WO2019057778A1

WO2019057778A1 - Method for measuring a pulse frequency, pulse frequency meter and computer program product

Info

Publication number: WO2019057778A1
Application number: PCT/EP2018/075360
Authority: WO
Inventors: Tilman Ruegheimer; Hubert Halbritter; Roland Heinrich Enzmann
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2017-09-19
Filing date: 2018-09-19
Publication date: 2019-03-28
Also published as: DE102017121715A1

Abstract

In the method, a pulse frequency meter (100) having a radiation source (1) and a radiation sensor (3) is provided. The radiation source emits radiation onto a body location (2). The pulse frequency meter can be operated in a first and a second operating mode. In the first operating mode, the radiation source is operated continuously in a scanning mode. In the second operating mode, the radiation source is operated cyclically with a predefinable test frequency (F 2) for a predefinable test time period (T_2) in the scanning mode.

Description

Method for measuring a pulse rate, pulse rate meter and computer program product A method for measuring a pulse rate is specified. In addition, a pulse rate meter and a computer program product are indicated.

An object to be solved is to specify a method for the energy-saving measurement of a pulse frequency. Further objects to be solved are to specify a pulse frequency meter and a computer program product for carrying out such a method. These objects are achieved by the method and the subject matters of the independent claims. Advantageous Aus ^¬ designs and developments are the subject of the dependent claims. In accordance with at least one embodiment of the method, a pulse frequency meter with a radiation source and a radiation sensor is provided.

In accordance with at least one embodiment, the radiation source emits radiation on a body site during operation. During operation, the radiation sensor detects a portion reflected by the body location or a portion of the radiation transmitted through the body location and supplies a corresponding measurement signal. For the implementation of the method, therefore, the radiation source is aligned so that it emits radiation to a body site. The body site may be any body site of a human or animal being suitable for pulse measurement. For example the part of the body a region of a wrist or a Fin ^¬ gers or a neck or temple. The radiation sensor is oriented to detect either a portion reflected by the body site or a portion of the radiation emitted by the radiation source through the body site.

The measurement signal supplied by the radiation sensor is, for ^example, an analog measurement signal, such as a current or voltage or charge pulse.

The radiation emitted by the radiation source is, for example, light in the blue or green or red or infrared spectral range. The light is, for example, predominantly green light on a wrist of a human being ^¬ sends, so penetrates into the area below the skin. The blood beneath the skin absorbs green light Staer ^¬ strongly than red light. During systole (contraction of the heart muscle), blood is forced through the vessels to the organs. Blood flow and vessel diameter increase in the blood vessels. During diastole (relaxing the heart muscle), the blood flows back through the vessels to the heart. The blood pressure in the vessels is reduced, the vessel diameter decreases in a row. The more blood that flows through the blood vessels or the larger the vessel diameter, the more green light is absorbed and the lower the proportion of reflected green light striking the radiation sensor. The constant waxing and waning of the reflected light can the converted by the radiation sensor in an increasing of and decreasing electrical measurement signal ^¬. On the basis of this measurement signal, the pulse frequency can then be determined. In accordance with at least one embodiment, the pulse-frequency ^{meter can be operated} in a first and a second operating mode. During the two operating modes, the radiation source is operated or driven differently. For example, the pulse-frequency meter additionally comprises a drive circuit which correspondingly activates or operates the radiation source depending on the operating mode set.

According to at least one embodiment, in the first loading operation mode, the radiation source continuously operated in a scanning mode ^¬. That is, as long as the first operating mode is turned on or set, the radiation ^¬ source is operated all the time and without interruption in the scanning mode.

The scanning mode may be a continuous mode in which the radiation source continuously emits radiation. Be ^¬ vorzugt the scan mode is but a pulsed mode in which the radiation source successively emits a single radiation pulse. A sampling frequency or repetition frequency with which the radiation pulses are emitted in the sampling mode is, for example, in the range between 20 Hz and 1000 Hz, in particular between 100 Hz and 600 Hz. Each radiation pulse has, for example, a length of at most 100 ys or at most 10 ys and / or of at least 0.1 ys.

According to at least one embodiment, in the second loading, the radiation source operating mode cyclically operated in the scan mode having a specified ^differently surrounded test frequency for a respective predetermined test period. The repetition rate for operating the radiation source in the scanning mode is this predefinable test frequency. The test period for which the radiation source is in each case operated in the scan mode, for example to values of at most 1/20 or Hoechsmann ^¬ least 1/10 or more than 1/5, or at most half or at most 80% of the duration of a cycle and / or set to at least 1/50 or at least 1/30 or at least 1/10 or at least 1/5 of the duration of a cycle. The duration of a cycle is the reciprocal of the predefinable test frequency. The predefinable test frequency is set, for example, to values of at most 10 Hz or at most 5 Hz.

