Light source time-division and frequency-division hybrid modulation device

Abstract

The invention discloses a light source time-division and frequency-division hybrid modulation device which comprises a plurality of light source modules and a trigger module, each light source module comprises an output channel, a modulator and an analog switch, the modulator is used for generating a time-division modulation waveform and / or a frequency-division modulation waveform, and the output channel is used for outputting a light source in a constant-current mode. The analog switches are connected between the output channel and the modulator and used for controlling the output channel to be opened and closed, and the trigger module is connected with the analog switches and used for adjusting the analog switches with the corresponding number to be started at the same time, so that one of time-division, frequency-division and time-division and frequency-division hybrid modulation is selected for use under the same device. And under the constant current output light source of the output channel, the flexible application under the scene of emphasizing different limitations on the light source is also realized.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly to a light source time-division and frequency-division hybrid modulation device. Background Art

[0002] Functional Near-Infrared Spectroscopy (fNIRS) utilizes the absorption and scattering relationships between near-infrared light of multiple wavelengths and chromophore substances (such as oxyhemoglobin, deoxyhemoglobin, etc.) in brain tissue to examine the concentration changes of these substances in brain tissue under specific conditions. These concentration changes can indirectly reflect the activities of neurons, cellular energy metabolism, and functions related to hemodynamics, thereby revealing the state and processing of the brain. Specifically, when the brain is active, the cerebral blood oxygen content in the active area increases, resulting in an increase in the concentration of oxyhemoglobin in the cortex of that area and a decrease in the concentration of deoxyhemoglobin. These changes will affect the propagation of light in brain tissue and are thus captured by near-infrared brain function imaging devices. By analyzing these light changes, the activities of the brain can be inferred.

[0003] When collecting cerebral blood oxygen by near-infrared brain function imaging technology, the modulation methods of its near-infrared light source are generally divided into time-division modulation and frequency-division modulation. In time-division modulation, only one light source takes effect at the same time at the light source emission end, which can avoid direct mutual crosstalk between different light sources. At the same time, in the case of using a laser light source, its total light intensity is much smaller than that of frequency-division modulation, reducing the possible irradiation pollution of the laser and making it safer to use. The disadvantage of time-division modulation is that the blood oxygen sampling rate of a single channel is not high, and the more channels there are, the lower the sampling rate. In frequency-division modulation, all light sources take effect simultaneously. The advantage is that multiple channels can be collected simultaneously, and the blood oxygen signal sampling rate of the entire system is much higher than that of time-division modulation. The disadvantages are that the system is complex, signal crosstalk may occur, and when all channels emit light simultaneously, the light intensity acting on the human body may be too high when using a laser light source, posing a risk of irradiation damage.

[0004] Near-infrared brain function imaging devices generally only adopt one of these two methods. When there are strict requirements for the light intensity of the light source in different specific scenarios such as the children's scenario, only time-division modulation can be used, or only frequency-division modulation can be used under the condition of high sampling rate requirements. Traditional devices in the past often could only meet one of them. Summary of the Invention

[0005] The object of the present invention is to propose a light source time-division and frequency-division hybrid modulation device for the technical problems existing in the background art.

[0006] To achieve the above technical object, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a light source time-division and frequency-division hybrid modulation device, which includes a plurality of light source modules and a trigger module. The light source module includes an output channel, a modulator, and an analog switch. The modulator is used to generate a time-division modulation waveform and / or a frequency-division modulation waveform. The output channel is used to output a constant current of the light source. The analog switch is connected between the output channel and the modulator to control the opening and closing of the output channel. The trigger module is respectively connected to a plurality of analog switches and is used to adjust the simultaneous activation of the corresponding number of analog switches.

[0008] Optionally, the light source time-division and frequency-division hybrid modulation device further includes a clock module, and the clock module is connected to the trigger module to control different states of the trigger module according to each clock cycle.

[0009] Optionally, the formula for the modulator to generate a time-division modulation waveform is:

[0010] where ω k is the frequency of the waveform, A k is the amplitude of the waveform, k is the serial number of the output channel, p is the number of light source modules, n is the current step sequence number, and δ[] is the unit impulse response.

[0011] Optionally, the formula for the modulator to generate a time-division modulation waveform is: F k = A K *sin(ω k ).

