Blood pressure measurement device and method

Abstract

This invention provides a blood pressure measuring device, including a substrate, a protrusion, an image sensing unit, a first light source, a second light source, and a control and processing unit. The first light source projects a first light beam toward the substrate. When a finger presses the protrusion, the first light beam undergoes total internal reflection, which is disrupted by the finger and reflected back, allowing the image sensing unit to obtain a bright area image. The control and processing unit calculates the number of light-receiving pixels in the image sensing unit based on the bright area image and compares it with the total number of light-receiving pixels in the image sensing unit to obtain a ratio value, thereby determining whether the pressure is sufficient. The second light source projects a second light beam toward the substrate. The second light beam passes through the substrate and the skin of the finger and is reflected by blood vessels, allowing the image sensing unit to obtain an image of changes in blood vessel volume. The control and processing unit calculates the systolic or diastolic blood pressure based on the image of changes in blood vessel volume.

Description

Technical Field

[0001] This invention relates to the field of medical technology, and in particular to a blood pressure measuring device and method. Background Technology

[0002] Photoplethysmography (PPG) is a non-invasive physiological parameter measurement technique. While most wearable devices (e.g., smartwatches, smart bands) can use PPG sensors to display real-time heart rate, these sensors use photoelectric sensors to detect changes in tissue blood volume. The measurement accuracy of wearable devices is affected by noise introduced by skin contact with the user or device's movement, environmental conditions, and ectopic heartbeats. Therefore, the effectiveness of using wearable devices to analyze heart rate abnormalities is often limited. Thus, reducing variability in skin and muscle conditions to improve accuracy is a pressing goal.

[0003] Well-known photoplethysmography (PPG) devices include photoelectric sensors and pressure sensors, with an average error of less than 5 mmHg and a standard deviation of less than 8 mm. This is because the tightness of skin and muscles is related to the accuracy of PPG measurement. Therefore, the main purpose of the pressure sensor is to monitor and confirm the degree of pressure applied by the finger to determine the tightness of the finger's skin and muscles, thereby improving the accuracy of PPG measurement.

[0004] However, well-known photoplethysmography devices have the following problems: First, they cannot be fabricated on glass in order to embed the pressure sensor; second, the configuration of the pressure sensor increases the cost; and third, when the photoelectric sensor and the pressure sensor are packaged as a module, the photoelectric sensor is easily contaminated during the packaging process of the pressure sensor, which can lead to failure. Summary of the Invention

[0005] The main objective of this invention is to provide a blood pressure measuring device and method that can determine whether the pressure applied by a finger is sufficient without the need for a pressure sensor.

[0006] To achieve the aforementioned objectives, the present invention provides a blood pressure measuring device, comprising a substrate, a protrusion, an image sensing unit, at least one first light source, at least one second light source, and a control and processing unit. The protrusion is disposed on the substrate and has a plurality of cutouts. The image sensing unit is disposed below the substrate and corresponds to the cutouts. The at least one first light source is disposed below one side edge of the substrate. The at least one second light source is disposed below the substrate. The control and processing unit is electrically connected to the image sensing unit, the at least one first light source, and the at least one second light source. In this system, at least one first light source projects a first ray toward the substrate, which undergoes total internal reflection within the substrate. When a finger presses on the hollowed-out portion of the protrusion, the total internal reflection of the first ray is disrupted by the finger and reflected. The image sensing unit receives the reflected first ray and obtains a bright area image. The control and processing unit calculates the number of light-collecting pixels (B) of the image sensing unit based on the bright area image and compares it with the number of light-collecting pixels (A) of the image sensing unit to obtain a ratio (B / A)% to determine whether the pressure applied by the finger is sufficient. At least one second light source projects a second ray toward the substrate, which penetrates the substrate and the skin of the finger and is reflected by a blood vessel. The image sensing unit receives the reflected second ray and obtains a blood vessel volume change image. The control and processing unit calculates a systolic blood pressure or a diastolic blood pressure based on the blood vessel volume change image.

[0007] In some embodiments, when the ratio value is between 90% and 98%, the control and processing unit determines that the pressure is sufficient; when the ratio value is less than 90%, the control and processing unit determines that the pressure is insufficient; and when the ratio value is greater than 98%, the control and processing unit determines that the pressure is excessive.

[0008] In some embodiments, the blood pressure measuring device further includes a reflective layer disposed between the protrusion and the substrate, the reflective layer being used to prevent the path of the first totally reflected light rays from being altered or disrupted before entering the cutouts.