The test frequency and / or the test period are, in particular, parameters that can be set or specified during the method.

When the radiation source is operated in the scanning mode in the second mode of operation during the test periods, the radiation source continuously emits radiation or pulsed mode radiation. For example, the radiation source then emits at least five or at least ten or at least 50 or at least 100 radiation pulses per test period. Between the test periods, the radiation source can be completely deactivated and emit no radiation at all. Alternatively, however, the radiation source between the test periods can also be operated with a reduced sampling or repetition frequency which, for example, is at most half or at most 1/5 or at most 1/10 or at most 1/20 of the sampling or repetition frequency in the sampling mode.

During the first and second mode of operation Strah ^¬ lung sensor may be continuous in operation. In accordance with at least one embodiment, the method comprises a step AI), in which the first operating mode is set. For example, the pulse rate meter is operated every time after setting the first mode of operation for at least two seconds, or at least five seconds, or at least ten seconds in the first mode of operation such that the radiation source is continuously lit for at least two seconds, or at least five seconds, or at least ten seconds the sampling mode is operated.

In accordance with at least one embodiment, the method comprises a step B1), in which the measurement signals of the radiation sensor recorded in or during the first operating mode are analyzed for pulse beats. The measurement signals of the radiation sensor are first digitized preferably to at ^¬ play by means of an analog-to-digital converter (ADC short), and then processed by a processor such as a microcontroller. The analysis of the measuring signals of the radiation sensor is preferably carried out in real time. That is, the measurement signals picked up by the radiation sensor are analyzed, for example, within at most one second after the detection. The step Bl) is therefore already executed, in particular, while the pulse frequency meter is still operated in the first operating mode.

In accordance with at least one embodiment, the method comprises a step Cl), in which a current pulse frequency is determined on the basis of the pulse beats found in step B1). The current pulse frequency determined in step Cl) represents an approximation value for the actual, current pulse frequency of the animal on which the pulse frequency measurement is carried out becomes. For example, the determined, current pulse rate is the actual pulse rate averaged over a period of at most five seconds or at most two seconds. The current pulse rate is preferably also determined in real time. For example, the actual pulse frequency is determined on the basis of measurement signals and output for the measuring signals, their detection within the past for two seconds or at most a Se ^¬ customer. In particular, the current pulse rate is a parameter or a variable that can be redetermined again and again during the procedure.

After the step AI), the pulse-frequency meter is operated in the first operating mode until the determination of a current pulse frequency is possible, ie, for example, until at least two or at least five or at least ten pulse beats have been found in the measurement signals.

In accordance with at least one embodiment, the method comprises a step D1) in which a pulse frequency expected for a subsequent period is determined on the basis of the pulse frequency determined in step Cl). In particular, the expected pulse rate is set equal to the current pulse rate determined in step Cl). The expected pulse rate is an estimate of a future or subsequent pulse rate, especially for pulse rates not yet measured with the radiation sensor. Since, in step Cl) the current pulse rate be ^¬ vorzugt in real time is determined, it can be predicted an expected pulse frequency ^¬ for a period, namely a subsequent period, which is in the future.

Because the pulse rate of a living being changes not suddenly but gradually in the control case can be, for example, be ^¬ accepted that in a subsequent period after the detection of the current pulse rate another pulse rate measurement would give a similar or identical pulse rate value. Therefore, the expected pulse rate can be set, for example, as the detected, current pulse rate. The expected pulse rate is preferably a parameter that can be ^reset or specified several times during the procedure.

In accordance with at least one embodiment, the method comprises a step A2), in which the second operating mode is set. In this case, the predeterminable test frequency for the cy clic ^¬'s operation of the radiation source is less than or equal to the expected pulse rate, which was determined in step Dl), specified or set. The radiation source is then repeated, for example, activated with this test frequency and operated at ^¬ closing over the specifiable test period in the scan mode.

In accordance with at least one embodiment, the method comprises a step B2), in which the measurement signals of the radiation sensor recorded in the or during the second operating mode are analyzed for pulse beats. In particular, therefore, the measurement signals recorded for the respective test periods or the measurement signals assigned to the respective test periods are analyzed for pulse beats. As in step Bl), this analysis is preferably carried out in real time.

