GB2059055A - X-Y co-ordinate referenced orientation sensing apparatus - Google Patents

Abstract

Apparatus, for monitoring by opto-electronic means the directional movements of arc and changes in the orientation of any member to which the apparatus is applied, operates by generating pairs of electronic signals representing intersection points of X-Y co- ordinates defining a matrix, which co-ordinates correspond to differing positions of orientation bubbles 14 within two transversely mounted spirit level chambers 11, one of which is illustrated. The bubbles 14 are irradiated by a source of light 8, 9, 10 and by deflection and diffraction modulate that radiation for detection at prescribed intensity levels by light sensors 1-7 arranged in matrix form, relative to several sides of the bubble chambers, which sensors are adjusted via appropriate circuitry to be sensitive to respective prescribed maximum and minimum levels of intensity. The apparatus may be used in writing instrument systems for mapping the movements of a hand held pen relative to a matrix, and for other purposes. <IMAGE>

Description

SPECIFICATION X-Y co-ordinate reference orientation sensing apparatus The present invention relates to X-Y co-ordinate referenced directional movement and orientation sensing apparatus for applying to a member to continuously monitor, and indicate by the electronic signalling of coded co-ordinate pairs, the directional movements of arc and changes in the orientation of the member as measured in relation to and by reference with a matrix defined by arrays of intersecting X-Y co-ordinates in either a horizontal plane radial to a vertical axis of the member, a vertical plane radial to a horizontal axis of the member or other plane radial to other axes.

The apparatus may be used for sensing, monitoring, digitizing and signalling the directional writing movements of a hand held writing instrument for communication with automatic logic systems for interpreting or reading electronically hand printed or hand written data for direct entry of that data, as it is written, into electronic data processing systems, thereby capturing data at source without the inherent duplications involved with conventional keyboard data entry terminals.The apparatus may also be used for monitoring the pitch and roll of floating vessells, the deviation from a level course of aircraft, the trajectory of rockets, missiles, projectiles, changes in the attitude of helicopters in flight or hovering, satellites in orbit, submarines and torpedoes, hand held television or cinematograph cameras, the elevation of radar scanners, radio and astronomical telescopes or the directional movement and changes in orientation of any member whose movements arising from occasional, intermittant or continuous changes in orientation it is desired to monitor, measure, interpret or use to control remote robot and automatic logic systems. Movement in any direction about a vertical or horizontal axis may be simultaneously sensed and indicated by the apparatus.

Directional movements of arc and changes in the orientation of a member being related, both may be simultaneously monitored by visual observation of the orientation indicating bubble in the type of spirit level customarily used in the construction industry to test the orientation of a member, and which member will normally be static for the instant of the test. Such levels are essentially only useful for indicating whether a member is in or not in a desired orientation and since visual observation of a bubble that is constantly moving or oscillating is less than convenient, are not generally used to monitor or measure progressive deviation of orientation or the directional linear or arcuate movements of a member that is in motion occasionally, intermittently or continuously.

A useful property of a bubble, apart from its linear mobility, is its ability to deflect light.

Another useful property is its ability to cast a shadow when illuminated by a source of visible light.

An object of the present invention is to enable accurate and meaningful monitoring of the directional movements of arc and progressive changes in the orientation of a member that is subject to occasional, intermittant, continuous or oscillatory movement and changes in orientation, and to do so without recourse to visual observation of an indicating bubble, and remotely from that bubble.