[0012] Optionally, the formula for the modulator to generate a frequency-division modulation waveform and a hybrid modulation of the frequency-division modulation waveform is:

[0013] where N = 2 K , 1 < K < log2A, C = {1, 2, 3,..., N}, N is the number of the output channels required to output the light source simultaneously, and A is the number of the output channels applied.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: It includes a plurality of light source modules and a trigger module. The light source module includes an output channel, a modulator, and an analog switch. The modulator is used to generate a time-division modulation waveform and / or a frequency-division modulation waveform. The output channel is used to output a constant current of the light source. The analog switch is connected between the output channel and the modulator to control the opening and closing of the output channel. The trigger module is respectively connected to a plurality of analog switches and is used to adjust the simultaneous activation of the corresponding number of analog switches, realizing the alternative use of time-division, frequency-division, and time-division and frequency-division hybrid modulation under the same device. And under the condition that the output channel outputs a constant current of the light source, it also realizes the flexible application in scenarios with different restrictions on the light source intensity. Description of the Drawings

[0015] Figure 1 This is a schematic structural diagram of the light source time-division and frequency-division hybrid modulation device in the embodiment of the present invention;

[0016] Figure 2 This is the application of the light source time-division and frequency-division hybrid modulation device in the embodiment of the present invention; a schematic flow logic diagram.

[0017] Reference numerals in the drawings: 100 light source module, 101 output channel, 102 modulator, 103 analog switch, 200 trigger module, 300 clock module. Specific embodiments

[0018] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0019] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0020] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or a specific connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0021] For ease of understanding, the following describes the specific process of the embodiment of the present invention. Please refer to Figure 1 - Figure 2, in the light source time-division and frequency-division hybrid modulation device according to the embodiment of the present invention, it includes a plurality of light source modules 100 and a trigger module 200. The light source module 100 includes an output channel 101, a modulator 102, and an analog switch 103. The modulator 102 is used to generate time-division modulation waveforms and / or frequency-division modulation waveforms. The output channel 101 is used to output a constant current to the light source. The analog switch 103 is connected between the output channel 101 and the modulator 102 to control the opening and closing of the output channel 101. The trigger module 200 is respectively connected to a plurality of analog switches 103 and is used to adjust the corresponding number of analog switches 103 to be enabled simultaneously.

[0022] Specifically, the output channel 101 can adopt a constant current drive circuit to ensure that the light source (such as LED / LD) outputs a stable optical power within a wide voltage range. The modulator 102 can select an integrated DDS chip to programmably generate square wave / sine wave signals and support the time-division and frequency-division hybrid modulation mode. The analog switch 103 can select a MOSFET array with a low on-resistance, and the switching time <10ns, supporting high-frequency switch control.

[0023] In this embodiment, the number of light source modules 100 is 16, that is, the number of output channels 101 is 16. The light source output by the output channel 101 with a constant current is a near-infrared light source. The total number of near-infrared light source channels is 16. Then the maximum cerebral blood oxygen sampling rate of time-division modulation is 1 / 16 / TAmin (TAmin is the minimum holding time required for the light source to maintain lighting to meet signal demodulation). The cerebral blood oxygen sampling rate of frequency-division modulation is extremely high. In the case of using the data window sliding demodulation method, it can be equivalent to the actual sampling rate of the system ADC. At this time, it can be considered that the cerebral blood oxygen sampling rate of frequency-division modulation no longer belongs to the limitation disadvantage of the system. In frequency-division modulation, all 16 light sources work simultaneously at different frequencies, and the receiving end demodulates each frequency signal in real time through a sliding window FFT or a digital lock-in amplifier. The sampling rate is theoretically equal to the sampling rate of the ADC (such as 1kHz - 100MHz) and is not limited by the number of light sources.

[0024] Assume that the light emission energy of each light source is El. Then, at any moment, the light energy acting on the human body by time-division modulation is El, and the light energy acting on the human body by frequency-division modulation is El * 16.

[0025] If time-division modulation is adopted and 2 light sources are lit simultaneously each time, then the maximum cerebral blood oxygen sampling rate is 1 / 8 / TAmin, and the light energy acting on the human body is El * 2. At this time, the sampling rate of the system is larger than that of time-division modulation, the light energy acting on the human body is smaller than that of frequency-division modulation, and the crosstalk between optical signals is smaller.

[0026] Further, the light source time-division and frequency-division hybrid modulation device further includes a clock module 300, and the clock module 300 is connected to the trigger module 200 to control different states of the trigger module 200 according to each clock cycle.

