GB2063179A

GB2063179A - Trackable writing instrument

Info

Publication number: GB2063179A
Application number: GB7938547A
Authority: GB
Original assignee: IMAGE DATA PRODUCTS Ltd
Current assignee: IMAGE DATA PRODUCTS Ltd
Priority date: 1979-11-07
Filing date: 1979-11-07
Publication date: 1981-06-03
Also published as: GB2063179B

Abstract

When writing pressure on a ball point refill in the interior of member 1 forces it up inside outer casing 5, cap 6 forces apart electrical contacts 3, 4, indicating to a control apparatus including sensing coils responsive to magnetic flux from electromagnet 2 that the writing instrument is in use. The coils measure the co-ordinate positions of the writing instrument. <IMAGE>

Description

SPECIFICATION An implement for use in writing The present invention relates to an implement for use in writing.

According to the present invention, there is provided an implement for use in writing, comprising: an elongate inner part; a coil for emitting magnetic flux when electrically energised, for co-operating with apparatus including a plurality of sensing coils for generating a signal representative of co-ordinate position of the implement; an elongate outer part mounted for longitudinal movement relative to the inner part; and a switch comprising first and second contacts in electrical contact with one another, the implement being such that, if the outer part is held in the hand and the implement used for writing, pressing of a writing part carried bythe implement on to a writing surface results in the outer part moving longitudinally relative to the inner part in a direction towards the surface whereby a portion of the implement separates the contacts to open the switch for indicating that the implement is being used for writing.

The said coil could be carried by the inner part. For example, the inner part could be a moulded member in which the coil is encapsulated.

The inner part could be shaped for receiving a writing part. The implement could then include means for holding a writing part in the inner part, for example a plug which has a screw-thread which engages with a screw-thread on the inner part.

The said contacts could be carried by the inner part, the said portion of the implement being on the outer part. For example, the outer part could be a sleeve around the inner part, the said portion being a cap on the sleeve.

One of the said contacts could be a spring contact, the implement being such that, if the outer part is held in the hand and the implement used for writing, pressing of a writing part carried by the implement on to a writing surface results in the outer part moving longitudinally relative to the inner part in a direction towards the surface whereby the said portion displaces the spring contact to separate the first and second contacts.

The implement could be provided, for example on the outer part, with a terminal arrangement having a first terminal electrically connected to one end of the coil, a second terminal electrically connected to another end of the coil and a third terminal electrically connected to one of the contacts, the other of the contacts being electrically connected to the said other end of the coil.

A member, for example a screw, could engage with the inner part, this member passing with clearance into an opening through the outer part whereby the outer part can move longitudinally relative to the inner part.

The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a longitudinal cross-section through an implement for use in writing, Figure 2 is a plan view of a spring contact in the implement, Figure 3 shows a ball-point pen refill received in an inner part of the implement and means for holding it in the inner part, Figure 4 shows part of an outer part and part of the inner part of the implement, and Figure 5 is a circuit diagram showing how electri cal components of the implement are connected in use of the implement.

Referring to the drawings, an implement for use in writing comprises a pen having an inner part in the form of a member 1 of moulded plastics material shaped internally to receive a ball-point refill and encapsulating a coil 2. The member 1 carries a first contact 3 which is a spring contact formed by bending a flat metal ring (see Figure 2) and a second contact 4, the contacts 3 and 4 being in electrical contact with one another when the pen is not used for writing, as shown. The member 1 is received in an outer part in the form of an aluminium tube 5 which has screwed on to it a cap 6 through which there is an aperture 7, the bend in the spring contact 3 bearing against the inside face of the top of the cap 6.

A ball-point pen refill 17 is received in the member 1 by being inserted point first through the aperture 7 in the cap 6 and into the member 1, the refill 17 being held firmly in place by a plug 18 of moulded plastics material which has an external screw-thread 19 which co-operates with an internal screw-thread 20 at the upper end of the member 1, the plug 19 being inserted through the aperture 7 and into the member 1 and screwed until the refill 17 is firmly seated, Figure 3 showing just the plug 18 engaging with the refill 17.

Fixed around the tube5 is an annular member 8 which carries a member 9 from which extends a cable 10, having three electrical conductors 11b, 12b, and 13b which are connected to respective ones of terminals 11a, 12a and 13a in the member 9 (see Figure 5). The terminal 1 1a is connected to the contact 4 via an electrical conductor 11; the terminal 13a is connected to one end of the coil 2 via an electrical conductor 13; the terminal 12a is connected to the other end of the coil 2 via an electrical conductor 12; and the contact 3 is connected to the conductor 12 and thereby to the other end of the coil 2 via an electrical conductor 14.The cable 10 is connected to a plug having four pins P1, P2, P3 and P4, the conductor 1 3b being connected to the pin P1, the conductor 1 2b being connected to the pins P2 and P3 and the conductor 1 1b being connected to the pin P4.

The members 8 and 9 are as near as possible to the centre of gravity of the pen with the plug 9 and refill 17 inserted, to reduce the effect of pulling by the cable 10 when the pen is used for writing.

The tube 5 has a small square hole 15 through it, in which hole there is a small screw 16 which engages with the member 1. The screw 16 has a small clearance in the hole 15, so that the tube 5 can move longitudinally relative to the member 1 - for example, by about 10,000ths of an inch.

