waves.
The system 10 may be a live storage or circulating conveyor on which individual material units are circulated until it is required to divert a particular unit or series of units. An example of such a system is a baggage handling system at a transportation counter. In such a system, the material unit would represent a rider's baggage circulating with others on the conveyor until claimed. When claimed the baggage or material unit 14 would be diverted onto the secondary track 13 to a baggage claim station.
To divert or separate any desired material unit 14 from the remaining units circulating in the system it is necessary to identify each unit. Here, the identification contemplated is a magnetic code recorded on a piece of magnetic material associated with each material unit 14. The code used to identify a material unit may be any suitable one such as a serially written binary code. When used hereafter the terms "identify," "identifying," "identification," or the like are meant to include the process of which a magnetic code is recorded or written on the magnetic material associated with the unit 14 or the process by which a recorded code is detected or read.
The apparatus of this invention includes two magnetic devices which are a magnetic head, for recording or reading, and a magnetic memory plate or surface 17. For the purpose of explanation, two magnetic heads 18 and 19 are shown at two separate stations 22 and 23. The magnetic heat 18 at the first station 32 is a recording or write head and the magnetic head 19 at the second station 23 is a detecting or reading head. The magnetic heads 18 and 19 are depicted as boxlike members in the figures for simplicity. The actual construction of these heads is not critical to the invention and various magnetic heads familiar to those skilled in the art may be used satisfactorily. An electromagnetic recording or write head should be chosen by considering its number of turns, head gap and width, and magnetic field level such that it will magnetize the memory plate deeply.
Preferably, the read head 19 is a polarity sensitive device such as shown in my U.S. Pat. No. 3,425,047 using a Hall effect crystal. Other magnetic flux sensitive devices such as shown in U.S. Pat. No. 2,974,277 to D. A. Wales or a magnetic responsive transistor may likewise be used to detect a recorded magnetic signal on the plate 17. A polarity sensitive read head does not depend on relative motion between it and the magnetic plate and, therefore, allows the plate to be read when it is motionless or traveling at high speed.
While the magnetic write head 18 and the magnetic read head 19 are described as being mounted at separate stations 22 and 23 it may be desirable to mount writing and reading heads at a single station. For instance, when a serially written binary code is used for identification it may be advantageous to provide a read head and a write head at the same station. In such a case the read head may be used to sense prerecorded clock or reference signals at specific locations on the memory plate 17 so that the write head will record at points on the plate having a predetermined relation to the location of the clock signals.
Serial recording and reading of data requires a minimum of magnetic heads at each station. Therefore, when cost and complexity are considered, a serial system is normally preferred to parallel or multichannel systems utilizing numerous simultaneously operating writing or reading heads at each station. Nevertheless, it should be understood that this invention may be advantageously employed in such parallel systems. Moreover, several reading or writing stations may be provided in a particular system when necessary.
The members supporting the magnetic write head 18 and the magnetic read head 19 are substantially the same and the same reference numerals have been used in the figures to indicate similar parts. Each head 18 and 19 is directly supported on a guide plate or vane 26. A magnetic head may be secured on a guide plate or vane 26. A magnetic head may be secured to the vane 26 by screws (not shown) or the like. The vane 26 is preferably made of a nonmagnetic metal such as stainless steel, aluminum, brass, or a plastic material so that it will not interfere with the operation of the head. Depending on the thickness of the vane material, it may be necessary or desirable to provide a recess or hole in the vane in the area of the magnet head to permit the head to be mounted as close as possible to the path of the memory plate 17. A second guide plate or vane 27 is provided at each station 22 and 23 opposite the vane 26 supporting the magnetic head.
The opposed vanes 26 and 27 are secured to a spacer plate 28 by a pair of bolts 29. The spacer plate 28 is slightly thicker than the magnetic memory plate 17 so that the central portions of the vanes 26 and 27 are parallel and spaced apart sufficiently to permit free movement of the memory plate 17 between them. The opposed vanes 26 and 27 confine the memory plate 17 to a regular path relative to the magnetic head 18 or 19 and insure that magnetic coupling will be optimized. A spacing of the magnetic heads of about 0.005 inch to 0.015 inch from the adjacent surface of the plate 17 has yielded excellent results. In addition to improving overall accuracy, it has been found that when the magnetic heads and plate are closely aligned in this manner, it is possible to significantly raise the practical bit or informational density on the plate. That is, more data or magnetic signals may be recorded per square inch of plate area than is possible if the magnetic heads are not closely aligned.
The spacer plate 28 is resiliently mounted on a set of elastic mounts of rubber or the like. The set of elastic mounts comprises a pair of elastic strips 31 at each end of the spacer plate 28 and a pair of elastic pads 32 at the center of the spacer plate 28. These elastic members 31 and 32 are secured to both sides of the spacer plate 28 by means of bolts 33 and a pair of upper tie bars 34. The elastic members 31 and 32 are gripped on their lower sides by a pair of lower tie bars 36 and associated bolts 37. A pair of spaced brackets 38 support the rubber mount assembly on a stationary member 39 which may be part of the conveyor frame structure.