[0009] In some embodiments, the blood pressure measuring device further includes an alarm unit electrically connected to the control and processing unit; wherein, when the control and processing unit determines that the pressure is insufficient or excessive, the alarm unit issues a reminder signal.

[0010] In some embodiments, the blood pressure measuring device further includes a light-diffusing light source disposed above the protrusion; wherein the light-diffusing light source projects a third light ray toward the substrate, the third light ray sequentially passing through the cutouts and the substrate, the image sensing unit receives the third light ray and obtains an actual bright area image; the control and processing unit determines an actual number of light-receiving pixels of the image sensing unit based on the actual bright area image.

[0011] To achieve the aforementioned objective, the present invention provides a blood pressure measurement method, comprising the following steps: when a finger presses a protrusion, the finger is inserted into a plurality of hollowed-out portions of the protrusion and pressed onto a substrate; at least one first light source is activated, the at least one first light source projects a first light ray toward the substrate, the first light ray undergoes total internal reflection inside the substrate, the total internal reflection of the first light ray is disrupted by the finger and reflected; an image sensing unit receives the reflected first light ray and obtains a bright area image; a control and processing unit calculates the number (B) of light-receiving pixels of the image sensing unit based on the bright area image, and The number of light-receiving pixels (A) of the image sensing unit is compared to obtain a ratio (B / A)% of the number of light-receiving pixels to determine whether the pressure of the finger pressing is sufficient. When the control and processing unit determines that the pressure is sufficient, at least one second light source is activated. The at least one second light source projects a second light beam in the direction of the substrate. The second light beam passes through the substrate and the skin of the finger and is reflected by a blood vessel. The image sensing unit receives the reflected second light beam and obtains an image of blood vessel volume change. The control and processing unit calculates a systolic blood pressure or a diastolic blood pressure based on the image of blood vessel volume change.

[0012] In some embodiments, the step of determining whether the pressure applied by the finger is sufficient further includes: when the ratio value is between 90% and 98%, the control and processing unit determines that the pressure is sufficient; when the ratio value is less than 90%, the control and processing unit determines that the pressure is insufficient; when the ratio value is greater than 98%, the control and processing unit determines that the pressure is excessive.

[0013] In some embodiments, the step of activating the at least one first light source further includes: a reflective layer disposed between the protrusion and the substrate, the reflective layer being used to prevent the path of the total internally reflected first light ray from being altered or disrupted before entering the cutouts.

[0014] In some embodiments, after determining whether the pressure applied by the finger is sufficient, the method further includes: when the control and processing unit determines that the pressure is insufficient or excessive, an alert unit issues a warning signal.

[0015] In some embodiments, prior to the step of pressing the protrusion with the finger, the method further includes: activating a light-diffusing light source, which projects a third light ray toward the substrate, the third light ray passing sequentially through the cutouts and the substrate, the image sensing unit receiving the third light ray and obtaining an actual bright area image; and the control and processing unit determining an actual number of light-receiving pixels of the image sensing unit based on the actual bright area image.

[0016] Compared with the prior art, the blood pressure sensing device and method provided in this application have at least the following beneficial effects:

[0017] The blood pressure sensing device of the present invention can determine whether the pressure applied by a finger is sufficient without the need for a pressure sensor, thereby confirming the tension of the finger's skin and muscles and improving the accuracy of photoplethysmography (PPG) measurement. Therefore, the blood pressure sensing device of the present invention can be fabricated on glass and applied in wearable devices (e.g., smartwatches or smart bracelets), reducing manufacturing costs. Furthermore, the image sensing unit does not need to be modularly packaged with the pressure sensor, so the image sensing unit will not malfunction due to dirt. Attached Figure Description

[0018] Figure 1A This is a schematic diagram of the structure of the first embodiment of the blood pressure measuring device of the present invention.

[0019] Figure 1B This is a schematic diagram of another embodiment of the blood pressure measuring device of the present invention.

[0020] Figure 2 This is a top view of the protrusion and image sensing unit of the present invention.

[0021] Figure 3 This is a block diagram of the structure of the first embodiment of the blood pressure measuring device of the present invention.

[0022] Figure 4 This is a flowchart of the first embodiment of the blood pressure measurement method of the present invention.

[0023] Figure 5 This is a schematic diagram showing the first light ray projected by the first light source of the present invention being totally reflected by the substrate.

[0024] Figure 6 This diagram illustrates the extent to which a finger is inserted into the cutout.

