TW201912103A - Optical fingerprint sensing device with biomedical sensing functions comprising at least one light emitting component for generating a light source and an image sensing module - Google Patents

Abstract

The present invention discloses an optical fingerprint sensing device with biomedical sensing functions, which mainly comprises at least one light emitting component for generating a light source and an image sensing module. The image sensing module is provided with a plurality of sensing units capable of receiving a light source reflected through a finger in a normal fingerprint sensing mode, and transmitting a measured brightness signal so as to obtain a fingerprint image. The image sensing module is further provided with a partial area therein, so that part of the sensing units of the sensing units are located in the partial area at the same time, and the sensing units located in the partial area are electrically connected through a first switch to perform in a biomedical sensing mode, and measure light intensity signals of a finger, in turn, variations in time domain of the light intensity signals are used as photoplethysmography (PPG) signals for subsequent biomedical applications.

Description

Optical fingerprint sensing device with biomedical sensing function

The invention relates to an optical fingerprint sensing technology, in particular to an optical fingerprint sensing device which can simultaneously have a biomedical sensing function.

Generally, the optical fingerprint sensor 10 generally uses a CMOS image sensor as a sensor for capturing images. The basic structure is as shown in FIG. 1 , and one or more light emitting diodes 12 emit light sources. To illuminate the surface of the finger to be tested, the fingerprint image is received by the high-resolution CMOS sensor 14. When the CMOS sensor 14 transmits an image, the brightness measured by each pixel in the CMOS sensor 14 is immediately transmitted in sequence until the entire image is transmitted, so as to obtain a faster image capturing speed. However, although the sensor design has the advantages of simple structure and fast image capture, in actual use, the entire image must be read after each reading, and the next time can be read.

In addition, the photoplethysmography (PPG) sensor 20 includes one or more light emitting diodes 22 and a photodiode 24, as shown in FIG. 2, through the light emitting diode. The generated light source 22 illuminates the finger 26 as the tissue to be tested, and uses the light source to enter the signal scattered by the finger 26, and then uses the photodiode 24 to detect the change in the light intensity to obtain blood pulsation. That is, since the PPG sensor 20 uses continuous sampling of optical signals to detect blood pulse waves, it is necessary to have a certain frequency to have sufficient time to resolve the blood waveform (usually at least 50 Hz or more). In addition, during the measurement of the PPG sensor, the motion artifact is the most influential signal, mainly due to the change of the light path or the movement of the finger and the sensor surface when the finger and the sensor move relative to each other. The light intensity and its source are greatly affected. Therefore, the PPG signal sensed by the PPG sensor usually cannot solve the influence of the moving noise, and can only be excluded by recognizing the mobile noise for the signal itself.

As mentioned earlier, since the optical fingerprint sensor structure is similar to the basic architecture of a reflective PPG sensor, the difference is that the reflective PPG sensor uses a photodiode and the optical fingerprint sensor uses a CMOS sensor. Since the PPG signal only needs one light intensity change, and the CMOS sensor belongs to the array type light intensity sensor, it should be feasible to use the light intensity signal received by the CMOS sensor as the PPG signal. However, there are still problems in how to combine the two and how many pixels are needed to provide light intensity information to form a PPG signal.

In view of this, the present invention provides an optical fingerprint sensing device having a biomedical sensing function.

The main object of the present invention is to provide an optical fingerprint sensing device having a biomedical sensing function, which utilizes the sum/average of light intensities of pixels in a specific range in a fingerprint sensor as light intensity. The time domain variation of the intensity is used as the PPG signal, and in the optical fingerprint sensing device, the light intensity variation of the pixel in a specific range can also be quickly taken for the related application of the PPG.

In order to achieve the above object, the present invention provides an optical fingerprint sensing device having a biomedical sensing function, comprising at least one light emitting component and an image sensing module, wherein the light emitting component generates a light source and can illuminate a finger; The image sensing module has a plurality of sensing units, and the sensing unit can receive the light source reflected by the finger in a normal fingerprint sensing mode, and sequentially transmit the measured brightness signals to obtain a fingerprint image; on the other hand, a portion of the image sensing module is further disposed such that a portion of the sensing units is located in the local region, and a portion of the sensing units located in the local region are respectively The first switch forms an electrical connection to simultaneously perform a biomedical sensing mode to measure the light intensity signal of the finger.

