GB2181610A - Monitoring apparatus - Google Patents

Abstract

Apparatus for monitoring movement of an element (70) along a path (12) comprises transmitter/receiver devices (14, 16) on the element arranged in front of a screen (18) which can allow a unique combination of radiation to be transmitted and received according to the position of the element along the path. <IMAGE>

Description

SPECIFICATION Monitoring apparatus This invention is concerned with monitoring apparatus and is particularly concerned with apparatus for monitoring translational movement of an element along a path.

In the specification of our copending UK patent application no. 8425407 there is disclosed apparatus for moving a tape cartridge between an allocated position in a store of cartridges and a record/playback position, the apparatus comprising elevator means arranged to move between the level of a selected cartridge ofthe store and the level of the record/playback position, and cartridge-displacing means mounted on the elevator means for engaging a selected cartridge to move the cartridge between the store and the elevator means and between the elevator means and the record/playback position, so as to present the selected cartridge to and withdraw the cartridge from the record/playback position with the cartridge in a horizontal attitude.

The cartridge-displacing means carried by the elevator means comprises, in the preferred embodiment disclosed in the aforesaid application, an arm portion which is arranged to be moved horizontally and entrain the selected magnetic storage tape cartridge for horizontal sliding movement between an elevator platform and a read/record head of a playback/recording unit and between the elevator platform and a selected location in a vertical stack of cartridges. In an automated apparatus it is critical that the movement of the arm portion is accurately controlled to ensure that at all times the selected cartridge is properly handled and does not become damaged, and thatthe equipment with which it is used is also not damaged.However, whilstthe present invention is hereinafter disclosed in the context of monitoring such horizontal movement it isto be clearly understood thatthe invention can be used in monitoring translational movement of other elements along a path.

According to the present invention, there is provided apparatus for monitoring translational movement of an element along a predetermined route, said apparatus comprising elongate means extending along said route; a plurality of detector means mounted for movement with said element and arranged to trace out respective paths over said elongate means during movement of the element; and physical-discerniblefeatures provided along the elongate means in correspondence with the said paths traced out by the detector means; each detector means being sensitive to the presence or absence of said features along its path and the disposition of said features being such as to produce unique detector output combinations at predetermined location, and/or over predetermined ranges of locations of said element along its route.

Preferably, each detector means comprises a radiation receiver, the apparatus further including radiation transmitter means.

Advantageously, in apparatus according to the last preceding paragraph, the radiation transmitter means is mounted for movement with said radiation receivers, the said physically-discernible features of the elongate means being areas having significantly different reflective characteristics to adjacent zones along the elongate means whereby said features are detected by the radiation receiver as differences in radiation reflected thereto from the transmitter means. Preferably, said elongate means is in the form of an apertured reflective bar, the or each aperture in the bar providing a non-reflective area while adjacent zones of the barprov- ided reflective areas.

In the reflectivity-dependent arrangements of the preceding paragraph, the transmitter means may be a single source providing a divergent beam arranged, where appropriate, to be reflected back to each receiver; however, it is preferred that each receiver has its own associated transmitter arranged to produce a substantially parallel beam of radiation.

As an alternative to the reflectivity-dependent arrangements of the last two preceding paragraphs, transmissivity-dependent arrangements can be provided. In these cases, the elongate means is interposed between the transmitter means and the radiation receivers and the said physically-discernible features are areas having significantly differenttransmissive characteristics to adjacent zones of the elongate means.

In a preferred form ofthe apparatus set out in any one of the last five preceding paragraphs, each detector means constitutes, either in part or in whole, a two-state switch. Advantageously, two detector means are provided, the arrangement being such that the associated four possible switch-output combinations serve to identifytwo point locations and two location ranges of said element along its route. The two point locations are, for example, positioned at opposite ends of a first one of said location ranges the second ofwhich extends on from said second point location.In this case and where the apertured-reflective bar discussed above is employed, the bar is advantageously apertured in correspondence with both radiation receivers at said first location, apertured in correspondence with one only of the radiation receivers over the first location range, apertured in correspondence with the other only of the radiation receivers over the second location range, and un-apertured in correspondence with said second point location.

It will, of course, be appreciated that more than two detector means can be provided where a larger number of point locations/location ranges are to be detected.

Furthermore, in its broadest conception the present invention envisages the use of detector means other than radiation receivers. Thus, for example, each detector means may be constituted by a microswitch; in this case, the physically discernible features to which the microswitches are sensitive will be constituted by depressions, grooves, lands, protuberances or actuating fingers. Instead of using microswitches it is equally possible to provide detector means in the form of capacitive or inductive sensors; for example an array of capacitor electrodes or plates may be provided arranged to cooperate with similar electrodes or plates of opposite polarity arranged along the elongate means and constituting said physically-discerniblefeatures.

The element itself may be moved along its route by means of a motor controlling a drive system for moving the element. If the motor is provided with a rotary optical counter on its output shaft, then togetherwith apparatus according to the invention, a very precise positioning of the element can be achieved.