According to the present invention there is provided X-Y co-ordinate referenced directional movement and orientation sensing apparatus for applying to a member to continuously sense, monitor and indicate by the electronic signalling of coded co-ordinate pairs to external logic system circuits, the directional movements of arc and changes in orientation of the member measured in relation to and by reference with a matrix defined by intersecting X-Y co-ordinate arrays, the apparatus includ ing::- separate X co-ordinate arrays radiation modulating means, Y Co-ordinate arrays radiation modulating means, each of said means being transverse to the other within a common plane, and each having a separate cylindrical chamber within which respectively a modulating fluid defines a modulating orientation bubble moveable in a linear direction therein in response to directional movements of arc or changes in the orientation of the apparatus, the respective chambers being individually encapsulated in a transaprent or translucent rectangular block of plastics material; radiation emitting means positioned in relation to the upper side of the chamber block to emit radiation vertically and evenly toward the underside of the chamber block so as at all times to impinge on the bubble irrespective of the position of the bubble within the chamber, and radiation receiving means including radiation detecting means positioned in arrays at regular or predetermined intervals in relation to the underside of the chamber block to receive that radiation which passes vertically by direct transmission through the modulating fluid, and further receiving means arrays including detecting means positioned in relation to the vertical side walls of the chamber block to receive radiation deflected laterally from either side of the bubble, the spacing and off-set placement of each receiving means array member relative to the others being such as to form from the respective receiving sides alternately a virtual overlapping window or continuum of radiation receiving area, each member of the respective arrays being arranged to generate a signal whenever the radiation received at that array member is, by direct transmission through the fluid in the case of the first mentioned array at a minimum or otherwise predetermined intensity, or by lateral deflection from the bubble in the case of the side wall arrays is at a maximum or otherwise predetermined intensity; the arrangement and placement of the repective emitting means and detecting means relative to each other and relative to the modulating means being such that at any instant, irrespective of the position of the bubble within the chamber, radiation from the emitting means passes by both direct transmission through the fluid and by lateral deflection from the bubble so as to be received at the designated intensity for that array by a member of one of the radiation receiving and detecting means arrays thereby generating a discrete signal or pulse indicating a specific component of the co-ordinate array for that modulating means and which together with the simultaneously generated signal from the other modulating means define a specific X-Y co-ordinate pair by reference to which the respective positions of the respective bubbles is identified, and by reference to successive changes in the co-ordinate pair signalled by the apparatus the directional movement or progressive change in the orientation of the member is indicated in a meaningful, useful and measurable way.

The respective radiation receiving means may thus respectively identify when the bubble within the respective chambers is in a particular position by either generating a signal when the bubble is at that location or interrupting a signal that is continuously generated when the bubble is absent from that location. Alternatively, the signals generated or interrupted may be mulitplexed signals.

The sensing of a particular bubble position within the respective chambers may be used as an end in itself such as to purely indicate that a particular or desired orientation has been reached or may be used in automatic systems for remotely monitoring the changes in the orientation of or directional movement of the member for measurement or interpretation or for activating equipment for contolling and correcting such movements. For example, the control gear of a ships stabilisation fins may be activated automatically in response to signals from the apparatus so as to maintain the vessell on an even keel. Similar control of the flight guidance systems of aircraft, submarines, torpedoes, rockets and like craft may be effected to maintain them on a level or desired course. The apparatus may be further used in tilt switches, joystick controls or in accelerometers.

The radiation emitting means may be located congruent to the upper surface of the respective chamber blocks so that radiation which is not passing directly through the fluid is deflected laterally from a central portion of both side edges of the bubble and thence impinges on one of the members of the detecting means via the receiving means arrays arranged along the side walls of the chamber block. Each member of the receiving means arrays may be so positioned that the centre of any receiving member is not directly opposite or in line radially to the chamber with any other.This embodiment enables accurate and continuous scanning of the position of the bubble within the respective chambers since whether the bubble is moving or stationary, radiation impinging on the receiving means is detected from one only of the receiving sides of the chamber block at a time in strict rotation and in linear progression by one detecting means member according to the movement of the bubble. This embodiment also enables a short chamber to be used as the receiving means arrays may effectively be positioned close together, thereby making miniaturisation possible through optimum use of the surface area available for the receiving means arrays, without permitting more than one detector member at a time to generate a signal.

The separate radiation modulating means are preferably mounted on adjustable supporting frames or within a protective housing so that each co-ordinate chamber may be adjusted independently of the other for initial calibration, or in the case of writing systems pre-set to compensate for any abnormal angles at which a writer may hold a pen.