In the biomedical sensing mode, turning on the switch causes the sensing units in the local area to be electrically connected together, exposing the data at a frequency, and sampling the light intensity signal, and then using the light. The time change of the intensity signal is used as a light volume description signal.

Or, in the biomedical sensing mode, a decoding circuit is based on a specific address signal, and the specific address signal corresponds to a specific address of the sensing unit, so that the image sensing module is only correspondingly obtained. The light intensity signal of the sensing unit in the local area, and the time change of the light intensity signal is used as the light volume description signal.

The purpose of the present invention, the technical contents, and the effects achieved by the present invention will be more readily understood by the detailed description of the embodiments.

Since the optical fingerprint sensing device of the present invention can receive a fingerprint image in the fingerprint sensing mode and can receive the signal intensity as a light volume description (PPG) signal in the biomedical sensing mode, the technical features of the present invention are described. Before describing the design concept of the biomedical sensing mode selected by the present invention.

For sensing devices, the use of a single pixel signal for sensing is extremely unreliable. One of the reasons is the hardware design problem. The risk of damage to the pixel is only possible with a particular single pixel; The reason is that the sampling area is too small to be unreliable, because a single pixel actually only accepts a small area of light intensity signal. If the area of the sample is just above the finger, or because of individual differences, the area is passed. There is not much blood flow information in the light, which will make the PPG signal quality poor. In addition, if a large area (for example, the entire frame) is selected, there is a disadvantage that on the one hand, the sensing device has a certain area, and the edge often receives a relatively large amount of external light or direct reflected light of the light emitting diode, and receives To a relatively large DC light intensity signal, the PPG signal implied in it will be very small; and if the sampling area is too large, it is equal to the PPG signal of the same area of skin, because the human blood flow is directional, so There is a time difference between the blood pulse waves at different positions, so it is not a good choice to select a large area to sample the light intensity to receive the PPG signal.

Therefore, for the present invention, a preferred option is to select a plurality of sensing units of a local area of an appropriate size (<sensing module boundary) as the range for performing the biomedical sensing mode in the image sensing module. The sum of each sensing unit within this range or the average received light intensity is used to form a PPG signal. In this way, it is possible to sample from a plurality of sensing units at a time, and because of the limited number (area) thereof, it does not capture light of an excessively large area (for example, <1/2* sensing module boundary). Intensity signal; if the central area is selected as the range of the biomedical sensing mode, the sensing area of the sensing module edge can be effectively avoided, thereby improving the sensing accuracy.

After understanding the inventive concept of the present invention, the technical features of the present invention will be described in detail in conjunction with the circuit block diagram of FIG. 3, and the optical fingerprint sensing device can be explained in the fingerprint sensing mode and the biomedical sensing mode, respectively. Sensing in the mode.

As shown in FIG. 3, the optical fingerprint sensing device 30 having the biomedical sensing function of the present invention includes an image sensing module 32, which can adopt a more common complementary metal oxide semiconductor (CMOS) sense. At least one light-emitting element 34 is disposed on at least one side of the image sensing module 32, and the light-emitting diode can be selected. The wavelength of the light source emitted by the light-emitting element 34 is 600-1200 nm (nm). In this embodiment, the light source generated by the light-emitting element 34 is uniformly illuminated by the finger, so that a light-emitting element 34 is disposed on each of the two sides of the image sensing module 32, and the image sensing module 32 is electrically connected to a decoding circuit. 36, another control circuit 38 is electrically connected to the light-emitting element 34 and the decoding circuit 36 and controls its operation, and the control circuit 38 switches the fingerprint sensing mode and the bio-sensing mode according to the user's selection instruction, and controls the circuit. 38 sends a control signal to transmit all the address signals to the decoding circuit 36 to expose and transmit the data to the plurality of sensing units 320 in the image sensing module 32. In other words, when the light-emitting element 34 generates a light source to illuminate a finger, each sensing unit 320 of the image sensing module 32 generates an action to receive the light reflected by the finger, and sequentially transmits the measured brightness signals. The image sensing module 32 is transmitted back to the full-frame image, which is the fingerprint sensing mode; of course, the full-frame image can obtain a complete fingerprint image through the image processing algorithm.

