Time measuring device, fluorescence lifetime measuring device, and time measuring method

Abstract

The time measuring device (10) of the present application comprises: a digital counter (20) that outputs a count signal according to a clock signal; a plurality of TAC circuits (12) (TAC circuits 12a-12j) that input a detection signal detected in a detector (4) and the clock signal, and output a measurement signal corresponding to the time between the detection signal and the clock signal; a control unit (14) that derives and outputs time information related to the detection signal based on the count signal output from the digital counter (20) and the measurement signal output from the TAC circuit (12); and a measurement gate (11) that switches the TAC circuit (12) to which the detection signal is input, taking into account the dead time of the TAC circuit (12).

Description

Technical Field

[0001] One aspect of the present invention relates to a time measuring device, a fluorescence lifetime measuring device, and a time measuring method. Background Technology

[0002] In fluorescence lifetime measuring devices and the like, which measure the fluorescence lifetime when a sample is irradiated with excitation light, a time measuring device is used that outputs information related to the time difference between the start pulse signal and the stop pulse signal. As such a time measuring device, a TAC (Time-Analog-Converter) method that outputs the time difference as an analog signal is known (see, for example, Patent Document 1). The TAC method has the advantage of higher time resolution compared to the TDC (Time-digital-converter) method, which measures time by outputting the time difference as a digital signal.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 2003-522946 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the time measurement device described above, if time is measured in a TAC (time-amplitude converter) circuit, a certain period of time becomes a dead time after the measurement, during which time measurement cannot be performed again. This dead time prevents the measurement efficiency from being fully improved. Furthermore, as mentioned above, while the TAC method has the advantage of high time resolution, it is difficult to perform time measurements of long-term phenomena (long-term measurements).

[0008] One aspect of the present invention is made in view of the above-mentioned facts, and its object is to provide a time measurement device, a fluorescence lifetime measurement device, and a time measurement method, which can reduce dead time and improve measurement efficiency, and achieve high time resolution and long-term measurement.

[0009] Technical solutions for solving the problem

[0010] One aspect of the present invention provides a time measuring device comprising: a counter that outputs a counting signal based on a clock signal; a plurality of first time-amplitude converters that receive a detection signal detected in a detector and a clock signal as inputs, and output a measurement signal corresponding to the time between the detection signal and the clock signal; a control unit that derives and outputs time information related to the detection signal based on the counting signal output from the counter and the measurement signal output from the first time-amplitude converters; and a first switching unit that switches the first time-amplitude converters to which the detection signal is input, taking into account the dead time of the first time-amplitude converters.

[0011] In one aspect of the time measurement apparatus of the present invention, a plurality of first time-amplitude converters are provided, each outputting a measurement signal corresponding to the time between a detection signal and a clock signal. Furthermore, in this time measurement apparatus, the switching of the first time-amplitude converter based on the input detection signal is performed, taking into account the dead time of the first time-amplitude converter. For example, when measuring time using only one first time-amplitude converter, a dead time occurs where measurement cannot be repeated after the measurement by the time-amplitude converter. Regarding this point, by multiplying the time-amplitude converters and switching them considering their dead time, the dead time can be significantly reduced by switching from a time-amplitude converter that cannot be measured again after measurement to a measurable time-amplitude converter. Additionally, in another aspect of the time measurement apparatus of the present invention, approximate time measurement dependent on the clock frequency (low time resolution and long time measurement) is performed by outputting a counting signal from a counter that operates synchronously with the clock signal, and fine time measurement (high time resolution and short time measurement) is performed by outputting a measurement signal corresponding to the time between the detection signal and the clock signal from the first time-amplitude converter, thus compensating for the measurement roughness of the counter. By combining these time measurement results to derive the final time information, high time resolution and long-term measurement can be achieved. As described above, the time measurement device according to one aspect of the present invention can reduce dead time, thereby improving measurement efficiency, and achieve high time resolution and long-term measurement.

[0012] Alternatively, the first switching unit can switch the first time-amplitude converter based on switching information preset considering the dead time. With this structure, the time-amplitude converter can be switched easily and appropriately based on preset information (switching information considering the dead time).

[0013] Alternatively, the control unit can derive time information representing the time up to the input detection signal by subtracting the time represented by the measurement signal from the time corresponding to the count value represented by the counting signal. Thus, the time up to the input detection signal can be derived with high accuracy based on the counting signal and the measurement signal.

[0014] Alternatively, the first switching unit can switch the first time-amplitude converter by inputting a detection signal to the first time-amplitude converter during the non-dead time. This can appropriately avoid the degradation of measurement efficiency due to the dead time of the first time-amplitude converter.