The magnetic identification or memory plate 17 is shown secured to the conveyor car 11. Alternatively the memory plate 17 is shown secured to the conveyor car 11. Alternatively the memory plate 17 may be secured to the material unit 14 itself. The plate 17 is clamped between a pair of mounting bars 41 with a set of bolts 42. A clevis-type structure 43 fixed to the mounting bars 41 permits the magnetic memory plate 17 to pivot on a mounting rod 44 extending from the conveyor car 11 in the direction of conveyor travel.
FIG. 2 shows the relative positions of the magnetic memory plate 17 and magnetic head 18 when the conveyor car 11 is in its nominal or theoretical path. The elastic mounts 31 and 32 normally support the guide plates in a generally vertical plane and the magnetic memory plate 17 also normally rests in a vertical plane. FIG. 3 shows a situation where the conveyor car 11 is displaced to the right of its theoretical path, due to side sway, structural vibration, or initial misalignment, such that the mounting rod 44 is misaligned with respect to the stationary member 39 which supports the magnetic head. Where the conveying medium or car 11 is misaligned with respect to the stationary member 39 both the magnetic memory plate 17 and the magnetic head 18 or 19 may pivot into mutual alignment.
As shown, the magnetic head may deflect in the direction of deviation of the conveying medium and the magnetic memory plate 17 may deflect towards the magnetic head. Ideally, the vanes 26 and 27 are relatively light in weight to facilitate their deflection during high-speed operation. The entrance and exit ends of both of the guide plates or vanes 26 and 27 have outwardly flared portions 46 and 47. The distance which the vanes 26 and 27 are flared transversely to the theoretical path of the memory plate determines the permissible or correctable misalignment in the system. As long as the magnetic memory plate 17 engages an area of the flared portion 46 or 47 of one of the vanes, the plate 17 and magnetic head will be accurately aligned.
Misalignment of plus or minus one-half inch vertically and horizontally at a reading station has been successfully accommodated in a system operating at a conveying speed of 35 ft./sec. Vertical misalignment problems may be eliminated by recording magnetic signals on the memory plate 17 with a vertical extent greater than the expected vertical displacement amplitude. This technique of recording elongated vertical signals also eliminates the risk of error when the horizontal misalignment is large enough to cause the memory plate to slide toward the upper sides of the guide plates 26 and 27. This sliding phenomena is illustrated in FIG. 3 where the lower edge of the memory plate is slightly displaced from the upper edge of the spacer plate 28.
In its preferred form, the magnetic memory plate 17 comprises a flexible magnetic elastomeric or rubber sheet. Flexibility allows the memory plate 17 to be more readily aligned to the magnetic head 18 or 19 as it passes between the vanes 26 and 27. In fact, the pivot arrangement provided by the clevis 43 may be eliminated if the memory plate 17 is sufficiently flexible. The use of a flexible memory plate also reduces impact forces during engagement of the guide plates or vanes 26 and 27 since the entire memory plate need not be deflected at once. An additional advantage of a flexible memory plate is that it may be used with a magnetic head at a sharp corner in a conveying system since the plate may adjust for differences between the conveyor path and that required by a magnetic head.
Type of elastomeric sheet forming the memory plate 17 is commercially available and comprises an elastomeric compound impregnated or filled with magnetic material such as iron oxide. Various combinations of elastomeric compounds and magnetic materials are available having satisfactory flexibility and magnetic properties for operation in temperature environments ranging between -40° F. and 500° F. In extreme environmental conditions a rubber memory plate alone may not be satisfactory. For instance, in high-temperature applications it has been found desirable to reinforce a rubber based magnetic memory plate with a flexible metal sheet. Further, while the preferred embodiment of this invention employs a flexible plate, various other magnetically responsive surfaces may be used. These may include conventional magnetic tape or surfaces sprayed with a magnetic flux sensitive coating comprising a binder and a disposed finely divided magnetic material.
In operation, the conveying car 11 is loaded with a material unit 14. When the magnetic memory plate 17 associated with this material unit passes the write station 22 a magnetic code representing or identifying the material unit is recorded on the plate by means of conventional external electronic circuitry. As the conveying car passes along the conveying path the memory plate eventually enters the read station 23 and the magnetic code is read by the magnetic read head 19. If the recorded code is recognized by the read head 19 and its associated electronic circuitry to represent a material unit to be diverted onto the secondary track 13 a track switch, not shown, will be energized by the electronic circuitry to divert the conveyor car.
A relatively simple material handling system has been chosen here to represent the type in which the invention may be employed. It should be appreciated that the invention may be used in various other systems. For instance, in an inventory control system the material units may be stored at fixed stations and the magnetic head may be conveyed past the material units to scan associated stationary memory plates. Various modifications and rearrangements of the described apparatus may be employed without departing from the scope of the invention as set out in the following claims.