Antifog mechanism for face masks with transparent material in the field of view of user between the user's eyes and the external environment

Abstract

Antifog mechanism for face masks with transparent material (4) in the field of view of user between the user's eyes and the external environment, which is exposed to ambient temperatures, is provided, characterized in that it includes a heating resistor containing membrane (1) or an electrically conductive membrane (1) with resistance per area millimetre, which is positioned over the transparent material (4) on the side facing the face, PID controller, an external temperature sensor positioned such that it records the temperature outside the mask or a temperature sensor recording the transparent material (4) inner side temperature and an internal temperature sensor, positioned such that it records the temperature inside the mask, control board performing data acquisition from the temperature sensors as well as implementation of PID controller and power source for supplying the mechanism components, wherein the PID controller controls the transparent material (4) inner side temperature and having taken into account the temperature sensor values adjusts the current coming from the power source, which passes through the membrane (1) resistance such that the transparent material (4) inner side temperature is maintained at a level higher than that of dew point.

Description

[0001] ANTIFOG MECHANISM FOR FACE MASKS WITH TRANSPARENT MATERIAL IN THE FIELD OF VIEW OF USER BETWEEN THE USER’S EYES AND THE EXTERNAL ENVIRONMENT The present invention relates to antifog mechanism for face masks with transparent material in the field of view of user between the user’s eyes and the external environment according to claim 1, as well as face mask with transparent material in the field of view of user between the user’s eyes and the external environment, which is exposed to ambient temperatures, characterized in that it includes antifog mechanism according to the invention. The present invention intends to disclose an antifog mechanism for face masks with transparent material in the field of view of user between the user’s eyes and the external environment. The mechanism prevents fogging of the mask, with low power consumption. This is achieved according to claim 1. According to the invention a face mask is also provided with transparent material in the field of view of user between the user’s eyes and the external environment, which is exposed to ambient temperatures, characterized in that it includes antifog mechanism according to the invention. Further implementations and applications of the invention is the object of the dependent claims. When the external and internal temperature of the mask are different, which allows occurrence of dew point and condensation, the mechanism is activated, which reduces this temperature difference and prevents condensation. E.g., taking a diving mask as an example, during the diving procedure the eyepiece glass tends to fog due to humidity coming from the diver’s skin, from the remaining water upon application of the mask as well as from exhalation air during pressure equalization. This happens as humidity which is very close to body temperature (~36οC) condenses on the eyepiece glass inner surface due to the lower temperature that it has. According to the invention and referring to claim 1 an antifog mechanism for face masks with transparent material in the field of view of user between the user’s eyes and the external environment, which is exposed to ambient temperatures, is provided, said antifog mechanism includes a heating resistor containing membrane or an electrically conductive membrane with resistance per area millimetre which is positioned over the transparent material on the side facing the face, that is on its inner side, PID controller, an external temperature sensor positioned such that it records temperature outside the mask or a temperature sensor recording the transparent material inner side temperature and an internal temperature sensor, positioned such that it records temperature inside the mask (internal temperature), that is the temperature in the chamber between the user’s face and the membrane, control board performing data acquisition from the temperature sensors as well as implementation of PID controller and power source (battery) for supplying the mechanism components, wherein the PID controller controls the transparent material inner side temperature and adjusts, having taken into account the temperature sensor values, the current coming from the power source, which passes through the membrane resistance such that the transparent material inner side temperature is maintained at a level higher than that of dew point. Preferably the transparent material inner side temperature is maintained at a level higher than that of dew point by a determined value (offset) guaranteeing prevention of mask fogging with the least possible power consumption. Preferably the controller is implemented in a MPU / CPU incorporated into electronic board of the system. The transparent material may be a single material or a combination of transparent materials and components in layers. E.g., preferably it may be tempered glass or transparent