GB2142727A

GB2142727A - Ultra portable electrocardiograph

Info

Publication number: GB2142727A
Application number: GB08316880A
Authority: GB
Inventors: Anthony John Turner; Catherine Turner
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-06-21
Filing date: 1983-06-21
Publication date: 1985-01-23
Also published as: GB8316880D0

Abstract

A battery powered electrocardiograph with normal ECG monitoring facilities is rendered extremely portable and freed from the need of any form of external power supply whilst in use by employing recently developed compact, low power consumption, high definition, dot matrix liquid crystal display screen 7. Signals for display are supplied to the integral driving clips of the screen 7 from ECG preamplifier 4 and horizontal time base 5 via RAM store and interface circuits 6. Traces may be frozen for comparison by opeating buttons 8, and correct functioning may be checked by test buttons 9 and 10 which cause test signals to be displayed. <IMAGE>

Description

SPECIFICATION Ultra portable electrocardiograph This invention relates to the production of an ultra portable electrocardiographic monitor.

Electrocardiographs form an extremely well established part of the various diagnostic tools available to the cardiologist for assessing the various functions, (or mal-functions,) of the heart.

They operate by exibiting, in graphical form, waveforms relating to extremely minute electrical signals appearing at electrodes attached to various parts of the body. These signals, in turn, relate directly to the functions of various parts of the heart, and from their skillful and experienced interpretation, various clinical conclusions can be drawn.

The readout generally takes the form of either (a) A trace, (or traces,) drawn by pens on moving strips of paper, or (b) A trace, (or traces,) indicated on the screens of cathode ray tubes.

Method (a) is generally employed for large, multi trace machines where a permanent record is required to be kept, though its use may also be found on certain resuscitation machines with single traces.

Method (b) is often used where long term, continuous monitoring is required, without the need for keeping a permanent record.

In recent years, increasing attention has been paid to applying computer technology to electrocadiographs, with a view to assisting or speeding up the diagnostic process, and several such complete systems are now in use.

(The IBM 5880 is one such example.) However, whilst much attention has been applied to such sophisticated equipment, little, (so far as the inventors know,) has been paid to the reduction in size of the basic ECG monitors, with the specific aims of thereby extending their availability and effective fields of use.

According to the present invention, battery powered high definition dot matrix liquid crystal display screens, with their necessary battery powered driving chips, RAM storage, and interface circuitry, are combined with suitable battery powered preamplifiers, horizontal time bases, and self checking circuits, to provide extremely portable electrocardiographic monitors, for general use, and for use in locations where a source of mains, or automotive, power supply is not available.

A specific example of the invention will now be described, with refernce to the accompanying drawings, Figs. 1 8 2, based, by way of example only, on a current high definition liquid crystal display screen now being manufactured by the Sharp Corporation of Japan, (their LM 24002G module.) Figure 1 shows, (at half full size,) the face plate of such an ECG monitor, with its display screen, control buttons, and attachments.

Such a monitor could have (a) An overall case size of 26cm by 8.5cm by 3.5cm, approx.

(b) A useable display screen size of 1 6.8cm by 5cm, and (c) A display screen resolution of 64 dots, (or elements,) vertically, by 240 dots, (or elements) horizontally.

Figure 2 provides a block schematic layout of the electronics involved.

A numbering system, (3 to 17 inclusive,) is used consistantly throughout the illustrations and the "CLAIMS" section of this application, to indicate the various electronic features, circuits, and controls of the device.

It must be emphasised that, although a unit built around Sharps LM 24002G display screen is described in detail here, it is not necessarily the intention of the inventors to confine their attentions to the use of this particular module. It is included for example only.

It must also be emphasised that it is not necessarily the intention of the inventors to confine themselves solely to the number of functions or facilities available on their portable ECG monitors to those described, illustrated and numbered 8, 9, 10, and 13 hereafter. It is their hope to be able to add to, or subtract from, the number of these facilities, (in the light of subsequent medical advice or requirements) without necessarily thereby invalidating their essential concept of the need for portability, and the freedom from a need for external power supply, for their ECG monitors.

Referring now in detail to the features common to both illustrations: Item 3~The "pick up" probe input sockets.

Item I The high gain preamplifier, with inbuilt input antistatic protection, and with suitable "low pass" filters to cut out extraneous electrical interference. This preamplifier to have a sufficient, linear output to enable the vertical element of the trace to be displayed, (via the RAM and "interface" circuitry to be described later,) on the display screen in conformity with the current International Standard for the same.

Item 5~The horizontal time base, designed to move the displayed trace, (via the RAM and "interface" circuitry to be described later,) horizontally along the display screen, at a rate to conform with the current International Standard for the same.

Item 6 The RAM and "interface" circuitry, designed to be capable of receiving signals from Items 4 and 5, (described above,) and from Items 8, 9 and 10, (to be described below,) and of presenting them, in suitable form, to the display screen, Item 7.

Item 7~The high definition dot matrix liquid crystal display screen, with integral driving chips, and with a resolution adequately to display the signals as emerging from Items 4 and 5, and as presented by Item 6, in useable graphical form.

Item 8~Additional circuitry to permit the "Freezing", if required, of part, or of all of the displayed trace, to enable direct trace comparisons to be made with respect to time, (for example, to enable a selected trace, recorded with the patient at rest, to be compared directly with the same waveform after the patient has been subjected to controlled exercise.) Item 9~Additional circuitry to permit a test display of horizontally or vertically travelling bars to be indicated on the display screen, prior to actual clinical use, to permit the correct functioning of the latter to be checked.

