# US 8,739,780 B2 · Low cost CPAP flow generator and humidifier assembly > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,780 B2 - Document ID: US8739780B2 - Status: Granted - Kind: B2 - Application number: 11/988,934 - Filed: 2006-08-15 - Published: 2009-09-17 - Granted: 2014-06-03 - Earliest claimed: 2005-08-15 - Assignees: ResMed Limited - Applicants: Zhuo Ran Tang; Cem Tarakci; John Michael Snow; Kenneth Lee; Steven Farrugia; Dmitri Anotolievich Doudkine; Ian Malcolm Smith - Inventors: Zhuo Ran Tang; Cem Tarakci; John Michael Snow; Kenneth Lee; Steven Farrugia; Dmitri Anotolievich Doudkine; Ian Malcolm Smith - Web page: https://patentgrep.com/patent/US8739780B2 ## CPC - A61M 16/0057: {Pumps therefor} - A61M 16/0051: {with alarm devices} - A61M 16/0069: {the speed thereof being controlled by respiratory parameters, e.g. by inhalation} - A61M 16/024: {including calculation means, e.g. using a processor} - A61M 16/1075: {by influencing the temperature (A61M16/1045 takes precedence)} - A61M 16/109: {the humidifying liquid or the beneficial agent} - A61M 16/142: {with semi-permeable walls separating the liquid from the respiratory gas} - A61M 16/16: Devices to humidify the respiration air {(A61M16/1045 takes precedence)} - A61M 2205/3368: Temperature - A61M 2205/3561: local, e.g. within room or hospital - A61M 2205/3584: using modem, internet or Bluetooth® - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} ## Abstract A CPAP device wherein humidification detection and/or control is performed by a microprocessor of the CPAP device without requiring a separate humidification control chip. The microprocessor may also control the flow generator motor and the flow generator display. Further, the microprocessor may include code to prevent ‘brown-out’, and/or to detect the availability (connection and/or operability) of the humidifier. Humidifier detection may be carried out using power consumption or temperature sensor signal analysis, e.g., facilitated by use of a pull-up resistor. ## Claims ### Claim 1 A continuous positive airway pressure (CPAP) device comprising: a flow generator including a microprocessor; a humidifier detachably coupled to the flow generator; and a temperature sensor in communication with the humidifier and adapted to produce a voltage signal provided to the flow generator microprocessor, wherein the microprocessor is programmed with a humidifier control program adapted to control power supply to the humidifier in accordance with output of the temperature sensor, and adapted to detect when the humidifier is substantially empty of water based on the output of the temperature sensor. ### Claim 2 (depends on 1) The CPAP device according to claim 1, wherein the humidifier control program includes machine readable code configured to: compare the voltage signal of the humidifier temperature (TH) to a maximum permissible temperature of the humidifier (TMAX); turn off power to the humidifier if the temperature is greater than TMAX; and turn on or keep on the power to the humidifier if the temperature is not greater than TMAX. ### Claim 3 (depends on 2) The CPAP device according to claim 2, wherein the comparison of TH to TMAX is periodically carried out upon expiration of a predetermined time period and, if TH is not greater than TMAX, power is provided to the humidifier for only a fraction of the predetermined time period. ### Claim 4 (depends on 3) The CPAP device according to claim 3, wherein the fraction is about 5-95% of the predetermined time period. ### Claim 5 (depends on 3) The CPAP device according to claim 3, wherein the predetermined time period is in the range of about 1-10 seconds. ### Claim 6 (depends on 3) The CPAP device according to claim 3, wherein the flow generator is in communication with a main power voltage detector, and the fraction is determined in accordance with the detected main power voltage. ### Claim 7 (depends on 1) The CPAP device according to claim 1, wherein the humidifier control program includes machine readable code configured to: compare the converted voltage signal of the humidifier temperature (TH) to a temperature range (TR), and turn off or keep off power supply to the humidifier if TH is within TR. ### Claim 8 (depends on 7) The CPAP device according to claim 7, wherein, if TH is not within TR, the code is configured to: turn off or keep off power supply to the humidifier if TH is greater than a maximum allowable temperature (TMAX), and if TH is not greater than TMAX, turn on or keep on the humidifier if TH is less than a minimum temperature (TMIN) and turn off or keep off the power supply to the humidifier if TH is not less than TMIN. ### Claim 9 (depends on 1) The CPAP device according to