[0025] Figure 7 A schematic diagram of the bright area image is shown.

[0026] Figure 8 This is a schematic diagram of the second light rays projected by the second light source of the present invention being reflected by blood vessels.

[0027] Figure 9This image shows a schematic diagram of changes in vascular volume as systolic blood pressure.

[0028] Figure 10 This image shows a schematic diagram of diastolic blood pressure changes in vascular volume.

[0029] Figure 11 This is a schematic diagram of the second embodiment of the blood pressure measuring device of the present invention.

[0030] Figure 12 This is a flowchart of the second embodiment of the blood pressure measurement method of the present invention.

[0031] [Explanation of Labels in the Attached Image]

[0032] 10: Substrate;

[0033] 20: Protrusion;

[0034] 21: Openwork section;

[0035] 30: Image sensing unit;

[0036] 31: Bright area image;

[0037] 32, 33: Imaging of changes in vascular volume;

[0038] 40: First light source;

[0039] 50: Second light source;

[0040] 60: Control and processing unit;

[0041] 70: Reflective layer;

[0042] 80: Warning unit;

[0043] 90: Light source for homogenizing light;

[0044] 100: Lens module;

[0045] H: Height range;

[0046] W: Width range. Detailed Implementation

[0047] The embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and component symbols, so that those skilled in the art can implement them after reading this specification.

[0048] Figure 1A This is a schematic diagram of the structure of the first embodiment of the blood pressure measuring device of the present invention. Figure 1B This is a schematic diagram of another embodiment of the blood pressure measuring device of the present invention. Figure 2 This is a top view of the protrusion 20 and the image sensing unit 30 of the present invention. Figure 3This is a block diagram of the structure of the first embodiment of the blood pressure measuring device of the present invention.

[0049] like Figure 1A , Figure 1B , Figure 2 and Figure 3 As shown, the present invention provides a blood pressure measuring device, including a substrate 10, a protrusion 20, an image sensing unit 30, a first light source 40, a second light source 50, and a control and processing unit 60. The protrusion 20 is disposed on the substrate 10 and has a plurality of cutouts 21. The first light source 40 is disposed below one side edge of the substrate 10. The second light source 50 is disposed below the substrate 10. The control and processing unit 60 is electrically connected to the image sensing unit 30, the first light source 40, and the second light source 50.

[0050] The image sensing unit 30 is a CMOS image sensor manufactured using semiconductor processes, comprising an array of a plurality of unit pixels disposed on a substrate. For example... Figure 1A As shown, the image sensing unit 30 is a thin image sensor. Because the thin image sensor does not include a lens module, its thickness is small, but its area is large. Figure 1B As shown, the blood pressure measuring device of the present invention further includes a lens module 100, which is disposed between the substrate 10 and the image sensing unit 30. The image sensing unit 30 and the lens module 100 form a lens-type image sensing module. Because the lens module 100 can focus light, the area of ​​the image sensing unit 30 is small, but the thickness of the lens-type image sensing module is large.

[0051] The control and processing unit 60 may be a microcontroller unit (MCU), which includes a central processing unit, a memory, a timer / counter, and a plurality of input / output interfaces.

[0052] Figure 4 This is a flowchart of the first embodiment of the blood pressure measurement method of the present invention. Figure 5 This is a schematic diagram showing the first light ray projected by the first light source 40 of the present invention being totally reflected by the substrate 10. Figure 6 A schematic diagram showing the extent to which the finger is inserted into the hollowed-out part 21. Figure 7 A schematic diagram of the bright area image 31 is shown. Figure 8 This is a schematic diagram of the second light rays projected by the second light source 50 of the present invention being reflected by blood vessels. Figure 9 This image shows a schematic diagram of changes in vascular volume as systolic blood pressure. Figure 10 This image shows a schematic diagram of diastolic blood pressure changes in vascular volume.

[0053] This invention provides a method for measuring blood pressure, comprising the following steps:

[0054] Step S10, as follows Figure 4 and Figure 5 As shown, when a finger presses the protrusion 20, the finger sinks into the hollowed-out portions 21 and presses onto the substrate 10.

[0055] Step S20, as follows Figure 4 and Figure 5 As shown, the first light source 40 is activated, and the first light source 40 projects a first ray of light toward the substrate 10. The first ray of light undergoes total internal reflection inside the substrate 10. The total internal reflection of the first ray of light is disrupted by the finger and reflected.

