JP4357342B2 - Mass spectrometer - Google Patents

Description

  The present invention relates to a mass spectrometry technique, and more particularly, to data processing for time-of-flight analysis in an apparatus for analyzing the mass of a sample by ionizing and accelerating the sample and measuring the time of flight according to the mass. It is related to effective technology.

  According to a study by the present inventor, TOF-MS (Time Of Flight Mass Spectrometry) in mass spectrometry technology ionizes a sample, accelerates the ions, and measures the time of flight of a plurality of ions to measure the mass. Analyze. As a method for measuring the time of flight of ions, a time-to-digital converter (TDC) method and an analog-to-digital converter (ADC) method are well known. In both methods, ions are accelerated at a predetermined time “0” and the time of flight of the ions is measured, but the measurement method is different.

  The TDC method measures the presence or absence of ions at the detected time. Therefore, even if a plurality of ions are detected at the same time, they are measured as one ion. On the other hand, in the ADC method, when a plurality of ions are detected at the same time, a difference in signal intensity that differs depending on the number of ions is detected as a voltage value and stored.

  When comparing these two methods, the TDC method cannot measure the ions that arrive at the same time, but the ADC method measures the ions that arrive at the same time as the difference in voltage value. is there. However, since the ADC method needs to acquire and store all voltage values being measured, the amount of hardware increases. On the other hand, the TDC method stores data when ions are detected, and thus has an advantage that the hardware scale is smaller than that of the ADC method.

  For example, mass spectrometers using the TDC method that can reduce the hardware scale are disclosed in Patent Documents 1 and 2 and the like. As a technique related to these Patent Documents 1 and 2, a technique examined by the present inventor as a premise of the present invention will be described with reference to FIG.

  FIG. 5 shows a mass spectrometer of the technique studied as a premise of the present invention. This mass spectrometer includes an introduction unit 3 that ionizes a sample and introduces the sample into a TOF unit, an ion launch signal generation unit 2 that generates a signal for accelerating the ions, and a reflector-type TOF unit in which the ejected ions fly. 4. A mass analysis unit including a detection unit 41 that detects ions that have arrived, an amplifier 5 that amplifies the signal, a TDC unit 9, and a measurement control CPU 8.

  The TDC unit 9 compares a signal from the amplifier 5 with a predetermined voltage value (Vref) and outputs a digital value, a serial-parallel (serial-parallel) converter 92, a clock oscillation source 94, and a frequency divider 95. , A counter 96, an OR circuit 93, and a FIFO 97. The serial-parallel converter 92 samples the signal from which ions are detected by the clock output from the clock oscillation source 94 and simultaneously performs serial-parallel conversion. At the same time, the counter 96 that has received the Counter START signal from the ion launch signal generator 2 starts counting, but this counter output data becomes a time code indicating the flight time of ions, and the output of the serial-para converter 92 The data is data corresponding to the time code of the counter output. The FIFO 97 stores the time code data and the output data of the serial-to-parallel converter 92. This writing is performed when all the output data of the serial-to-parallel converter 92 is logically "High". The data stored in the FIFO 97 is read out from the measurement control CPU 8 after one ion implantation is completed and all data is stored.

  In the TDC system as described above, since the detection signal of ions is processed as a digital signal (High and Low), as described above, ions detected at the same time (hardware cannot be identified) cannot be counted. There is a principle disadvantage that detection efficiency is lowered. In order to compensate for this, measurement is performed by n ion implantations, and the n times of data integration results are subjected to histogram processing. Accordingly, data is transferred to the measurement control CPU every n measurement data.

  Moreover, in the TOF part of the mass spectrometer described above, the detection sensitivity can be improved by having a plurality of ion detection parts. For example, in the technology using the TDC method, data storage of ion detection signals output from a plurality of detection units is realized by simply having the same number of TDC units as shown in FIG. 5 in parallel with the ion detection signals. Is an easy way. This is simply having a plurality of TDC units in parallel, and therefore it is necessary to perform parallel, time-division or parallel processing on a plurality of stored data by the CPU control circuit after data storage.

