PPG Sensor and Its Operating Method

Abstract

A photoplethysmogram (PPG) sensor includes: a pixel array that collects light; a pixel sampler that converts the light collected by the pixel array into a plurality of pixel data; a valid area determiner that determines a valid area and an invalid area of the pixel array based on the pixel data; a power controller that is operable to cut off power supply to the invalid area of the pixel array; and a PPG data generator that generates PPG data according to the pixel data corresponding to the valid area in the pixel data.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2019 - 0071376, titled "PPG Sensor and Method of Operating the Same", filed with the Korean Intellectual Property Office on June 17, 2019, which is incorporated herein by reference in its entirety. Technical Field

[0003] Embodiments relate to a photoplethysmogram (PPG) sensor and a method of operating the same. Background Art

[0004] A photoplethysmogram (PPG) sensor uses a complementary metal - oxide - semiconductor image sensor (CIS) to obtain a PPG signal from light reflected by blood flow. The PPG sensor is typically mounted on a wearable device such as a smartwatch or a small device such as wireless earphones. Summary of the Invention

[0005] Embodiments relate to a photoplethysmogram (PPG) sensor including: a pixel array that collects light; a pixel sampler that converts the light collected through the pixel array into a plurality of pixel data; an effective area determiner that determines an effective area and a non - effective area of the pixel array based on the pixel data; a power controller that can operate to cut off power supply to the non - effective area of the pixel array; and a PPG data generator that generates PPG data according to the pixel data corresponding to the effective area among the pixel data.

[0006] Embodiments also relate to a photoplethysmogram (PPG) sensor including: a pixel array that collects light; a pixel sampler that converts the light collected through the pixel array into a plurality of pixel data; a light amount determiner that determines whether to cut off power supply based on the amount of light collected for the pixel data; a power controller that is operable to cut off power supply to the pixel array according to a command from the light amount determiner; and a PPG data generator that generates PPG data according to the pixel data.

[0007] Embodiments also relate to a method of operating a photoplethysmogram (PPG) sensor, the method including: converting light collected through a pixel array into a plurality of pixel data; determining an effective area and a non - effective area of the pixel array based on the pixel data; cutting off power supply to the non - effective area of the pixel array; and generating PPG data according to the pixel data corresponding to the effective area among the pixel data.

[0008] The embodiment also relates to a photoplethysmogram (PPG) system, including: a light source; a PPG sensor arranged to receive light emitted by the light source and reflected from a user's skin; and an application that receives PPG data from the PPG sensor. The PPG sensor may include: a pixel array that collects light reflected from the user's skin; a pixel sampler that converts the light collected through the pixel array into a plurality of pixel data; an active area determiner that determines an active area and an inactive area of the pixel array based on the pixel data; a power controller operable to cut off power supply to the inactive area of the pixel array; and a PPG data generator that generates PPG data according to the pixel data corresponding to the active area among the pixel data. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Features will become apparent to those skilled in the art by referring to the accompanying drawings in which:

[0010] Figure 1 A photoplethysmogram (PPG) sensing device according to an exemplary embodiment is shown;

[0011] Figure 2 and Figure 3 is a diagram for explaining an active area determiner according to an exemplary embodiment;

[0012] Figures 4 to 6 is a diagram for explaining a power controller according to an exemplary embodiment;

[0013] Figure 7 A method of operating a PPG sensor according to an exemplary embodiment is shown;

[0014] Figure 8 is a diagram for explaining an example result of determining an active area of a PPG sensor according to an exemplary embodiment; and

[0015] Figure 9 is a diagram for explaining an example of using a PPG sensor according to an exemplary embodiment. DETAILED DESCRIPTION

[0016] Figure 1 A photoplethysmogram (PPG) sensing device according to an exemplary embodiment is shown.

[0017] Referring Figure 1 , a PPG sensing device 1 according to an exemplary embodiment may include a PPG sensor 10 and an application 15.

[0018] The PPG sensing device 1 can measure blood flow changes by irradiating light onto the skin at a short distance. The PPG sensing device 1 can be installed on a wearable device such as a smartwatch or a fitness band, or a small device such as wireless earphones, and can be used to measure, for example, the heart rate. When the PPG sensor 10 generates PPG data by measuring blood flow changes, the application 15 can implement various functions by utilizing the PPG data.

