WO2016136011A1

WO2016136011A1 - Optical sensor and electronic device

Info

Publication number: WO2016136011A1
Application number: PCT/JP2015/077832
Authority: WO
Inventors: 伸弘高橋
Original assignee: シャープ株式会社
Priority date: 2015-02-24
Filing date: 2015-09-30
Publication date: 2016-09-01

Abstract

The purpose of the present invention is to provide an optical sensor for outputting digital output values such that periodic variations in the digital output values can be more accurately to be detected. The optical sensor (2) comprises a light receiving element (3) and an analog-to-digital conversion circuit (4) for converting analog output values output from the light receiving element (3) to digital output values (6). The optical sensor (2) is provided with a number adding unit (9) for adding chronological identification numbers to the digital output values (6).

Description

Optical sensor and electronic device

The present invention relates to an optical sensor and an electronic device including the optical sensor.

The optical sensor has a function of detecting a detection object and detecting a distance from the detection object, and its application fields are expanding.

For example, in an electronic device such as a smart device such as a smartphone, a model including a display panel for displaying an image and a touch panel so that a touch operation on the display panel can be performed becomes common. ing. In some cases, an optical sensor (proximity sensor) is mounted in order to reduce power consumption and prevent malfunction of the touch panel. In a smartphone or the like, generally, a voice output unit that listens to a call voice by applying a user's ear is provided adjacent to a display panel and a touch panel. When the user puts his ear on the sound output unit, the user does not see the display panel or perform a touch operation. Therefore, an optical sensor (proximity sensor) that detects that the user's face has approached the audio output unit is installed, and when the user's face has approached the audio output unit, the operation of the display panel or touch panel is turned off. To achieve low power consumption and prevention of touch panel malfunction.

As another application example of the optical sensor, a pulse measuring function using the optical sensor can be cited. Due to the recent increase in health management orientation, there is a strong demand to easily measure the pulse rate using smart devices such as smartphones, and the number of smart devices equipped with such functions is increasing. If it is possible to easily measure the pulse rate using a smart device, it is expected that body abnormalities such as arrhythmia can be quickly discovered and contributed to daily health management.

Patent Document 1 discloses a pulse oximeter capable of measuring a pulse rate and blood oxygen saturation using an optical sensor. According to this configuration, it is possible to simplify the pulse rate and blood oxygen saturation by capturing the periodic movement of arterial blood pumped from the heart as a periodic change in the amount of light incident on the light receiving part of the optical sensor. Can be measured.

Further, in Patent Document 2, by combining an optical sensor with an acceleration sensor, the body motion (body motion component) and the motion due to pulsation are separated, and the pulse rate is calculated by removing the body motion component from the pulse wave component. Thus, there is disclosed a pulse meter that can perform highly accurate pulse measurement even during exercise.

Japanese Patent Publication “Japanese Patent Laid-Open No. 10-201743 (published on August 4, 1998)” Japanese Patent Publication “Japanese Patent Laid-Open No. 2004-358271 (published on December 24, 2004)”

In order to accurately measure the pulse rate by the above-described conventional method, a control unit represented by a dedicated microprocessor for controlling the optical sensor is necessary for the following reason. This is because in order for the control unit to accurately measure the pulse rate, it is necessary to frequently take out digital output values from the optical sensor at accurate time intervals and to capture periodic changes in the digital output values. However, when such an optical sensor is mounted on a smart device such as a smartphone or a tablet terminal, the optical sensor is not a dedicated control unit, and various devices such as a plurality of other sensors, a touch panel controller, and a communication module are used. It is controlled by a control unit such as a microprocessor that performs control at once. This is because the optical sensor mounted on the smart device is required to be inexpensive and small. In the case of such a control unit that controls various devices at once, the frequency of repeatedly performing irregular processing on a plurality of devices is high, so for an optical sensor that is one of a plurality of devices, It is difficult to access frequently at precise time intervals. Therefore, it is difficult to accurately measure the pulse rate in a smart device including a control unit that controls such various devices at once. This becomes more prominent as the processing capability of the control unit is lower.