claim 1, wherein the humidifier control program includes machine readable code configured to determine whether the humidifier is available. ### Claim 10 (depends on 9) The CPAP device according to claim 9, wherein the microprocessor executes a humidifier control program to: receive output, and signal whether the humidifier is available based on the output. ### Claim 11 (depends on 10) The CPAP device according to claim 10, wherein a signal is generated to indicate that the humidifier is not available if the output is not within the possible range of operability of the humidifier. ### Claim 12 (depends on 10) The CPAP device according to claim 10, wherein a signal is generated to indicate that the humidifier is attached and operational if the output is within the possible range of operability of the humidifier. ### Claim 13 (depends on 11) The CPAP device according to claim 11, wherein the possible range of operability is between about 5°-70° C. ### Claim 14 A continuous positive airway pressure (CPAP) device comprising: a flow generator including a microprocessor; a humidifier detachably coupled to the flow generator; a temperature sensor in communication with the humidifier and adapted to produce a voltage signal provided to the flow generator microprocessor, and an analog-to-digital converter (ADC) and a pull-up resistor in communication with the ADC, wherein the ADC provides a signal to the microprocessor having a first value if the humidifier is not available and a second value, different from the first value, if the humidifier is connected and operable, wherein the microprocessor is programmed with a humidifier control program adapted to control power supply to the humidifier in accordance with output of the temperature sensor. ### Claim 15 (depends on 14) The CPAP device according to claim 14, wherein the microprocessor includes code to signal availability of the humidifier in accordance with the signal provided from the ADC to the microprocessor via the pull-up resistor. ### Claim 16 (depends on 14) The CPAP device according to claim 14, wherein power is supplied to the humidifier, and if the converted voltage signal from the ADC to the microprocessor indicates power loss attributable only to the pull up resistor, then a signal is generated to indicate unavailability of the humidifier, and wherein if the converted voltage signal indicates power loss which is different from the power loss attributable only to the pull-up resistor, then a signal is generated to indicate availability of the humidifier. ### Claim 17 (depends on 1) The CPAP device according to claim 1, further comprising a cradle to support the flow generator and the humidifier. ### Claim 18 (depends on 17) The CPAP device according to claim 17, wherein the cradle includes the temperature sensor and a heater plate with a heating element in communication with the humidifier, the temperature sensor being in thermal communication with the heating element. ### Claim 19 (depends on 1) The CPAP device according to claim 1, wherein the temperature sensor comprises a thermistor. ### Claim 20 (depends on 1) The CPAP device according to claim 1, wherein the flow generator includes main electrical components consisting essentially of the microprocessor, a motor, a power supply unit and a display. ### Claim 21 (depends on 1) The CPAP device according to claim 1, wherein the microprocessor is programmed with machine readable code to control the motor and the display. ### Claim 22 A method for controlling a humidifier of a continuous positive airway pressure (CPAP) device, comprising: monitoring a temperature of the humidifier; generating a voltage signal representative of the humidifier temperature; converting the voltage signal to a digital signal; applying the digital signal to a microprocessor of a flow generator of the CPAP device, supplying power to the humidifier in accordance with the digital signal, and determining whether the humidifier is substantially empty of water based upon the digital signal. ### Claim 23 (depends on 22) The method according to claim 22, wherein the microprocessor includes a humidifier control program having machine readable code configured to: compare the converted voltage signal of the humidifier temperature (TH) to a maximum permissible temperature of the humidifier (TMAX); turn off power to the humidifier if the temperature is greater than TMAX; and turn on or keep on the power to the humidifier if the temperature is not greater than TMAX. ### Claim 24 (depends on 23) The method according to claim 23, further comprising periodically comparing TH to TMAX upon expiration of a predetermined time period and, if TH is not greater than TMAX, providing power to the