  For example, a technique for processing ion detection signals output from a plurality of detection units is disclosed in Patent Document 3 and the like. As a technique related to this Patent Document 3, a technique examined by the present inventor as a premise of the present invention will be described with reference to FIG.

FIG. 8 shows an example of a technique studied as a premise of the present invention, in which the ion detection signals output from a plurality of detection units do not simply have the TDC units shown in FIG. 5 in parallel. Here, the TDC unit 901 particularly in the case of two channels is shown as an example. CH1 and CH2 are input terminals of two input ion detection signals, and the data sampled by the serial-parallel converters 92-1 and 92-2 via the comparators 91-1 and 91-2 are added to the adder 98. At this time, a time code is simultaneously output from the counter 961 from the clock oscillation source 941 via the frequency dividing circuit 951, and these two data are stored in the FIFO 971 one after another. In the data storage, all sample data is temporarily stored in the FIFO 971, and then all data is read out by the measurement control CPU 8.
JP 2002-260577 A JP 2002-245963 A Special table 2001-504265 gazette

  By the way, the following problems can be considered in the technique of the TDC system examined as the premise of the present invention described above.

  In the technique in the TDC system, an error due to asynchronous measurement of a signal at time 0 or an error in an asynchronous absorption means for reducing the error due to asynchronous measurement occurs. For example, in the mass spectrometer of FIG. 5 described above, FIG. 6 (operation of the counter 96: clock 94a, counter START signal 2a, counter operation start signal 96a) shows an error that occurs when synchronizing with an asynchronous clock. Therefore, an error corresponding to the clock cycle occurs. In order to reduce this error, it is necessary to have a circuit or the like that stores a time difference (ter) equal to or less than the clock period. In this case, there is a first problem that the circuit scale increases.

  In the TDC method, as described above, when ions arrive simultaneously within a certain range, there is a time zone in which ion detection is impossible. For example, FIG. 7 (operation of serial-parallel converter 92: clock 94a, comparator output signal 91a, sampling data 92a) shows an example. The case where the pulse width of the ion detection signal is smaller than the sampling clock period as in Example 1 (3) and the case where the time interval between successive ions is shorter than the clock period as in Example 2 (2). In each case, a data storage leak occurs. This is the second problem.

  Furthermore, there is a third problem in the integration calculation that is a feature of the TDC system. That is, in the TDC method, as described above, ion implantation is performed a plurality of times to perform measurement, and a spectrum obtained from the result of the histogram processing is analyzed. For example, in the example shown in FIG. 6, the data measured by one ion implantation is temporarily stored in the FIFO, and then the stored data is transferred to the measurement control CPU every time one ion implantation is completed. Yes. For this reason, when ions are detected at a speed higher than the transfer speed from the TDC unit to the measurement control CPU, there is a third problem that the operation of the mass analysis unit becomes inactive and the measurement time becomes long. .

  Therefore, the present invention solves the above-described three problems, and its object is to minimize the measurement pause time and further improve the measurement accuracy and ion detection resolution in TDC data processing. An object of the present invention is to provide a mass spectrometer that can be used.

  Further, in the above-described technology for processing a plurality of ion detection signals at the same time, the data stored in the plurality of FIFOs is transferred to the CPU in order to simply perform the parallel processing by providing a plurality of TDC units shown in FIG. There is a problem that it is necessary to perform transfer by time division or parallel processing, which increases the transfer processing time and the circuit scale.

  In the technique shown in FIG. 8, all data after the addition processing in the adder 98 is stored in the FIFO 971. Therefore, all data during the sample time is stored regardless of the presence or absence of ions. The FIFO 971 that can be transferred to the measurement control CPU 8 is required, which causes a problem that the circuit scale increases.

  Further, when ions are detected at a speed higher than the transfer speed from the TDC unit to the measurement control CPU, the problem that the operation of the mass analysis unit is in a dormant state and the measurement time becomes long is 1 for the TDC unit. This is more noticeable than when only the base is used.

