Blood pressure measuring device and method

Abstract

The invention provides a blood pressure measuring device which comprises a substrate, a protruding part, an image sensing unit, a first light source, a second light source and a control and processing unit. The first light source projects first light towards the substrate, when a finger presses the protruding part, total reflection of the first light is damaged by the finger and reflected, the image sensing unit obtains a bright area image, and the control and processing unit calculates the number of light receiving pixels of the image sensing unit according to the bright area image. And comparing with the number of light-receiving pixels of the image sensing unit to obtain a proportion value so as to judge whether the pressure is sufficient or not. The second light source projects second light towards the substrate, the second light penetrates through the substrate and the skin of the finger and is reflected by the blood vessel, the image sensing unit obtains a blood vessel volume change image, and the control and processing unit calculates systolic pressure or diastolic pressure according to the blood vessel volume change image.

Description

Technical Field

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

[0002] Photoplethysmography (PPG) is a non-invasive physiological parameter measurement technology. Although most wearable devices (e.g., smart watches, smart bracelets) can use photoplethysmography 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 the noise introduced by the impact of skin contact on user or device movement, environmental conditions, and ectopic heartbeats. Therefore, the effect of using wearable devices to analyze heart rate abnormalities is usually limited. Therefore, how to reduce the variation of skin muscle conditions to improve accuracy is an urgent goal to improve.

[0003] The well-known photoplethysmography measurement device includes a photoelectric sensor and a pressure sensor, and the average error is less than 5 mmHg and the standard deviation is less than 8 mm. The reason is that the tightness of the skin muscles is related to the measurement accuracy of the photoplethysmography. Therefore, the main purpose of the pressure sensor is to monitor and confirm the pressure applied by the finger to confirm the tightness of the finger skin muscles, thereby improving the measurement accuracy of the photoplethysmography.

[0004] However, the conventional photoelectric plethysmography device has the following problems: first, it cannot be made 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 in a module, the photoelectric sensor is easily contaminated during the process of packaging the pressure sensor, resulting in failure. Summary of the invention

[0005] The main purpose of the present invention is to provide a blood pressure measurement device and method, which can determine whether the pressure applied by a finger is sufficient without providing a pressure sensor.

[0006] In order 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 hollow portions. The image sensing unit is disposed below the substrate and corresponds to the hollow portions. The at least one first light source is disposed below a 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. The at least one first light source projects a first light beam toward the substrate, and the first light beam forms a total reflection inside the substrate. When a finger presses the hollow parts of the protrusion, the total reflection of the first light beam is destroyed by the finger and reflected. The image sensing unit receives the reflected first light beam and obtains a bright area image. The control and processing unit calculates a number of light-receiving pixels (B) of the image sensing unit according to the bright area image, and compares the number of light-receiving pixels (A) of the image sensing unit to obtain a ratio (B / A)% of the number of light-receiving pixels to the number of light-receiving pixels, 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, and the second light beam penetrates 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 a blood vessel volume change image. The control and processing unit calculates a systolic pressure or a diastolic pressure according to the blood vessel volume change image.

[0007] In some embodiments, 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; when the ratio is greater than 98%, the control and processing unit determines that the pressure is too high.

[0008] In some embodiments, the blood pressure measuring device further comprises a reflective layer, which is disposed between the protrusion and the substrate, and is used to prevent the path of the totally reflected first light from being changed or destroyed before entering the hollow portions.

[0009] In some embodiments, the blood pressure measurement device further includes an alarm unit, which is 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 sends a reminder signal.