An object of the present invention is to provide an optical sensor that outputs a digital output value that can more accurately capture periodic changes in digital output values, and an electronic device that can more accurately capture periodic changes in digital output values. And to provide.

In order to solve the above problems, an optical sensor of the present invention is an optical sensor including a light receiving element and an analog-to-digital conversion circuit that converts an analog output value output from the light receiving element into a digital output value. A number adding unit for adding a time series identification number to the digital output value is provided.

The optical sensor includes a number adding unit that adds a time series identification number to the digital output value. By using a digital output value to which such a time series identification number is added, it is possible to easily grasp when there is a missing digital output value or when a digital output value is received in duplicate. Therefore, according to the said structure, the optical sensor which outputs the digital output value which can catch the periodic change of a digital output value more correctly is realizable.

In order to solve the above-described problems, an electronic apparatus according to the present invention includes the above-described optical sensor and a control unit that controls a plurality of devices including the optical sensor.

According to the above configuration, it is possible to realize an electronic device that can accurately capture a periodic change in a digital output value.

According to one embodiment of the present invention, an optical sensor that outputs a digital output value that can more accurately detect a periodic change in the digital output value, and a periodic change in the digital output value can be more accurately captured. Can be realized.

It is a block diagram which shows the structure of the principal part of the smart phone by which the pulse measurement function using the optical sensor which concerns on one Embodiment of this invention is mounted. It is a figure for demonstrating the case where a pulse rate is calculated using the conventional digital output value, and the case where a pulse rate is calculated using the digital output value to which the time series identification number was added. It is a block diagram which shows the structure of the principal part of the smart phone by which the pulse measurement function using the optical sensor which concerns on other one Embodiment of this invention is mounted. It is a block diagram which shows the structure of the principal part of the smart phone by which the pulse measurement function using the optical sensor which concerns on another one Embodiment of this invention is mounted. It is a block diagram which shows the structure of the principal part of the smart phone by which the pulse measurement function using the optical sensor which concerns on another one Embodiment of this invention containing the control part provided with the correction | amendment process part is mounted. It is a figure for demonstrating the case where the correction process part shown in FIG. 5 correct | amends the digital output value to which the time series identification number was added. It is a block diagram which shows the structure of the principal part of the smart phone by which the pulse measurement function using the optical sensor which concerns on another one Embodiment of this invention containing the control part provided with the digital filter was mounted.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, processing methods, and the like of the configurations described in this embodiment are merely one embodiment, and the scope of the present invention should not be construed as being limited thereto. Further, the drawings are schematic, and the ratio and shape of dimensions are different from actual ones.

In each embodiment described below, a smartphone equipped with a pulse measurement function using an optical sensor will be described as an example of an electronic device. However, the present invention is not limited to this, for example, A pulse oximeter that measures a pulse rate and blood oxygen saturation using an optical sensor may be used. Furthermore, it may be an electronic device including an optical sensor that outputs a digital output value regardless of whether it is a portable type or a fixed type (a type that is placed and used).

[Embodiment 1]
An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram illustrating a configuration of a main part of a smartphone 21 equipped with a pulse measurement function using the optical sensor 2 and the control unit 20.

The smartphone 21 includes a sensor device 10 including the light emitting element 1 and the optical sensor 2 and a control unit 20.

(Light emitting element)
In the present embodiment, since pulse measurement is performed using the light-emitting element 1 and the optical sensor 2, the light-emitting element 1 has a wavelength of 600 nm to 700 nm or 800 to 900 nm, which is a wavelength that is well absorbed by blood. It is preferable to use an LED element or a laser that emits light. This is because the absorption rate of arterial blood pulsated from the heart periodically changes in accordance with the heartbeat. By detecting this cycle, the pulse rate can be calculated. In this embodiment, an LED element that emits light having a wavelength of 600 nm to 700 nm is used, but the present invention is not limited to this.

(Optical sensor)
The optical sensor 2 has a light receiving element 3 sensitive to the wavelength of light emitted from the light emitting element 1, and an analog output value output according to the amount of light having the above wavelength received by the light receiving element 3 as a digital output value (digital Output data) 6, and an analog-to-digital conversion circuit 4 that converts the output data 6 and a number adding unit 5 that adds a time-series identification number to the digital output value 6.