[0019] The PPG sensor 10 can include a pixel array 100, a pixel light quantity signal acquirer 110, a timing generator 120, a light quantity determiner 130, an active area determiner 140, a data processor 150, a PPG data generator 160, and a power controller 170. The pixel array 100 can collect light through an optical system such as a lens.

[0020] In an example embodiment, the pixel array 100 can be implemented as a photodiode array. The pixel array 100 can be an active pixel sensor (APS) array and can include pixels with various structures. For example, the pixel array 100 can be implemented as a three-transistor active pixel sensor (3-Tr APS) in which one pixel includes three transistors and one photodiode, or a 4-Tr APS in which one pixel includes four transistors and one photodiode.

[0021] The pixel array can have multiple rows and multiple columns. The pixel light quantity signal acquirer 110 can select or not select (e.g., deselect) a specific row among the rows constituting the pixel array 100 by enabling or disabling the specific row.

[0022] The pixel light quantity signal acquirer 110 can sample the light collected through the pixel array 100 and provide corresponding pixel data. The pixel light quantity signal acquirer 110 can include one or more of the following: a correlated double sampler (CDS) that can be used to remove noise generated when reading out pixels, an analog-to-digital converter (ADC) that can be used to convert an analog pixel signal into digital data, and a transimpedance amplifier (TIA) that can be used to convert the photocurrent generated by the photodiode into an electrical signal.

[0023] In another example embodiment, the pixel array 100 can be implemented as a digital pixel sensor array having an array of digital pixel sensors that perform analog-to-digital conversion. The digital pixel sensor array can include one or more of an ADC and a digital memory in each pixel, and can immediately convert the electrical signal generated according to the light collected through the optical system into a digital signal and store the digital signal in the digital memory. Therefore, the digital pixel sensor can output a digital signal instead of a voltage signal.

[0024] When the pixel array 100 is implemented as a digital pixel sensor array, the internal configuration of the pixel light amount signal acquirer 110 can be different from that when the pixel array 100 is implemented as an APS array. Similar to the case where the pixel array 100 is implemented as an APS array, the pixel light amount signal acquirer 110 can select or not select (e.g., deselect) a specific row by enabling or disabling a specific row among the rows constituting the pixel array 100.

[0025] The timing generator 120 can select or not select (e.g., deselect) a specific column by enabling or disabling a specific column among the columns constituting the pixel array 100. The timing generator 120 can operate and be used together with the pixel light amount signal acquirer 110 to select or not select (e.g., deselect) a specific pixel in the pixel array 100. Therefore, the pixel light amount signal acquirer 110 and the timing generator 120 can select or not select (e.g., deselect) a specific pixel by enabling or disabling the row and column where the specific pixel among the multiple pixels constituting the pixel array 100 is located.

[0026] The power controller 170 can supply power to the pixel array 100 or cut off the power supply to the pixel array 100. For example, the power controller 170 can cut off the power supply to the entire pixel array 100 or a part of the pixel array 100 by operating together with the light amount determiner 130 or the effective area determiner 140, as described in further detail below.

[0027] When the power controller 170 cuts off the power supply to a part of the pixel array 100, the power controller 170 can cut off the power supply to the pixels corresponding to a specific row by controlling the pixel light amount signal acquirer 110; can cut off the power supply to the pixels corresponding to a specific column by controlling the timing generator 120; or can cut off the power supply to only a specific pixel by using both the pixel light amount signal acquirer 110 and the timing generator 120.

[0028] The light amount determiner 130 can determine whether to cut off the power supply to the pixel array 100 based on the amount of light collected for multiple pixel data. When the light amount determiner 130 determines to cut off the power supply to the pixel array 100, the light amount determiner 130 can send a command to the power controller 170 to cut off the power supply to all pixels of the pixel array 100. Then, the power controller 170 can cut off the power supply to the pixel array 100 according to the command from the light amount determiner 130.

[0029] For example, when all or at least some of the values in the pixel data exceed a predetermined first light amount reference value, the light amount determiner 130 may send a command to the power controller 170 to cut off the power supply to the entire pixel array 100. Here, when the value of specific pixel data exceeds the predetermined first light amount reference value, this may indicate that the light of this pixel data is saturated, so this pixel data cannot be used to acquire PPG data. Therefore, the predetermined first light amount reference value may be set to a value determined statistically and / or empirically for determining whether the light of the pixel data is saturated.