The present invention is further provided with a partial area 321 in the range of the image sensing module 32. The central area of the image sensing module 32 is described as a preferred embodiment and is located in the partial area 321 . A plurality of sensing units (for example, 4*4) 320 are electrically connected to each other by the first switch 322, and the sensing units are electrically connected to the other decoding circuit through the first switch 322. 362, when the first switch 322 is turned on, each of the sensing units 320 connected in the local area 321 is equipotential, so that the brightness average of the plurality of sensing units 320 can be obtained, that is, the local area 321 is The sensing unit 320 is integrated into a large sensing unit having a certain area of measured brightness to simultaneously perform a biomedical sensing mode to measure the light intensity signal of the finger. Therefore, in the biomedical sensing mode, the first switch 322 is turned on by the decoding circuit 362, so that the sensing units 320 in the local area 321 are electrically connected together, and at a frequency higher than the fingerprint sensing mode. Exposing and transmitting data, sampling the light intensity signal, and taking the time change (time domain change) of the light intensity signal as a light volume description (PPG) signal, the PPG signal can be widely used to estimate the heart rate through the biomedical algorithm. Heart rate variability analysis, blood pressure or arrhythmia detection.

In addition, the present invention can further utilize the addressing mode to perform the biomedical sensing mode. As shown in FIG. 3, when the optical fingerprint sensing device 30 having the biomedical sensing function of the present invention is in the biomedical sensing mode, The control circuit 38 transmits a pre-planned specific address signal (sense unit addressed to the local area) to the decoding circuit 362, so that the image sensing module 32 only responds to the sensing in the local area 321 The light intensity signal of the unit 320 is used as a light volume description signal for the time variation of the light intensity signal. Here, although the decoding circuit used in the present invention is divided into the decoding circuit 36 and the decoding circuit 362, the two decoding circuits 36 and 362 can be integrated by actual user requirements.

Furthermore, in the biomedical sensing mode, the problem of moving noise may occur. Therefore, the present invention can use the region other than the partial region 321 of the image sensing module 32 as the reference region in the biomedical sensing mode. 323. Obtain all or part of the fingerprint images of the at least two time points in the reference area 323 as an image comparison, to assist whether the overall finger has a relative displacement when the PPG signal is detected, and determine whether it is a mobile noise segment. In other words, in the biomedical sensing mode, all or part of the fingerprint images of at least two time points can be obtained in the reference area 323 by using the foregoing method, so as to observe whether the image has relative movement between at least two time points. Whether there is a mobile noise segment in the light volume description (PPG) signal. The image signal of the reference area 323 may be all reserved or partially reserved in an address manner.

Each sensing unit 320 may include only a single pixel (Pixel) or multiple pixels at the same time. If it is a single pixel, its structure is as shown in FIG. 3, and each sensing is performed. The unit is considered a single pixel. If each of the sensing units 320 includes a plurality of pixels 3201, please refer to FIG. 4, where four pixels are taken as an example, and the pixels 3201 are electrically connected to each other by the second switch 3202. Sexually connected to enable simultaneous operation; please refer to FIG. 3 and FIG. 4 simultaneously, when the first switch 322 and the second switch 3202 are simultaneously turned on, the sensing unit 320 located in the local area 321 is fully charged. Sexually connected together for subsequent sampling of light intensity signals. The first switch 322 and the second switch 3202 described above may be a transistor switch, such as an NMOS switch. Since each pixel 3201 has an image capturing function for completely transmitting data, when the first switch 322 and the second switch 3202 are turned on, the lower resolution and the higher transmission rate or the lower hardware can be used. Resources to capture image fingerprints or light intensity values.

The optical fingerprint sensing device with the biomedical sensing function proposed by the invention, if in the fingerprint sensing mode, is the same as the existing optical fingerprint sensing device, and uses all the sensing units to perform fingerprinting through the same or similar driving manner. Sensing to obtain a complete fingerprint image; if in the biomedical sensing mode, the sum of the lightness of the sensing unit (pixel) in a specific local range in the fingerprint sensor is used as the light intensity to borrow The time-domain variation of the light intensity is used as a PPG signal, and in the optical fingerprint sensing device, the light intensity variation of the pixel in a specific range can be quickly captured to perform the related application of the PPG signal.