There now follows a detailed description which is to be read with reference to the accompanying drawing of an apparatus according to the present invention; it isto be clearly understood that this apparatus has been selected for description to illustrate the invention by way of example and not byway oflimitation.

The drawing is a perspective schematic view of a preferred embodiment of the invention and illustrates apparatus which is intended for use in monitoring the transport of a data storage magnetic tape cartridge between a recording/playback head and an allocated location in a cartridge storage stack as for example of the type disclosed in our copending UK patent application no.8425407 in which a selected cartridge can be transferred between the storage stack and the head, by horizontal movement of an entraining arm portion of the apparatus disclosed therein and byvertical movement of a platform between the horizontal level ofthe head and that of the allocated location.

The illustrated apparatus is adapted to be mounted for vertical movement with the platform (not shown in the drawing), and the elementwhosetranslational movement is desired to be monitored is an arm portion 70 arranged to entrain the cartridge, the translational movement being the horizontal movement of the arm portion between the recording/playback head and the platform position and between the platform position and the allocated location in the storage stack.

The element(orarm portion) is indicated diagrammatically at70 and is mounted on a block 10which,as indicated by the arrows 12, can be moved bidirectionally along a single horizontal axis, to or from the elevator position along a guide rail 13.

The block 10 has mounted thereon two transceiver units provided by first and second infrared emitter/ detector units 14,16 which are mounted vertically one above the other, the two units being electrically connected to control systems for moving the arm portion 70 and the block lOon which the arm portion is fastened. The two units 14,16are arranged to emit parallel, horizontal beams of infrared radiation.

Spaced from the block 10 and extending parallel to its horizontal axis of movement is an elongate radiationreflective metal screen 18 which extends the length of the path of movement ofthe block 10. This screen 18 is fixed such that the block 10 moves parallel to it and is mounted for vertical movement with the platform. A first elongate slot 20 formed in the screen 18 extends from adjacent one end ofthe screen to approximately halfway along the screen. A second elongate slot 21 extends approximately from this half-way location towards the other end ofthe screen 18. The slot 20 is formed horizontally opposite the path traced by the second emitter/detector unit 16 so that as the block 10 travels along its path,the infrared radiation is transmitted through the slot.Adjacent the one end of the screen, the slot is extended upwards, as indicated at22, so that, atthat position only, when the emitter unit 14 is opposite the portion 22 ofthe slot, radiation is transmitted therethrough. Thereafter, as the block 10 moves along its path, radiation which is emitted by the emitter 14 is reflected by the screen 18 backto the corresponding detector.

Between the adjacent ends of the slots 20,21, a portion 23 ofthe screen is continuous.

The second slot 21 is formed horizontally opposite the first emitter/detector unit 16 so that as the block 10, supporting the arm portion 70, continues along its path, radiation from the unit 16 passes through the slot whilst radiation from the unit 14 is reflected back to the detectorthereof.

Thus when the apparatus is in use, it can monitor the movement of the arm portion 70 along the aforement ioned path. If the reflection of radiation and its detection is designated by abinary '1' whilst the non-reflection (and so non-detection) of radiation is designated by a '0', then this can be represented bythe following table with reference to the positions indicated in the drawing.

A A < - > B B Unit14 0 1 1 0 Unit16 0 0 1 1 In relation to the apparatus disclosed in our aforesaid co-pending UK application, position Acorresponds to the position at which a cartridge entrained by the arm portion 70 is located at the recording/playback unit, position B corresponds to the position at which the cartridge is positioned on the elevator platform by the arm portion, and position C corresponds to the position at which the arm portion 70 engages a cartridge in the latter's allocated position in a stack of cartridges, while A < - > B and B < - > C indicate the positions of the arm portion 70 as it is moved between positions A and B and positions B and C.At position B, the arm portion 70 may be raised/lowered between the position, at which it can be moved horizontallytowards or from the recording/playback unit, and the position at which it can be returned to or extracted from its location in a cartridge track.

Thus the position of the arm portion 70 along its path can be uniquely determined, and control of its movement effected. A control system associated with the apparatus will acknowledge the zero detector re sponse atA as indicating that the horizontal movement of the arm portion commences orterminates atthat point, and thus will start or stop the drive motortherefor at that position. Where the arm portion 70 has previously stopped at A an overriding instruction from the control system causes the motorto beenergisedto move the arm portion towards position B.During such movement, operation of the drive motor is then under the control of the control system underthe command of the response of the detector of the unit 14tothe reflected radiation received thereby. At position B, both units 14 and 16 receive reflected radiation which the control system interprets as an instruction to stop the motor. Thus the motor is de-energised while the arm portion is located over the vertically-movable platform, with or without a cartridge positioned on the platform. When the platform attains the desired vertical position, a further overriding instruction is provided by the control system to re-energisethe motor to effectfurthertranslational movement of the arm portion 70 from position B to position C, and subsequently by the same method from position B to position A.