[0030] When all the values of the pixel data exceed the first light amount reference value, the light amount determiner 130 may send a command to the power controller 170 to cut off the power supply to the entire pixel array 100. In another embodiment, when some of the values in the pixel data exceed the first light amount reference value, the light amount determiner 130 may send a command to the power controller 170 to cut off the power supply to the entire pixel array 100. In the latter case, when, for example, 80% of the values of the pixel data exceed the first light amount reference value, the light amount determiner 130 may send a command to the power controller 170 to cut off the power supply to the entire pixel array 100.

[0031] In another example, when all or at least some of the values in the pixel data are less than a predetermined second light amount reference value, the light amount determiner 130 may send a command to the power controller 170 to cut off the power supply to the entire pixel array 100. Here, when the value of specific pixel data is less than the predetermined second light amount reference value, this may indicate that the light of this pixel data is low, so this pixel data cannot be used to acquire PPG data. Therefore, the predetermined second light amount reference value may be set to a value determined statistically and / or empirically for determining whether the light of the pixel data is low.

[0032] When all the values of the pixel data are less than the second light amount reference value, the light amount determiner 130 may send a command to the power controller 170 to cut off the power supply to the entire pixel array 100. In another embodiment, when some of the values in the pixel data are less than the second light amount reference value, the light amount determiner 130 may send a command to the power controller 170 to cut off the power supply to the entire pixel array 100. In the latter case, when, for example, 75% of the values of the pixel data are less than the second light amount reference value, the light amount determiner 130 may send a command to the power controller 170 to cut off the power supply to the entire pixel array 100.

[0033] The valid area determiner 140 may distinguish the valid area and the non-valid area of the pixel array 100 based on multiple pixel data. The valid area determiner 140 may send a command to the power controller 170 to cut off the power supply to some pixels of the pixel array 100 (e.g., the pixels of a subset of the pixel array 100 corresponding to the non-valid area). Then, the power controller 170 may cut off the power supply to the non-valid area of the pixel array 100 according to the command from the valid area determiner 140.

[0034] Details on how the valid area determiner 140 distinguishes the valid area and the non-valid area of the pixel array 100 and how the power controller 170 cuts off the power supply to the non-valid area of the pixel array 100 will be described below with reference to Figures 2 to 6 to describe in detail.

[0035] The data processor 150 may perform various image processing operations on multiple pixel data. For example, the data processor 150 may perform image signal processing (ISP) on the pixel data corresponding to the valid area of the pixel array 100. Examples of image signal processing may include general imaging processing operations, such as interpolation, color correction, gamma correction, color space conversion, white balance adjustment, exposure adjustment, and special operations required to process or adjust PPG data.

[0036] The PPG data generator 160 generates PPG data according to multiple pixel data. For example, the PPG data generator 160 may generate PPG data according to the pixel data corresponding to the valid area of the pixel array 100, for example, using digital summation.

[0037] In an exemplary embodiment, the PPG data generator 160 may measure the signal quality of the pixel data corresponding to the valid area of the pixel array 100, and when the measured signal quality remains at a predetermined quality reference value or a higher quality reference value, continuously generate PPG data according to the pixel data corresponding to the valid area. If the signal quality measured by the PPG data generator 160 is less than the predetermined quality reference value, the pixel light amount signal acquirer 110 may collect light again through the pixel array 100 and generate multiple new pixel data, and the valid area determiner 140 may distinguish the valid area and the non-valid area of the pixel array 100 based on the new pixel data.

[0038] The application 15 may be implemented as hardware such as an electronic circuit, software such as an application program, or a combination of hardware and software that performs various functions using the PPG data received from the PPG sensor 10.

[0039] In an exemplary embodiment, the pixel light amount signal acquirer 110 may generate a plurality of pixel data by collecting light through the pixel array 100 according to a signal generated by a timer. For example, the pixel light amount signal acquirer 110 may generate a plurality of pixel data by collecting light through the pixel array 100 according to a signal generated when a user wears a wearable device or wireless earphones or according to a signal generated at a predetermined interval.

[0040] In an exemplary embodiment, the pixel light amount signal acquirer 110 may generate a plurality of pixel data by collecting light through the pixel array 100 according to a signal generated by an external sensor. For example, when it is determined that the sensed value generated by an acceleration sensor or a proximity sensor is meaningful, the pixel light amount signal acquirer 110 may generate a plurality of pixel data by collecting light via the pixel array 100.