[0015] Alternatively, multiple first-time amplitude converters can be configured with a number corresponding to the dead time. This allows for appropriate avoidance of the dead time's influence by switching between first-time amplitude converters.

[0016] Alternatively, multiple first-time amplitude converters can be configured with a number corresponding to the amount of signal detected by the detector. Therefore, by setting a number of first-time amplitude converters corresponding to the amount of signal, the influence of dead time can be appropriately avoided by switching the first-time amplitude converters.

[0017] Alternatively, the aforementioned time measuring device may further include a second time-amplitude converter, which outputs a signal corresponding to the synchronization signal of the phenomenon, which is related to the detection signal detected in the detector. The control unit further considers the signal corresponding to the synchronization signal and derives time information. Thus, the actual time of the phenomenon related to the detection signal can be considered, and the time information related to the detection signal can be derived with higher accuracy.

[0018] Alternatively, the aforementioned time measuring device may include multiple second time-amplitude converters and a second switching unit that, taking into account the dead time of the second time-amplitude converters, switches the second time-amplitude converters to which the input synchronization signal is received. This can appropriately avoid the degradation of measurement efficiency due to the dead time of the second time-amplitude converters.

[0019] One aspect of the fluorescence lifetime measuring apparatus of the present invention is a fluorescence lifetime measuring apparatus for measuring the lifetime of fluorescence emitted from a measurement object, comprising: the aforementioned time measuring device; a light source that irradiates the measurement object with light generated from it; a detector that detects the fluorescence from the measurement object irradiated with light from the light source and outputs a detection signal; and a signal generating unit that controls the light output of the light source and outputs a synchronization signal that synchronizes the light source and the time measuring device. According to this fluorescence lifetime measuring apparatus, the aforementioned time measuring device can be used to effectively measure fluorescence lifetime, and high temporal resolution and long-term measurement of fluorescence lifetime can be achieved.

[0020] One aspect of the present invention is a time measurement method implemented by a time measurement device that measures time while switching multiple time-amplitude converters, and includes: a selection step, selecting one time-amplitude converter of a detection signal detected in an input detector based on the dead time of each of the multiple time-amplitude converters; an acquisition step, inputting the detection signal and a clock signal to the selected time-amplitude converter to obtain a measurement signal corresponding to the time between the detection signal and the clock signal; and an export and output step, exporting and outputting time information related to the detection signal based on a count signal corresponding to the clock signal and the measurement signal. According to this time measurement method, dead time can be reduced, thereby improving measurement efficiency, and high time resolution and long-term measurement can be achieved.

[0021] In the time measurement method described above, another approach is to select a time-amplitude converter within the non-dead-time range during the selection process. This can appropriately avoid the degradation of measurement efficiency due to the influence of dead time.

[0022] Invention Effects

[0023] According to one aspect of the present invention, dead time can be reduced, thereby improving measurement efficiency, and high temporal resolution and long-term measurement can be achieved. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the fluorescence lifetime measurement device of this embodiment.

[0025] Figure 2 This is a diagram illustrating multiple TAC measurements.

[0026] Figure 3 This is a diagram illustrating multiple TAC measurements.

[0027] Figure 4 This is a diagram illustrating the export of time information.

[0028] Figure 5 This is a diagram illustrating the export of time information.

[0029] Figure 6 This is a diagram illustrating the export of time information.

[0030] Figure 7 This is a diagram schematically illustrating one example of a modified time measuring device. Detailed Implementation

[0031] Hereinafter, with reference to the accompanying drawings, a detailed description of one embodiment of the time measuring device, time measuring method, and fluorescence lifetime measuring device of the present invention will be provided.

[0032] Figure 1This diagram schematically illustrates the fluorescence lifetime measuring apparatus 1 of this embodiment. The fluorescence lifetime measuring apparatus 1 is a device for measuring the lifetime of fluorescence emitted from a sample S (the object to be measured).

[0033] The fluorescence spectrum of organic materials or fluorescent probes is an important parameter for controlling and evaluating the function or properties of a sample, such as peak wavelength or fluorescence intensity. However, since information on time-integrated fluorescence spectra is obtained, only integrated information can be obtained when the sample contains multiple substances or reaction systems. In this case, an effective method for evaluating the function or properties of a sample is to measure the fluorescence lifetime in the sub-nanosecond to millisecond time range, from the time the sample is photoexcited by pulsed light until it returns to the ground state. In the fluorescence lifetime measuring apparatus 1 of this embodiment, the detection timing of fluorescence is derived by the time measuring device 10 (described later), the frequency distribution of the detection timing is obtained by detecting fluorescence multiple times, and the fluorescence lifetime of the sample S is estimated based on this frequency distribution.