Based on the analysis in step B2) as ^¬ derum example, a current pulse rate are determined or calculated, expected pulse frequency to be confirmed or to deviate from the expected pulse rate are detected. This information can be displayed by means of an Ad ^¬ gege rätes a user, for example. In at least one embodiment, the method of measuring a pulse rate provides a pulse rate meter with a radiation source and a radiation sensor. The radiation source emits radiation to a body site during operation. During operation, the radiation sensor detects a portion reflected by the body location or a portion of the radiation transmitted through the body locations and supplies a corresponding measurement signal. The pulse frequency meter is operable in a first and a second operating mode. In the first mode of operation, the radiation source is continuously operated in a scanning mode. In the second operating mode, the radiation source is operated cyclically with a predeterminable test frequency ^¬ for a respective predetermined test period in the scan mode. The method comprises a step AI) in which the first operating mode is set. In step Bl) recorded in the first mode of the measurement signals of the radiation sensor on pulsations ana are lysed ^¬. In a step Cl), a current pulse frequency is determined on the basis of the pulse rates found in step B1). In a step D1), a pulse rate expected for a subsequent period is determined on the basis of the pulse frequency determined in step Cl). In a step A2), the second operating mode is set, wherein the test frequency is less than or equal to the expected pulse frequency from the step Dl) is given. In a step B2), the measurement signals of the radiation sensor recorded in the second operating mode are analyzed for pulse beats.

The present invention is based in particular on the finding that the energy consumption of pulse rate ^meters used today, in particular optical pulse rate meters, is still high. For example, pulse frequency ^{measurement is} a major consumer of energy in smartwatches. In order to reduce the energy consumption of the pulse rate meter, the inventors have developed a method in which the pulse frequency meter is temporarily operated in a second operating mode (power saving mode). In the second operating mode, the radiation source is not operated continuously in a scanning ^¬ mode, but only for each test periods. In between the radiation source is, for example, not Betrie ^¬ ben or with a low power consumption. The radiation source is operated in particular only in such periods in the scanning mode in which the measurement of a pulse beat is expected. In this second operating mode insbeson ^¬ wider so it is tested whether the pulse rate has changed to a predetermined pulse frequency. In this way, the time during which the radiation source consumes much energy due to the scanning mode can be reduced. The Ener ^¬ sumption for the entire pulse rate measurement is thus reduced.

In accordance with at least one embodiment, the steps AI), Bl), Cl), D1), A2), B2) are carried out in the stated order.

According to at least one embodiment is carried out, a step for analyzing the measurement signals on pulsations, in which the measurement signals are evaluated for a charac ^¬ rule for a pulse of the reference point. The reference point is a point in the measurement signals of the radiation sensor, which is cha ^¬ rakteristisch for a pulse and can be identified by which a pulse. The reference point is thus an indication of a pulse beat. According to at least one embodiment, be specified in the second operation mode, the timing of the activation of the radiation ^¬ source, the test periods and the test frequency so that due to the expected pulse rate are each a, an, in particular in each case precisely, the reference point is expected within a test period. Especially in the two ^¬ th mode of operation including the start time of the operation of the radiation source in the scan mode or the phase of the cyclical Betreibens can be specified in the scan mode. The phase, the test time span and the test frequency are then specified in particular such that an indication of a pulse beat is expected in the measurement signals of each individual test period. The phase, the test time span and the test frequency are in particular parameters of the method.

In accordance with at least one embodiment, the reference point is a maximum or a minimum or an inflection point in a supplied measurement signal curve. For example, therefore, the measurement signals are evaluated as a function of time for the analysis of the measured signals to pulse rates. An extreme value such as a maximum or a minimum, or a turning point in the measurement signals as a function of time is then evaluates ge ^¬ as a pulse. In accordance with at least one embodiment, the method comprises a step C2), in which the current pulse frequency is determined on the basis of the pulse beats which were found in step B2). It is doing so determined on the basis of the detected for the second Be ^¬ operating mode measurement signals the current pulse rate. The step C2) is preferably carried out during the second operating mode. The actual pulse frequency added from the second operating mode which is determined Messsig dimensional ^¬ can, previously determined in step Dl) to confirm or deviate from the expected pulse rate. The determined at step C2) current pulse rate may be outputted at ^¬ play and are shown, for example with a display device.