  Therefore, another object of the present invention is to provide a mass spectrometer capable of minimizing measurement pause time with a small circuit scale even in TDC data processing for simultaneously processing a plurality of ion detection signals. It is in.

  As a means for solving the above problems in the present invention, the first problem is solved by generating a timing signal for ion implantation from the TDC section. In the technology studied as the premise of the present invention, the signal received as the measurement start signal of the TDC unit is generated from the TDC unit in the present invention, and thus the error of the start signal is eliminated in principle. That is, it is possible to provide means for generating the timing of the ion launch signal.

  Next, the second problem is that by providing a pulse detection toggle FF that operates only at the rising edge of the ion detection signal, the sensitivity twice as high as that of the technique studied as the premise of the present invention is realized. . That is, it becomes possible by providing means for sampling the ion detection signal detected at the change point.

  Next, the third problem is that a circuit for directly time-converting the acquired ion detection data is provided, and a memory for histogram processing corresponding to the converted time data is further provided so that the measurement pause time does not occur. To solve this problem. In other words, it is possible to provide means for converting data read from the FIFO storing data sampled with the high-speed clock into time data and integrating the data using the data converted into the time data as an address.

  Specifically, in the present invention, the sample is ionized and accelerated / flighted, and after the detection signal obtained by detecting the flying ions is converted into a digital signal, the digital signal is sampled and stored in the mass analysis unit. Applied to the device, a counter that determines the timing for accelerating ions, a change point detector that changes the output value according to the rise or fall of the detection signal, and a change after sampling the output of the change point detector A data converter that converts point information into signal presence / absence information, a FIFO that stores the output of the data converter, a time converter that reads data from the FIFO and converts it to the flight time of ions, and a time converter Histogram processing corresponding to the set time data is performed, and a memory for storing the processing data using this time data as an address is arbitrarily combined. It is as it has in the suit.

  Further, as a means for solving the problems in the TDC type data processing that processes the plurality of ion detection signals at the same time, the present invention digitizes the ion detection signals output from the plurality of detection means by using a plurality of sampling means. This is possible by adding all the data output from the plurality of detection means after taking in the data, and further providing means for excluding data in which the ion signal was not detected from the added data. Become.

  Specifically, in the present invention, the sample is ionized and accelerated / flighted, the flying ions are detected by a plurality of detection means, and detection signals from the plurality of detection means are converted into digital signals, and then the digital signals are converted. Applied to a mass spectrometer having means for sampling and storing data, and a counter for determining the timing for accelerating ions, and a change in rising or falling of each detection signal output from a plurality of detection means From multiple change point detectors that change the output value, multiple data converters that convert each change point information into signal presence / absence information after sampling each output of the multiple change point detectors, and multiple data converters An arithmetic unit for processing the output of the first, a FIFO for storing the output of the arithmetic unit, and data from the FIFO are read and converted to ion flight time And time converter performs histogram processing corresponding to the converted time data in time converter, and a memory for storing the processed data to the time data as an address are those provided in any combination.

  According to the present invention, it is possible to reduce measurement errors and data leakage at the time of measurement as compared with the data processing of the TDC method based on the technique studied as the premise of the present invention, and to perform the histogram processing in hardware, thereby performing the mass analysis unit. The downtime can be easily reduced.

  In addition, according to the present invention, even in TDC type data processing provided with a plurality of ion detection means, the pause time of the mass analysis unit can be achieved by performing the histogram processing function common to all channels with a small circuit scale. Can be easily shortened.

  As a result, it is possible to provide a mass spectrometer capable of minimizing measurement pause time in the TDC system and further improving measurement accuracy and ion detection resolution.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
First, an example of the configuration of a mass spectrometer according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 shows a configuration example of a mass spectrometer according to this embodiment.