[0034] like Figure 1 As shown, the fluorescence lifetime measurement device 1 comprises: a pulse generator 2 (signal generation unit), a light source 3, a detector 4, a computer 5, a display device 6, an input device 7, and a time measurement device 10. Furthermore, in Figure 1 In the diagram, the clock generation circuit 9 (described later) in the structure of the fluorescence lifetime measuring device 1 is omitted. Figure 3 The illustration is shown.

[0035] Based on instructions from the computer 5, the pulse generator 2 outputs synchronized (e.g., timing-matched) pulse signals to the light source 3 and the reference gate 15 of the time measuring device 10 (details to be described later). The pulse generator 2 controls the light output of the light source 3 and outputs the control signal as a pulse signal. Based on this pulse signal, the reference gate 15 outputs a synchronization signal to either the TAC circuit 16a or the TAC circuit 16b (details to be described later). Since timing-matched pulse signals are input to the light source 3 and the reference gate 15, the synchronization signal output from the reference gate 15 is a signal that corresponds (synchronizes) with the illumination (excitation light) from the light source 3.

[0036] The light source 3 outputs excitation light illuminating the sample S based on the pulse signal output from the pulse generator 2. The light source 3 can be an LED (Light Emitting Diode), a laser source, an SLD (Super Luminescent Diode), a lamp system, etc. The intensity of the excitation light can be set, for example, to emit one photon when the sample S is irradiated with the excitation light. Fluorescence corresponding to the excitation light is output from the sample S irradiated with the excitation light.

[0037] Detector 4 detects the fluorescence from sample S and outputs the detection signal to the measuring gate 11 of time measuring device 10 (details will be described later). As detector 4, a photomultiplier tube, avalanche photodiode, PIN photodiode, etc. can be used.

[0038] Computer 5 derives the fluorescence lifetime based on the measurement results output from time measuring device 10 (more specifically, control unit 14). Specifically, computer 5 derives the frequency distribution of fluorescence detection times based on the fluorescence time information (fluorescence detection time) contained in the measurement results, and calculates the fluorescence lifetime of sample S based on this frequency distribution. Computer 5 is, for example, composed of an arithmetic unit such as a CPU and a storage unit such as RAM or flash memory. Furthermore, computer 5 may also perform the functions of control unit 14 of time measuring device 10.

[0039] Display device 6 is a monitor electrically connected to computer 5, displaying the fluorescence lifetime analysis results of the sample S. Input device 7 is a keyboard or mouse, etc., which can be used to input and set the fluorescence lifetime analysis conditions or measurement conditions.

[0040] The time measuring device 10 is a time measuring device that calculates the measurement time from the input of the first trigger signal to the input of the second trigger signal. The time measuring device 10 can be applied to various devices and systems that derive the difference in input times of two signals (the first trigger signal and the second trigger signal) input at different times. In this embodiment, as described above, the time measuring device 10 is applied to a fluorescence lifetime measuring device 1 that measures the lifetime of fluorescence emitted from the sample S.

[0041] like Figure 1As shown, the time measuring device 10 includes: a measuring gate 11 (first switching unit), a TAC (Time-Analog-Converter) circuit 12 (first time-amplitude converter), a TAC control unit 13, a control unit 14, a reference gate 15 (second switching unit), and a TAC circuit 16 (second time-amplitude converter). More specifically, the time measuring device 10 has multiple TAC circuits 12a-12j as TAC circuit 12, multiple TAC control units 13a-13f as TAC control unit 13, and multiple TAC circuits 16a and 16b as TAC circuit 16. The multiple TAC circuits 12a-12j are connected in parallel with respect to the measuring gate 11, and the multiple TAC circuits 16a and 16b are connected in parallel with respect to the reference gate 15. Furthermore, in Figure 1 In the text, the digital counter 20 described later in the structure of the time measuring device 10 is omitted (see reference). Figure 3 The diagram shows the digital counter 20. This digital counter 20 can be located within the TAC control unit 13, or it can be located separately from the TAC control unit 13.