The modulating fluid may be a spirit such as butenol or alcohol and may additionally include a suitable colouring agent active as a filter to certain radiation wavelengths according to the light source used. A movement dampening agent may also be included, such as glycerol, to prevent over sensitive bubble movement in some applications of the apparatus. Alternatively, the modulating fluid may be a liquified gas such as butane.

The radiation emitting means may be a light emitting diode or any array of light emitting diodes, preferably emitting radiation in the infra-red wavelength of the electromagnetic spectrum.

The radiation receiving means preferably includes radiation detecting means such as a light dependent resistor sensitive to the wavelength of the radiation emitted by the emitting means; directional movement and orientation signalling means and transistorised logic gated switching circuitry, which may include Schmitt triggers for switching the signalling means in response to the intensity of radiation impinging on the respective members of the detecting means so that an output signal in binary code representing the X-Y co-ordinate pairs may be generated for decoding by an external electronic logic control or computer system. A radio transmitter may also be included to communicate the coded signals to distant external control centres. The radiation receiving means may be optic fibres emitting radiation toward detecting means located externally of the modulating means.

The essential features and further optional features of the invention will now be described in greater detail, and with reference to the accompanying drawings where these features are illustrated in preferred form. It is to be understood, however, that the essential features and optional features of the invention are not limited to the specific forms of these features as illustrated in the drawings.

In the drawings: Figure 1 is a block diagram respresenting the essential active elements of the apparatus according to the present invention and serves to illustrate the radiation pathways from the respective emitting means for X s Y coordinate components via the respective modulating means, receiving means and detecting means arrays for signal output from individual switching networks X1-X7 and Y1-Y7 respectively. Radiation emitted from the emitting stages is received by the respective receiving means stages modulated by the modulating means stages which are interposed between the respective emitting means and receiving means.The intensity of radiation received by the receiving means arrays is at a maximum for the odd numbered array members and at a minimum for the even numbered array members, the placement of which relative to the modulating means chamber blocks correspond to the side walls and underside of the blocks respectively.

Figure 2 is a third angle sectional drawing of one of the two transversely mounted, identical, and replaceable co-ordinate modulating means for use in the present invention.

Figures 3 8 5 are example maximum radiation intensity detecting signalling and switching network means circuit diagrams representing alternative embodiments of the apparatus not constructed in accordance with the present invention but which are capable of being used in accordance with the present invention.

Figures 4 8 6 are example minimum radiation intensity detecting, signalling and switching metwork means circuit diagrams also representing alternative emodiments of the apparatus not constructed in accordance with the present invention but which are capable of being used in accordance with the present invention.

Figures 7 8 8 respectively are examples of the maximum and minimum radiation intensity detecting, signalling and switching network means circuit diagrams representing apparatus according to the present invention.

Figures 9 8 10 are schematic illustrations of two of several possible transverse positionings of the X 8 Y co-ordinate modulating means shown in elevation and plan views.

Fig. 2 illustrates by way of example one only of the two identical, separate directional movement of arc and orientation co-ordinate modulating means which comprise the apparatus, each having an array of radiation emitting means 8, 9 s 10, radiation receiving means 1 to 7 and radiation modulating means 28. The modulating means 28 has a chamber 11 charged with modulating fluid 1 3 defining an orientation bubble 14 moveable linearly in the chamber 11 according to the directional movement of arc or changes in the attitude of the modulating means 28 and is encapsulated in a rectangular block 1 2 of transparent or translucent plastic material.

The chamber 11 of modulating means 28 is illustrated as an elongated tube of glass or clear plastics material sealed at both ends, but may be of the conventional arcuate shaped type as used in common spirit levels. The modulating fluid 1 3 is preferably a spirit such as butenol or alcohol and may additionally include a suitable colouring agent active as a filter to certain radiation wavelengths according to the light source used, and may further include glycerol or like substance to retard excessive velocity of bubble movement.

Alternatively, the modulating fluid may be a liquified gas such as butane.

The modulating means 28 may alternatively be a dome shaped vessell of glass or clear plastics material charged with a fluid defining a modulating bubble. In this embodiment a single modulating means, encased in a square block of transparent or translucent plastic may suffice, with suitably arranged X 8 Y coordinate receiving means arrays, to achieve the same results as a pair of longitudinal, transversely arranged modulating means as herein described.

