GB2035643A - Position-determination e.g. for manual data input - Google Patents

Abstract

An arrangement for determining the position of a selected element in a matrix array of elements (E) each capable of emitting radiation when energised, e.g. DCEL devices used in a visual display panel linked to a computer, incorporates a detector (6) having a movable pick-up head (7) capable of being selectively presented to any one of said elements to which the pick-up head is presented is energised, means (8) operable to energise all the elements periodically and substantially simultaneously, and a control (9) responsive to an output signal from the detector, which indicates that the detector has been presented to an element of the array, to energise each row or column of elements sequentially, and cause the detector to generate a second signal when the elements in the row or column having the selected element are energised, and means responsive to the second signal to energise each of the elements in that row or column sequentially, for causing the detector to generate a third signal when the selected element in that row or column is energised. <IMAGE>

Description

SPECIFICATION Improvements in or relating to position determining arrangements This invention relates to position determining arrangements, more especially for use in determining electrically the position of a particular element in an array of elements which are capable of emitting radiation when energised.

The invention is especially applicable to computers having a visual display panel in which information is displayed by the energisation of various light-emitting elements, and in which a user can indicate the type of information required to be displayed, or feed back information into the computer, by presenting a movable detector to a selected element of the array.

In such an arrangement it is necessary for the computer to be able to identify unambiguously the element which has been selected in order for it to make the correct response.

In an array of elements in the form of a matrix consisting of rows and columns it is possible to identify any element of the matrix by two unique co-ordinates, one representing its horizontal displacement and another its vertical displacement.

The co-ordinates of an element to which the detector is presented can then be identified by sequentially scanning the elements, that is to say by energising them in turn, and noting the coincidence of a signal generated by the detector and an electrical address.

The rate at which this can be done is governed by the optical performance of the elements and the size of the array, and can be expressed by the inequality T > N.td where T is the time required to identify any element, N is the number of elements in the array and td is the response time of an element, that is the time taken for the element to respond to an electrical pulse applied to it.

It is desirable for an identification or scanning sequence to be interposed within a normal display sequence, so that fresh information or questions can be fed into the computer by presenting the detector to another element.

Preferably such scanning sequences should be undetectable by the human eye, so that the displayed information appears to be continuous and uninterrupted.

Accordingly the total scanning time T should be kept below a threshold value at which it effectively interrupts the display.

The scanning technique described above is satisfactory with elements such as Light-Emitting Diodes having very rapid optical rise and fall times, but is less so with elements having a slower optical performance, for example D.C. Electroluminescent Devices, since these require slower scanning which significantly reduces the number of elements which can be used in the array.

An object of the invention isto provide a positioning determining arrangement which makes use of an alternative scanning technique.

According to the invention an arrangement for determining the position of a selected element in an array of elements arranged in a plurality of rows and/or columns, and each capable of emitting radiation when energised, incorporates a detector capable of being selectively presented to any one of said elements and of generating an output signal when the element to which it is presented is energised, means operable to energise all the elements periodically and substantially simultaneously, means responsive to an output signal from the detector, which indicates that the detector has been presented to an element of the array, to energise each row or column of elements sequentially, and cause the detector to generate a second signal when the elements in the row or column having the selected element are energised, and means responsive to the second signal to energise each of the elements in that row or column sequentially, for causing the detector to generate a third signal when the selected element in that row or column is energised.

It will be seen that the second and third signals accurately determine the position of the selected element, and this information can then be stored or used to initiate certain operations, depending upon the element selected.

Thus the first signal produced when all the elements are energised not only yields the information that the detector is ready to acquire positional information, but also initiates the scanning of the rows or columns during which the second signal is produced. This second signal indicates the row or column in which the selected element is located, and also initiates the scanning of the elements in that row or column to produce the third signal when the selected element is energised.

The time taken to energise all the elements simultaneously is clearly tod regardless of the size of the array.