[0010] In some embodiments, the blood pressure measurement device further includes a light emitting sheet light source, which is arranged above the protrusion; wherein the light emitting sheet light source projects a third light in the direction of the substrate, and the third light passes through the hollow portions and the substrate in sequence, and the image sensing unit receives the third light 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] In order to achieve the aforementioned object, the present invention provides a blood pressure measurement method, comprising the following steps: when a finger presses a protrusion, the finger sinks into a plurality of hollow parts of the protrusion and presses on a substrate; at least one first light source is activated, and the at least one first light source projects a first light toward the substrate, and the first light forms a total reflection inside the substrate, and the total reflection of the first light is destroyed by the finger and is reflected; an image sensing unit receives the reflected first light and obtains a bright area image; a control and processing unit calculates a number of light-receiving pixels (B) of the image sensing unit according to the bright area image, and The control and processing unit compares the light receiving pixel number (A) with the light receiving pixel number of the image sensing unit to obtain a ratio value (B / A)% of the light receiving pixel number to the light receiving pixel number to determine whether the pressure applied by the finger is sufficient; when the control and processing unit determines that the pressure is sufficient, at least one second light source is activated, and the at least one second light source projects a second light ray toward the substrate, and the second light ray penetrates the substrate and the skin of the finger and is reflected by a blood vessel; the image sensing unit receives the reflected second light ray and obtains a blood vessel volume change image; the control and processing unit calculates a systolic pressure or a diastolic pressure based on the blood vessel volume change image.

[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 too high.

[0013] In some embodiments, the step of activating the at least one first light source further includes: a reflective layer is disposed between the protrusion and the substrate, and the reflective layer is used to prevent the path of the totally reflected first light from being changed or destroyed before entering the hollow portions.

[0014] In some embodiments, after the step of determining whether the pressure of the finger pressing is sufficient, the method further includes: when the control and processing unit determines that the pressure is insufficient or too high, an alarm unit sends a reminder signal.

[0015] In some embodiments, before the step of the finger pressing the protrusion, the step further includes: starting a light emitting plate light source, the light emitting plate light source projects a third light in the direction of the substrate, the third light sequentially passes through the hollow portions and the substrate, the image sensing unit receives the third light 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.

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

[0017] The blood pressure sensing device of the present invention can determine whether the pressure of the finger pressing is sufficient without setting a pressure sensor, so as to confirm the tightness of the finger skin muscle, thereby improving the measurement accuracy of the photoplethysmogram. Therefore, the blood pressure sensing device of the present invention can be made on glass and applied to wearable devices (such as smart watches or smart bracelets), which can reduce the manufacturing cost, and the image sensing unit does not need to be packaged with the pressure sensor in a module, so the image sensing unit will not fail due to dirt. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1A 2 is a schematic structural diagram of a first embodiment of a blood pressure measuring device according to the present invention.

[0019] Figure 1B FIG. 4 is a schematic structural diagram of another embodiment of the blood pressure measuring device of the present invention.

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

[0021] Figure 3 FIG. 4 is a structural block diagram of a first embodiment of a blood pressure measuring device according to the present invention.

[0022] Figure 4 FIG. 4 is a flow chart of a first embodiment of a blood pressure measurement method according to the present invention.

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

[0024] Figure 6 A diagram showing the extent to which a finger sinks into a hollow portion.

[0025] Figure 7 A schematic diagram showing the bright area image.

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

[0027] Fig. 9Schematic diagram showing changes in vascular volume as a function of systolic blood pressure.

[0028] Fig.10 A schematic diagram showing changes in vascular volume as a function of diastolic blood pressure is shown.

[0029] Fig.11 FIG. 4 is a schematic structural diagram of a second embodiment of a blood pressure measuring device according to the present invention.

[0030] Fig.12 FIG. 4 is a flow chart of a second embodiment of a blood pressure measurement method according to the present invention.

[0031] [Description of Reference Numerals]

[0032] 10: Substrate;

[0033] 20: protrusion;

[0034] 21: hollow part;

[0035] 30: image sensing unit;

[0036] 31: bright area image;

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

[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: homogenizer light source;

[0044] 100: lens module;

[0045] H: height range;

[0046] W: Width range. DETAILED DESCRIPTION

[0047] The following is a more detailed description of the embodiments of the present invention with reference to the accompanying drawings and component symbols, so that those skilled in the art can implement the embodiments according to the embodiments after reading the specification.