[0042] TAC circuit 12 is a time-amplitude converter that outputs an analog signal (amplitude) from the time difference between the input first trigger signal and the input second trigger signal. TAC circuit 12 is configured, for example, to measure a time of 10 ns. Specifically, TAC circuit 12 uses the detection signal detected in detector 4 as the first trigger signal and outputs a time-amplitude converter from clock generation circuit 9 (see reference 1). Figure 3 The clock signal output by the detector 4 is used as the second trigger signal, and the analog signal (amplitude) corresponding to the time interval between the detection signal and the clock signal is output as a measurement signal to the TAC control unit 13. That is, the TAC circuit 12 receives the detection signal and the clock signal detected by the detector 4 as inputs, and outputs a measurement signal corresponding to the time interval between the detection signal and the clock signal. The TAC circuit 12 receives the input detection signal via the measurement gate 11.

[0043] The TAC control unit 13 is an AD converter that converts the measurement signal (amplitude) input from the TAC circuit 12, i.e., the analog signal, into a digital signal. The TAC control unit 13 outputs the digital signal after AD conversion as a measurement signal to the control unit 14. As described above, the time measuring device 10 has multiple TAC control units 13a to 13f as the TAC control unit 13. Figure 1As shown, the TAC control unit 13a receives measurement signal input from TAC circuits 12a and 12b, the TAC control unit 13b receives measurement signal input from TAC circuits 12c and 12d, the TAC control unit 13c receives measurement signal input from TAC circuits 12e and 16a, the TAC control unit 13d receives measurement signal input from TAC circuits 12f and 12g, the TAC control unit 13e receives measurement signal input from TAC circuits 12h and 12i, and the TAC control unit 13f receives measurement signal input from TAC circuits 12j and 16b.

[0044] The measuring gate 11 receives the first trigger signal, i.e., the detection signal, from the detector 4 and outputs the detection signal to the TAC circuit 12. In detail, the measuring gate 11 outputs the detection signal input from the detector 4 to only one of the multiple TAC circuits 12a to 12j. Figure 2 and Figure 3 This diagram illustrates multi-TAC measurement. Multi-TAC measurement here refers to a measurement method that switches between and utilizes multiple TAC circuits 12a to 12j.

[0045] like Figure 2 As shown, the measuring gate 11 has multiple gate circuits 11a-11j arranged in a one-to-one correspondence with multiple TAC circuits 12a-12j in the preceding stage of the TAC circuits 12a-12j. The multiple gate circuits 11a-11j of the measuring gate 11 are configured such that only one is active (in a state that receives a detection signal input). The inactive gate circuits 11a-11j are set to a standby state (in a state that does not receive a detection signal input). The measuring gate 11 receives a detection signal only from one of the multiple TAC circuits 12a-12j by switching between the active gate circuits 11a-11j.

[0046] The measuring gate 11 considers the dead time of multiple TAC circuits 12a-12j and switches the TAC circuits 12a-12j that receive the input detection signal. Here, dead time refers to the time after a time measurement in TAC circuit 12 during which another time measurement cannot be performed. Each TAC circuit 12a-12j has equivalent performance and the same dead time. However, the dead times of each TAC circuit 12a-12j can also be different. For example, in... Figure 2In the example shown, the measuring gate 11 first activates gate circuit 11a and sets the other gate circuits 11b to 11j to standby mode. In this state, when a detection signal is input to the measuring gate 11 from the detector 4, the detection signal is input only to gate circuit 11a, and then to the TAC circuit 12a via gate circuit 11a. The TAC circuit 12a outputs a measurement signal corresponding to the time between the detection signal and the clock signal. A certain time after processing the output of this measurement signal becomes a dead time during which time measurement cannot be performed again in the TAC circuit 12a. Therefore, the measuring gate 11 activates the second gate circuit 11b and sets the other gate circuits 11a, 11c to 11j to standby mode. In this state, when a detection signal is input to the measuring gate 11 from the detector 4, the detection signal is input only to gate circuit 11b, and then to the TAC circuit 12b via gate circuit 11b. Furthermore, similar to TAC circuit 12a, TAC circuit 12b also has a dead time. Therefore, the measurement gate 11 then activates the third gate circuit 11c and sets the other gate circuits 11a, 11b, 11d to 11j to standby. In this way, the measurement gate 11 sequentially switches the TAC circuits 12a to 12j that receive the input detection signal by activating only one of the gate circuits 11a to 11j corresponding to each TAC circuit 12a to 12j. According to this method, the dead time of lost photons is not the dead time of TAC circuit 12 (the dead time in TAC processing), but only the switching time of gate circuits 11a to 11j. Since the dead time in TAC processing is, for example, 150 ns, and the switching time of the gate circuits is, for example, 1 ns, this method can significantly shorten the dead time of lost photons.