The time taken to detect the row or column in which a selected element is located will be at most n.td where n is the total number of rows or columns, and the time taken to detect the selected element in that row or column will be m.td where m is the number of elements in the row or column.

Therefore with an array of elements arranged in a matrix consisting of n rows (or columns) and m columns (or rows) the maximum time T required for determining the position of an element selected will be given by T=td(1 +n+m) However with a conventional sequential scanning technique the maximum scanning time required will be given by T = td. n. m.

Thus provided the number of elements in the matrix is greater than 2 x 3 a reduction in scan time can be achieved for elements having a given response time.

Alternatively it then becomes possible to employ elements, such as D.C. Electroluminescent Devices, having greater optical response times than, say, Light Emitting Diodes, without reducing the number of elements in the array, compared with arrange ments utilising conventional sequential scanning techniques.

Although the invention is particularly applicable to arrays of D.C. electroluminescent devices it can also be applied to arrays of other elements such as Light Emitting Diodes which emit light or other radiation when suitably energised.

The invention also incorporates within its scope computers having visual display panels and incorporating positioning determining arrangements as above described.

In accordance with a further aspect of the invention a process for determining the position, in an array of elements arranged in a plurality of rows and/or columns, and each capable of emitting radiation when energised, of a selected element to which a detector responsive to said radiation is presented, comprises the steps of energising all of the elements periodically and substantially simultaneously, and in response to a signal from the detector indicating that it has been presented to an element of the array, energising the elements in each row or column sequentially, to cause the detector to generate a second signal when the elements in the row or column containing the selected element are energised, and subsequently energising each of the elements in that row or column sequentially to cause the detector to generate a third signal when the selected element is energised, and determining the position in the array of the selected element from the second and third signals.

One particular application of the invention will now be described by way of example with reference to the accompanying schematic drawing.

In the drawing 1 represents a display panel comprising two sets of conductors 2, 3 disposed at right angles to each other, and between each intersection of the conductors there is disposed an electroluminescent element E capable of being energised by the application of a unidirectional voltage between the respective conductors.

The panel is conveniently formed on a light transmissive substrate with the conductors so arranged that a element which is energised emits light through the substrate. Such panels are themselves well known; the substrate may, for example, consist of a glass plate having one set of conductors formed as light-transmissive conducting strips on a surface of the plate; a suitable phosphor may then be applied over the conducting strips with the second set of conductors formed as conducting strips on the surface of the phosphor at right angles to the first set, so that electroluminescent elements are formed atthe intersections of the two sets of conductors. However the display panel can be formed in any suitable manner, and its precise construction is not material to the present invention.

The conductors 2, 3, have connected to them respective leads 4, 5 for enabling a unidirectional voltage to be applied between a conductor of one set and a conductor of the other set for energising the electroluminescent element at the junction of the two conductors.

The display panel 1 forms part of a computer terminal, and has associated with it a detector 6 incorporating a movable pick-up head 7 capable of being presented to any one of the elements and arranged to convert an optical signal produced on the energisation of the element to which the pick-up head is presented into an electrical signal, which is fed into the computer.

The pick-up head may be arranged to carry an optical signal to a converter in the display panel unit for example by means of optical fibres, or alterna timely the pick-up head may itself incorporate means for converting an optical signal directly to an electrical signal which is subsequently fed to the computer.

For energising the elements the computer incorporates an output unit, represented diagrammatically at 8, for applying an energising voltage between appropriate pairs of conductors, underthe control of a control circuit 9.

Now it is necessary for the computer to identify a particular element to which the pick-up head 7 is presented, in order to enable it to store or process data in response to the selection of that element.

In order to achieve this the control circuit causes the output unit to energise the elements of the display in a sequence of different modes as follows.

The first mode (Mode I) consists in periodically energising all the elements simultaneously to a high brightness condition for a time td corresponding to the response time of the elements. The application of the pick-up head to a selected element, say 4A, will result in a signal being transmitted to the computer to indicate that the detector is ready to identify the particular element, and this initiates the second mode (Mode II). In this mode each row (or column) of the array of elements is illuminated in sequence, and a first position signal is generated when the particular row (or column) containing the element two which the pick-up head is presented is illuminated, thus yielding one of the co-ordinates needed for identification.This information is then retained in a computer memory for use in the third mode (Mode Ill) which will be initiated by a successful detection of an optical output during the Mode II scan.