The pen is intended to be used with apparatus for generating signals representative of co-ordinate positions of the implement, the apparatus including a plurality of sensing coils responsive to magnetic flux from the coil 2 and a computer for processing signals from the sensing coil to recognise characters written by the pen. In use of the implement, the plug is plugged into a socket S in the computer, an alternating current being applied to the conductor 13 to electrically energise the coil 2 via a conductor 13c, and the conductor 12 and thereby the conductor 14 is earthed as a of a conductor 1 2c being earthed. Pins P3 and P4 are connected to respective inputs of an exclusive - OR gate 24 via conductors 20 and 21, each of which is connected to + 5 volts via 1 kip resistors 22 and 23 respectively.The writing surface, for example a sheet of paper, is placed over the sensing coils and the pen used to write thereon, being held in the hand via the tube 5. In response to the refill 17 being pressed down as a result of starting to write, the tube 5 and thereby the cap 6 move longitudinally relative to the member 1 in a direction towards the writing surface (as a result of the clearance between the screw 16 and the hole 15), whereby the cap 6 presses down the spring contact 3 and separates it from the contact 4.As a result of this, the conductor 11 and thereby the conductor 21 (previously at earth potential due to the contact 3 being in contact with contact 4) attains a potential of between 0 and +5 volts, so that an output signal is produced from the gate 24 on a conductor 1 1c indicating to the computer that the pen is being used for writing and that signals from the sensing coils are to be processed for the sake of recognising characters being written.In response to lifting the pen from the writing surface, the tube 5 and the member 1 attain their original relative positions, as a result of which contact 3 again makes contact with the contact 4 whereby the conductor 11 and thereby conductor 21 is placed at earth potential, so that there is again earth potential at both inputs of the gate 24 and there is no output signal on the conductor 1 1c, indicating to the computer that signals from the sensing coils should be ignored. If the plug is removed from the socket, each of the conductors 20 and 21 is at a potential between 0 and +5 volts so in this case as well there is no output signal from the gate 24, indicating to the computer that any signals from the sensing coils should be ignored.

As will be seen from Figure 2, the contact 3 has a gap in it. This has the effect that, if the implement is dropped, accidental separation of contacts 3 and 4 is not caused due to relative movement of the member 1 and the tube 5. The amount of relative movement which is required to separate the contacts 3 and 4 is set by the position to which the cap 6 is screwed on to the tube 5, this being adjustable.

Claims

1. An implement for use in writing, comprising: an elongate inner part; a coil for emitting magnetic flux when electrically energised, for co-operating with apparatus including a plurality of sensing coils for generating a signal representative of a coordinate position of the implement; an elongate outer part mounted for longitudinal movement relative to the inner part; and a switch comprising first and second contacts in electrical contact with one another, the implement being such that, if the outer part is held in the hand and the implement used for writing, pressing of a writing part carried by the implement on to a writing surface results in the outer part moving longitudinally relative to the inner part in a direction towards the surface whereby a portion of the implement separates the contacts to open the switch for indicating that the implement is being used for writing.

2. An implement according to claim 1, wherein the said coil is carried by the inner part.

3. An implement according to claim 2, wherein the inner part is a moulded member in which the coil is encapsulated.

4. An implement according to any preceding claim, wherein the inner part is shaped for receiving a writing part.

5. An implement according to claim 4, wherein the inner part is shaped for receiving a ball-point pen refill.

6. An implement according to any preceding claim, wherein the said contacts are carried by the inner part, the said portion of the implement being on the outer part.

7. An implement according to claim 6, wherein the outer part comprises a sleeve around the inner part, the said portion being a cap on the sleeve.

8. An implement according to claim 4 or any of claims 5 to 7 as dependent on claim 4, which includes means for holding a writing part in the inner part.

9. An implement according to claim 8, wherein the said means comprises a plug which has a screw-thread which engages with a screw-thread on the inner part.

10. An implement according to any preceding claim, wherein one of the said contacts is a spring contact, the implement being such that, if the outer part is held in the hand and the implement used for writing, pressing of a writing part carried by the implement on to a writing surface results in the outer part moving longitudinally relative to the inner part in a direction towards the surface whereby the said portion displaces the spring contact to separate the first and second contacts.

11. An implement according to any preceding claim, provided with a terminal arrangement having a first terminal electrically connected to one end of the coil, a second terminal electrically connected to another end of the coil and a third terminal electrically connected to one of the contacts, the other of the contacts being electrically connected to the said other end of the coil.

12. An implement according to claim 11, wherein the terminal arrangement is on the outer part.

13. An implement according to any preceding claim, wherein a member engages with the inner part, this member passing with clearance into an opening through the outer part whereby the outer part can move longitudinally relative to the inner part.

14. An implement according to claim 13, wherein the said member is a screw.

15. An implement according to claim 10 or any of claims 11 to 14 as dependent upon claim 10, wherein the said spring contact comprises a flat ring which has been bent.

16. An implement according to claim 15, wherein there is a gap in the ring.

17. An implement for use in writing, substantially as herein described with reference to the accompanying drawings.