[0056] Step S30, as Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the image sensing unit 30 receives the reflected first light and obtains a bright area image 31.

[0057] Step S40, as follows Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the control and processing unit 60 calculates the number of light-collecting pixels (B) of the image sensing unit 30 based on the bright area image 31, and compares it with the number of light-collecting pixels (A) of the image sensing unit 30 to obtain a ratio (B / A)% of the number of light-collecting pixels to the number of light-collecting pixels, so as to determine whether the pressure of the finger pressing is sufficient. The calculation of the number of pixels is based on the DN value (digital number) of each unit pixel reaching a set low standard.

[0058] Step S50, as follows Figure 4 and Figure 8 As shown, when the control and processing unit 60 determines that the pressure is sufficient, it activates the second light source 50. The second light source 50 projects a second light beam toward the substrate 10. The second light beam passes through the substrate 10 and the skin of the finger and is reflected by a blood vessel.

[0059] Step S60, as follows Figure 4 , Figure 8 , Figure 9 and Figure 10 As shown, the image sensing unit 30 receives the reflected second light and obtains an image 32, 33 of blood vessel volume change.

[0060] Step S70, as follows Figure 4 , Figure 8 , Figure 9 and Figure 10As shown, the control and processing unit 60 calculates a systolic blood pressure or a diastolic blood pressure based on the images 32 and 33 of the vascular volume change.

[0061] Furthermore, such as Figure 9 As shown, image 32, showing changes in vascular volume, is significantly darker, with smaller bright areas and larger dark areas. This is because the blood vessels are in a constricted state, resulting in a smaller vessel diameter. Figure 10 As shown, the image 33 showing changes in vascular volume is significantly brighter, with a larger bright area and a smaller dark area. This is because the blood vessels are in a dilated state, resulting in a larger diameter.

[0062] Therefore, the blood pressure sensing device of the present invention can determine whether the pressure applied by the finger is sufficient without the need for a pressure sensor, thereby confirming the tension of the finger's skin and muscles and improving the measurement accuracy of photoplethysmography (PPG). Consequently, the blood pressure sensing device of the present invention can be fabricated on glass and applied in wearable devices (e.g., smartwatches or smart bracelets), reducing manufacturing costs. Furthermore, the image sensing unit 30 does not need to be modularly packaged with the pressure sensor, thus preventing the image sensing unit 30 from malfunctioning due to dirt.

[0063] In a preferred embodiment, step S40 further includes: when the ratio value is between 90% and 98%, the control and processing unit 60 determines that the pressure is sufficient; when the ratio value is less than 90%, the control and processing unit 60 determines that the pressure is insufficient; when the ratio value is greater than 98%, the control and processing unit 60 determines that the pressure is excessive.

[0064] like Figure 1A As shown, in a preferred embodiment, the height H of the protrusion 20 is between 100 and 2000 μm, and the width W of the protrusion 20 is between 300 and 2000 μm. Within this height range H and width range W, the degree to which a finger sinks into the hollow portions 21 can be controlled to occupy approximately 90-98% of the space of the hollow portions 21, thus the proportion can be controlled between 90-98%. If the height range H of the protrusion 20 exceeds 2000 μm and the width range W is less than 300 μm, then the hollow portions 21 are too deep and too narrow. Even with extreme force, the degree to which the finger sinks into the hollow portions 21 will only occupy less than approximately 90% of the space of the hollow portions 21, resulting in a proportion less than 90%. If the height range H of the protrusion 20 is less than 100 μm and the width range W is more than 2000 μm, then the hollowed-out portion 21 is too shallow and too wide. With just a little force, the finger can easily sink into the hollowed-out portion 21 and occupy more than 98% of the space, resulting in a ratio greater than 98%.

[0065] like Figure 2As shown, in a preferred embodiment, there are four cutouts 21, making the protrusions 20 form a grid pattern. Therefore, the grid-shaped protrusions 20 make it easier for fingers to sink into the cutouts 21 and press against the substrate 10. In some embodiments, the number of cutouts 21 ranges from three to nine.

[0066] In a preferred embodiment, since green light can penetrate the skin and be reflected by blood vessels, the second light source 50 is preferably a green light unit pixel.

[0067] like Figure 1A and Figure 1B As shown, in a preferred embodiment, in order not to affect the appearance of the smartwatch or smart bracelet, the protrusion 20 is preferably made of a light-transmitting material, such as acrylic or glass.