polycarbonate or a combination of tempered glass or transparent polycarbonate with a plane comprised of augmented reality display where information is displayed in monochrome or color (RGB) form on the mask glass, through micro-displays and optical waveguides, e.g., on the one or both eyepieces. In view of the fact that condensation and heat transfer is higher at the edges of the transparent material geometry due to heat transfer through the transparent material and state of the art plastic parts of the mask tangent to the transparent material, the resistor in the membrane is preferably positioned around the transparent material geometry circumference to compensate for heat loss at the edges. In case of an electrically conductive membrane with resistance per area millimetre heat dissipation is uniform in the entirety of transparent material surface as the membrane is positioned uniformly. The transparent material inner side temperature is calculated based on the values of the internal and external temperature sensors and of transparent material thermal conductivity through a characteristic curve or a reference table (temperature lookup table). In case a sensor of temperature of the transparent material inner side is provided, there is no need for external temperature sensor and temperature lookup table, as the PID controller uses the transparent material inner side temperature value provided by the temperature sensor. According to an implementation of the invention control of the transparent material inner side temperature by the PID controller is performed through a characteristic curve or a reference table (Heating Power lookup table) based on the internal temperature, transparent material inner side temperature, transparent material thermal conductivity, and dew point. Dew point (Dew point temperature) occurs for 1013 mbar pressure inside the mask as a function of internal temperature T, and relative humidity RH inside the mask according to the following formula: where Td is dew point, T is current internal temperature, RH is relative humidity, m=17.62, and Tn=243.21 ºC Altitude differences outside water add a small negligible error to the PID controller. The calculation of relative humidity RH is done by means of evaluation or calibration through a characteristic curve or a reference table (RH lookup table) by taking also into account that: • Body temperature is ~36C • The volume inside the mask is constant. • Humidity molecules mainly come from the face surface which is enclosed in the mask and from breathing in case the nose also is inside the mask. Water loss from skin is calculated through an empirical model based on skin temperature. Total water loss from skin grows as temperature rises. A common observation lies in the fact that for every 1ºC skin temperature rise the total water loss from skin grows by about 5-10% under certain conditions. A simplified equation based on the above approach is:TEWLT = TEWL0 × (1 + α × (T − T0))Where: • TEWLT= estimated TEWL in temperature T (g / m2 / h) • TEWL0= basic TEWL value in reference temperature T0typically in 32ºC (g / m3 / h) • α = the TEWL increase rate per ºC (usually, 0.05 to 0.1 or 5-10% rise per ºC) • T = Skin temperature • T0= Reference temperature, usually 32 ºC Taking into account also the skin surface the total water loss is: Total water loss = TEWLTx Skin surface. Then is calculated humidity as a percent: We calculate the amount of water added to the air-bearing space air. This is known from the above calculation and is called mass of water vapor (mwater) in grams. Then, we calculate the absolute humidity value. Absolute humidity is the mass of water vapor per volume unit and is given by:Absolute Humidity Where: • mWATER = mass of water vapors that was added • VAIR = Volume of the closed air-bearing space in cubic metres (m3). The units of absolute humidity are g / m3. Then, we calculate water vapor saturation pressure in this particular temperature. Saturation pressure is dependent on temperature. In each temperature this value gives us the amount of water vapors the air can have before it is completely saturated (100%). For this calculation, of saturation pressure (PSAT) in a specific temperature T, the simplified Magnus equation can be employed. Where: • Psat = Water vapor saturation pressure in hPa • T = Temperature in ºC We convert absolute humidity to partial pressure of water vapors. T0 achieve this, we use the ideal gas law. Where: Pwater = water vapor partial pressure in Pa R = water vapor gas constant = 461.5 j / kg.K T = Temperature in Kelvin (k) thus T(K) = T(ºC) + 273.15 M = water molecular mass = 18.01528 g / mol mwater = water vapor mass Vair = Air volume (m3) To calculate humidity as a percent (RH) we take the fraction of water vapor partial pressure over water vapor saturation pressure. Relative Humidity (RH) = Where: Pwater = water vapor partial pressure in Pa Psat = Water vapor saturation pressure in hPa Now, to calculate dew point we have: Where: Tdew = Dew point temperature T = Air temperature RH = Relative humidity α = 17.27 / β = 237.70C in temperatures over 0 and α = 21.875 / β = 265.50C in temperatures below 0. The above relation applies in atmospheric pressure. In case we want to calculate dew point temperature in higher