The bubble 14 in Fig. 2 is preferably elongated and has a depth approximately half the diameter and a length less than half the length of the tube 11. The modulating means chamber block 1 2 is a sliding fit into a plastic box housing 1 5 of opaque plastic material, the lid 1 6 of which is a tight fit. The box 1 5 has integral base mounting brackets 29 8 30 so that the base may be adjustably mounted on or within a member, and transversely to the second co-ordinate modulating means (not shown), by means of screws with lock nuts (not shown) through holes 22, 23, 24, 8 25, the securing of which compresses adjustment springs 20 8 21 fastened in threaded holes 26 8 27 by screws (not shown).The respective X 8 Y co-ordinate modulating means of the apparatus may thus be individually adjusted for initial calibration relative to the member or a known level surface by raising or lowering either ends of the respective modulating means.

The box lid 16 has recessed holes 31, 32 8 33 for mounting the radiation emitting means array members 8, 9 & 8 10, the terminals 17, 18 & 8 19 of which protrude from the box 1 5 to permit electrical connection to a power supply circuit. The box 1 5 is illustrated as having recessed holes 34, 35 8 36, which may be circular or slotted, in its base for mounting the individual receiving means array members 2, 4 8 6 (referred to in Fig. 1 as Array 2, and recessed circular or slotted holes 37, 38, 39 8 40 in its side walls for mounting the receiving means array members 1 8 5 (referred to in Fig. 1 as Array 1), and receiving means array members 3 & 7 (referred to in Fig. 1 as Array 3).The spacing of the receiving means array members 2, 4 8 6 is such that the distance between their centres is greater than the length of the bubble 14, the spacing of receiving means array members 1 8 5 and 3 8 7 respectively is such that the distance between their centres is less than the length of the bubble 14. The total number of the individual receiving means array members may be more or less than the seven illustrated in Fig. 2.

Subject to the proviso that no receiving means member should have its centre directly in line with the centre of any other, and that receiving means members placed in Array 2 (Fig. 1) should be placed one bubble length apart, members of receiving means Arrays 1 8 3 (Fig. 1) in particular, may be placed as close together as possible so as to provide a virtual continuum of receiving means surface area from the alternate receiving means sides of the chamber 11. This preferred arrangement provides maximum accuracy in identifying minute changes in the attitude of the modulating means.

The radiation receiving means 1 to 7 illustrated in Fig. 2 are shown as optic fibres, the external ends of which lead out to emit radiation onto the sensitive surface of the respective radiation detecting means located externally of the modulatig means 28, but may alternatively be the separate detecting means members. Each member of the receiving means array 1-7 preferably includes its own separate signalling means and transistorised switching network for switching the signalling means in response to changes in the intensity of radiation impinging on the detecting means, and said means are individually adapted to be activated in response to a predetermined level of radiation.For the receiving means array members 1, 3, 5 s 7 the radiation intensity is preferably at a maximum, and for the receiving means array members 2, 4 and 6 the radiation intensity is preferably at a minimum. Figs. 3, 5 s 7 illustrate example alternative circuit diagrams fulfilling these requirements for maximum radiation intensity detection and signalling by the odd numbered receiving means array members, while Figs.

4, 6 8 8 illustrate example alternative circuit diagrams fulfilling the requirements for minimum radiation detecting and signalling by the even numbered received means array members. It is to be understood, however, that whilst one example only of each type of circuit usable with the apparatus is illustrated, each member of the receiving means arrays is provided with its own separate cuircuit in accordance with the predetermined level of radiation intensity for that member.

The detecting means included in the receiving means 1 to 7 (Fig. 2) are preferably light dependent resistors such as a photocell 1 (Figs. 3, 4, 5 or 6), photo-diode, phototransistor, or infra-red detectors 1 (Figs. 7 s 8) as such devices have a resistance which varies with the amount of radiation impinging on the sensitive part thereof.