[0068] like Figure 1A and Figure 1B As shown, in a preferred embodiment, the blood pressure measuring device of the present invention further includes a reflective layer 70, which is disposed between the protrusion 20 and the substrate 10. Step S20 further includes: as shown in Figure 1. Figure 5 As shown, the reflective layer 70 is used to prevent the path of the first totally internalized light ray from being altered or disrupted before entering the cutouts 21. In this way, the reflective layer 70 can maintain total internal reflection of the first light ray within the substrate 10, and the first light ray will not penetrate through the light-transmitting protrusions 20. Preferably, the reflective layer 70 is made of metal, such as gold, silver, aluminum, or alloys thereof.

[0069] like Figure 3 As shown, in a preferred embodiment, the blood pressure measuring device of the present invention further includes an alarm unit 80, which is electrically connected to the control and processing unit 60. After step S40, the device further includes: step S51, as... Figure 4 As shown, when the control and processing unit 60 determines that the pressure is insufficient, the warning unit 80 will issue a reminder signal to remind the user to increase the pressure of their finger or move their finger laterally to increase the number of light-receiving pixels in the image sensing unit 30; step S51, as Figure 4 As shown, when the control and processing unit 60 determines that the pressure is too high, the warning unit 80 will issue a reminder signal to remind the user to reduce the pressure of their finger, thereby reducing the number of light-receiving pixels in the image sensing unit 30. The warning unit 80 includes, but is not limited to, a buzzer, a voice player, and a display screen. The reminder methods include, but are not limited to, sound, voice, light signals, patterns, or text. The buzzer can emit a sound, the voice player can emit a voice signal, and the display screen can display light signals, patterns, or text.

[0070] In some embodiments, the number of first light sources 40 can be multiple to improve the uniformity of illumination in the bright area image 31, but the manufacturing cost is high. However, in practical applications, only one first light source 40 is needed to achieve the above-mentioned effects, resulting in the lowest manufacturing cost.

[0071] In some embodiments, the number of second light sources 50 can be multiple to improve the resolution of the images 32 and 33 showing changes in blood vessel volume, but this results in higher manufacturing costs. However, in practical applications, only one second light source 50 is needed to achieve the above-mentioned effects, resulting in the lowest manufacturing cost.

[0072] Figure 11 This is a schematic diagram of the second embodiment of the blood pressure measuring device of the present invention. Figure 11 As shown, the structural difference between the second embodiment and the first embodiment is that the blood pressure measuring device of the present invention further includes a light-diffusing light source 90, which is disposed above the protrusion 20.

[0073] Figure 12 This is a flowchart of the second embodiment of the blood pressure measurement method of the present invention. Figure 12 As shown, the difference between the second embodiment and the first embodiment lies in that, prior to step S10, the method further includes: step S80, activating the light-diffusing light source 90, which projects a third light beam toward the substrate 10, the third light beam sequentially passing through the cutouts 21 and the substrate 10, and the image sensing unit 30 receiving the third light beam and obtaining an actual bright area image; step S90, the control and processing unit 60 determining the actual number of light-receiving pixels of the image sensing unit 30 based on the actual bright area image. Therefore, before starting blood pressure measurement, the blood pressure measurement method of the present invention can further confirm the actual number of light-receiving pixels of the image sensing unit 30 through the light-diffusing light source 90, and set the actual number of light-receiving pixels of the image sensing unit 30 as the pressure judgment benchmark of the control and processing unit 60, thereby improving the accuracy of the pressure judgment of the control and processing unit 60.

[0074] The above description is merely for explaining preferred embodiments of the present invention and is not intended to limit the present invention in any way. Therefore, any modifications or changes made to the present invention without departing from the principles described in this application shall fall within the protection scope of this application.

Claims

1. A blood pressure measuring device, characterized in that, include: One substrate; A protrusion is provided on the substrate and has a plurality of cutouts; An image sensing unit is disposed below the substrate and corresponds to the plurality of cutout portions; At least one first light source is disposed below one side edge of the substrate; At least one second light source is disposed below the substrate; A control and processing unit is electrically connected to the image sensing unit, the at least one first light source, and the at least one second light source; In this embodiment, at least one first light source projects a first light ray toward the substrate, and the first light ray undergoes total internal reflection inside the substrate. When a finger presses on the plurality of hollowed-out portions of the protrusion, the total internal reflection of the first light ray is disrupted by the finger and reflected. The image sensing unit receives the reflected first light ray and obtains a bright area image. The control and processing unit calculates the number of light-collecting pixels B of the image sensing unit based on the bright area image and compares it with the number of light-collecting pixels A of the image sensing unit to obtain a ratio (B / A)% of the number of light-collecting pixels B to the number of light-collecting pixels A, so as to determine whether the pressure of the finger pressing is sufficient. The at least one second light source projects a second light beam toward the substrate. The second light beam passes through the substrate and the skin of the finger and is reflected by a blood vessel. The image sensing unit receives the reflected second light beam and obtains an image of blood vessel volume change. The control and processing unit calculates a systolic blood pressure or a diastolic blood pressure based on the image of blood vessel volume change.