In accordance with at least one embodiment, the method comprises a step E2) executed subsequently to step C2), in which a change in the current pulse frequency determined in step C2) is detected in comparison with the predefined, predetermined pulse frequency predetermined in step D1). The step E2) is preferably carried out while the pulse frequency meter is still in the second operating mode. For example, if the current pulse frequency determined in step E2) deviates from the expected pulse frequency predetermined in step D1) by at least a threshold value of, for example, 0.01 Hz or 0.05 Hz or 0.1 Hz or 0.5 Hz, considered a change.

According to at least one embodiment, is executed subsequently to the step E2) is a step A2_l) in which the second operating mode is set, the test period Lan ger ^¬ is specified as in step A2). In particular, therefore, the pulse frequency meter is still operated in the second operating mode, but with a new specification for the length of the test periods. If it is determined in step E2), that the current pulse rate has changed, is increased by the step A2_l) the likelihood that further pulsations in the aufgenom ^¬ men during the second operating mode measurement signals are found. For example, in step A2_l), the duration of the test periods is set increased by a factor of at least 1.5 or at least 2 or at least 5 with respect to the length of the test periods from step A2). In accordance with at least one embodiment, the method comprises a step D2) executed subsequently to steps C2) and E2), in which a pulse frequency expected for a subsequent period is determined on the basis of the current pulse frequency determined in step C2). For example, the ^expected pulse rate is set equal to the current pulse rate determined in step C2).

According to at least one embodiment, the method includes a step A2_2) in which the second operating mode is ^¬ represents, with the test frequency is less than or equal to the expected pulse rate from step D2) is specified. The step A2_2) thus follows the step D2). By step A2_2), the second operating mode of the pulse-frequency meter is continued, but with a modified, in particular adapted test frequency.

According to at least one embodiment is changed several times between the first operating mode and the two-th mode of operation during the procedural ^¬ proceedings.

In accordance with at least one embodiment, the first operating mode is subsequently set to step B2) if, in step B2), no pulse beat is found in the measurement signals of one or more successive test periods. Is in no pulse found a test period or more test time ^¬ tension associated measurement signals, an indication of this may be that the actual pulse ^¬ frequency deviates from the expected pulse rate. To determine the cur- rent pulse rate again and determine an appropriate expect ^¬ tete pulse rate can therefore be at least vorrüber- continuously changed into the first operating mode in which the probability of measuring heartbeats is greater.

In accordance with at least one embodiment, the first operating mode is subsequently set to step E2) if a change in the current pulse frequency is detected in step E2).

In accordance with at least one embodiment, the test frequency is predetermined in step A2) such that the pulse frequency expected in step D1) is an integer multiple and at least twice the test frequency. Characterized erwartungsge ^¬ Mäss is operated only every second or every third or every fourth or every nth pulse of the radiation source in the scanning mode, so that in the withdrawn in the second operating mode ^¬ measuring signals only every second or every third or every fourth or every nth pulse beat appears. If the actual pulse rate does not change for the duration of two ^¬ th mode of operation, such a test frequency is sufficient to determine the current pulse frequency ^¬ or, for example, in step C2) to confirm.

In accordance with at least one embodiment, step E2) is followed by step A2_3), in which the second operating mode is set, wherein the test frequency is set to be less than or equal to the expected pulse frequency and greater than the test frequency in step A2). For example, in step A2), the test frequency is predetermined such that the expected pulse frequency is an n-fold of the test frequency, where n is an integer greater than or equal to 2. In step A2_3), the second mode of operation is then continued with an increased Testfre ^acid sequence. The increased test frequency, which is specified in step A2_3), is selected, for example, such that the expected pulse frequency is an m-fold of the test frequency, where m is an integer smaller than n. By continuing the second operating mode with an increased test frequency, for example, the pulse beat can be found again and the current pulse rate can be redetermined.

The steps A2), A2_l), A2_2) and A2_3) are each the start of the second operating mode, only with different parameters. After these steps, the procedure can be continued in the same way. In particular, all steps that are described as subsequent to step A2) can also be carried out subsequently to steps A2_l), A2_2) and A2_3) and vice versa. In addition, a pulse rate meter is specified. The pulse frequency meter is in particular configured to perform a method described here. That is, SämT ^¬ Liche disclosed in connection with the method features are also disclosed for the pulse rate meter and vice versa.

According to at least one embodiment, the Pulsfre ^¬ quenzmesser a radiation source and a radiation sensor.

According to at least one embodiment of the Pulsfrequenzmes- ser is adapted to perform a method described herein by ^¬. For example, the pulse frequency meter also includes a drive circuit with, for example, a processor, such as a microcontroller. According to at least one embodiment, the radiation source ^¬ the pulse rate meter includes a light emitting diode or a La ^¬ serdiode. For example, the semiconductor material is based on LED or the laser diode on AlInGaN or on AlInGaP or on AlInGaAs.