[0048] Figure 1A 2 is a schematic structural diagram of a first embodiment of a blood pressure measuring device according to the present invention. Figure 1B FIG. 4 is a schematic structural diagram of another embodiment of the blood pressure measuring device of the present invention. Figure 2 It is a top view of the protrusion 20 and the image sensing unit 30 of the present invention. Figure 3FIG. 4 is a structural block diagram of a first embodiment of a blood pressure measuring device according to 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 hollow portions 21. The first light source 40 is disposed below a 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 obtained by semiconductor manufacturing process, including a plurality of unit pixels arranged in an array on a substrate. Figure 1A As shown, the image sensing unit 30 is a thin image sensor. Since the thin image sensor does not include a lens module, the thickness of the thin image sensor is small, but the area of ​​the thin image sensor 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 gather 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 and output interfaces.

[0052] Figure 4 FIG. 4 is a flow chart of a first embodiment of a blood pressure measurement method according to the present invention. Figure 5 It is a schematic diagram of the first light 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 a finger is sunk into the hollow portion 21. Figure 7 A schematic diagram of a bright area image 31 is shown. Figure 8 It is a schematic diagram of the second light projected by the second light source 50 of the present invention being reflected by a blood vessel. Fig. 9 Schematic diagram showing changes in vascular volume as a function of systolic blood pressure. Fig.10 A schematic diagram showing changes in vascular volume as a function of diastolic blood pressure is shown.

[0053] The present invention provides a blood pressure measurement method, comprising the following steps:

[0054] Step S10, as Figure 4 and Figure 5 As shown, when a finger presses the protrusion 20 , the finger sinks into the hollow portions 21 and presses on the substrate 10 .

[0055] Step S20, as Figure 4 and Figure 5 As shown, the first light source 40 is activated, and the first light source 40 projects a first light toward the substrate 10 . The first light forms a total reflection inside the substrate 10 , and the total reflection of the first light is destroyed by the finger and is 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 Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the control and processing unit 60 calculates a light receiving pixel number (B) of the image sensing unit 30 according to the bright area image 31, and compares it with a light receiving pixel number (A) of the image sensing unit 30 to obtain a ratio value (B / A)% of the light receiving pixel number to the light receiving pixel number to determine whether the pressure of the finger pressing is sufficient. The calculation of the pixel number is that the DN value (digital number) of each unit pixel reaches the set lower standard.

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

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

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

[0061] Further, if Fig. 9 As shown, the blood vessel volume change image 32 is obviously darker, the bright area is smaller, and the dark area is larger. This is because the blood vessel is in a contracted state and the diameter of the blood vessel is smaller. Fig.10 As shown, the blood vessel volume change image 33 is obviously brighter, the bright area is larger, and the dark area is smaller. This is because the blood vessel is in a dilated state and the diameter of the blood vessel is larger.

[0062] Thus, the blood pressure sensing device of the present invention can determine whether the pressure of the finger pressing is sufficient without setting a pressure sensor, so as to confirm the tightness of the finger skin muscle, thereby improving the measurement accuracy of the photoplethysmogram. Therefore, the blood pressure sensing device of the present invention can be made on glass and applied to wearable devices (such as smart watches or smart bracelets), which can reduce the manufacturing cost, and the image sensing unit 30 does not need to be packaged with the pressure sensor in a module, so the image sensing unit 30 will not fail 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 too high.