The light emitted from the light emitting element 1 is reflected by a finger, an arm or the like and is incident on the light receiving element 3. At this time, the light is reflected not only from the surface of the finger or arm but also from the blood vessel including the arterial blood therein and is incident on the light receiving element 3. In the present embodiment, since a photodiode is used as the light receiving element 3, the light receiving element 3 passes a current proportional to the amount of received light. This current value is an analog output value output from the light receiving element 3, and this analog output value is converted into a digital output value 6 by the analog-digital conversion circuit 4. Thereafter, a time series identification number is added to the digital output value 6 input to the signal addition unit 5 by the signal addition unit 5, and a digital output value 9 to which the time series identification number is added is generated. 5 outputs a digital output value 9 to which a time-series identification number is added. That is, a digital output value 9 to which a time series identification number is added is output from the sensor device 10 including the light emitting element 1 and the optical sensor 2 to the outside via the signal adding unit 5.

The time series identification number can be easily grasped based on the digital output value 9 to which this time series identification number is added when there is a missing digital output value or when the digital output value is received in duplicate. If it is possible to easily calculate one period from the digital output value 9 to which the time series identification number is added and how many pulsations are present in one minute from this one period, For example, a decimal or hexadecimal time series identification number may be used. In this embodiment, decimal numbers from 0 to n are used as shown in the digital output value 9 to which the time-series identification number is added in FIG.
(Control part)
The digital output value 9 with the time series identification number added is output from the sensor device 10, but the time series identification number is added under the control of the control unit 20 represented by the microprocessor of the smartphone 21 that controls the sensor device 10. The digital output value 9 thus read is read out at a constant time interval. At this time, the digital output value 9 to which the time series identification number output from the sensor device 10 is added is preferably read by the control unit 20 using a communication method such as I2C.

As shown in FIG. 1, the control unit 20 includes an exclusion / interpolation processing unit 7 and a cycle detection unit 8.

FIG. 2 is a diagram for explaining a case where a pulse rate is calculated using a conventional digital output value and a case where a pulse rate is calculated using a digital output value 9 to which a time-series identification number is added. is there. 2A and 2B show a case where a conventional digital output value is used, and FIG. 2C shows a case where a digital output value 9 to which a time series identification number is added is used.

Generally, the control unit 20 controls a plurality of devices such as a communication module and a touch panel controller in addition to the sensor device 10, and the control unit 20 adds the time series identification number of the optical sensor 2 at regular time intervals. It is difficult to read the digital output value 9 that has been read. This is because the control unit 20 needs to control other devices irregularly.

If there is a dedicated control unit for controlling the optical sensor, the digital output value from the optical sensor can be read out along the actual pulse waveform as shown in FIG. When the device is controlled all at once, the controller is more likely to miss the digital output value from the optical sensor, as shown in FIG. If the control unit does not notice that the digital output value has been missed, the control unit determines that the period from the peak value to the peak value is one cycle based on the solid line circle in FIG. One cycle is determined to be shorter than the original case where there is no value, and the pulse rate cannot be calculated accurately.

Therefore, as shown in FIG. 2C, when the digital output value 9 to which the time series identification number is added is used, each digital output value 9 to which the time series identification number is added has a time series number. Therefore, if the time series identification numbers are not in time series order, for example, if the time series identification numbers are not sequential numbers, the control unit 20 missed the digital output value 9 to which the time series identification numbers are added. You can notice that. When the control unit 20 notices that it has missed the digital output value 9 to which the time-series identification number is added, it can detect an accurate cycle by performing removal or interpolation by the exclusion / interpolation processing unit 7. The pulse rate can be calculated accurately.

As shown in FIG. 2C, for example, when the eighth digital output value is read by the control unit 20 after the sixth digital output value, it is determined that there is no seventh digital output value. 20 can be judged. When the control unit 20 determines that there is no seventh digital output value, the exclusion / interpolation processing unit 7 performs the following interpolation processing to generate a seventh digital output value.