The Mode Ill scan energises in sequence the elements in the row (or column) identified by the Mode II scan, and a second position signal is generated when the selected element is energised.

The first and second position signals thus indicate the absolute address of the element to which the pick-up head is presented. A successful detection of an optical output in the three modes thus provides the required positional information.

It will be seen that the maximum time T2 required for the Mode II scan will be n.td, which will occur when the element to be detected is the last row to be scanned. Similarly the maximum time T3 required for the Mode Ill scan will be m.td, which will occur when the element selected is the last of the elements to be scanned.

Accordingly the maximum time (T) required to identify a selected element by a detection arrangement is given by the expression T = T1 + T2 + i = td (1 + n + m) On the other hand the maximum time required to identify a selected element using a conventional sequential scanning technique is given by T = td. n. m.

Accordingly for any matrix array n x m which is greater than 3 x 2 (or 2 x 3) the scanning arrangement in accordance with the invention enables a more rapid yet unambiguous identification of a selected element to be obtained than arrangements utilising a conventional sequential scan.

An optional additional mode can be accessed, following the termination of the Mode Ill scan, in order to verify the positional code obtained is correct, for example by re-energising the element in a uniquely discernible pattern.

Any suitable forms of circuits can be employed for producing the required scanning modes and these can readily be constructed utilising existing compu terand logic techniques.

Claims (9)

1. An arrangement for determining the position of a selected element in an array of elements arranged in a plurality of rows and/or columns, and each capable of emitting radiation when energised, incorporating a detector capable of being selectively presented to any one of said elements and of generating an output signal when the element to which it is presented is energised, means operable to energise all the elements periodically and substantially simultaneously, means responsive to an output signal from the detector, which indicates that the detector has been presented to an element of the array, to energise each row or column of elements sequentially, and cause the detectorto generate a second signal when the elements in the row or column having the selected element are energised, and means responsive to the second signal to energise each of the elements in that row or column sequentially, for causing the detector to generate a third signal when the selected element in that row or column is energised.

2. An arrangement according to Claim 1 wherein the elements are D.C. Electroluminescent Devices.

3. An arrangement according to Claim 1 wherein the elements are Light Emitting Diodes.

4. An arrangement according to any one of Claims 1 to 3 wherein array of elements forms part of a visual display panel of a computer terminal.

5. An arrangement according to Claim 4 wherein the detector incorporates a movable pick-up head capable of being manually presented to any one of the elements of the array, and a converter arranged to convert an optical signal produced on the energisation of the element to which the pick-up head is presented into an electrical signal for feeding into the computer.

6. An arrangement according to Claim 5 wherein the pick-up head is connected to a flexible lighttransmitting cable capable of carrying an optical signal from the pick-up head to said converter.

7. An arrangement according to Claim 5 wherein the pick-up head incorporates said converter for converting an optical signal into an electrical signal, and is connected to a flexible electrically conducting cable arranged to carry the electrical signal from the pick-up head for feeding into the computer.

8. A process for determining the position, in an array of elements arranged in a plurality of rows and/or columns, and each capable of emitting radiation when energised, of a selected element to which a detector responsive to said radiation is presented, comprising the steps of energising all of the elements periodically and substantially simultaneously, and in response to a signal from the detector indicating that it has been presented to an element of the array, energising the elements in each row or column sequentially, to cause the detector to generate a second signal when the elements in the row or column containing the selected element are energised, and subsequently energising each of the elements in that row or column sequentially to cause the detector to generate a third signal when the selected element is energised, and determining the position in the array of the selected element from the second and third signals.

9. A position determining arrangement substantially as shown in and as hereinbefore described with reference to the accompanying drawing.