The radiation emitting means 8, 9 s 10 (Fig. 2) is preferably an array of light emitting diodes emitting radiation in the infra-red wavelength of the electromagnetic spectrum but may alternatively be a source of visible light such as an incandesent light bulb, the light of which may be evenly diffused by a translucent diffusion screen. This latter embodiment may be used in conjunction with a chamber encased in a block of translucent plastic to cast a shadow of the bubble on the walls of the chamber block, and which shadow will vary the amount of radiation impinging on the receiving means.

The respective switching networks are preferably transistorised since transistors have two discrete states, conducting or non-conducting, and may by initial calibration of the apparatus, be turned on when the bubble 14 (Fig.

2) is adjacent to the receiving means array member dedicated to that network, and turned off when the bubble is not adjacent the receiving means array member dedicated to that network.

The signalling means may be visual signalling means such as a light emitting diode 11 (Figs. 3 s 4), 6 (Figs. 5 Et 6) leo (Figs. 7 Et 8), or a signal lamp, or may be a signal output connection point monitored by the light emitting diode for signal output to an external supervisory logic circuit for monitoring the output signals of each signalling means circuits. Audible signalling means such as a bell or tone generator may also be provided. Alternatively the signalling means may include a radio transmitter so that signals generated by the apparatus may be communicated to monitors at a remote distance from the member.

In the preferred arrangement illustrated by Fig. 2 in conjunction with, either Figs. 3 s 4 or Figs. 5 8 6 or Figs. 7 s 8, an array of light emitting diodes 8, 9 8 10 are positioned adjacent the upper side of the chamber block 1 2 to emit radiation toward the underside of the chamber block through the tube 11 and fluid 13, and members 1,3,5 s 7 of the receiving means arrays are positined to receive radiation reflected laterally accross the tube by a central portion of the side edges of the bubble 14, on which the light image is mirrored, and members 2, 4 8 6 of the receiving means arrays are positioned to receive radiation passing directly through the fluid 13.

As mentioned above, each receiving means member 1, 3, 5 8 7, has its own independent signalling means and switching network operable in response to maximum radiation intensity, whereas each receiving means member 2, 4 8 6 has its own independent signalling means and switching network operable in response to minimum radiation intensity.

Therefore, when the central portion of a side edge of bubble 14 is directly in line with any one of receiving means members 1, 3, 5 or 7 maximum radiation will be impinging on that member and the switching network associated with that member will alone be activated. When, however, the bubble 14 is directly interposed between the light source 8, 9 s 10 and any one of receiving means members 2, 4 or 6 minimum radiation will be impinging on that member, since the bubble, tube and liquid diffract light, and the switching network associated with that member will alone be activated.

For example, in Fig. 2 the bubble 14 is illustrated as being interposed between the emitting means 8, 9 s 10 and receiving means member 4, and since minimum radiation will be impinging thereon the switching network associated with that member will alone be activated, thereby generating a signal indicating the fourth datum along that particular modulating means co-ordinate. If the bubble 14 now moves within the chamber 11 so that its centre edge is directly in line with receiving means member 3 maximum radiation will be impinging on that member and the switching network associated with that member will be activated thereby generating a signal indicating the third datum along that co-ordinate, but due to the now increased light incidence upon receiving means member 4 the switching network associated with that member will be deactivated.Since the modulating means for the second co-ordinate functions in the same manner signalling will occur as two discrete signals each indicating a respective datum point which together represent a pair of X-Y co-ordinates.

The example switching networks illustrated in Figs. 5 8 6 are operable in response to maximum radiation and minimum radiation intensity respectively. Both networks include a light dependent resistor 1 and a potentiometer 2, which form a voltage divider; two NPN transistors 4 8 7 arranged in a darlington-pair amplifier configuration, a capacitor 5 (optional), and a light emitting diode 6 connected between the common collector of transistors 4 8 7 and the positive terminal of the power supply 8. The networks may be connectable to the power supply 8 by control switch 9.