[0047] The measuring gate 11 switches the TAC circuits 12a to 12j that receive input detection signals based on switching information pre-set considering dead time. This switching information specifies the switching order of the TAC circuits 12a to 12j (the effective order for gate circuits 11a to 11j) so that no detection signals are input to the TAC circuits 12a to 12j during the dead time. That is, the measuring gate 11 switches the TAC circuits 12a to 12j so that the input destination of the detection signal is the TAC circuits 12a to 12j during the non-dead time. As a prerequisite for this switching, the plurality of TAC circuits 12a to 12j are provided with a number corresponding to the dead time of the TAC circuit 12. The number corresponding to the dead time refers to the number of TAC circuits 12 that are not input to the TAC circuit 12 during the dead time when switching the TAC circuits 12 in a manner that inputs detection signals sequentially to each TAC circuit 12. Furthermore, the multiple TAC circuits 12a to 12j are configured with a number corresponding to the signal quantity detected by the detector 4. The number corresponding to the signal quantity detected by the detector 4 refers to the number of times a detection signal is not input to the TAC circuit 12 during the dead time, even when the detection signal is input with the maximum conceived signal quantity, and when switching the TAC circuit 12 in a manner that the detection signal is input sequentially to each TAC circuit 12.

[0048] Control unit 14, based on digital counter 20 (reference) Figure 3 The counting signal output from the TAC circuit 12 and the measurement signal output from the TAC circuit 12 and converted into a digital signal in the TAC control unit 13 are used to export and output time information related to the detection signal detected by the detector 4. Figure 3 As shown, the digital counter 20 is a counter that receives a detection signal from the detector 4 and a clock signal from the clock generation circuit 9 as inputs. The digital counter 20 operates synchronously with the clock signal and outputs a count signal to the control unit 14 based on the clock signal (counting the clock signal). While this type of digital counter 20 can measure the detection signal for a long time, it is difficult to improve the time resolution. The control unit 14 achieves high time resolution and long-term measurement of the time information related to the detection signal by combining the time measurement result of the digital counter 20 with the time measurement result of the TAC circuit 12, which has high time resolution.

[0049] Figures 4-6 This is a diagram illustrating the derivation of the aforementioned time information. In Figures 4-6 In the diagram, the horizontal axis represents the time axis. For example... Figure 4 As shown, the digital counter 20 counts the clock signal and outputs a count signal. Figure 4The image shows an example where the digital counter 20 outputs counting signals representing 23, 24, 25, 26, 27, and 28. As mentioned above, the digital counter 20 operates synchronously with a clock signal. Furthermore, as... Figure 4 As shown, currently, the TAC circuit 12 measures the time difference T from the input detection signal TRG1 from detector 4 to the next clock signal TRG2 of the input detection signal TRG1. In the measurement signal output by the TAC circuit 12, such as... Figure 5 As shown, starting from the moment of input detection signal TRG1 (time t1), the voltage (amplitude) begins to increase in accordance with the detection signal TRG1, and starting from the moment of input clock signal TRG2 (time t2), the voltage (amplitude) remains constant in accordance with the clock signal TRG2.

[0050] The control unit 14 derives time information representing the time up to the detection signal input to the TAC circuit 12 by subtracting the time represented by the measurement signal from the time corresponding to the count value represented by the counting signal. That is, in Figure 4 In the example shown, the control unit 14 derives time information (23-T) representing the time up to the input of the detection signal TRG1 to the TAC circuit 12 by subtracting the time information (time difference T) represented by the measurement signal from the time (23) corresponding to the count value represented by the counting signal. This time information can be derived by inputting the clock signal of the digital counter 20 and corresponding to the clock signal of the input TAC circuit 12 (the count value represented by the clock signal of the input TAC circuit 12 is uniquely determined).

[0051] In the structure of switching multiple TAC circuits 12, the control unit 14 derives time information based on information from each TAC circuit 12, thereby enabling appropriate time measurement even in multi-photon situations. Figure 6 In the example shown, the TAC circuit 12, which first outputs the input detection signal, is... Figure 6 After recording the time information as TAC1, the second TAC circuit 12 (recorded as TAC1) is derived. Figure 6 The time information recorded in the middle (referred to as TAC2) is then used to derive the time information of the third TAC circuit 12 (which receives the input detection signal). Figure 6 The time information recorded is TAC3. That is, in Figure 6In the example shown, the control unit 14 derives time information related to the measurement result of TAC1 by subtracting the time information represented by the measurement signal output by TAC1 from the time corresponding to the count value represented by the counting signal (23). Similarly, it derives time information related to the measurement result of TAC2 by subtracting the time information represented by the measurement signal output by TAC2 from the time corresponding to the count value represented by the counting signal (24). Finally, it derives time information related to the measurement result of TAC3 by subtracting the time information represented by the measurement signal output by TAC3 from the time corresponding to the count value represented by the counting signal (27). The control unit 14 outputs the derived time information (measurement result) to the computer 5.