[0041] In an exemplary embodiment, the pixel light amount signal acquirer 110 may generate a plurality of pixel data by collecting light through the pixel array 100 according to a user signal. For example, the pixel light amount signal acquirer 110 may generate a plurality of pixel data by collecting light through the pixel array 100 according to a signal generated by a user's manipulation.

[0042] Figure 2 and Figure 3 are diagrams for explaining the effective area determiner 140 according to an exemplary embodiment.

[0043] In Figure 2 , (a) indicates pixels in a part of the pixel array 100. For ease of description, pixel data in (a) is shown for light amounts represented by the integers 1 to 10. The pixel data may be, for example, output from the ADC of the above-described pixel light amount signal acquirer 110, or may correspond to an ADC code output from a digital pixel sensor array.

[0044] In Figure 2 , (b) shows the effective area indicated for the pixels corresponding to the pixel data values 4 to 8 in (a). An example of setting the effective area and the non-effective area will be described in detail below with reference to Figure 3 .

[0045] In Figure 2 's (b), as an example, the pixels corresponding to the pixel data values 4 to 8 may be determined to have meaningful values when acquiring PPG data. The pixel data values of other pixels (i.e., the pixels not marked as the effective area, i.e., the non-effective area) may be 1, 2, 3, 9, or 10. It may be determined that the pixels corresponding to the pixel data values 1, 2, 3, 9, and 10 have light values that cannot be used to acquire PPG data.

[0046] In Figure 2In (c), other pixels (i.e., pixels not marked as valid regions, i.e., non-valid regions) are shown as powered-off regions. Since the pixels included in the powered-off regions (i.e., non-valid regions) are not considered to provide useful values when acquiring PPG data, the power supply to these pixels can be cut off, thereby improving the power supply efficiency of the PPG sensor 10.

[0047] Although the power supply is cut off pixel by pixel as an example in Figure 2 , the power controller 170 can cut off the power supply to the pixels corresponding to a specific row and / or cut off the power supply to the pixels corresponding to a specific column according to specific implementation purposes. For example, the power controller 170 can enable the rows included in the valid region and disable the rows included in the non-valid region by controlling the pixel light amount signal acquirer 110. When both valid pixels and non-valid pixels are included in a row, it can be determined whether the row is valid or non-valid based on various criteria according to the operation strategy of the PPG sensing device 1, where the operation strategy is determined according to specific implementation purposes. As a simple example, a strategy can be set in the PPG sensing device 1 such that when the number of valid pixels in a row is greater than the number of non-valid pixels in that row, the row is included in the valid region, and when the number of valid pixels in a row is less than the number of non-valid pixels in that row, the row is included in the non-valid region.

[0048] As another example, the power controller 170 can enable the columns included in the valid region of the pixel array 100 and disable the columns included in the non-valid region by controlling the timing generator 120. When both valid pixels and non-valid pixels are included in a column, it can be determined whether the column is valid or non-valid based on various criteria according to the operation strategy of the PPG sensing device 1, where the operation strategy is determined according to specific implementation purposes. As a simple example, a strategy can be set in the PPG sensing device 1 such that when 75% or more of the pixels in a column are valid pixels, the column is included in the valid region, and when 75% or more of the pixels in a column are non-valid pixels, the column is included in the non-valid region.

[0049] Referring to Figure 3 , in order to set the valid region and the non-valid region in the pixel array 100, the valid region determiner 140 can set a first interval reference value X1 and a second interval reference value X2 based on a plurality of pixel data. The valid region determiner 140 can include pixel data having values between the first interval reference value X1 and the second interval reference value X2 in the valid region, and can include pixel data having values not between the first interval reference value X1 and the second interval reference value X2 in the non-valid region. In Figure 3In the example shown, the horizontal axis represents the ADC code values that each pixel of the pixel array 100 can have, and the vertical axis represents the number of pixels (i.e., frequency) in the pixel array 100 corresponding to each ADC code value.

[0050] In an example embodiment, the valid region determiner 140 may dynamically reset the first interval reference value X1 and the second interval reference value X2 during the operation of the PPG sensor 10. For example, if the mean is located far from the right side, the valid region determiner 140 may shift the second interval reference value X2 to the left by multiplying the second interval reference value X2 by a weight. As another example, the valid region determiner 140 may shift the first interval reference value X1 or the second interval reference value X2 to the left or right by multiplying at least one of the first interval reference value X1 and the second interval reference value X2 by a weight.