  The mass spectrometer according to the present embodiment uses a TDC method in which a sample is ionized to accelerate and fly, a detection signal obtained by detecting the flying ions is converted into a digital signal, the digital signal is sampled, and data is stored. Data processing technology is used, the sample is ionized and introduced into the TOF unit 4, the ion launching signal generating unit 2 that generates a signal 2 a for accelerating the ions, and the ejected ions fly. A reflector type TOF unit 4, a detection unit 41 for detecting arriving ions, an amplifier 5 for amplifying the signal 4 a, a TDC unit 6 connected to the mass analysis unit, and a TDC unit 6 It consists of connected control CPU1.

  The TDC unit 6 compares the signal 5a from the amplifier 5 with a predetermined voltage value (Vref) and outputs a digital value, and a change that changes the output value in response to a rising or falling change of the detection signal. Change after the point detector 62, the serial converter 63, the clock oscillation source 64, the frequency divider 65, the counter 67 that determines the timing for accelerating ions, and the output of the change point detector 62 are sampled via the serial converter 63. A data converter 66 that converts point information into signal presence / absence information, a FIFO 68 that stores the output of the data converter 66, a time converter 70 that reads out data from the FIFO 68 and converts the data to the flight time of ions, and a time converter 70 A memory 71 that performs histogram processing corresponding to the converted time data and stores the processed data using the time data as an address. Constructed.

  In the TDC unit 6, the counter 67 receives the measurement start signal 1a from the control CPU 1 and generates a START signal 67b for generating an ion launch signal. This START signal 67b corresponds to time “0” for measuring the flight time of ions. The change point detector 62 toggles the output at the rising timing of the output signal 61a of the comparator 61. The serial-parallel converter 63 receives the output signal 62a of the change point detector 62 from the clock oscillation source 64. Sampling is performed with the output clock 64a, and further subjected to serial-parallel conversion to be output as an output signal 63a.

  Next, the data converter 66 performs data conversion (detection data) on the assumption that the “High” information exists only in the clock cycle in which the rising edge of the pulse is detected. At the same time, a time code indicating the ion flight time is output from the counter 67, and the OR circuit 69 takes the logical sum of all the data 66a and writes the write signal to the FIFO 68 when "High" is output. 69a is generated.

  The data written in the FIFO 68 is read by the time converter 70. At this time, time data in which ions in units of clock periods are detected is generated from the time code and the detection data immediately after the reading. In the memory 71, ion detection information is written using the generated time data as an address signal of the memory. Therefore, when n measurements are performed, from the second time onward, the integrated results up to the previous time are read, and the ion detection information is added to the data and written again.

  In the TDC unit 6, data processing after serial-parallel conversion is performed by the frequency-divided clock 65a obtained by frequency-dividing the clock 64a by the frequency divider 65, and the frequency-divided number and the parallelized number at the time of serial-parallel conversion are the same. To do.

  Next, the operation principle of the change point detector 62, the serial-parallel converter 63, and the data converter 66 will be described with reference to FIG. FIG. 2 shows an operation example of the change point detector 62, the serial-parallel converter 63, and the data converter 66.

  As shown in FIG. 2, when the output signal 61a ((1), (2), (3)) from the comparator is input to the change point detector 62, the conversion output from the change point detector 62. The point data 62a also changes at the rising timing. The conversion point data 62a is input to the serial-parallel converter 63, and the sampling data 63a output from the serial-parallel converter 63 is a result of sampling the conversion point data 62a with the clock 64a. Further, only the cycle in which the sampling data 63a has changed is detected to generate “High”.

  Next, operation principles of the FIFO 68, the time converter 70, and the memory 71 will be described with reference to FIG. FIG. 3 shows an operation example of the FIFO 68, the time converter 70, and the memory 71.

  In FIG. 3, in the processing example until the data fetched into the FIFO 68 is stored in the memory 71 via the time converter 70, the contents stored in the FIFO 68 and the data before the conversion by the time converter 70 (time code, data converter output) Data) and data after conversion (time information when ions are sampled) are shown.