[0052] TAC circuit 16 is a time-amplitude converter circuit that outputs an analog signal (amplitude) as the time difference between the input first trigger signal and the input second trigger signal. TAC circuit 16 outputs a signal corresponding to a synchronization signal of a phenomenon related to the detection signal detected in detector 4. The phenomenon related to the detection signal detected in detector 4 refers to the fluorescence from sample S detected in detector 4. The synchronization signal of the phenomenon refers to the synchronization signal output by reference gate 15 to TAC circuit 16 based on the pulse signal output by pulse generator 2 to light source 3 and reference gate 15 at the same (e.g., identical) moment. That is, the synchronization signal here refers to a signal synchronized with the excitation light illuminating sample S from light source 3 for fluorescence detection. Specifically, TAC circuit 16 outputs the synchronization signal input from reference gate 15 as the first trigger signal, the clock signal output from clock generation circuit 9 as the second trigger signal, and an analog signal (amplitude) corresponding to the time difference between the synchronization signal and the clock signal as a signal corresponding to the aforementioned synchronization signal to TAC control unit 13. The time measuring device 10 has two TAC circuits 16a and 16b as TAC circuit 16. TAC circuit 16a outputs a signal corresponding to the aforementioned synchronization signal to TAC control unit 13c. Additionally, TAC circuit 16b outputs a signal corresponding to the aforementioned synchronization signal to TAC control unit 13f. TAC control units 13c and 13f convert the signals input from TAC circuits 16a and 16b into digital signals and output them to control unit 14. Furthermore, control unit 14 can further consider the signal corresponding to the aforementioned synchronization signal to derive time information. That is, control unit 14 can also determine the start time (starting point) of the phenomenon based on the signal corresponding to the aforementioned synchronization signal, and derive time information related to the detection signal detected by detector 4 with higher accuracy.

[0053] The reference gate 15, taking into account the dead time of the TAC circuit 16, switches the TAC circuits 16a and 16b to which the aforementioned synchronization signal is input. The reference gate 15 receives a pulse signal input from the pulse generator 2 and outputs the corresponding synchronization signal to only one of the TAC circuits 16a and 16b. Based on preset switching information considering the dead time, the reference gate 15 switches the TAC circuits 16a and 16b to which the synchronization signal is input. This switching information is specified in a manner that the synchronization signal is not input to the TAC circuits 16a and 16b during the dead time.

[0054] Next, the function and effect of the time measuring device 10 and the fluorescence lifetime measuring device 1 equipped with the time measuring device 10 in this embodiment will be explained.

[0055] The time measuring device 10 of this embodiment includes: a digital counter 20 that outputs a counting signal based on a clock signal; a plurality of TAC circuits 12 (TAC circuits 12a to 12j) that receive a detection signal detected by the detector 4 and a clock signal as input, and output a measurement signal corresponding to the time between the detection signal and the clock signal; a control unit 14 that derives and outputs time information related to the detection signal based on the counting signal output from the digital counter 20 and the measurement signal output from the TAC circuits 12; and a measurement gate 11 that switches the TAC circuit 12 to which the input detection signal is received, taking into account the dead time of the TAC circuit 12.

[0056] In this time measurement device 10, multiple TAC circuits 12 are provided that output measurement signals corresponding to the time between the detection signal and the clock signal. Furthermore, in this time measurement device 10, the dead time of the TAC circuits 12 is taken into account when switching the TAC circuits 12 that receive the input detection signal. For example, when measuring time using only one TAC circuit 12, a dead time occurs where the measurement cannot be repeated after the measurement by the TAC circuit 12. Regarding this point, by multiplying the TAC circuits 12 and switching the TAC circuits 12 considering their dead time, it is possible to switch from a TAC circuit 12 that cannot be measured again after measurement to a measurable TAC circuit 12, thereby significantly reducing the aforementioned dead time. Furthermore, in the TAC circuit 12 of this embodiment, a count signal is output by the digital counter 20, which operates synchronously with the clock signal, to perform approximate time measurement dependent on the clock frequency (low time resolution and long-term measurement). The TAC circuit 12 also outputs a measurement signal corresponding to the time difference between the detection signal and the clock signal, thereby performing fine time measurement to compensate for the measurement roughness of the digital counter 20 (high time resolution and short-term measurement). By combining these time measurement results to derive the final time information, high time resolution and long-term measurement can be achieved. As described above, the time measuring device 10 according to this embodiment can reduce dead time, thereby improving measurement efficiency and achieving high time resolution and long-term measurement. An example of the time resolution of the time measuring device 10 is 0.25 ps, and an example of long-term measurement is 24 hours or more. Furthermore, the time resolution here refers to the measurement unit, not the overall time resolution of the measurement system.