The embodiments described above are only for explaining the technical idea and the features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the contents of the present invention and to implement the invention. Equivalent changes or modifications made by the spirit of the present invention should still be included in the scope of the present invention.

10‧‧‧Optical fingerprint sensor

12‧‧‧Lighting diode

14‧‧‧CMOS sensor

20‧‧‧Light volume description sensor

22‧‧‧Lighting diode

24‧‧‧Light diode

26‧‧‧ fingers

30‧‧‧Optical fingerprint sensing device with biomedical sensing function

32‧‧‧Image Sensing Module

320‧‧‧Sensor unit

3201‧‧‧ pixels

3202‧‧‧Second switch

321‧‧‧Local area

322‧‧‧First switch

323‧‧‧Reference area

34‧‧‧Lighting elements

36, 362‧‧‧ decoding circuit

38‧‧‧Control circuit

Figure 1 is a schematic diagram of a conventional optical fingerprint sensor. Figure 2 is a schematic diagram of a conventional reflective PPG sensor. Figure 3 is a block diagram of the circuit of the present invention. Figure 4 is a schematic view showing the structure of the sensing unit used in the present invention as a multi-pixel.

Claims (15)

An optical fingerprint sensing device with a biomedical sensing function, comprising: at least one light emitting component that generates a light source to illuminate a finger; and an image sensing module that has a plurality of sensing units, The sensing unit receives the light source reflected by the finger in the fingerprint sensing mode, and sequentially transmits the measured brightness signal; wherein the image sensing module is provided with a partial area and is located in the A portion of the sensing units in the local area are electrically connected by the first switch to simultaneously perform a biomedical sensing mode to measure the light intensity signal of the finger. An optical fingerprint sensing device having a biomedical sensing function according to claim 1, wherein in the biomedical sensing mode, the first switch is turned on to enable a portion of the sensing units located in the local region to be electrically The two are connected together, exposed at a frequency and transmitted data, and sample the light intensity signal, and then use the time change of the light intensity signal as the light volume description signal. An optical fingerprint sensing device with a biomedical sensing function according to claim 1, wherein in the biomedical sensing mode, a decoding circuit causes the image sensing module to obtain only correspondingly according to a specific address signal. The light intensity signal of the sensing unit located in the local area is used as the light volume description signal with the time variation of the light intensity signal. An optical fingerprint sensing device having a biomedical sensing function according to claim 1, wherein the wavelength of the light source is 600 to 1200 nanometers (nm). The optical fingerprint sensing device with biomedical sensing function according to claim 2 or 3, wherein the light volume description signal can be used to estimate heart rate, heart rate variability analysis, blood pressure or arrhythmia detection. The optical fingerprint sensing device of claim 2 or 3, wherein each of the sensing units comprises a pixel or a plurality of pixels. The optical fingerprint sensing device of claim 6, wherein each of the sensing units includes the plurality of pixels, and the plurality of pixels respectively form an electrical property by using the second switch. Connect to activate at the same time. The optical fingerprint sensing device of claim 7, wherein the first switch and the second open relationship are simultaneously turned on, so that a portion of the sensing units located in the local area are electrically Connected together for subsequent sampling of the light intensity signal. An optical fingerprint sensing device having a biomedical sensing function according to claim 2 or 3, wherein in the biomedical sensing mode, at least an area other than the partial region of the image sensing module is obtained. All or part of the fingerprint image of the two time points is used to determine whether there is noise caused by the movement of the light volume description signal by comparing relative displacement of all or part of the fingerprint images of the at least two time points. The optical fingerprint sensing device with biomedical sensing function according to claim 9, wherein the partial fingerprint image is obtained by addressing. The optical fingerprint sensing device of claim 1, wherein the local region is a central region of the image sensing module. An optical fingerprint sensing device having a biomedical sensing function as claimed in claim 1, wherein the first open relationship is a transistor switch. An optical fingerprint sensing device having a biomedical sensing function according to claim 7, wherein the second open relationship is a transistor switch. An optical fingerprint sensing device having a biomedical sensing function according to claim 1, wherein the light emitting element is a light emitting diode. The optical fingerprint sensing device with biomedical sensing function according to claim 1, wherein the image sensing module is a complementary metal oxide semiconductor (CMOS) sensor.