In the exclusion / interpolation processing unit 7, it is preferable that the interpolation processing is performed using linear interpolation or polynomial interpolation. For example, when the number added to the digital output value is 0, 1, 2, 3, 4, 5,... And the seventh digital output value is missed, the linear interpolation is performed. This is an interpolation method in which the output value is added to a value obtained by dividing the difference between the sixth digital output value and the eighth digital output value into two equal parts to obtain a seventh digital output value. On the other hand, in the polynomial interpolation, for example, when the number added to the digital output value is 0, 1, 2, 3, 4, 5,. This is an interpolation method for estimating the seventh digital output value by constructing an approximate expression with reference to the values of 8 and 9, and expressing this by a polynomial expression.

Further, by using the digital output value 9 to which the time series identification number is added, for example, the control unit 20 once reads the digital output value 9 to which the time series identification number is added, and then adds the time series identification number. When the digital output value 9 to which the time series identification number is added is read again before the digital output value 9 is updated (when the same digital output value is read twice). Based on the number added to the digital output value 9 to which the time series identification number is added, the control unit 20 determines that they are the same digital output value, and excludes one of the digital output values and uses it for the calculation of the cycle. Therefore, the pulse rate can be calculated accurately. Such processing is also called exclusion processing. The exclusion / interpolation processing unit 7 also performs this exclusion process.

As described above, the period can be detected more accurately by the interpolation process or the exclusion process performed by the exclusion / interpolation processing unit 7, and the pulse rate can be accurately calculated.

In the present embodiment, the time series identification number is a serial number, but it goes without saying that the number can be identified as long as it is identifiable or ranked according to a certain method.

The cycle detection unit 8 detects the change cycle of the digital output value in which the digital output value 9 to which the time series identification number is added periodically changes. This change period is calculated by how many times the digital output value is output (updated) in one period from the peak value to the peak value. Furthermore, the pulse rate [bit / minute] is calculated by calculating how many times one period from the peak value to the peak value is 1 minute.

In the present embodiment, the case where the control unit 20 performs the exclusion process and the interpolation process has been described as an example. However, if any one of the exclusion process and the interpolation process is performed by the control unit, the conventional process is performed. Compared to, the period can be detected more accurately, and the pulse rate can be calculated accurately.

[Embodiment 2]
Hereinafter, based on FIG. 3, the smart phone 21a which is other one Embodiment of this invention is demonstrated. For convenience of explanation, members having the same functions as those described in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

FIG. 3 is a block diagram showing a configuration of a main part of the smartphone 21a equipped with a pulse measurement function using the optical sensor 2a and the control unit 20 of the sensor device 10a.

In the first embodiment described above, the signal adding unit 5 adds the time series identification number to all the digital output values 6 output from the analog-to-digital conversion circuit 4, but the signal adding unit according to the present embodiment. The unit 5a also has a configuration for adding a time series identification number at a constant period (a constant interval). Therefore, the user of the smartphone 21a adds a time series identification number to all the digital output values 6 output from the analog-digital conversion circuit 4 as necessary, or sets the time series at a constant cycle (a constant interval). You can choose whether to add an identification number.

When the user of the smartphone 21a selects to add a time-series identification number at a constant period (a constant interval), for example, digital output from the analog-digital conversion circuit 4 as shown in FIG. A time-series identification number is added to data1, data3, data-1... In the output value 6.

The above configuration can be suitably used when it is not necessary to use all the digital output values 6 output from the analog-digital conversion circuit 4.

[Embodiment 3]
Hereinafter, based on FIG. 4, the smart phone 21b which is other one Embodiment of this invention is demonstrated. For convenience of explanation, members having the same functions as those described in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

FIG. 4 is a block diagram showing a configuration of a main part of a smartphone 21b equipped with a pulse measurement function using the optical sensor 2b and the control unit 20 of the sensor device 10b.

As shown in the figure, the optical sensor 2b includes a signal output unit 11. The signal output unit 11 controls the timing at which the digital output value 9 to which the time-series identification number is added is updated. A signal 12 for transmitting to is output. For example, the signal 12 is preferably output as High or Low and is used as an interrupt input to the control unit 20. As a result, the control unit 20 can know the timing at which the digital output value 9 to which the time-series identification number is added is updated. Therefore, the control unit 20 needs to additionally include a timer for setting a read interval. Disappear.