humidifier for only a fraction of the predetermined time period. ### Claim 25 (depends on 24) The method according to claim 24, wherein the fraction is about 5-95% of the predetermined time period. ### Claim 26 (depends on 24) The method according to claim 24, wherein the predetermined time period is about 1-10 seconds. ### Claim 27 (depends on 22) The method according to claim 22, wherein the microprocessor has a capacity of about 100-150 bytes. ### Claim 28 (depends on 22) The method according to claim 22, further comprising determining whether the humidifier is available. ### Claim 29 (depends on 28) The method according to claim 28, wherein the humidifier availability is determined by: receiving output from an analogue to digital converter (ADC) and signaling whether the humidifier is available based on the ADC output. ### Claim 30 (depends on 29) The method according to claim 29, further comprising generating a signal to indicate that the humidifier is not available if the output from the ADC is not within the permissible range of operability of the humidifier. ### Claim 31 (depends on 29) The method according to claim 29, further comprising generating a signal to indicate that the humidifier is attached and operational if the output from the ADC is within the permissible range of operability of the humidifier. ### Claim 32 (depends on 30) The method according to claim 30, wherein the permissible range of operability is between about 5°-70° C. ### Claim 33 A method for controlling a humidifier of a continuous positive airway pressure (CPAP) device, comprising: monitoring a temperature of the humidifier; generating a voltage signal representative of the humidifier temperature; converting the voltage signal to a digital signal; applying the digital signal to a microprocessor of a flow generator of the CPAP device, supplying power to the humidifier in accordance with the digital signal, and providing the flow generator with a pull-up resistor. ### Claim 34 (depends on 33) The method according to claim 33, further comprising providing the microprocessor with code to signal availability of the humidifier in accordance with the signal provided to the microprocessor via the pull-up resistor. ### Claim 35 (depends on 33) The method according to claim 33, wherein power is supplied to the humidifier, and if the converted voltage signal supplied to the microprocessor indicates power loss attributable only to the pull-up resistor, then a signal is generated to indicate unavailability of the humidifier, and wherein if the converted voltage signal indicates a power loss which is different from the power loss attributable only to the pull-up resistor, then a signal is generated to indicate availability of the humidifier. ### Claim 36 (depends on 22) The method according to claim 22, further comprising programming the microprocessor with machine readable code to control motor and display functions. ### Claim 37 A continuous positive airway pressure (CPAP) device comprising: a flow generator including a microprocessor; a humidifier detachably coupled to the flow generator; and a temperature sensor in communication with the humidifier and adapted to produce a voltage signal provided to the flow generator microprocessor, wherein the microprocessor is programmed with a humidifier control program adapted to detect when the humidifier is substantially empty of water based on the output of the temperature sensor. ### Claim 38 (depends on 37) The CPAP device according to claim 37, wherein the microprocessor determines whether the humidifier is substantially empty based upon a rate of change of temperature detected by the temperature sensor. ### Claim 39 A method for controlling a humidifier of a continuous positive airway pressure (CPAP) device, comprising: monitoring a temperature of the humidifier; generating a voltage signal representative of the humidifier temperature; converting the voltage signal to a digital signal; applying the digital signal to a microprocessor of a flow generator of the CPAP device, and determining whether the humidifier is substantially empty of water based upon the digital signal. ### Claim 40 (depends on 39) The method according to claim 39, wherein the humidifier is determined to be substantially empty based upon a rate of change of the temperature. ### Claim 41 (depends on 1) The CPAP device according to claim 1, wherein the microprocessor determines whether the humidifier is substantially empty based upon a rate of change of temperature detected by the temperature sensor. ### Claim 42 (depends on 22) The method according to claim 22, wherein the humidifier is determined to be substantially empty based upon a rate of change of the temperature.