  As shown in FIG. 3, when the time code 67 a from the counter 67 and the sampling data 66 a from the data converter 66 are input to the FIFO 68, the data of the cycle marked with ○ is written into the FIFO 68. Then, the time converter 70 converts the data 68a (time code, sampling data) read from the FIFO 68 into time data 70b in units of resolution, which is the generation cycle time of the clock oscillation source 64.

  In the example of FIG. 3, one cycle of the clock is 1 ns, the data after serial-parallel conversion is 4-bit data, and the data on the left in the figure is sampling data that is temporally older. Therefore, in the time code “0” and the serial-transformed data “0101”, ions are detected at 1 ns and 3 ns. Also, the time code “1” and serial data “0001” indicate that ions were detected at 7 ns, and thereafter, conversion is performed similarly to 19 ns, 26 ns,. Detection information is written in the memory 71 using the converted time data 70b as an address signal.

  Next, data storage at the time of ion detection in the memory 71 will be described with reference to FIG. FIG. 4 shows an example of data storage when ions are detected in the memory 71.

  FIG. 4 shows an example in which ion implantation is performed 256 times and the time data described in FIG. 3 is stored 256 times. As shown in the figure, addresses 1, 3, 7, 19, 26 stores data. Address 0 corresponds to 0 ns of flight time, address 1 corresponds to 1 ns, address 2 corresponds to 2 ns, and so on.

  As described above, according to the present embodiment, by outputting a timing signal for ion implantation from the counter 67, an error at the start of measurement can be eliminated in principle. Further, by using the change point detector 62 and the data converter 66, even a signal that is difficult to detect ions can be easily detected by the technique studied as the premise of the present invention. Furthermore, since the integration processing of the measurement can be performed a plurality of times without using the control CPU 1 by using the time converter 70 and the memory 71, there is no measurement pause due to the data transfer processing, and the histogram processing is performed when reading from the memory 71. Therefore, it is possible to increase the efficiency of data processing.

(Embodiment 2)
First, an example of the configuration of a mass spectrometer according to the second embodiment of the present invention will be described with reference to FIG. FIG. 9 shows a configuration example of the mass spectrometer according to the present embodiment.

  The mass spectrometer according to the present embodiment ionizes a sample, accelerates and flies, detects the flying ions by a plurality of detection means, converts detection signals from the plurality of detection means as digital signals, In this example, a digital signal is sampled and data is stored in a TDC system. Components having the same functions as those in FIG. 1 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. To do.

  That is, in the present embodiment, there are a plurality (two in the figure) of detection units 41-1 and 41-2 and amplifiers 5-1 and 5-2 constituting the mass analysis unit, and accordingly, the TDC unit. Reference numeral 601 denotes comparators 61-1 and 61-2 that compare the ion detection signals output from the amplifiers 5-1 and 5-2 with a predetermined voltage value (Vref) and output digitized data. Change point detectors 62-1 and 62-2, serial-parallel converters 63-1 and 63-2, and change point detectors 62-1 and 62-2 that change output values in accordance with changes in the rise or fall of Are sampled through the serial-parallel converters 63-1, 63-2, and then converted from change point information to signal presence / absence information, data converters 66-1, 66-2, data converters 66-1, 66 -2 adder (calculation) ) 72, OR circuit 691, FIFO 681 storing the output of adder 72, time converter 701 for reading out data from FIFO 681 and converting it to the flight time of ions, and histogram processing corresponding to the time data converted by time converter 701 And a memory 711 for storing processing data using the time data as an address.

  Next, operation principles of the adder 72, the FIFO 681, the time converter 701, and the memory 711 will be described with reference to FIG. FIG. 10 shows an operation example of the adder 72, the FIFO 681, the time converter 701, and the memory 711.

  In FIG. 10, in the processing example until the data fetched into the FIFO 681 is stored in the memory 711 via the time converter 701, the contents stored in the FIFO 681 and the data before the conversion by the time converter 701 (time code, data converter output) Data) and data after conversion (time information when ions are sampled) are shown.