pressures, we have to calculate the actual pressure of water vapors. Where: RH = Relative humidity as a percent (0%) Psat = Water vapor saturation pressure in hPa in a specific temperature T. This can be calculated employing the Magnus equation for temperatures between 0-50ºC. Now, the water vapor pressure must be adjusted for higher ambient pressures. Where: Padj vapor = adjusted water vapor pressure in higher pressures Pvapor = Water vapor pressure calculated from relative humidity Pair = Air-bearing space pressure in bara Patm = Atmospheric pressure (1.01325 bara) Finally, the dew point temperature is calculated employing the inverse Magnus- Tetens equation. Tdew= Where: α = 17.27 b = 237.7 ºC Padj vapor = adjusted water vapor pressure in higher pressures Alternatively, concerning relative humidity RH calculation, it can be assumed that the relative humidity on the inner side of the mask is 98% or it can be provided a sensor of humidity inside the mask. In instances of underwater use, e.g. for diving masks, for greater precision in dew point calculation and referring to the above paragraphs a sensor of pressure inside the mask may be provided. Alternatively, the PID controller control point is set the same as that of internal temperature (by definition, dew point can’t be above ambient temperature, that is, in this particular case, internal temperature, and is a little lower than this temperature). According to a preferred implementation of the invention the antifog mechanism also includes a transparent insulating layer, which for example can be transparent gel with low thermal conductivity coefficient or air, which forms the transparent material inner side. In this case, the PID controller controls the temperature of the insulating layer inner surface, which forms the transparent material inner surface, whereas in case a temperature sensor is provided which records the transparent material inner side temperature this sensor records the insulating layer inner side temperature. In case the mechanism includes membrane containing heating resistor or electrically conductive membrane with resistance per area millimetre and transparent insulating layer, in view of the fact that the effect of external temperature is considerably reduced due to the inner insulating layer, the heating resistor or electrically conductive membrane needs only to reduce the small temperature difference between the inside of the mask and the insulating layer inner surface, as by definition dew point can’t be above ambient temperature, that is, in this particular case, internal temperature. Thus, the mechanism power consumption is considerably lower than that of a mask without insulating layer. The antifog mechanism according to the invention can be incorporated into any face mask with transparent material in the field of view of user between the user’s eyes and the external environment, which is exposed to ambient temperatures. For example, it can be incorporated into the masks below, which are mentioned by class: 1. Diving and Underwater Jobs: o Diving masks (lenses made from tempered glass or polycarbonate). o Free diving masks (low volume masks with transparent lenses). o Full face masks for diving (with transparent fronts). o Professional diving helmets (with full transparent visor). 2. Aviation and High Altitude Activities: o Fighter jet pilot helmets (oxygen masks with transparent visors). o High altitude pilot masks (oxygen masks with visors). o Astronaut helmets (full transparent visor for oxygen and protection). 3. Winter and Extreme Sports: o Ski goggles (lenses made from transparent plastic or polycarbonate). o Snowboard goggles (transparent visors for wind protection). o Helmets for ice climbing (with transparent shields). 4. Motorcycles and Race Cars: o Full face motorcycle helmets (transparent or non-transparent visors). o Motocross helmets (goggles with transparent lenses). o Race Helmets (transparent visors for visibility and safety). 5. Air Speed Sports: o Skydiving helmets (transparent visors for wind protection). o Paragliding helmets (with visors or goggles). o Wingsuit flying helmets (transparent visors for wind protection). 6. Industrial and Manufacturing / Constructing Jobs: o Welding masks (automatic darkness glass visors). o Grinding masks (transparent plastic or glass visors for protection from fragments). o Sandblasting masks (full face shields with transparent glass) 7. Off-road and Extreme Sports: o Off-road cycling helmets (transparent or non-transparent visors). o ATV driver helmets (full face helmets with transparent shields). o Mountain bike helmets (goggles with transparent lenses). 8. Firefighting and Rescue: o SCBA firefighter masks (transparent visors for visibility and breathing). o Rescue helmets (with transparent face shields for protection). 9. Dangerous Environment Jobs: o Hazmat suits (masks with full face transparent visors). o Chemical protection masks (transparent visors for protection from chemical splashes). o Nuclear power plant suits (masks with full face glass visors). 10. Aerospace industry and Outer Space Exploration: o Astronaut helmets (full face transparent visors for isolation of air supply from vacuum). o Jetpack pilot helmets (transparent visors for wind protection in high speed).

