Forehead temperature measurement system with high accuracy

A forehead temperature measurement system, configured to measure a forehead temperature of a person at a distance, comprising:

• a display;
• a substrate;
• a lens;
• and
• a sensing chip, arranged on the substrate, and comprising:
• a first image sensor, comprising a first pixel array having a first number of pixels and having a first field of view configured to cover a face of the person during an operation to receive optical energy from the face via the lens to output a first image frame having the first number of pixels;
• a second image sensor;
• a first thermal sensor, comprising a second pixel array having a second number of pixels and having a second field of view configured to cover the face of the person during the operation to receive far infrared light from the face via the lens to output a first thermal image having the second number of pixels, which is smaller than the first number of pixels;
• and
• a processor, coupled to the first image sensor, the second image sensor and the first thermal sensor, and configured to
• recognize a first forehead region and calculate a forehead area according to the first image frame,
• interpolate the first thermal image to cause the second number of pixels to become the first number of pixels to form an interpolated first thermal image,
• map a pixel range of the first forehead region in the first image frame to the interpolated first thermal image, by overlapping the first number of pixels of the image frame on the first number of pixels of the interpolated first thermal image, to determine a first mapped region, as a determined temperature measuring range of the first thermal sensor, and a measured forehead temperature,
• determine an environment temperature according to a temperature value of a pixel in the interpolated first thermal image, wherein the pixel is outside and directly adjacent to the first mapped region of the first forehead region when the forehead area is larger than an area threshold, and
• control the second image sensor to capture a second image frame when a size of the forehead area is smaller than the area threshold to cause the forehead temperature measurement system to be adapted to different distances to compensate for a temperature deviation caused by the distance from the person and environmental temperature fluctuation in a telemetric forehead temperature measurement to prevent false alarm from happening,
• wherein the first number of pixels is arranged to have a sufficient number to cause the first image frame to contain sufficient details for the processor to recognize the forehead region, and
• wherein when the forehead area is larger than the area threshold, the processor is further configured to
• calibrate the measured forehead temperature according to the size of the forehead area and the environment temperature,
• output a digital value as a flag signal upon the calibrated forehead temperature being higher than a predetermined temperature, and
• output the calibrated forehead temperature,
• the display is configured to
• receive the calibrated forehead temperature and show the received calibrated forehead temperature thereon, and
• receive the flag signal and generate a warning indicating that a body temperature of the person is too high.

A forehead temperature measurement system, configured to measure a forehead temperature of a person at a distance, comprising:

• a display;
• a substrate;
• a lens;
• and
• a sensing chip, arranged on the substrate, and comprising:
• a first image sensor, comprising a first pixel array having a first number of pixels and having a first field of view configured to cover a face of the person during an operation to receive optical energy from the face via the lens to output a first image frame having the first number of pixels;
• a first thermal sensor, comprising a second pixel array having a second number of pixels and having a second field of view configured to cover the face of the person during the operation to receive far infrared light from the face via the lens to output a first thermal image having the second number of pixels, which is smaller than the first number of pixels;
• and
• a processor, coupled to the first image sensor and the first thermal sensor, and configured to
• recognize a forehead region according to the first image frame,
• interpolate the first thermal image to cause the second number of pixels to become the first number of pixels to form an interpolated first thermal image,
• map a pixel range of the forehead region in the first image frame to the interpolated first thermal image, by overlapping the first number of pixels of the image frame on the first number of pixels of the interpolated first thermal image, to determine a mapped region as a determined temperature measuring range of the first thermal sensor,
• determine an environment temperature according to a temperature value outside the mapped region,
• find a pixel of interest which has a maximum temperature inside the mapped region, and recognize a ratio of a size of the forehead region in a corresponding region in the first image frame corresponding to a size of the pixel of interest, and
• calculate a measured forehead temperature according to the maximum temperature, the ratio and the environment temperature when the ratio is lower than a ratio threshold to cause the forehead temperature measurement system to be adapted to different distances to compensate for a temperature deviation caused by the distance from the person and environmental temperature fluctuation in a telemetric forehead temperature measurement to prevent false alarm from happening,
• wherein when a forehead area is larger than an area threshold, the processor is further configured to
• calibrate the measured forehead temperature according to a size of the forehead area and the environment temperature,
• output a digital value as a flag signal upon the calibrated forehead temperature being higher than a predetermined temperature, and
• output the calibrated forehead temperature,
• the display is configured to
• receive the calibrated forehead temperature and show the received calibrated forehead temperature thereon, and
• receive the flag signal and generate a warning indicating that a body temperature of the person is too high,
• wherein the environment temperature is a measured temperature value of a pixel in the interpolated first thermal image directly adjacent to the pixel of interest having the maximum temperature,
• wherein the first number of pixels is arranged to have a sufficient number to cause the first image frame to contain sufficient details for the processor to recognize the forehead region.

A forehead temperature measurement system, configured to measure a forehead temperature of a person at a distance, comprising:

• a substrate;
• a lens;
• and
• a sensing chip, arranged on the substrate, and comprising:
• an image sensor, comprising a first pixel array having a first number of pixels and having a first field of view configured to cover a face of the person during an operation to receive optical energy from the face via the lens to output an image frame having the first number of pixels;
• a thermal sensor, comprising a second pixel array having a second number of pixels and having a second field of view configured to cover the face of the person during the operation to receive far infrared light from the face via the lens to output a thermal image having the second number of pixels, which is smaller than the first number of pixels;
• and
• a processor, coupled to the image sensor and the thermal sensor, and configured to
• recognize a forehead region according to the image frame,
• interpolate the thermal image to cause the second number of pixels to become the first number of pixels to form an interpolated thermal image,
• map a pixel range of the forehead region in the image frame to the interpolated thermal image, by overlapping the first number of pixels of the image frame on the first number of pixels of the interpolated thermal image, to determine a mapped region as a determined temperature measuring range of the thermal sensor,
• determine a pixel of interest having a maximum temperature inside the mapped region as a measured forehead temperature, and
• calibrate the measured forehead temperature according to uniformity of temperature differences between the measured forehead temperature and temperatures of pixels directly adjacent to the pixel of interest in the interpolated thermal image, wherein a calibration value is small in response to high uniformity, and the calibration value is large in response to low uniformity to cause the forehead temperature measurement system to be adapted to different positional relationship with respect to a user to compensate for a temperature deviation caused by the distance from the person and environmental temperature fluctuation in a telemetric forehead temperature measurement to prevent false alarm from happening,
• output a digital value as a flag signal upon the calibrated forehead temperature being higher than a predetermined temperature, and
• output the calibrated forehead temperature;
• and
• a display, configured to
• receive the calibrated forehead temperature and show the received calibrated forehead temperature thereon, and
• receive the flag signal and generate a warning indicating that a body temperature of the person is too high,
• wherein the uniformity of temperature differences is determined according to a first temperature difference between the maximum temperature and a first adjacent temperature of the maximum temperature as well as a second temperature difference between the maximum temperature and a second adjacent temperature of the maximum temperature,
• wherein the first number of pixels is arranged to have a sufficient number to cause the image frame to contain sufficient details for the processor to recognize the forehead region.