According to at least one embodiment of the radiation ^¬ sensor comprises a photodiode. For example, the semiconductor material of the photodiode ^¬ on AlInGaN or AlInGaP or AlInGaAs based.

According to at least one embodiment, the pulse rate ^{meter is} a clock, for example a wristwatch. A clock can therefore be designed as a pulse frequency meter described here. The watch may be, for example, a heart rate monitor or a smartwatch. In particular, therefore, a clock is also specified with such a pulse frequency meter.

In addition, a computer program product is specified. The computer program ^product comprises an executable program code, wherein the program code executes a method described here by a data processing device. So all of those disclosed in connection with the process described herein features are set ^¬ beard and vice versa for the computer program product.

Hereinafter, a method described herein and a pulse frequency meter described herein with reference to drawings using exemplary embodiments will be explained in more detail. The same reference numerals thereby indicate like elements in the one ^¬ individual figures. There are, however, shown to scale covers, rather, individual elements for bes ^¬ sera understanding may be exaggerated.

Show it: Figures 1 and 2 embodiments of a Pulsfrequenzmes ^¬ sers,

FIGS. 3A to 3C show exemplary embodiments of graphs for different operating modes of a pulse frequency meter,

Figures 4A to 4D are flowcharts of embodiments of methods for measuring a pulse rate, Figure 5 shows an embodiment of a pulse rate meter in a schematic circuit diagram.

In the figure 1, an embodiment 100 is shown a Pulsfre ^¬ quenzmessers, which is operated in its intended operation. The pulse-frequency meter 100 comprises a radiation source 1, for example a light-emitting diode, and a radiation sensor 3, for example a photodiode. The Strah ^¬ radiation source 1 is operated in a scanning mode and emit ^¬ advantage, for example, light pulses with a sampling frequency of 500 Hz or repetitions. The light pulses can ^¬ example, be in the green spectral range. The light pulses are directed to a body site 2, in this case a wrist of a human arm. The portion of the radiation reflected by the body part 2 is recorded by the radiation sensor 3.

Depending on how much blood flows through the wrist at a certain time, more or less of the radiation coming from the radiation source 1 is reflected by the body site 2 and detected by the radiation sensor 3. Based on this, the pulse rate at which blood is pumped through the wrist can be measured. 2 shows an embodiment of a pulse rate ^¬ diameter 100 is shown. In the present case, the pulse frequency ^meter 100 is a wristwatch, for example a heart rate monitor or a smartwatch. In addition to the pulse rate measurements, this watch can have other functions.

On the inside of the clock 100, ie at the side of the clock usually facing the wrist, a radiation source 1 and a radiation sensor 3 are arranged.

In the Figure 3A shows an embodiment of a second Be ^¬ operation mode of the pulse rate meter is based on the graph represents Darge ^¬. The upper graph shows an actual pulse, for example in a human wrist, as a function of time. A maximum in this graph represents a point in time where a lot of blood flows through the blood vessels and thus the blood vessels are correspondingly dilated.

In the middle graph, the radiation intensity emitted by the radiation source 1 is shown as a function of time. It can be seen that the radiation source 1 in the second operating mode is operated repeatedly in each case for a test time period T_2 in a scanning mode. The repetition rate for operating the radiation source 1 in the scanning mode corresponds to a test frequency F_2. While the radiation ^¬ source 1 is operated for each of the test periods T_2 in the scan mode, the radiation source 1 emits a plurality of radiation pulses (vertical lines). For example, the repetition frequency for the radiation pulses, ie the sampling frequency, is chosen to be 500 Hz. Between the test periods T_2, the radiation source 1 is deactivated and does not emit radiation at any time. Alternatively, the radiation source 1 between the test periods but also with a reduced Repetitionsfrequenz, for example, by a factor of at least 2 smaller than in the range of test periods T_2, operated. In the present case, the test periods T_2 are selected to be shorter than the reciprocal of the test frequency F_2. For example, the radiation source 1 during the second operating mode only currency ^¬ rend at most half the time Betrie ^¬ ben in the scan mode.