The potentiometer 2 in Fig. 5 is shown connected between the positive terminal of power supply 8 and the base of transistor 4 via resistor 3 and the light dependent resistor 1. In Fig. 6 the position of the potentiometer 2 and light dependent resistor 1 are interchanged from their position in Fig. 5, thereby producing the converse of the maximum radiation activated switching action of the network illustrated in Fig. 5. The transistors 4 8 7 having two discrete states, conducting or non-conducting, are in one state when the radiation intensity, corresponding to a particular bubble position within the modulating means, is at the prescribed intensity for the detecting means member served by the network and in the other when the radiation intensity, corresponding to a different bubble position within the modulating means, is not at the prescribed intensity.

The potentiometer 2 enables the resistance in the voltage divider to be adjusted so that the signalling means 6 may be switched on for different levels of radiation intensity. Resistor 3 is provided to protect the base-emitter junction of transistor 4, transistor 7 being provided to increase the current gain of the switch so that only a small current is required to switch on the signalling means 6.

Figs. 3 s 4 illustrate example alternative switching networks corresponding to the same function as the networks shown in Figs. 5 8 6 respectively, but which are more sensitive, stable and faster in operation. Both networks include a light dependent resistor 1 and a potentiometer 2 to form a voltage divider; two NPN transistors 4 8 8, and a PNP transistor 9 arranged in a Schmitt trigger configuration. In Fig. 4 the position of the light dependent resistor 1 and the potentiometer 2 are interchanged from their position in Fig. 3, thereby producing the converse of the maximum radiation intensity activated switching action of the network illustrated in Fig. 3. The potentiometer 2 determines the level of radiation intensity for which the signalling means 11 is turned on.

When the light dependent resistor 1 (Fig. 4) is strongly radiated its resistance is low and this raises the voltage at the base of transistor 4 turning this transistor on. With transistor 4 turned on current flows through resistor 6 and the voltage at the collector of transistor 4 is close to ground, hence transistor 8, and transistor 10, which forms part of the collector load of transistor 8 are off and the light emitting diode 11 emits no signal. When the level of radiation intensity impinging on the light dependent resistor 1 falls to the prescribed minimum intensity, a state corresponding to the bubble 1 4 (Fig. 2) being interposed between the emitting means 8, 9 s 10 (Fig. 2) and any one of receiving means members 2, 4 or 6 (Fig. 2), the voltage at the base of transistor 4 (Fig. 4) rises and this transistor begins to turn off.As it does so, the collector voltage of transistor 4 begins to rise and switches on transistor 8 which in turn switches on transistor 1 0. The switching action is rapid and precise since the common emitter connection of tansistors 8 and 4 provides positive feedback and a regenerative action occurs. As transistor 8 approaches cutoff, resistor 5 ceases to conduct and the emitter voltage of transistor 4 falls close to zero, resulting in the emitter voltage of transistor 8 being close to ground and the voltage accross the base-emitter junction increases thereby increasing current flow through this transistor. More current is thus flowing through resistors 6 8 7 and transistor 4 is driven into cut-off thus activating the signalling means 11 in response to minimum radiation intensity.

Conversely, the network of Fig. 3 is operable in response to maximum radiation intensity, a state corresponding to the bubble 14 (Fig. 2) having its centre edge adjacent any one of receiving means members 1, 3, 5 or 7. In practice, to ensure maximum sensitivity of the apparatus, the bias network of the respective transistors is adjusted so that they are either just on or just off according to the prescribed level of radiation.

Figs. 7 8 8 respectively illustrate examples of the preferred maximum and minimum radiation intensity switching networks according to the present invention, their counterparts being shown in block diagram form only. The networks include radiation detecting means 1 being a photo-transistor or infra-red detector, potentiometer 2, operational amplifier 3, a PNP transistor 8 and signalling means 10.

The networks may be connected to a power supply 11 by control switch 1 2. The operational amplifier 3 is operated in both networks 7 8 8 in the differential mode by applying a d.c. voltage difference accross the inverting and non-inverting input terminals T2 and T3 respectively. When the voltage accross these terminals is zero, there is no output, but a small voltage accross these terminals is amplified to give a large voltage at the output terminal T6.