[0051] Figures 4 to 6 is a diagram for explaining a power controller according to an example embodiment.

[0052] Reference Figures 4 to 6 , the power controller 170 may enable the rows and columns included in the valid region of the pixel array 100 and disable the rows and columns included in the non-valid region of the pixel array 100 by controlling the pixel light amount signal acquirer 110 and the timing generator 120.

[0053] For example, Figure 5 shows a pixel array 100 for an example case, in which the valid region of the pixel array 100 includes valid pixels corresponding to the first, third, and fourth columns of the first row, pixels corresponding to the first, third, and fourth columns of the second row, a pixel corresponding to the second column of the third row, and pixels corresponding to the first, second, and fourth columns of the fourth row.

[0054] In this case, when the pixel light amount signal acquirer 110 selects the first row, the power controller 170 may set the column enable signals input to the first, third, and fourth columns to logic high and the column enable signal input to the second column to logic low by controlling the timing generator 120, thereby cutting off the power supply to the pixel corresponding to the second column of the first row. Similarly, when the pixel light amount signal acquirer 110 selects the third row, the power controller 170 may set the column enable signal input to the second column to logic high and the column enable signals input to the first, third, and fourth columns to logic low by controlling the timing generator 120, thereby cutting off the power supply to the pixels corresponding to the first, third, and fourth columns of the third row.

[0055] Figure 7 shows a method of operating a PPG sensor according to an example embodiment.

[0056] Reference Figure 7 Figure 7 [0000141], the method of operating the PPG sensor 10 according to the exemplary embodiment may include: obtaining data for determining the effective region of the pixel array 100 (operation S701). Obtaining the data (operation S701) may include: converting the light collected by the pixel array 100 into a plurality of pixel data.

[0057] Additionally, the method may include: determining whether to cut off the power supply based on the amount of light collected for the pixel data (operation S703). When determining whether to cut off the power supply (operation S703), it may be determined whether all or at least some of the values in the pixel data exceed a predetermined first light amount reference value. When determining whether to cut off the power supply (operation S703), it may be determined whether all or at least some of the values in the pixel data are less than a predetermined second light amount reference value.

[0058] If it is determined that all or at least some of the values in the pixel data exceed the predetermined first light amount reference value or are less than the predetermined second light amount reference value, the power supply to the pixel array 100 may be cut off based on the determination (operation S707).

[0059] If it is determined that all or at least some of the values in the pixel data do not exceed the predetermined first light amount reference value and are equal to or greater than the predetermined second light amount reference value, a first interval reference value X1 and a second interval reference value X2 may be set based on the pixel data (operation S705).

[0060] The pixel data having values between the first interval reference value X1 and the second interval reference value X2 may be included in the effective region, and the pixel data having values not between the first interval reference value X1 and the second interval reference value X2 may be included in the non-effective region, thereby distinguishing the effective region and the non-effective region of the pixel array 100 and cutting off the power supply to the non-effective region (operation S709).

[0061] Cutting off the power supply to the non-effective region (operation S709) may include: enabling the rows included in the effective region of the pixel array 100 and disabling the rows included in the non-effective region, enabling the columns included in the effective region of the pixel array 100 and disabling the columns included in the non-effective region, or enabling the rows and columns included in the effective region of the pixel array 100 in total and disabling the rows and columns included in the non-effective region.

[0062] In the exemplary embodiment, the first interval reference value X1 and the second interval reference value X2 may be dynamically reset during the operation of the PPG sensor 10.

[0063] Next, PPG data can be generated based on the pixel data corresponding to the effective region in the pixel data (operation S711).

[0064] Next, the signal quality of the pixel data corresponding to the effective region can be measured (operation S713). When the signal quality remains at or above a predetermined quality reference value (Yes in operation S715), PPG data can be continuously generated based on the pixel data corresponding to the effective region. On the other hand, when the signal quality is less than the predetermined quality reference value (No in operation S715), a plurality of new pixel data can be generated.

[0065] In an exemplary embodiment, generating pixel data can include: generating a plurality of pixel data by collecting light through the pixel array 100 according to a signal generated by a timer.