In the lower graph of Figure 3A is provided ^¬ represent provided by the radiation sensor 3 due to the light reflected from the body part 2 radiation measurement signal as a function of time. At the time of the strongest blood flow through the wrist, the portion of the radiation absorbed by the body site is greatest. Accordingly, then the supplied from the radiation source 3 measurement signal is the lowest. Signifi ^¬ edge measurement signals occur only during the duration of the test ^{¬ time} periods T_2. Outside the test periods T_2 there is hardly a significant measurement signal due to the deactivated radiation source 1. In these periods, a small measurement signal, for example due to ambient light auftau ^¬ chen. The measuring signals of the radiation sensor 3 shown in the lower graph of FIG. 3A can be analyzed for pulse beats. For this, the measurement signals are examined for example charak ^¬ istic reference points R. In the present case, for example, an extreme value in the form of a minimum in the measuring signals is an indication of a pulse beat. The finding of a reference point R in the measurement signals can therefore be evaluated as a pulse beat. From the time interval of Reference points R or the pulses can then be determined a current pulse rate P_mes.

In the present case, the test frequency F_2 of the second operating mode, the test periods T_2 and the phase with which the radiation source 1 is cyclically operated in the scanning mode are predetermined such that exactly one pulse point which signals a reference point R is found in the measuring signals for each test period T_2 , This is made possible, on the one hand, by the fact that, as can be seen in the upper graph of FIG. 3A, the actual pulse frequency barely changes over time. On the other hand, as explained later, an expected pulse rate P_exp was previously determined, which was to be expected for the time period shown in FIG. 3A. This makes it possible to irradiate the body site 2 always at the time when the blood flow is greatest. In the intervening periods, the radiation source is deactivated to save energy.

FIG. 3B again shows an embodiment for the second operating mode. Unlike in FIG. 3A, the test frequency F_2 is only half as large as the expected pulse frequency P_exp. The test periods T_2 in the present case are less than a quarter of the duration of a cycle. Insofar as the radiation source 1 for less than a quarter of the time is operated during the second operating mode in the touch mode ^¬ Ab. As a result, energy is again saved in comparison with the second operating mode shown in FIG. 3A. However, only every second pulse beat is thereby detected by the radiation sensor 3.

In the Figure 3C an embodiment of the first Be ^¬ operating mode is shown in which the radiation source for a predetermined time T 1 of, for example, at least five Seconds or at least ten seconds continuously in the sampling mode (see middle graph). In the measurement signals of the radiation sensor 3, the charakteris ^¬-Nazi reference points R then can be found and a current pulse rate P_mes can be determined. On the basis of this current pulse frequency P_mes, the second operating mode shown in FIGS. 3A and 3B can then be set.

FIG. 4A shows a flow chart for a first exemplary embodiment of the method for measuring a pulse frequency. A pulse rate meter 100 as described above is provided therefor. In a step AI), the first operating mode is set for the pulse frequency meter 100. During the first operating mode, the radiation source 1 is operated continuously in the scanning mode, as shown for example in the middle graph of FIG. 3C.

In a step Bl), the measurement signals recorded by the radiation sensor 3 in the first operating mode are analyzed for pulse impacts. In this case, as shown in the lower graph of FIG. 3C, characteristic reference points R, can be evaluated as an indication of a measured pulse beat.

On the basis of the time interval between measured pulse beats can then be determined in a step Cl) a current pulse rate P_mes. The current pulse rate P_mes is at least an approximate value for the actual pulse rate of the animal at which the pulse measurement is performed. In a step Dl) is based on the in step Cl) ermit ^¬ telten current pulse frequency P_mes a for a subsequent period, so in the near future, for example, for at least the next five seconds or at least the next ten Seconds, an expected pulse rate P_exp determined. In ^¬ example, is set as the expected pulse rate P_exp previously determined in step Cl) current pulse rate P_mes. In a step A2), the second operating mode is then set ^¬ . For this purpose, the expected pulse frequency P_exp is predetermined as test frequency F_2 (see middle graph of FIG. 3A). The test periods T_2, for example, set such that the radiation source 1 for a maximum of half the time is operated during the second operating mode in the touch mode ^¬ Ab.

In a step B2), the measured signals recorded for the second operating mode are then analyzed for pulse beats (see lower graph of FIG. 3A). If no pulse beats are found in these measuring signals, then it is possible to switch back to the first operating mode.