In the present embodiment, the signal 12 is output in accordance with the output timing of the digital output value 9 with the time-series identification number added from the optical sensor 2b. However, the present invention is not limited to this. Instead, the signal 12 may be output in accordance with the timing at which the analog-digital conversion circuit 4 outputs the digital output value 6 or the timing at which the number adding unit 5 adds the time series identification number to the digital output value 6.

[Embodiment 4]
Hereinafter, based on FIG. 5 and FIG. 6, the smart phone 21c which is other one Embodiment of this invention is demonstrated. For convenience of explanation, members having the same functions as those described in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

FIG. 5 is a block diagram showing a configuration of a main part of a smartphone 21c equipped with a pulse measurement function using the optical sensor 2b of the sensor device 10b and the control unit 20a.

As shown in the drawing, the control unit 20a of the smartphone 21c is provided with an exclusion / correction processing unit 7a, which does not use the interpolation data obtained as in the first to third embodiments described above. When the control unit 20a notices that the digital output value 9 to which the time-series identification number is added is missed, the control unit 20a determines how long the digital output value is missed, and the exclusion / correction processing unit 7a performs a correction reflecting this period.

FIG. 6 is a diagram for explaining an example of correction performed by the exclusion / correction processing unit 7a. As shown in the figure, for example, when the control unit 20a reads the eighth digital output value next to the sixth digital output value, the control unit 20a determines that there is no seventh digital output value. it can. When the control unit 20a determines that there is no seventh digital output value, the exclusion / correction processing unit 7a performs correction (temporal correction) on the eighth and subsequent digital output values. In other words, the exclusion / correction processing unit 7a performs correction for reflecting the period in which the digital output value is missed with respect to the digital output value after the missed period. Specifically, it is possible to determine how much correction should be performed by detecting the change cycle of the digital output value in which the digital output value 9 to which the time series identification number is added periodically changes.

In the present embodiment, the case where the control unit 20a performs the exclusion process and the correction process has been described as an example. However, if any one of the exclusion process and the correction process is performed by the control unit, a conventional process is performed. Compared to, the period can be detected more accurately, and the pulse rate can be calculated accurately.

[Embodiment 5]
Hereinafter, based on FIG. 7, the smart phone 21d which is other one Embodiment of this invention is demonstrated. For convenience of explanation, members having the same functions as those described in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

FIG. 7 is a block diagram showing a configuration of a main part of a smartphone 21d equipped with a pulse measurement function using the optical sensor 2b and the control unit 20b of the sensor device 10b.

As shown in the figure, the digital output value interpolated by the exclusion / interpolation processing unit 7 of the control unit 20b is processed by the digital filter 14 formed of a low-pass filter or a high-pass filter, and then the period detection unit 8 The period is calculated by the period detection unit 8. By providing the digital filter 14, the period can be detected more accurately by removing low frequency noise and high frequency noise, and the pulse rate can be calculated accurately.

In the present embodiment, the case where the digital filter 14 is provided between the exclusion / interpolation processing unit 7 and the period detection unit 8 has been described as an example. However, the present invention is not limited to this, and is described above. A digital filter 14 may be provided between the exclusion / correction processing unit 7a and the cycle detection unit 8 illustrated in FIG. Further, after any of the exclusion process, the correction process, and the interpolation process is performed, the process may be performed using the digital filter 14 before being input to the period detection unit 8.

Note that the optical sensors described in Embodiments 1 to 5 described above can also be used as proximity sensors other than during pulse measurement. The light emitted from the light emitting element 1 is reflected from the human face and is incident on the light receiving element 3, so that it can be detected that there is a human face in the vicinity of the optical sensor. By turning it off, it is possible to reduce power consumption and prevent malfunction of the touch panel.

[Summary]
An optical sensor according to aspect 1 of the present invention is an optical sensor including a light receiving element and an analog-to-digital conversion circuit that converts an analog output value output from the light receiving element into a digital output value. A number adding unit for adding a time series identification number is provided.