[0027] Specifically, since the software control system is not a real-time system most of the time, when using a non-real-time system to control the light source drive, there will be asynchronization during the process of simultaneously controlling the on / off and switching of two light sources. At this time, incorrect data will be collected during data acquisition. For example, during the process of switching light sources 1 and 2 to 3 and 4, because 1 and 2 are asynchronous (such as 2 lagging), when the system originally collects data of light sources 3 and 4, it actually collects part of the information of 2, which will make the actually parsed data inaccurate. In this embodiment, the clock module 300 is used to execute the time-division modulation light source control logic. As shown in the following table, each clock rising edge triggers a shift operation, and the states of Q0 to Q7 are sequentially passed from the previous stage, and the value of Q7 is filled back to Q0.

[0028] The Nth clock cycle Clk States of Q0 to Q7 0 10000000 1 01000000 2 00100000 3 00010000 4 00001000 5 00000100 6 00000010 7 00000001 8 10000000

[0029] Further, the formula for the modulator 102 to generate a time-division modulation waveform is:

[0030]

[0031] where ω k is the frequency of the waveform, A k is the amplitude of the waveform, k is the serial number of the output channel 101, p is the number of light source modules 100, n is the current step ordinal number, and δ[] is the unit impulse response.

[0032] The formula for the modulator 102 to generate a time-division modulation waveform is: F k = A k *sin(ω k ), Formula 2.

[0033] The formula for the modulator 102 to generate a frequency-division modulation waveform and the hybrid modulation of the frequency-division modulation waveform is:

[0034] Formula 3:

[0035] where N = 2 K , 1 < K < log2 A, C = {1, 2, 3,..., N}, N is the number of the output channels 101 required to output light sources simultaneously, and A is the number of the output channels 101 applied.

[0036] The specific execution logic is:

[0037] Set the working state according to the application requirements of treating patients, such as frequency-division modulation, time-division modulation, or time-division and frequency-division hybrid modulation;

[0038] If the working state is set to frequency division modulation, each light source module 100 follows Formula 2, then controls the waveform output according to the control logic, and finally the process ends.

[0039] If the working state is set to time division modulation, each light source module 100 follows Formula 1, then controls the waveform output according to the control logic, and finally the process ends.

[0040] If the working state is set to time division and frequency division hybrid modulation, and the number of simultaneously working light sources N is set, then each light source module 100 follows Formula 3, then controls the waveform output according to the control logic, and finally the process ends.

[0041] The above is a light source time division and frequency division hybrid modulation device or multiple implementation manners provided in combination with specific contents, and it is not considered that the specific implementation of the present invention is only limited to these descriptions. Those that are similar or identical to the method, structure, etc. of the present invention, or those that make several technical deductions or substitutions under the premise of the inventive concept of the present invention, should be regarded as the protection scope of the present invention.

Claims

1. A time-division and frequency-division hybrid modulation device for a light source, characterized in that It includes a plurality of light source modules (100) and a trigger module (200). The light source module (100) includes an output channel (101), a modulator (102), and an analog switch (103). The modulator (102) is used to generate a time-division modulation waveform and / or a frequency-division modulation waveform. The output channel (101) is used to output a light source with a constant current. The analog switch (103) is connected between the output channel (101) and the modulator (102) to control the opening and closing of the output channel (101). The trigger module (200) is respectively connected to a plurality of the analog switches (103) and is used to adjust the simultaneous enabling of the corresponding number of the analog switches (103).

2. The time-division and frequency-division hybrid modulation device for a light source according to claim 1, wherein, It further includes a clock module (300). The clock module (300) is connected to the trigger module (200) to control different states of the trigger module (200) according to each clock cycle.

3. The time-division and frequency-division hybrid modulation device for a light source according to claim 1, characterized in that, The formula for the modulator (102) to generate a time-division modulation waveform is: Among them, the ω k is the frequency of the waveform, the A k is the amplitude of the waveform, k is the serial number of the output channel (101), p is the number of the light source modules (100), n is the current step ordinal number, and δ[] is the unit impulse response.

4. A light source time-division and frequency-division hybrid modulation device according to claim 3, characterized in that, The formula for the modulator (102) to generate a time-division modulation waveform is: F k = A k *sin(ω k ).

5. A time-division and frequency-division hybrid modulation device for a light source according to claim 4, characterized in that, The formula for the modulator (102) to generate a frequency-division modulation waveform and a mixed modulation of the frequency-division modulation waveform is: where N = 2 K , 1 < K < log2A, C = {1, 2, 3, ..., N}, where N is the number of the output channels (101) of the light source required to be output simultaneously, and A is the number of the output channels (101) of the application

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