However, FIG. 4A shows the case in which pulse beats are found in the measurement signals of the second operating mode. On the basis of these pulse beats, for example, in a step C2), the current pulse frequency P_mes can again be determined. In a step E2), it can be determined whether the current pulse frequency P_mes determined in step C2) deviates from the predefined pulse frequency P_exp specified in step D1). If such a deviation exists, for example, the first operating mode can be set again. The method is then continued or restarted, for example, in step AI) of FIG. 4A. In the flow chart of Figure 4B, a second embodiment of a method for measuring a pulse rate is shown. As explained in connection with FIG. 4A, first of all steps A1) to E2) are carried out in succession. In step E2), for example, a Variegated ^¬ tion of the current pulse frequency P_mes is then recognized from the expected pulse rate P_exp. Then, in step A2_l), the second operating mode is set again, this time depending ^¬ but with specification of longer test periods T_2. For example, the duration of the test periods T_2 in step A2_l) is 1.5 times longer than in step A2).

By the longer trial periods T_2 the probability can be increased at a friendliness Variegated ^¬ tion of the actual current pulse frequency that are found in the captured to the test periods T_2 measurement signals pulsations. Accordingly, in a step B2_l) the measurement signals for the extended test periods T_2 are analyzed for pulse beats. Has the actual current pulse rate changed only slightly, so you can recalculate the ak ^¬ tual pulse rate based on this new measurement signals and, for example, displayed on a display device. If, however, no pulse beat is found in step B2_1), this can be an indication that the actual current pulse frequency has changed too much. Then, for example, it is possible to move back to the first operating mode and to continue or ^restart the method in step AI).

FIG. 4C shows a flowchart according to a third exemplary embodiment of the method. Until step E2), the method of FIG. 4C is identical to the method of FIGS. 4A and 4B. After the step E2) is determined in a step D2) based on the in step C2), current pulse frequency P_mes new for a subsequent period expected pulse rate P_exp. Then, in a step A2_2), the second operating mode is again set ^¬ , this time taking into account the newly determined, expected pulse rate P_exp. For example, in step A2_2, the test frequency F_2 is set equal to the expected pulse rate P_exp from step D2).

The measured signals detected for this newly set second operating mode are then analyzed in turn for pulse beats in a step B2_2). If a current pulse frequency P_mes can be determined from these measurement signals, this is forwarded, for example, to a display device. Otherwise, it is again possible, at least temporarily, to switch to the first operating mode and to continue or restart the method in step AI).

In the flow chart of FIG. 4D, the process up to step E2) is substantially identical to the previously described methods. However, in step A2), the test frequency F_2 was not set to the expected pulse rate P_exp given in step D1), but only half or one-third or one-fourth of this value (see, for example, middle graph of FIG. 3B). Then at step E2) detected that the current pulse frequency changes, the step A2_3) can be carried out, in which again the second operating mode but is now set at a higher Testfre ^acid sequence F_2. For example, the Testfre ^acid sequence F_2 in step A2_3) is then equal to the determined in step Dl), set expected pulse rate P_exp. The measured signals recorded for this newly set second operating mode are in turn analyzed for pulse beats (step B2_3)). Depending on whether these measurement signals are sufficient to To determine the current pulse rate, the second mode of operation can then be continued or, for example, go back to the first mode of operation. FIG. 5 shows a circuit diagram of an embodiment of a pulse rate meter 100. The pulse frequency ^¬ knife 100 is particularly adapted to perform one of the methods described before ^¬ forth. The pulse frequency meter 100 comprises a radiation source 1 and a radiation sensor 3, both of which are each in the form of a diode. The radiation detected by the radiation sensor 3 is converted, for example, into a charge pulse. This can be for example by means of an analog-to-digital converter ( "analog-to-digital-converter" ADC) 40 into a digital signal umgewan- delt. This digital signal is then provided to a Prozes ^¬ sor 5, for example a microcontroller The current pulse rate P_mes and the expected pulse rate P_exp can be determined with the processor 5. The processor 5 can then output digital signals again to control a current source 41. The current source 41 controls the radiation source 1. the Prozes ^¬ sor 5 can in particular have a data and / or program memory in which a program code is stored, which carries out the reference to the figures 4A to 4D loading prescribed method, when executed, the program code is at ^¬ way of example in the step AI. ) and run in the illustrated or described order.

The radiation source 41 and the analog-to-digital converter 40 may, for example, be integrated in an analog front-end 4 (AFE). The invention is not limited by the description based on the embodiments of these. Rather, the invention includes any new feature and any combination of features, which in particular includes any combination of features in the claims, even if these features or this combination itself is not explicitly specified in the patent claims ^¬ Chen or embodiments.