[0064] like Figure 1A As shown, in a preferred embodiment, a height range H of the protrusion 20 is between 100 and 2000 μm, and a width range W of the protrusion 20 is between 300 and 2000 μm. Between the height range H and the width range W, the degree of the finger sinking into the hollow portions 21 can be controlled to occupy about 90 to 98% of the space of the hollow portions 21, so the ratio value can be controlled to be between 90 and 98%. If the height range H of the protrusion 20 exceeds 2000 μm and the width range W is less than 300 μm, the hollow portions 21 are too deep and too narrow. Even if the finger is extremely strong, the degree of the finger sinking into the hollow portions 21 will only occupy less than about 90% of the space of the hollow portions 21, resulting in a ratio value less than 90%. If the height range H of the protrusion 20 is less than 100 μm and the width range W is greater than 2000 μm, the hollow portions 21 are too shallow and too wide. With just a slight force, the fingers will easily sink into the hollow portions 21 to occupy more than about 98% of the space of the hollow portions 21, resulting in a ratio value greater than 98%.

[0065] like Figure 2As shown, in a preferred embodiment, the number of the hollow portions 21 is four, so that the protrusion 20 is in a field shape. Therefore, the field-shaped protrusion 20 makes it easier for fingers to sink into the hollow portions 21 and press on the substrate 10. In some embodiments, the number of the hollow portions 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 smart watch 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 comprises a reflective layer 70, and the reflective layer 70 is disposed between the protrusion 20 and the substrate 10. Step S20 further comprises: Figure 5 As shown, the reflective layer 70 is used to prevent the path of the totally reflected first light from being changed or destroyed before entering the hollow portions 21. In this way, the reflective layer 70 can maintain the total reflection of the first light inside the substrate 10, and the first light will not penetrate the light-transmissive protrusion 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 measurement device of the present invention further comprises an alarm unit 80, and the alarm unit 80 is electrically connected to the control and processing unit 60. After step S40, the method further comprises: step S51, as shown in FIG. Figure 4 As shown, when the control and processing unit 60 determines that the pressure is insufficient, the warning unit 80 will send a reminder signal to remind the user to increase the force of the finger pressing, or move the finger laterally to increase the number of light-receiving pixels of the image sensing unit 30; step S51, such as Figure 4 As shown, when the control and processing unit 60 determines that the pressure is too high, the warning unit 80 will send a reminder signal to remind the user to reduce the force of the finger pressing to reduce the number of light-receiving pixels of 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 method includes but is not limited to sound, voice, light, pattern or text. The buzzer can make a sound, the voice player can make a voice, and the display screen can display a light, pattern or text.

[0070] In some embodiments, the number of the first light source 40 can be plural to improve the uniformity of light received by the bright area image 31, but the manufacturing cost is higher. However, in actual application, only one first light source 40 is needed to achieve the above effect, and the manufacturing cost is the lowest.

[0071] In some embodiments, the number of second light sources 50 can be plural to improve the resolution of the vascular volume change images 32 and 33, but the manufacturing cost is higher. However, in actual application, only one second light source 50 is needed to achieve the above effect, and the manufacturing cost is the lowest.

[0072] Fig.11 FIG. 2 is a schematic diagram of the structure of the second embodiment of the blood pressure measuring device of the present invention. Fig.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 source 90 of a uniform light sheet disposed above the protrusion 20 .

[0073] Fig.12 FIG. 2 is a flow chart of a second embodiment of the blood pressure measurement method of the present invention. Fig.12 As shown, the difference between the method of the second embodiment and the first embodiment is that: before step S10, it further includes: step S80, starting the light-distributing sheet light source 90, the light-distributing sheet light source 90 projects a third light in the direction of the substrate 10, the third light sequentially passes through the hollow parts 21 and the substrate 10, the image sensing unit 30 receives the third light and obtains an actual bright area image; step S90, the control and processing unit 60 determines the actual number of light-receiving pixels of the image sensing unit 30 according to the actual bright area image. Thus, before starting to measure blood pressure, 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-distributing sheet light source 90, and set the actual number of light-receiving pixels of the image sensing unit 30 as the pressure judgment reference of the control and processing unit 60, so as to improve the accuracy of the pressure judgment of the control and processing unit 60.

[0074] The above description is only used to explain the preferred embodiments of the present invention, and is not intended to limit the present invention in any form. Therefore, any modification or change of the present invention made without departing from the principles described in this application shall fall within the scope of protection of this application.

