Heater control for infant warmer

• US 6,464,627 B1
• Filed: 10/02/2000
• Issued: 10/15/2002
• Est. Priority Date: 02/12/2000
• Status: Expired due to Fees

• Current Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Original Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Inventors: Falk, Steven M.
• Primary Examiner(s): Shaver, Kevin
• Assistant Examiner(s): SZMAL, BRIAN SCOTT
• Application Number:
  US09/677,275
• Time in Patent Office: 743 Days
• Field of Search: 600/22, 600/21, 128/736
• US Class Current: 600/22
• CPC Class Codes: A61G 11/00 Baby-incubators; Couveuses
• CPC Class Codes: A61G 2203/46 for temperature
• CPC Class Codes: G05D 23/1912 whose output amplitude can take more than two discrete values

Abstract

A heater control system for use with a radiant heater of an infant warmer. The system utilizes a patient skin temperature and a set temperature inputted by a user and initially subtracts the patient temperature from the set point temperature to arrive at a differential signal identified as the Patient Temperature Gradient (PTG). That PTG is the used to directly control the power to the radiant heater by modifying the power to the heater depending upon the sign and the magnitude of the PTG. Thus, the method of the present invention is not a proportional control system but seeks and finds its own level of power that is not governed by any specific temperature difference and will adjust the heater power where the resulting heater power adjustment may be different for a variety of conditions.

Claims

1. A method of controlling the energy to a radiant heater for supplying heat to an infant contained in an infant apparatus, said method comprising the steps of:

a. measuring the skin temperature of an infant in the infant apparatus,

b. inputting a set temperature desired for the infant,

c. generating an error signal indicative of the difference between the input set temperature and the skin temperature of an infant to obtain a patient temperature gradient (PTG),

d. providing a source of a first pouncer level to the radiant heater, and

e. making an incremental adjustment to the first power level to the radiant heater to provide a second power level to the radiant heater by adding or subtracting to the first power level an incremental level of power that is determined by the magnitude and sign of the PTG.

2. A method of controlling the energy to a radiant heater as defined in claim 1 wherein said step of measuring the skin temperature of an infant comprises using an electronic component to provide a signal representative of the skin temperature and said step of inputting a set temperature comprises inputting a signal representative of the set temperature.

3. A method of controlling the energy to a radiant heater as defined in claim 2 wherein said step of generating a error signal comprises using a differential amplifier to subtract the analog signals obtained in steps a and b.

4. A method of controlling the energy to a radiant heater as defined in claim 1 wherein said method is carried out repetitively at a predetermined time interval.

5. A method of controlling the energy to a radiant heater as defined in claim 4 wherein said time interval is about 30 seconds.

6. A method of controlling the energy to a radiant heater as defined in claim 4 wherein said step of making an incremental adjustment to the first power level comprises adding or subtracting an incremental level that is a predetermined percentage of full power to the heater at each time interval.

7. A method of controlling the energy to a radiant heater as defined in claim 6 wherein said step of making an incremental adjustment to the first power level comprises establishing a series of ranges of values for the PTG and making the incremental adjustment of power a predetermined percentage depending upon the magnitude and sign of the PTG being within one of the series of ranges.

8. A method of controlling the energy to a radiant heater as defined in claim 7 wherein the incremental adjustment to the power is based on the PTG being within the following series of ranges:

−

0.3 to −

0.15 C.;

subtract 5% from the last heater power

−

0.15 to 0.05 C.;

use last heater power

.05 to 0.15 C.;

add 1% to the last heater power

0.15 to 0.25 C.;

Add 5% to the last heater power

0.25 to 0.35 C.;

add 10% to the last heater power

0.35-0.50 C.;

add 15% to the last heater power.