Item 10~Additional circuitry to permit a suitably attenuated test waveform to be injected into the input of Item 4, to enable a test to be made of the correct functioning of this item, and also of items 5, 6, and 7, prior to the actual clinical use of the complete instrument.

Item 11~The overall instrument "ON/OFF" switch.

Item 12~The overall instrument replaceable, re-chargeable battery power supply pack, (or packs.) Item 13~Additional item, or items, to enable a test to be carried out on the state of charge of the battery pack, or packs, to be carried out, prior to the actual clinical use of the instrument. (This item is shown, in the illustrations, as being additional circuits, using a pair of light emitting diodes as the display medium, but, in practice, many other devices could be used for this purpose, such as, for example, a miniature "battery state" meter, or meters.

Item 14 Socket for an external battery charger connection to be made to the instruments internal battery pack, or packs.

Item 15~Suitable external mains powered battery charger, with provision for charging the battery pack, or packs, within the instrument, and charging the same, seperately from the instrument, and with a suitable "ON/OFF" switch, fuses, overload protection, and "over charge" cut outs, and suitable "state of charge indication".

Item 1 6-A suitable folding stand, attached to the body of the instrument case, to enable the instrument to be adjusted to a suitable and convenient viewing angle, when in use.

Item 1 7-A suitable metal, (or metal/plastic) instrument outer case.

Claims

1. A portable electrocardiograph, in which a high definition dot matrix liquid crystal display screen, togeather with its driving chips, is specifically allied to suitable RAM storage, interface circuitry, preamplifier, horizontal time base, and self checking circuits all battery powered, in the interest of compactness, portability, and freedom, in use, from the need of an external source of power supply.

2. A portable electrocardiograph, as claimed in Claim 1, in which one of the self checking circuits mentioned in Claim 1 enables the entire display screen to be checked, prior to the clinical use of the instrument.

[ Figures: Item 9].

3. A portable electrocardiograph, as claimed in Claims 1 and 2, in which a further self checking circuit mentioned in Claim 1 enables the preamplifier, horizontal time base, RAM storage, interface circuitry, drivers and display screen, to be checked, prior to the clinical use of the instrument. [ Figures: Item iol.

4. A portable electrocardiograph, as claimed in Claims 1, 2, and 3, and provided with a suitable device, or devices, or circuit, or circuits, to enable the satisfactory state of charge of the instruments internal batteries to be checked prior to the clinical use of the instrument. [Figures: Item 1 3 ] .

5. A portable electrocardiograph, as claimed in Claims 1, 2, 3 and 4, and provided with an integral folding stand, to enable the instrument to be adjusted to a convenient viewing angle when in use. [Figures: Item 16 ] .

6. A portable electrocardiograph, as claimed in Claims 1, 2, 3, 4 and 5, and provided with suitable built in screen lighting facilities, to enable the displayed trace, or traces, or other information displayed, to be viewed in conditions of poor ambient lighting.

7. A portable electrocardiograph, as claimed in claims 1, 2, 3, 4, 5, and 6, and provided with the facility to freeze, in use, either the whole, or part, or parts, of the displayed trace, or traces, or other information displayed on the screen, whilst at the same time to permit the remainder of the display, where applicable, to proceed normally. [ Figures: Item 8].

8. A portable electrocardiograph, as claimed in Claims 1, 2, 3, 4, 5, 6, and 7, and provided with the facility to indicate, on the display screen, information additional to the ECG trace being displayed, but derived directly therefrom. Such information could, for example, take the form of a pulse rate readout, or readouts, per minute, numerically, or by means of a calibrated bar lenght, or calibrated bar lengths. Such additional information may be shown at one end of the screen only, or at both ends of the screen, below the ECG trace, to enable it to be frozen along with its relevant section of ECG trace, as claimed in Claim 7.

9. A portable electrocardiograph, as claimed in Claims 1, 2, 3, 4, 5, 6, 7, and 8, and provided with independently startable electronic "stop watch" facilities, the read out of which could appear, numerically, at low level on the display screen, and the purpose of which would be to note the length of time taken for the ECG trace, on part of the screen, taken with the patient after exercise, to return to the type of trace, on another part of the screen, previously frozen, with the patient at rest. Such electronic "stop watch" could alternatively have its numerical read out independant of the main display screen, whilst still being integral to the complete instrument.

10. A portable electrocardiograph, as claimed in Claims 1, 2, 3, 4, 5, 6, 7, 8, and 9, and provided with the integral facility of taking its input signals from a built in short range radio receiver, actuated by a suitable cardiac signal preamplifier controlling a suitable sho#rt range radio transmitter, to permit, for example, basic cardiac monitoring to be carried out of athletes during training, at a distance. Such short range radio transmitters and receivers to operate in the mode, and on the frequencies, currently permitted for such uses within the United Kingdom, and to comply with all relevant United Kingdom legislation.

11. A portable electrocardiograph, as claimed in Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, in which any or all of the self checking circuits, as claimed in Claims 2, 3, and 4, are activated by the instruments overall "ON" switch, instead of by their own separate command buttons, if this method is found to be more convenient in use. Such activation to be sequential in practice, and the total length of time occupied by the whole self checking process to be as found to be the most practicable, in use.