  As shown in FIG. 10, when the time code 67a from the counter 67 and the sampling data 66-1a and 66-2a from the data converters 66-1 and 66-2 are input to the FIFO 681, a cycle indicated by a circle Are written in the FIFO 681. Then, the time converter 701 converts the data 681-1a and 681-2a (time code, sampling (addition) data) read from the FIFO 681 into time data 701b in units of resolution that is the generation period time of the clock oscillation source 64. Convert.

  In the example of FIG. 10, one cycle of the clock is 1 ns, the data after serial-parallel conversion is 4-bit data, and the left data in the figure is the sampling data 66-1 a and 66-2 a that are older in time. Further, the addition data 72a indicates a result obtained by adding the sampling data 66-1a and 66-2a in the adder 72 in units of one clock cycle. The sampling data 66-1a is the same data as in FIG. 3 of the first embodiment, and the sampling data 66-2a is serial data “0001” only when the time code 67a is “1”. Are all "0". Accordingly, in the addition data, the addition operation between the sampling data 66-1a and 66-2a is performed at the time code “1”, and “0002” is output. The other addition data 72a is the same as the sampling data 66-1a.

  Subsequently, in the time converter 701, ions are detected in 1 ns and 3 ns in the time code “0” and the serial-transformed data “0101”. In addition, the time code “1” and serial data “0002” indicate that ions were detected at 7 ns, and thereafter, conversion is performed similarly to 19 ns, 26 ns,. The detection information is written in the memory 711 using the converted time data 701b as an address signal. When writing to the memory 711, addition writing is performed on data already stored at the same address.

  By operating as described above, a plurality of ion detection signals can be simultaneously stored in the memory 711 that performs one histogram process.

  As described above, in the present embodiment, the comparators 61-1 and 61-, which are circuits that sample signals with respect to the ion detection signals output from the plurality of detection units 41-1 and 41-2. 2. Since it can be realized by a circuit configuration having only the change point detectors 62-1 and 62-2, serial-parallel converters 63-1 and 63-2, and data converters 66-1 and 66-2 in parallel, In addition to minimizing the scale, measurement pause time, etc., histogram processing of a plurality of ion signals output at the end of measurement can also be completed, so that the processing efficiency can be improved.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments of the invention. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, in the above embodiment, the change point detector is inserted and the ion detection signal is sampled by the serial-parallel converter and the data converter. However, the change point detector is not inserted and the output of the comparator is output. Is directly connected to the serial-parallel converter, and then the data converter generates the rising transition of the data.

  In the second embodiment, the adder is inserted immediately before the FIFO. However, there is no problem if it is inserted after the FIFO. When the adder is inserted in the subsequent stage of the FIFO, only the Write signal to the FIFO may be generated by the logical sum of all bits, or the output from the data converter may be stored individually. There are various circuit realization methods when this adder is provided, but the results of ion detection detected with the same clock are added before the time conversion of the output from the plural data converters provided by the time converter. It can be easily inferred that this is realized.

  In the above embodiment, the case has been described where the data taken into the FIFO is stored in the memory via the time converter and transferred from the memory to the control CPU. However, the data taken into the FIFO is directly transferred to the control CPU. You may make it read by.