[0057] For example, when organic EL luminescent materials such as TADF are photoexcited, luminescence in the nanosecond (ns) and millisecond (ms) ranges can be generated. Thus, in cases where luminescence with a very large time-unit difference in decay characteristics is generated, a measuring device capable of long-term measurement while maintaining high time resolution is needed for efficient fluorescence lifetime measurement. In such fluorescence lifetime measurements, the time measuring device 10 of this embodiment, which achieves high time resolution and long-term measurement, can be effectively utilized. Furthermore, the measurement object of the time measuring device 10 is not limited to TADF as described above, but can include other phosphors or objects exhibiting phenomena other than luminescence.

[0058] Furthermore, the aforementioned time measuring device 10 performs time measurements by switching multiple TAC circuits 12. For example, in fluorescence lifetime measurements, time measurements can be performed with a higher light intensity (e.g., 10 times the current intensity). Currently, when the luminescence intensity of the sample is strong, filters are used to significantly attenuate the luminescence for measurement, resulting in significant signal loss. However, according to the time measuring device 10, time measurements can be performed with high precision while suppressing this signal loss.

[0059] Alternatively, the measuring gate 11 can switch the TAC circuit 12 based on pre-set switching information that takes into account the dead time. With this structure, the TAC circuit 12 can be switched easily and appropriately based on pre-set information (switching information that takes into account the dead time).

[0060] Alternatively, the control unit 14 can derive time information representing the time up to the input detection signal by subtracting the time represented by the measurement signal from the time corresponding to the count value represented by the counting signal. Thus, the time up to the input detection signal can be derived with high accuracy based on the counting signal and the measurement signal.

[0061] Alternatively, the measurement gate 11 can be used to switch the TAC circuit 12 by inputting a detection signal to the TAC circuit 12 during the non-dead time. This can appropriately avoid the degradation of measurement efficiency due to the dead time of the TAC circuit 12.

[0062] Alternatively, multiple TAC circuits 12 can be configured with a number corresponding to the dead time. Therefore, the influence of the dead time can be appropriately avoided by switching the TAC circuits 12.

[0063] Alternatively, multiple TAC circuits 12 can be configured with a number corresponding to the signal quantity detected by detector 4. Therefore, by setting a number of TAC circuits 12 corresponding to the signal quantity, the influence of dead time can be appropriately avoided by switching the TAC circuits 12.

[0064] Alternatively, the time measuring device 10 may also include: multiple TAC circuits 16 (TAC circuits 16a, 16b), whose outputs a signal corresponding to the synchronization signal of the phenomenon related to the detection signal detected in the detector 4; the control unit 14 further considers the signal corresponding to the synchronization signal and derives time information. Thus, the actual time of the phenomenon related to the detection signal can be considered, and the time information related to the detection signal can be derived with higher accuracy.

[0065] Alternatively, the time measuring device 10 may also include a reference gate 15, which switches the TAC circuit 16 to receive the input synchronization signal, taking into account the dead time of the TAC circuit 16. This can appropriately avoid the degradation of the reference signal's measurement efficiency due to the dead time of the TAC circuit 16.

[0066] The fluorescence lifetime measuring device 1 of this embodiment is a fluorescence lifetime measuring device for measuring the lifetime of fluorescence emitted from a sample S. It includes: the aforementioned time measuring device 10; a light source 3 that irradiates the sample S with light generated from the light source 3; a detector 4 that detects the fluorescence from the sample S irradiated with light from the light source 3 and outputs a detection signal; and a pulse generator 2 that controls the light output of the light source 3 and outputs a synchronization signal to the light source 3 and the time measuring device 10 to synchronize them. According to this fluorescence lifetime measuring device 1, the aforementioned time measuring device 10 can be used to effectively measure fluorescence lifetime, and high temporal resolution and long-term measurement of fluorescence lifetime can be achieved.

