Electrocardiograph with improved stylus control circuits

• US 3,908,641 A
• Filed: 06/07/1974
• Issued: 09/30/1975
• Est. Priority Date: 06/07/1974
• Status: Expired due to Term

• Current Assignee: Donald William Judson, Glenn Roy Jr. Tormey
• Original Assignee: Donald William Judson, Glenn Roy Jr. Tormey
• Inventors: Judson, Donald William, Tormey, Glenn Roy Jr.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/477,255
• Time in Patent Office: 480 Days
• Field of Search: 128/2.5Q,2.6BF,2.6R,2.6V 346/33ME,51,52,54,57,76R,87,139C,143 219/216
• US Class Current: 600/523
• CPC Class Codes: A61B 5/333 Recording apparatus specially adapted therefor
• CPC Class Codes: A61B 5/338 Recording by printing on paper

Abstract

An electrocardiograph unit employing a marker stylus and a writing stylus for recording signals on heat sensitive paper is disclosed. The writing stylus, upon operation of a run switch, is heated first by an immediate burst of high energy heating current and then is heated by a predetermined threshold level of heat current. The marker stylus receives continuous heat and upon operation of the run switch, automatically generates a series of time reference marks by momentary movements into and out of contact with the paper. An operator can selectively open and close an encoding switch which overrides the automatic timing feature and commands the marker stylus to encode '"'"''"'"''"'"''"'"'Morse Code type'"'"''"'"''"'"''"'"' signals on the paper. These coding signals are indicative of the particular cardiac waveforms then being written on the paper by the writing stylus.

Claims

1. An electrocardiograph unit having means for receiving and amplifying signals derived from electrodes placed on a patient'"'"''"'"'s body, a strip chart recorder supplied with heat sensitive paper and a waveform stylus for recording said waveforms in visible form, the improvement comprising:

a marker stylus provided with continuous heat when the electrocardiac unit is in operation;

means for automatically moving said marker stylus into and out of contact with said paper, thereby applying a time reference mark on the heat sensitive paper; and

means, responsive to an operator for overriding said automatic maker stylus moving means and moving said marker stylus into and out of contact with said paper under control of the operator, thereby supplying encoded marks indicative of the electrocardiograph waveform then being written on said paper by said waveform stylus.

2. An electrocardiograph in accordance with claim 1 and further comprising:

a run switch operable for bringing the heat sensitive paper from a stopped position to a selected speed; and

means for applying an initial surge of heating current in excess of a predetermined level to said waveform stylus in response to operation of the run switch.

3. An electrocardiograph in accordance with claim 2 wherein:

said heat applying means includes means for automatically reducing the heating current to said predetermined level immediately following application of said initial surge of heating current to said waveform stylus.

4. An electrocardiograph in accordance with claim 2 wherein said heating cUrrent applying means comprises:

an amplifier receiving an input voltage upon operation of said run switch;

an electrical coil for heating the waveform stylus; and

means connecting said coil in a negative feedback loop for said amplifier.

5. An electrocardiograph in accordance with claim 4 and further comprising:

means connecting a source of potential through said run switch to an input terminal of said amplifier for initially supplying a high spike voltage followed by a lower steady state voltage to said amplifier.

6. An electrocardiograph in accordance with claim 5 wherein said connecting means comprises:

a resistance/capacitor circuit connected between the potential source and the input terminal of said amplifier.

7. An electrocardiograph unit having means for receiving and amplifying signal combinations from electrodes placed on a patient'"'"''"'"'s body and a strip chart recorder supplied with heat sensitive paper for recording waveforms indicative of various signal combinations, the unit comprising:

a heated waveform stylus for recording individual waveforms indicative of signal combinations selected by an operator;

a run switch operable for bringing the heat sensitive paper from a stopped position to a selected speed; and

means for applying heat by applying an initial surge of heating current in excess of a predetermined level to said waveform stylus in response to operation of the run switch, said heat applying means including means for automatically reducing the heating current to said predetermined level immediately following application of said initial surge of heating current to said waveform stylus.

8. An electrocardiograph in accordance with claim 7 wherein said heat applying means comprises:

a negative feedback amplifier receiving an input potential upon operation of said run switch; and

a heater coil for said stylus connected in the feedback circuit of said amplifier.

9. An electrocardiograph in accordance with claim 8 and further comprising:

a marker stylus provided with continuous heat when the electrocardiograph unit is in operation;

means for automatically moving said marker stylus into and out of contact with said paper, thereby applying a time reference mark on the heat sensitive paper; and

manually operative means overriding said automatic marker stylus moving means for supplying encoded marks indicative of the electrocardiograph waveform then being recorded on said paper by said marker stylus.

10. An electrocardiograph in accordance with claim 7, further comprising:

means for increasing the initial surge of heating current supplied by said heat applying means when a faster paper speed is utilized.