2. The blood pressure measuring device as described in claim 1, characterized in that, When the ratio is between 90% and 98%, the control and processing unit determines that the pressure is sufficient; when the ratio is less than 90%, the control and processing unit determines that the pressure is insufficient; and when the ratio is greater than 98%, the control and processing unit determines that the pressure is excessive.

3. The blood pressure measuring device as described in claim 1, characterized in that, It also includes a reflective layer disposed between the protrusion and the substrate, the reflective layer being used to prevent the path of the first light ray, which is totally internalized, from being altered before entering the plurality of cutouts.

4. The blood pressure measuring device as described in claim 1, characterized in that, It also includes an alarm unit electrically connected to the control and processing unit; wherein, when the control and processing unit determines that the pressure is insufficient or too high, the alarm unit issues a warning signal.

5. The blood pressure measuring device as described in claim 1, characterized in that, It also includes a light-diffusing light source, which is disposed above the protrusion; wherein the light-diffusing light source projects a third light ray toward the substrate, the third light ray sequentially passes through the plurality of cutouts and the substrate, the image sensing unit receives the third light ray and obtains an actual bright area image; the control and processing unit determines an actual number of light-receiving pixels of the image sensing unit based on the actual bright area image.

6. A method for measuring blood pressure, said blood pressure measurement method being implemented based on a blood pressure measuring device as described in any one of claims 1 to 5, characterized in that, Includes the following steps: When a finger presses on a protrusion, the finger is inserted into the plurality of hollowed-out portions of the protrusion and pressed onto a substrate; At least one first light source is activated, and the at least one first light source projects a first ray toward the substrate. The first ray undergoes total internal reflection inside the substrate. The total internal reflection of the first ray is disrupted by the finger and reflected. An image sensing unit receives the reflected first light and obtains a bright area image; A control and processing unit calculates the number of light-collecting pixels B of the image sensing unit based on the bright area image, and compares it with the number of light-collecting pixels A of the image sensing unit to obtain a ratio (B / A)% of the number of light-collecting pixels B to the number of light-collecting pixels A, so as to determine whether the pressure of the finger pressing is sufficient. When the control and processing unit determines that the pressure is sufficient, it activates at least one second light source, which projects a second light beam toward the substrate. The second light beam passes through the substrate and the skin of the finger and is reflected by a blood vessel. The image sensing unit receives the reflected second light and obtains an image of blood vessel volume change. The control and processing unit calculates a systolic blood pressure or a diastolic blood pressure based on the image of the change in blood vessel volume.

7. The blood pressure measurement method as described in claim 6, characterized in that, The step of determining whether the pressure applied by the finger is sufficient further includes: when the ratio value is between 90% and 98%, the control and processing unit determines that the pressure is sufficient; when the ratio value is less than 90%, the control and processing unit determines that the pressure is insufficient; when the ratio value is greater than 98%, the control and processing unit determines that the pressure is excessive.

8. The blood pressure measurement method as described in claim 6, characterized in that, The step of activating the at least one first light source further includes: a reflective layer disposed between the protrusion and the substrate, the reflective layer being used to prevent the path of the total internally reflected first light ray from being altered before entering the plurality of cutouts.

9. The blood pressure measurement method as described in claim 6, characterized in that, Following the step of determining whether the pressure applied by the finger is sufficient, the system further includes: when the control and processing unit determines that the pressure is insufficient or excessive, an alert unit issues a warning signal.

10. The blood pressure measurement method as described in claim 6, characterized in that, prior to the step of pressing the protrusion with the finger, it further includes: A light-diffusing light source is activated, and the light-diffusing light source projects a third light ray toward the substrate. The third light ray passes sequentially through the plurality of cutouts and the substrate. The image sensing unit receives the third light ray and obtains an actual bright area image. The control and processing unit determines the actual number of light-receiving pixels of the image sensing unit based on the actual bright area image.

Images