[0067] The present invention has been described above as one embodiment, but the present invention is not limited to the above embodiment. For example, it has been described that the time measuring device 10 includes a TAC circuit 16 related to a synchronization signal and a reference gate 15, but when the moment of the phenomenon of the object of time measurement (repetition moment, etc.) can be grasped, such as... Figure 7 As shown, a structure without TAC circuit 16 and reference gate 15 can also be adopted.

[0068] Furthermore, the number of TAC circuits 12 is not limited to the number described in the embodiment (8), for example... Figure 7 As shown, the number of TAC circuits 12 can be 6 (TAC circuits 12a to 12f) or other numbers. For example, in fluorescence lifetime measurement, the appropriate number of these TAC circuits 12 preferably varies depending on the measured fluorescence lifetime value. For example, if the measured fluorescence lifetime value is 5 μs or less, the number of TAC circuits 12 can be set to 8 (or less); if the measured fluorescence lifetime value is longer than 5 μs, 9 or more TAC circuits 12 can be used.

[0069] [Symbol Explanation]

[0070] 1… Fluorescence lifetime measuring device, 2… Pulse generator (signal generation unit), 3… Light source, 4… Detector, 10… Time measuring device, 11… Measuring gate (first switching unit), 12… TAC circuit (first time amplitude converter), 14… Control unit, 15… Reference gate (second switching unit), 16… TAC circuit (second time amplitude converter), 20… Digital counter (counter), S… Sample (object to be measured).

Claims

1. A time measuring device, comprising: A counter that outputs a counting signal based on a clock signal; Multiple first time-amplitude converters are provided with a detection signal detected in the detector and a clock signal as inputs, and output a measurement signal corresponding to the time interval between the detection signal and the clock signal. The control unit, based on the counting signal output from the counter and the measurement signal output from the first time-amplitude converter, derives and outputs time information related to the detection signal; and The first switching unit considers the dead time of the first time-amplitude converter and switches the first time-amplitude converter that is input with the detection signal.

2. The time measuring device according to claim 1, wherein, The first switching unit switches the first time-amplitude converter based on switching information preset in advance, taking into account the dead time.

3. The time measuring device according to claim 1 or 2, wherein, The control unit derives time information representing the time up to the input of the detection signal by subtracting the time represented by the measurement signal from the time corresponding to the count value represented by the counting signal.

4. The time measuring device according to claim 1 or 2, wherein, The first switching unit switches the first time amplitude converter by inputting the detection signal to the first time amplitude converter during periods other than the dead time.

5. The time measuring device according to claim 1 or 2, wherein, The plurality of first time amplitude converters are configured with a number corresponding to the dead time.

6. The time measuring device according to claim 1 or 2, wherein, The plurality of first time amplitude converters are configured with a number corresponding to the amount of signal detected by the detector.

7. The time measuring device according to claim 1 or 2, wherein, It also includes: a second time-amplitude converter, whose output is a signal corresponding to the synchronization signal of the phenomenon, the phenomenon being related to the detection signal detected in the detector. The control unit further considers the signal corresponding to the synchronization signal and derives the time information.

8. The time measuring device according to claim 7, wherein, Equipped with: multiple of the second time-amplitude converters, It also includes a second switching unit that takes into account the dead time of the second time-amplitude converter and switches the second time-amplitude converter that is input with the synchronization signal.

9. A fluorescence lifetime measuring device, wherein, It is a fluorescence lifetime measuring device that measures the lifetime of fluorescence emitted from the object being measured. have: The time measuring device according to any one of claims 1 to 8; A light source, which produces light by illuminating the object being measured; The detector detects the fluorescence of the measurement object irradiated with light from the light source and outputs the detection signal; and The signal generating unit controls the light output of the light source and outputs a synchronization signal to the light source and the time measuring device to synchronize them.

10. A time measurement method, wherein, This is a time measurement method implemented by a time measuring device that simultaneously switches between multiple time-amplitude converters to measure time. Include: In the selection process, based on the dead time of each of the plurality of time-amplitude converters, a time-amplitude converter is selected from the detection signals detected in the input detector. The process involves inputting the detection signal and clock signal into the selected time-amplitude converter to obtain a measurement signal corresponding to the time between the detection signal and the clock signal. and The export and output process involves exporting and outputting time information related to the detection signal based on the counting signal corresponding to the clock signal and the measurement signal.

11. The time measurement method according to claim 10, wherein, In the selection process, the time-amplitude converter that is not in the dead time is selected.

Images