[0066] In an exemplary embodiment, generating pixel data can include: generating a plurality of pixel data by collecting light through the pixel array 100 according to a signal generated by an external sensor.

[0067] In an exemplary embodiment, generating pixel data can include: generating a plurality of pixel data by collecting light through the pixel array 100 according to a user signal.

[0068] The method may further include: performing image processing on the pixel data corresponding to the effective region.

[0069] Figure 8 is a diagram for explaining an example of determining an effective region of the PPG sensor 10 according to an exemplary embodiment. In Figure 8 the horizontal axis represents rows, the vertical axis represents columns, and the legend represents pixel values.

[0070] Reference Figure 8 shows that approximately half of the pixels of the pixel array 100 are included in the effective region, while the other half are included in the non-effective region. Thus, since the power supply controller 170 cuts off the power supply to the non-effective region as described above, a significant power reduction of the PPG sensor 10 is observed.

[0071] Figure 9 is a diagram for explaining an example of using a PPG sensor according to an exemplary embodiment.

[0072] Reference Figure 9, the PPG sensor 10 according to an exemplary embodiment may be used together with a light source 20. The light source 20 may be, for example, a light-emitting diode (LED) that illuminates a user's skin. The PPG sensor 10 may be, for example, a PPG sensor based on an APS pixel array that collects light reflected from the skin and may obtain PPG data based on the collected light. The PPG sensor 10 may determine an active area and an inactive area of the pixel array 100 based on an acquired image signal under the control of a processor 30 (e.g., an application processor (AP)), and may be interconnected with an external sensor 40 such as an acceleration sensor or a proximity sensor as described above, and / or may be interconnected with other devices through a communication device 50 such as a Bluetooth module.

[0073] By summarizing and reviewing, the PPG sensor may be set to operate for a long time in an environment where very limited power is provided. In this way, the embodiment may minimize the power consumption of the PPG sensor. The embodiment may provide a PPG sensor and a method of operating the PPG sensor that improve power efficiency by reducing the power consumption of the pixel array.

[0074] As will be understood by those skilled in the art, some aspects of the embodiments herein may be described and / or illustrated with reference to functional blocks, units, or modules. The blocks, units, or modules may be implemented by dedicated hardware or as a combination of dedicated hardware for performing some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) for performing other functions. The blocks, units, or modules of the embodiments may be physically separated into two or more interacting and discrete blocks, units, or modules, or the blocks, units, or modules may be physically combined into more complex blocks, units, or modules. Those skilled in the art will understand that these blocks, units, or modules may be physically implemented by electronic (or optical) circuits such as logic circuits, discrete components, microprocessors, hardwired circuits, memory elements, wiring connections, etc., where the electronic (or optical) circuits may be formed using semiconductor-based manufacturing technologies or other manufacturing technologies. In the case where the blocks, units, or modules are implemented by a microprocessor or the like, they may be programmed with software (e.g., microcode) to perform the various functions discussed herein and may optionally be driven by firmware or software.

[0075] Example embodiments have been disclosed herein, and although specific terms are employed, they are used only for and are to be interpreted in a general descriptive sense and not for purposes of limitation. In some instances, as would be recognized by one of ordinary skill in the art at the time of filing the present application, unless otherwise expressly stated, features, characteristics, and / or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and / or elements described in connection with other embodiments. Accordingly, those skilled in the art will appreciate that various changes in form and detail may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. A photoplethysmogram (PPG) sensor, comprising: A pixel array that collects light; A pixel sampler that converts the light collected by the pixel array into a plurality of pixel data; A valid region determiner that determines a valid region and an invalid region of the pixel array based on the pixel data; A power controller that can operate to cut off power supply to the invalid region of the pixel array; And A PPG data generator that generates PPG data according to the pixel data corresponding to the valid region in the pixel data, wherein: The valid region determiner sets a first interval reference value and a second interval reference value based on the pixel data; The valid region determiner includes, in the valid region, the pixel data having values existing between the first interval reference value and the second interval reference value in the pixel data; and The valid region determiner includes, in the invalid region, the pixel data having values not existing between the first interval reference value and the second interval reference value in the pixel data.

2. The PPG sensor according to claim 1, wherein The power controller enables the rows included in the valid region and disables the rows included in the invalid region by controlling the pixel sampler.

3. The PPG sensor according to claim 2 further comprises: A timing generator that enables or disables the columns of the pixel array, wherein the power controller enables the columns included in the valid region and disables the columns included in the invalid region by controlling the timing generator.