It is a block diagram which shows the mass spectrometer by Embodiment 1 of this invention. It is explanatory drawing which shows operation | movement of a change point detector, a serial para converter, and a data converter in the mass spectrometer by Embodiment 1 of this invention. It is explanatory drawing which shows operation | movement of FIFO, a time converter, and a memory in the mass spectrometer by Embodiment 1 of this invention. It is explanatory drawing which shows the data storage at the time of the ion detection to memory in the mass spectrometer by Embodiment 1 of this invention. It is a block diagram which shows the mass spectrometer examined as a premise of this invention. It is explanatory drawing which shows operation | movement of a counter in the mass spectrometer examined as a premise of this invention. It is explanatory drawing which shows operation | movement of a serial para converter in the mass spectrometer examined as a premise of this invention. It is a block diagram which shows the principal part of the mass spectrometer which has the input channel of the several ion detection signal examined as a premise of this invention. It is a block diagram which shows the mass spectrometer by Embodiment 2 of this invention. It is explanatory drawing which shows operation | movement of an adder, FIFO, a time converter, and a memory in the mass spectrometer by Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Control CPU, 2 ... Ion implantation signal generation part, 3 ... Introduction part, 4 ... TOF part, 41, 41-1, 41-2 ... Detection part, 5,5-1, 5-2 ... Amplifier, 6, 601 ... TDC section, 61, 61-1, 61-2 ... comparator, 62, 62-1, 62-2 ... change point detector, 63, 63-1, 63-2 ... serial-parallel converter, 64 ... clock Oscillation source, 65 ... frequency divider, 66, 66-1, 66-2 ... data converter, 67 ... counter, 68, 681 ... FIFO, 69, 691 ... OR circuit, 70, 701 ... time converter, 71, 711 ... Memory, 72 ... Adder, 8 ... Measurement control CPU, 9,901 ... TDC unit, 91, 91-1, 91-2 ... Comparator, 92, 92-1 and 92-2 ... Serial converter, 93 ... OR circuit, 94, 941 ... Clock oscillation source, 95, 951 ... Frequency divider, 96, 61 ... counter, 97,971 ... FIFO, 98 ... adder.

Claims (6)

An introduction unit that ionizes a sample, an ion launch signal generation unit that generates a signal for accelerating ions ionized by the introduction unit, and ions ejected by a signal generated by the ion launch signal generation unit fly. A mass analysis unit comprising a TOF unit and a detection unit for detecting a detection signal based on the arriving ions;
A counter that outputs a timing signal for determining a generation timing of a signal generated by the ion launch signal generator in response to a measurement start signal from a control CPU independent of the mass analyzer, and a clock generation source that generates a clock When the change point detector for outputting change point data of two values that vary in accordance with only the rise of the change of the detection signal, and sampling based on the clock outputted to the change point data from said clock generation source, 1 A TDC unit including a serial-to-parallel converter that generates sampling data that is signal presence / absence information based on presence / absence of change of change point data in the clock ;
A mass spectrometer characterized by comprising: The mass spectrometer according to claim 1,
The TDC unit further includes
A data converter that performs data conversion assuming that there is High information only in a clock cycle in which the sampling data is 1, a FIFO that stores an output from the data converter, and an output from the FIFO is read out And a time converter that converts the time of flight to ion flight time. The mass spectrometer according to claim 2,
The TDC unit further includes
A mass spectrometer comprising a memory that performs histogram processing corresponding to time data converted by the time converter and accumulates processing data using the time data as an address. An introduction unit that ionizes a sample, an ion launch signal generation unit that generates a signal for accelerating ions ionized by the introduction unit, and ions ejected by signals generated by the ion launch signal generation unit fly. A mass analysis unit comprising a TOF unit and a plurality of detection units for detecting detection signals based on the arriving ions,
A counter that outputs a timing signal for determining a generation timing of a signal generated by the ion launch signal generator in response to a measurement start signal from a control CPU independent of the mass analyzer, and a clock generation source that generates a clock A plurality of change point detectors that output binary change point data that changes only in response to a change in the rising edge of the detection signal, and the change point data based on a clock output from the clock generation source. A TDC unit that includes a plurality of serial-parallel converters that sample and generate sampling data that is signal presence / absence information based on presence / absence of change in change point data within one clock ;
A mass spectrometer characterized by comprising: The mass spectrometer according to claim 4,
The TDC unit further includes
A plurality of data converters for performing data conversion assuming that there is High information only in a clock cycle in which each of the sampling data is 1, an arithmetic unit for performing processing on outputs from the plurality of data converters, A mass spectrometer comprising: a FIFO that stores an output from the computing unit; and a time converter that reads an output from the FIFO and converts the output into an ion flight time. The mass spectrometer according to claim 5, wherein
The TDC unit further includes
A mass spectrometer comprising a memory that performs histogram processing corresponding to time data converted by the time converter and accumulates processing data using the time data as an address.

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