In practice, the apparatus would be encased together with the apparatus with which it is to be used in a casing, obscuring the apparatus from view. Thus when the apparatus isset-up, it can provide an immediate indicator, via the control system, as to the initial position of the arm portion 70 and thus of whether or not a cartridge is at the playbackirecording position. Alternatively,it can be used to initialise a system.

In the embodiment disclosed in our aforesaid copending UK patent application, the guide rail is a threaded shaftco-operating with a threaded bore in the block 10,the shaft being rotatably driven by a motorthrough suitable reduction gearing. In an alternative embodiment, the block 10 may, as shown in the drawing, slide on a guide rail, the movement of the block then being governed by, for example, coupling the block to an endless belt extending around pulleys, one of which is driven through suitable reduction gearing by a motor. In both cases, the motor may carry an optical counter whereby the control system can determine the precise position of the block 10, and thus of the arm portion 70, between positions A and C.

Obviously, the form and position ofthe two slots can be different from that shown in the drawing, provided that the detection or non-detection of radiation by one or the other or both of the two detector units 14 and 16 is uniquely detectable at each of the two positions A and B and between A and B and C.

As an alternative to the above-described embodiment in which the screen is provided with slots, the screen may be solid and coated with, for example, a matt black coating which will absorb radiation incidentthereon, in which case strips of reflective material may be provided on the screen to reflect radiation where required.

Claims (9)

1. Apparatus for monitoring translational movement of an element along a predetermined route, said apparatus comprising: elongate means extending along said route; a plurality of detector means mounted for movement with said element and arranged to trace out respective paths over said elongate means during movement of the element; and physically-discernible features provided along the elongate means in correspondence with the said paths traced out by the detector means, each detector means being sensitive to the presence or absence of said features along its path and the disposition of said features being such asto produce unique detector-output combinations at predetermined locations, and/or over predetermined ranges of locations, of said element along its route.

2. Apparatus according to claim 1, wherein each detector means comprises a radiation receiver, the apparatus further including radiation transmitter means.

3. Apparatus according to claim 2,wherein the radiation transmitter means is mounted for movement with said radiation receivers, the said physically-discernible features of the elongate means being areas having significantly different reflective characteristics to adjacent zones along the elongate means whereby said features are detected by the radiation receiver as differences in radiation reflected thereto from the transmitter means.

4. Apparatus according to claim 3, wherein said elongate means is in the form of an apertured reflective bar, the or each aperture in the bar providing a non-reflective area while adjacent zones of the bar provide reflective areas.

5. Apparatus according to claim 3 or claim 4, wherein each radiation receiver has its own associated radiation transmitter.

6. Apparatus according to claim 2, wherein the elongate means is interposed between the transmitter means and the radiation receivers and the said physically-discernible features are areas having significantly differenttransmissive characteristics to adjacent zones of the elongate means.

7. Apparatus according to any one of the preceding claims, wherein each detector means constitutes, either in part or in whole, a two-state switch.

8. Apparatus according to claim 7, wherein two detector means are provided, the arrangement being such thatthe associated four possible switch-output combinations serve to identify two point locations and two location ranges of said element along its route.

9. An arrangementfortransferring a cartridge between a store and a record/playback position, said arrangementcomprising elevator means arranged to move between the level of a selected cartridge ofthestore and the level of the record/playback position, and cartridge-displacing means mounted on the elevator means and including an element for engaging a selected cartridge to move the latter between the store and the elevator means and between the elevator means and the record/playback position; the cartridgedisplacing means further including control means provided with apparatus, according to claim 1, for monitoring the movement of the element, said apparatus being arranged to provide respective unique detectoroutput combinations: 1) when the element is positioned between the store and the elevator means, 2) When the element is positioned atthe location ofthe elevator means, 3) when the element is positioned between the elevator means and the record/playback position.

9. Apparatus according to claim 7when dependent on claim 4, wherein said two point locations are positioned at opposite ends of a first one of said location ranges the second of which extends on from said second point location, the elongate bar being apertured in correspondence with both radiation receivers at said first location, apertured in correspondence with one only of the radiation receivers over the first location range, apertured in correspondence with the other one of the radiation receivers over the second location range, and un-apertured in correspondence with said second point location.

10. Apparatus for monitoring translational movement of an element along a predetermined route, said apparatus being substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed, and havethefollowing effect: *(a) Claims 1,9 above have been deleted ortextually amended.

*(b) Newortextually amended claims have been filed asfollows: CLAIMS

1. Apparatus for monitoring translational movement of an element along a predetermined route, said apparatus comprising: elongate means extending along said route; a plurality of detector means mounted for movement with said element and arranged to trace outrespective paths over said elongate means during movement of the element; and physically-discernible features provided along the elongate means in correspondence with the said paths traced out by the detector means, each detector means being sensitive to the presence or absence of said features along its path and the disposition of said features being such as to produce a respective unique detector-output combination both for a predetermined location of interest of the element along its route and for a predetermined range of locations of interest of said element along its route.