[0002] 11 . Recreation and Sports: o Paintball masks (full face masks with transparent visors). o Airsoft masks (transparent protective shields). o Fencing masks (certain advanced models with transparent visors).

[0003] 12. Scientific and Environment Jobs: o Volcanologist helmets (transparent face shields for protection from ashes and fragments). o Hurricane hunter helmets (full face shields for wind and fragment protection). o Sea biologists (diving masks with transparent lenses).

[0004] 13. Motorized Water Sports: o Jet-ski helmets (transparent face shields). o Powerboat racing helmets (transparent visors for wind and water protection).

[0005] 14. Jobs in Extreme Environments: o Deep water diving helmets (with transparent front windows for visibility). o Polar expedition helmets (with transparent visors for wind protection).

[0006] 15. Mine and Tunnel Jobs: o Mine helmets with visors (transparent plastic shields for eye and face protection). o Workers in tunnels (masks with transparent visors). The present invention can be fully understood from the following detailed description in relation to the attached drawings in which: Figure 1 shows a section of the mask transparent material including a transparent insulating layer according to a form of the invention, and Figure 2 shows a schematic perspective view of a mask which includes antifog mechanism according to a form of the invention. In Figure 1 are shown a membrane containing heating resistor or an electrically conductive membrane with resistance per area millimetre 1, insulating layer 2 and tempered glass or transparent polycarbonate 3. In this case the insulating layer 2 and tempered or transparent polycarbonate 3 form the transparent material 4. In Figure 2 is shown a mask 5 which includes antifog mechanism according to a form of the invention. They are also to be seen internal temperature sensor 6, positioned in such a way that it records the temperature inside the mask 5, external temperature sensor 8 as well as a box 7 for the electronic board of the system, into which the MPU / CPU is incorporated, the power source and other electronic modules.

Claims

AMENDED CLAIMS received by the International Bureau on 11 March 2026 (11.03.2026)1 . Antifog mechanism for face masks with transparent material (4) in the field of view of user between the user’s eyes and the external environment, which is exposed to ambient temperatures, the antifog mechanism including a membrane (1 ) containing heating resistor or an electrically conductive membrane (1 ) with resistance per area millimetre, which is positioned over the transparent material (4) on the side facing the face, PID controller, an external temperature sensor positioned such that it records the temperature outside the mask or a temperature sensor recording the transparent material (4) inner side temperature and an internal temperature sensor, positioned such that it records the temperature inside the mask, control board performing data acquisition from the temperature sensors as well as implementation of PID controller and power source for supplying the mechanism components, wherein the PID controller controls the transparent material (4) inner side temperature and having taken into account the temperature sensor values adjusts the current coming from the power source, which passes through the membrane (1 ) resistance such that the transparent material (4) inner side temperature is maintained at a level higher than that of dew point, characterized in that in case an external temperature sensor is provided the transparent material (4) inner side temperature is calculated based on the values of the internal and external temperature sensors and of transparent material thermal conductivity through a characteristic curve or a reference table (temperature lookup table), whereas in case a sensor of temperature of the transparent material (4) inner side is provided the PID controller uses the transparent material (4) inner side temperature value provided by the temperature sensor.