Claims

1. A blood pressure measuring device, characterized in that: include: a substrate; A protrusion is disposed on the substrate and has a plurality of hollow portions; An image sensing unit is disposed below the substrate and corresponds to the hollow portions; At least one first light source is disposed below one side of the substrate; At least one second light source is disposed below the substrate; a control and processing unit electrically connected to the image sensing unit, the at least one first light source and the at least one second light source; The at least one first light source projects a first light beam toward the substrate, and the first light beam forms a total reflection inside the substrate. When a finger presses the hollow parts of the protruding part, the total reflection of the first light beam is destroyed by the finger and reflected. The image sensing unit receives the reflected first light beam and obtains a bright area image. The control and processing unit calculates a number of light-receiving pixels (B) of the image sensing unit according to the bright area image, and compares it with a number of light-receiving pixels (A) of the image sensing unit to obtain a ratio (B / A)% of the number of light-receiving pixels to the number of light-receiving pixels, so as to determine whether a pressure of the finger pressing is sufficient. The at least one second light source projects a second light in the direction of the substrate, the second light penetrates 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 a blood vessel volume change image, and the control and processing unit calculates a systolic pressure or a diastolic pressure based on the blood vessel volume change image.

2. The blood pressure measuring device according to claim 1, wherein: 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; when the ratio is greater than 98%, the control and processing unit determines that the pressure is too high.

3. The blood pressure measuring device according to claim 1, wherein: The invention also comprises a reflection layer, which is arranged between the protrusion and the substrate, and is used to prevent the path of the first light beam which is totally reflected from being changed or damaged before entering the hollow parts.

4. The blood pressure measuring device according to claim 1, wherein: It also includes a warning unit, which is 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 warning unit sends a reminder signal.

5. The blood pressure measuring device according to claim 1, wherein: It also includes a light-distributing sheet light source, which is arranged above the protrusion; wherein the light-distributing sheet light source projects a third light in the direction of the substrate, and the third light passes through the hollow portions and the substrate in sequence, and the image sensing unit receives the third light 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 blood pressure measurement method, characterized in that: The following steps are involved: When a finger presses a protrusion, the finger sinks into a plurality of hollow portions of the protrusion and presses on a substrate; Activate at least one first light source, the at least one first light source projects a first light beam toward the substrate, the first light beam forms a total reflection inside the substrate, and the total reflection of the first light beam is destroyed 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 a number of light-receiving pixels (B) of the image sensing unit according to the bright area image, and compares it with a number of light-receiving pixels (A) of the image sensing unit to obtain a ratio (B / A)% of the number of light-receiving pixels to the number of light-receiving pixels to determine whether a pressure applied by the finger is sufficient; When the control and processing unit determines that the pressure is sufficient, at least one second light source is activated, and the at least one second light source projects a second light in the direction of the substrate, and the second light penetrates 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 a blood vessel volume change image; The control and processing unit calculates a systolic pressure or a diastolic pressure according to the blood vessel volume change image.

7. The blood pressure measurement method according to claim 6, wherein: 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 too high.

8. The blood pressure measurement method according to claim 6, wherein: The step of activating the at least one first light source further includes: a reflective layer is disposed between the protrusion and the substrate, and the reflective layer is used to prevent the path of the totally reflected first light from being changed or damaged before entering the hollow parts.

9. The blood pressure measurement method according to claim 6, wherein: After the step of determining whether the pressure of the finger pressing is sufficient, the method further includes: when the control and processing unit determines that the pressure is insufficient or too high, a warning unit sends a warning signal.

10. The blood pressure measurement method according to claim 6, wherein before the step of pressing the protrusion with the finger, the method further comprises: A light emitting plate light source is activated, and the light emitting plate light source projects a third light ray toward the substrate. The third light ray passes through the hollow portions and the substrate in sequence. 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 according to the actual bright area image.

Images