In the minimum radiation intensity network illustrated by Fig. 8, resistors 5 s 6 hold the non-inverting input terminal T3 at half the supply voltage. The potentiometer 2, resistor 4, and the photo-transistor 1 hold the inverting input terminal T2 at a voltage dependent upon the intensity of radiation impinging on the detecting means 1 which is determined by the adjustment of potentiometer 2. The resistors accross the input make a Wheatstonebridge circuit in which the photo-transistor 1 is the active element.

When the voltage at terminal T2 is slightly less than the voltage at terminal T3, which occurs when the bubble 14 (Fig. 2) is not directly interposed between any one of receiving means members 2, 4 or 6 and emitting means 8, 9 & 1 0, i.e. the photo-transistor is iradiated, the voltage at the base of transistor 8 (Fig. 8) will be close to the positive supply voltage and this transistor will be turned off, since it is a PNP type, and the emitting means 10 emits no signal.When however, the bubble is directly interposed between emitting means 8, 9 s 10 (Fig. 2) and any one of receiving means members 2, 4 or 6 so that minimum radiation impinges on detecting means 1 (Fig. 8), the voltage at terminal T2 will be higher than that at terminal T3, the base of transistor 8 will go negative thereby switching this transistor on and the signalling means 10 will be activated. The converse of this minimum radiation intensity activated switching action is achieved by the network of Fig. 7 in which the positions of the potentiometer 2 and photo-transistor 1 are interchanged. Alternatively, this effect may be achieved by using an NPN transistor in place of the PNP type.

Various modifications may be made' to the apparatus arrangement and the circuitry to suit different applications. For example, in an alternative embodiment not illustrated, additional receiving means may be positioned adjacent the ends of tube 11 (Fig. 2) to receive radiation deflected by an end edge of bubble 14, the additional receiving means each having its own separate signalling and switching means networks operable in response to a predetermined intensity of radiation.

A separate housing for all external circuity may be provided to protect the circuits and prevent interference from stray light.

As previously mentioned the apparatus may be used in electronic writing instruments to indicate to external logic circuits, by reference to successive X-Y co-ordinate pairs signalled, the directional movements of the writing instrument. In this application of the apparatus, the respective modulating means would preferably be mounted within, or on top of the upper end of a pen barrel incorporating a contact pressure switch, the writing leverage of the pen barrel fulcrummed in the crook of the writer's hand, causing the respective coordinate bubbles to move in the same direction as the writing point of the pen, thereby making possible the electronic mapping of the written characters formed.

The apparatus may also be used to monitor and provide corrective guidance to the direction and elevation of mobile vehicles such as ships and aircraft, and aid in the sighting of moveable equipment such as astronomical telescopes and cameras that require to be aimed at a target from a level plane.

Thus it will be seen that the apparatus of the present invention provides a novel means of generating coded signals of binary or coordinate pairs indicative of the directional movement of arc or changes in the orientation of a member to external electronic logic sys tem circuits in a useful and meaningful way, and is furthermore of reasonably simple construction.

Claims (11)