2. Antifog mechanism for face masks with transparent material (4) in the field of view of user between the user’s eyes and the external environment, which is exposed to ambient temperatures, the antifog mechanism including a membrane (1 ) containing heating resistor or anelectrically conductive membrane (1 ) with resistance per area millimetre, which is positioned over the transparent material (4) on the side facing the face, PID controller, an external temperature sensor positioned such that it records the temperature outside the mask or a temperature sensor recording the transparent material (4) inner side temperature and an internal temperature sensor, positioned such that it records the temperature inside the mask, control board performing data acquisition from the temperature sensors as well as implementation of PID controller and power source for supplying the mechanism components, wherein the PID controller controls the transparent material (4) inner side temperature and having taken into account the temperature sensor values adjusts the current coming from the power source, which passes through the membrane (1 ) resistance such that the transparent material (4) inner side temperature is maintained at a level higher than that of dew point, characterized in that control of the transparent material (4) inner side temperature by means of the PID controller is performed through a characteristic curve or a reference table (Heating Power lookup table) based on the internal temperature, transparent material (4) inner side temperature, transparent material (4) thermal conductivity, and dew point.

3. Antifog mechanism for face masks with transparent material (4) in the field of view of user between the user’s eyes and the external environment, which is exposed to ambient temperatures, the antifog mechanism including a membrane (1 ) containing heating resistor or an electrically conductive membrane (1 ) with resistance per area millimetre, which is positioned over the transparent material (4) on the side facing the face, PID controller, an external temperature sensor positioned such that it records the temperature outside the mask or a temperature sensor recording the transparent material (4) inner side temperature and an internal temperature sensor, positioned such that it records the temperature inside the mask, control board performing data acquisition from the temperature sensors as well as implementation of PID controller and power source for supplying the mechanism components, whereinthe PID controller controls the transparent material (4) inner side temperature and having taken into account the temperature sensor values adjusts the current coming from the power source, which passes through the membrane (1 ) resistance such that the transparent material (4) inner side temperature is maintained at a level higher than that of dew point, characterized in that to calculate dew point the relative humidity RH inside the mask is estimated by means of evaluation or calibration through a characteristic curve or a reference table (RH lookup table), taking also into account that body temperature is ~36C, the volume inside the mask is constant and that humidity molecules mainly come from the face surface which is enclosed in the mask and from breathing in case also the nose is inside the mask or in that to calculate dew point it is assumed that the relative humidity on the inner side of the mask is 98%.

4. Antifog mechanism according to claim 1 , 2 or 3, characterized in that it also includes a transparent insulating layer (2), which forms the transparent material (4) inner side.

5. Antifog mechanism according to claim 1 or 2, characterized in that it includes sensor of humidity inside the mask for recording the relative humidity to calculate dew point.

6. Antifog mechanism according to claim 1 , 2, 3, 4 or 5, characterized in that in case of a mask for underwater use to calculate dew point is provided a sensor of pressure inside the mask or the control point of PID controller is set the same as that of the internal temperature.

7. Antifog mechanism according to claim 1 , 2, 3, 4, 5 or 6, characterized in that the resistor in the heating resistor containing membrane (1 ) is positioned around the transparent material geometry circumference to compensate for heat loss at the edges, whereas in case of an electrically conductive membrane (1 ) with resistance per area millimetre heatdissipation is uniform in the entirety of transparent material surface as the membrane (1 ) is positioned uniformly.

8. Antifog mechanism according to claim 1 , 2, 3, 4, 5, 6 or 7, characterized in that the PID controller maintains the transparent material (4) inner side temperature at a level higher than that of dew point by a determined value (offset) guaranteeing prevention of mask fogging with the least possible power consumption.

9. Face mask with transparent material (4) in the field of view of user between the user’s eyes and the external environment, which is exposed to ambient temperatures, characterized in that it includes antifog mechanism according to claim 1 , 2, 3, 4, 5, 6, 7 or 8.

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