Reference sign list

1 radiation source

2 body site

3 radiation sensor

4 analog front-end

5 processor

40 analog-to-digital converter

41 Current source for the radiation source 1

100 pulse rate meter

T 1 period

F 2 test frequency

T 2 test period

P mes determined, current pulse rate

P exp expected pulse rate

R reference point

Claims

claims

1. A method for measuring a pulse rate at which a pulse frequency meter (100) with a radiation source (1) and egg ^¬ nem radiation sensor (3) is provided, wherein the radiation source (1) emits radiation in operation on a Kör ^¬ perstelle (2) and one of the body part (2) reflected portion or by the part of the body (2) detects the transmitted fraction of the radiation of the radiation sensor (3) and a corresponding measurement signal lie ^¬ fert,

the pulse frequency meter (100) is operable in a first and a second operating mode,

in the first operating mode, the radiation source (1) is operated by ^¬ going in a scanning mode,

the radiation source in the second operating mode (1) zyk ^¬ lisch with a predeterminable test frequency (F_2) each for a predetermined test period (T_2), is in the scan mode be ^¬ exaggerated said method comprising the steps of: AI) setting the first operating mode (1 );

Bl) analyzing the measured signals of the radiation sensor (3) recorded in the first operating mode for pulse beats;

Cl) determining a current pulse rate (P_mes) based on the pulse rates found in step Bl);

Dl) determining a pulse rate (P_exp) expected for a subsequent period on the basis of the pulse rate (P_mes) determined in step Cl);

A2) setting the second operating mode, wherein the test frequency ^¬ (F_2) is less than or equal to the expected pulse rate (P_exp) from the step Dl) is specified;

B2) analyzing the recorded in the second mode of operation measuring signals of the radiation sensor (3) to pulse beat.

2. The method according to claim 1,

wherein the step is carried out for the analysis of the measurement signals for pulse beats:

- Analyzing the measurement signals to a reference point (R) characteristic for a pulse beat.

3. The method according to claim 2,

wherein in the second operating mode, the times of activation of the radiation source (1), the test periods (T_2) and the test frequency (F_2) are predetermined so that due to the expected pulse rate (P_exp) each expected a reference point (R) within a test period (T_2) becomes.

4. The method according to claim 2,

wherein the reference point (R) is a maximum or minimum or inflection point in a supplied measurement signal curve.

5. The method according to any one of the preceding claims,

further comprising the step:

C2) determining the current pulse rate (P_mes) based on the pulse beats found in step B2).

6. The method according to claim 5,

following step C2), the following step is carried out:

E2) detecting a change in the detected in step C2) current pulse rate (P_mes) against the expected pulse rate (P_exp).

7. The method according to claim 6,

wherein subsequent to the step E2) the following step is performed by ^¬: A2_l) setting the second operating mode, wherein the test ^¬ period (T_2) is specified longer than in step A2).

8. The method according to at least claim 6,

following steps C2) and E2) following steps are carried out:

D2) determining a pulse rate (P_exp) expected for a subsequent period on the basis of the current pulse frequency (P_mes) determined in step C2);

A2_2) Setting the second operating mode, wherein the test frequency ^¬ (F_2) is less than or equal to the expected pulse frequency (P_exp) from step D2) is specified.

9. The method according to any one of the preceding claims,

in which several times between the first operating mode and the second operating mode is changed.

10. The method according to any one of the preceding claims, wherein subsequent to the step B2), the first operating mode is set when in step B2) in the measurement signals of one or more consecutive test periods (T_2) no pulse beat is found.

11. The method according to at least claim 6,

wherein, following step E2), the first operating mode is set if a change in the current pulse frequency (P_mes) is detected in step E2).

12. The method according to any one of the preceding claims, wherein in the step A2) (the test frequency F_2) is set so that the expected pulse rate (P_exp) (an integer multiple ^¬ and at least twice the test frequency F_2) be transmits ^¬.

13. Method according to claims 6 and 12,

following step E2), the following step is carried out:

A2_3) Setting the second operating mode, wherein the test frequency (F_2) is set to be less than or equal to the expected pulse frequency (P_exp) and greater than the test frequency (F_2) in step A2).

14. Pulse frequency meter (100), comprising:

a radiation source (1),

- A radiation sensor (3), wherein

- The pulse frequency meter (100) is adapted to perform a method according to any one of the preceding claims.

15. Pulse frequency meter (100) according to claim 14,

wherein the radiation source (1) comprises a light-emitting diode or a La ^¬ serdiode.

16. Pulse frequency meter (100) according to one of the preceding claims,

wherein the radiation sensor (3) comprises a photodiode.

17. Computer program product comprising an executable program code, wherein the program code by a data processing ^¬ device performs a method according to one of claims 1 to 13.