In the optical sensor according to aspect 2 of the present invention, the light receiving element may be sensitive to light having a wavelength that is absorbed by blood.

According to the above configuration, for example, the pulse rate and blood oxygen saturation can be measured using the optical sensor.

In the optical sensor according to aspect 3 of the present invention, the timing at which the analog-to-digital conversion circuit outputs the digital output value, the timing at which the number adding unit adds a time-series identification number to the digital output value, and the optical sensor to the above It is preferable that a signal output unit is provided that outputs a signal at each timing selected from timings at which a signal in which a time series identification number is added to a digital output value is output.

According to the above configuration, the control unit that reads the digital output value to which the time series identification number is added can know the timing at which the digital output value to which the time series identification number is added is updated. In addition, it is not necessary to separately provide a timer for setting the reading interval.

In the optical sensor according to aspect 4 of the present invention, the number adding unit may add a time series identification number to a part of the digital output value.

According to the above configuration, the number adding unit adds a time series identification number with a constant period (a constant interval) to the digital output value output from the analog-digital conversion circuit. Therefore, it can be suitably used when it is not necessary to use all the digital output values output from the analog-digital conversion circuit.

The electronic device according to the fifth aspect of the present invention is characterized by including the above-described optical sensor and a control unit that controls a plurality of devices including the optical sensor.

In the electronic device according to the sixth aspect of the present invention, the control unit generates an interpolated value of the digital output value based on a signal in which a time series identification number is added to the digital output value, It is preferable that a signal processing unit that performs at least one of exclusion and temporal correction of the digital output value is provided.

In the electronic device according to aspect 7 of the present invention, it is preferable that the signal processing unit generates an interpolation value of the digital output value, and the interpolation value is calculated by linear interpolation or polynomial interpolation.

According to the above configuration, the interpolation value of the digital output value can be generated relatively easily.

In the electronic device according to the eighth aspect of the present invention, it is preferable that the control unit includes a digital filter, and the digital output value processed by the signal processing unit is processed by the digital filter.

According to the above configuration, by providing the digital filter, the period can be detected more accurately by removing low frequency noise and high frequency noise, and the pulse rate can be calculated accurately.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the technical means disclosed in different embodiments can be appropriately combined. Such embodiments are also included in the technical scope of the present invention.

The present invention can be suitably used for an optical sensor and an electronic device including the optical sensor.

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Optical sensor 2a Optical sensor 2b Optical sensor 3 Light receiving element 4 Analog-digital conversion circuit 5 Number addition part 5a Number addition part 6 Digital output value 7 Exclusion / interpolation processing part (signal processing part)
7a Exclusion / correction processing unit (signal processing unit)
8 Cycle detection unit 9 Digital output value with time series identification number added 9a Digital output value with time series identification number added 10 sensor device 10a sensor device 10b sensor device 11 signal output unit 12 signal output from signal output unit 14 Digital filter 20 Control unit 20a Control unit 20b Control unit 21 Smartphone (electronic device)
21a Smartphone (electronic equipment)
21b Smartphone (electronic equipment)
21c Smartphone (electronic equipment)
21d Smartphone (electronic equipment)

Claims

An optical sensor comprising a light receiving element and an analog-to-digital conversion circuit that converts an analog output value output from the light receiving element into a digital output value,
An optical sensor comprising a number adding unit for adding a time series identification number to the digital output value.
2. The optical sensor according to claim 1, wherein the light receiving element is sensitive to light having a wavelength absorbed by blood.
The timing at which the analog-to-digital conversion circuit outputs the digital output value, the timing at which the number adding unit adds a time series identification number to the digital output value, and the time series identification number from the optical sensor are added to the digital output value. The optical sensor according to claim 1, further comprising: a signal output unit that outputs a signal at each timing selected from timings at which the received signal is output.
An electronic apparatus comprising: the optical sensor according to any one of claims 1 to 3; and a control unit that controls a plurality of devices including the optical sensor.
The control unit generates an interpolated value of the digital output value, excludes the digital output value, and temporally corrects the digital output value based on a signal obtained by adding a time series identification number to the digital output value. The electronic device according to claim 4, further comprising a signal processing unit that performs at least one.