1. X-Y co-ordinate referenced directional movement and orientation sensing apparatus for applying to a member to continuously monitor, and indicate by the electronic signalling of coded co-ordinate pairs to external logic system circuits, the directional movements of arc and changes in the orientation of the member as measured in relation to and by reference with a matrix defined by arrays of intersecting X-Y co-ordinates in either a horizontal plane radial to a vertical axis of the member, a vertical plane radial to a horizontal axis of the member or other plane radial to other axes, the apparatus including::-- sepa- rate X co-ordinate arrays radiation modulating means, Y co-ordinate arrays radiation modulating means, each of said means being transverse to the other within a common plane, and each having a separate cylindrical chamber within which a a modulating fluid defines a modulating orientation bubble moveable linearly therein in response to directional movements of arc or changes in the orientation of the apparatus, the respective chambers being individually encapsulated in a transparent or translucent rectangular block of plastics material; radiation emitting means positioned in relation to the upper side of the chamber block to emit radiation vertically and evenly toward the underside of the chamber block so as at all times to impinge on the bubble irrespective of the position of the bubble within the chamber, and radiation receiving means including radiation detecting means positioned in arrays at regular or predetermined intervals in relation to the under side of the chamber block to receive that radiation which passes vertically by direct transmission through the fluid, and further receiving means arrays including detecting means positioned in relation to the vertical side walls of the chamber block to receive radiation deflected laterally from either side edge of the bubble, the spacing and off-set placement of each receiving means array member relative to the others being such as to form from the respective receiving sides of the chamber block alternately a virtual overlapping continuum or window of radiation receiving area, each member of the respective arrays being arranged to generate a signal whenever the radiation received at that array member is, by direct transmission through the fluid in the case of the first mentioned array at a minimum or otherwise predetermined intensity, or by lateral deflection from the bubble in the case of the side wall arrays is at a maximum or otherwise predetermined intensity; the arrangement and placement of the respective emitting means and detecting means relative to each other and relative to the modulating means being such that at any instant, irrespective of the position of the bubble within the chamber, radiation from the emitting means passes by both direct transmission through the fluid and by lateral deflection from the bubble so as to be received at the designated intensity for that array by a member of one of the radiation receiving and detecting means arrays alone thereby generating a discrete signal or pulse indicating a specific component of the co-ordinate array for that modulating means, and which together with the simultaneously generated signal from the other modulating means define a specific X-Y co-ordinate pair by reference to which the respective positions of the respective bubbles is identified, and by reference to successive changes in the co-ordinate pair signalled by the apparatus the directional movement or progressive change in the orientation of the member is indicated in a meaningful, useful and measurable way.

2. Apparatus as claimed in claim 1, wherein the transversely mounted chambers are each defined by an elongated tube and the respective orientation bubble have a depth approximately half the diameter and a length less than half the length of the tube.

3. Apparatus as claimed in claim 1 or claim 2, wherein the respective radiation emitting means comprises an array of light emitting diodes positioned adjacent the upper side of the respective chamber blocks.

4. Apparatus as claimed in any preceding claim, wherein the radiation receiving means comprises arrays of optic fibres arranged to emit radiation toward the sensitive surface of the respective detecting means arrays, and further includes for each, separate directional movement and orientation signalling means and switching networks for switching each signalling means in response to changes in the intensity of radiation impinging on the respective detecting means array members.

5. Apparatus as clainied in claim 1 or claim 4 wherein no member of the radiation receiving means arrays has its centre directly in line with the centre of any other relative to the radius of the chamber.

6. Apparatus as claimed in claim 1 or claim 4 wherein a a proportion of the detecting means arrays members for each chamber, with associated signalling means and switching means networks, are adjusted to be operable in response to a lower level of radiation intensity than that prescribed for the other detecting means array members.

7. Apparatus as claimed in any preceding claim, wherein the radiation modulating means is supported on a mounting frame or within a box housing, the base of which is adjustably mounted on or within the member.

8. Apparatus as claimed in claim 4, wherein the individual switching networks each include a switching member having two discrete states, the switching member being in one state when the bubble is adjacent to or interposed between the receiving means member served by that network, and the emitting means, and in the other state when the bubble is not adjacent to or interposed between that receiving means member served by that network, and the emitting means.

9. Apparatus as claimed in claim 1 or claim 4 or claim 8, wherein when one pair of X-Y co-ordinate signalling means are activated, all other signalling means are deactivated.

10. Apparatus as claimed in any preceding claim wherein the the radiation receiving means includes additional members positioned adjacent each end of the respective chamber blocks to receive radiation deflected longitudinally from the end edges of the respective bubbles, said means including separate detecting means, signalling and switching network means operable in response to maximum radiation intensity.

11. Apparatus as claimed in any preceding claim, wherein the chambers, radiation emitting means and radiation receiving means are fitted in respective box housings in predetermined relationship to each other.

1 2. X-Y co-ordinate reference directional movement and orientation sensing apparatus as claimed in claim 1 substantially as described herein and with reference to and as illustrated in the accompanying drawings.