4. The PPG sensor according to claim 1 further comprises: A light amount determiner that determines whether to cut off power supply based on the amount of light collected for the pixel data, wherein the power controller cuts off the power supply to the pixel array according to a command from the light amount determiner.

5. The PPG sensor according to claim 4, wherein, When the values of all or at least some of the pixel data in the pixel data exceed a predetermined first light amount reference value, the light amount determiner sends a command to the power controller to cut off the power supply to the entire pixel array.

6. The PPG sensor according to claim 4, wherein, When the values of all or at least some of the pixel data in the pixel data are less than a predetermined second light amount reference value, the light amount determiner sends a command to the power controller to cut off the power supply to the entire pixel array.

7. The PPG sensor according to claim 1, wherein, The PPG data generator measures the signal quality of the pixel data corresponding to the valid region, and continuously generates the PPG data according to the pixel data corresponding to the valid region when the signal quality remains at a predetermined quality reference value or a higher quality reference value.

8. The PPG sensor according to claim 7, wherein, When the signal quality measured by the PPG data generator is less than the quality reference value, the pixel sampler collects light again through the pixel array and generates a plurality of new pixel data.

9. The PPG sensor according to claim 1, wherein, The pixel sampler generates the pixel data by collecting light through the pixel array according to a signal generated by a timer.

10. The PPG sensor according to claim 1, wherein, The pixel sampler generates the pixel data by collecting light through the pixel array according to a signal generated by an external sensor.

11. The PPG sensor according to claim 1, wherein, The pixel sampler generates the pixel data by collecting light through the pixel array according to a user signal.

12. A photoplethysmogram (PPG) sensor, comprising: A pixel array that collects light; A pixel sampler that converts the light collected by the pixel array into a plurality of pixel data; A light quantity determiner that determines whether to cut off the power supply based on the amount of light collected for the pixel data; A power controller that can operate to cut off the power supply to the pixel array according to a command from the light quantity determiner; And A PPG data generator that generates PPG data according to the pixel data.

13. The PPG sensor according to claim 12, wherein, When all or at least some of the pixel data in the pixel data exceeds a predetermined first light quantity reference value, the light quantity determiner sends a command to the power controller to cut off the power supply to the entire pixel array.

14. The PPG sensor according to claim 12, wherein, When all or at least some of the pixel data in the pixel data is less than a predetermined second light quantity reference value, the light quantity determiner sends a command to the power controller to cut off the power supply to the entire pixel array.

15. The PPG sensor according to claim 12 further comprises: An effective area determiner that determines the effective area and the non-effective area of the pixel array based on the pixel data, wherein the power controller cuts off the power supply to the non-effective area of the pixel array.

16. The PPG sensor according to claim 15, wherein, The effective area determiner sets a first interval reference value and a second interval reference value based on the pixel data, The effective area determiner includes, in the effective area, pixel data having values existing between the first interval reference value and the second interval reference value among the pixel data; And The effective area determiner includes, in the non-effective area, pixel data having values not existing between the first interval reference value and the second interval reference value among the pixel data.

17. The PPG sensor according to claim 16, wherein, The power controller enables the rows included in the effective area and disables the rows included in the non-effective area by controlling the pixel sampler.

18. The PPG sensor according to claim 17, further comprising: A timing generator that enables or disables the columns of the pixel array, wherein the power controller enables the columns included in the effective area and disables the columns included in the non-effective area by controlling the timing generator.

19. A photoplethysmogram (PPG) system, comprising: A light source; The PPG sensor according to claim 1, wherein the PPG sensor is arranged to receive the light emitted by the light source and reflected from the skin of a user; And An application that receives PPG data from the PPG sensor.

20. A photoplethysmogram (PPG) system, comprising: A light source arranged to emit light to the skin of a user; A pixel array including pixels, wherein the pixel array is arranged to collect the light reflected from the skin of the user; And A power supply controller coupled to the pixel array, wherein the power supply controller is configured to cut off the power supply to the non-effective area of the pixel array and supply power to the effective area of the pixel array, wherein: The active area of the pixel array includes pixels in the pixel array corresponding to the amount of light between the first reference value and the second reference value, and the non-active area of the pixel array includes pixels in the pixel array corresponding to the amount of light not between the first reference value and the second reference value.

Images