JPS6341004B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data display method suitable for use in monitoring analog signal waveforms.

Conventionally, a mass spectrometer is attached with a monitoring oscilloscope, and the oscilloscope is used to monitor a mass spectrum signal obtained as a result of sweeping a magnetic field. However, with such an oscilloscope, if the sweep time is long, the previously displayed waveform disappears, and while it is fine when the sweep time is fixed, it becomes difficult to create a sweep signal for the oscilloscope when it can be changed arbitrarily. There was a problem. In addition, recent mass spectrometers are often equipped with a processing device that processes data using a computer, and although it is possible to monitor spectra using this processing device, it is not possible to monitor the spectrum in real time due to the delay in data transfer time. and expensive processing equipment must be purchased.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a data display method capable of monitoring signal waveforms in real time with a simple configuration. The present invention will be explained in detail below using the drawings.

FIG. 1 shows an example of an apparatus for carrying out the method according to the present invention, and in the figure, 1 is a mass spectrometer. The mass spectrometer measures a mass spectrum by, for example, sweeping an analysis magnetic field, and the obtained spectrum signal a is sent to a digital peak hold circuit 3 via an AD converter 2. The mass spectrometer 1 also generates a sweep state signal b which is "1" during the sweep period and "0" during the other periods, and this signal b is sent to the AND gate 5 directly or via the zoom circuit 4. 6 is a changeover switch for this purpose. A sampling clock pulse for the A-D converter 2 generated from an oscillator 7 is also supplied to the AND gate 5, and the clock pulse is sent to a counter 9 or a variable division ratio via a changeover switch 8 during the sweep period. The signal is sent to the frequency dividing circuit 10. The frequency division ratio of the frequency division circuit 10 is set by the output of the division circuit 12 which calculates the value obtained by dividing the count value of the counter 9 by the output of the raster number signal generator 11, and the frequency division output is The signal is sent to the peak hold circuit 3 as a reset signal, and is also sent as a write command signal to the memory 15, which will be described later.

13 is a cathode ray tube CRT for waveform display, 14 is a CRT
The control device 15 is a memory that stores data to be displayed on the CRT 13. Then, the CRT control device 14 performs raster scanning on the CRT 13 in the vertical direction, and sends data to the memory 15 via the multiplex circuit 16.
A read command signal is sent to the CRT to sequentially read out the stored data and display it as a bright spot on the CRT screen. The peak hold circuit 3 sends the hold value at that time for each reset signal as storage data to the memory 15, and the storage address of the data is specified by the output of the counter 17 that counts the reset signal.
The multiplex circuit 16 during the retrace period of the CRT.
This is done by sending the data to the memory 15 via the .

In the above configuration, 384 rasters are drawn on the CRT 13 by vertical raster scanning, as shown in FIG. Display is performed. That is, the memory 15 is used to store data (e.g. 8 bits) indicating the position of the bright spot for each raster from the 1st to the 384th raster.
It has a storage area up to address 383, and the CRT control device 14 stores data from address 0 in synchronization with raster scanning.
Data up to address 383 is read out repeatedly in sequence, and bright spots are displayed by increasing the brightness at positions corresponding to the data values for each raster.

Next, a procedure for storing data in the memory 15 will be explained. The mass spectrometer 1 repeatedly sweeps the analysis magnetic field based on the sweep signal shown in FIG. 3a,
A spectrum signal a as shown in FIG. 3b is obtained for each sweep period. And the spectrum signal is A-D
The signal is sampled at a sufficiently short period by the converter 2, converted into a digital signal, and sent to the peak hold circuit 3. At this time, if the number of sampling data within the sweep period is, for example, four times the number of rasters, ie, 1536, then the frequency division ratio of the frequency divider 10 is set to 1/4. Therefore, one frequency divided output signal is generated from the frequency divider 10 for every four pieces of sampling data,
The output signal is sent to the peak hold circuit 3 as a reset signal and to the memory 15 as a write command signal, respectively. Based on the reset signal, the peak hold circuit 3 transfers the sampling data held at the time of reset (the maximum value of the four sampling data) to the memory 15 which is in the write state only at that time by the write command signal. send to On the other hand, the counter 17 counts the reset signal from 0 to 383 (corresponding to the number of rasters on the CRT), and the count value is
Since the read command signal from 4 is sent as a write address command signal to the memory 15 during each retrace period, for example, the read command signal is not present, the spectrum signal data obtained during each sweep period is stored in the memory 15 while being sequentially replaced. Ru. Therefore, the spectral waveform obtained in accordance with the sweep is displayed in real time on the screen of the CRT 13 that reads and displays the data in the memory 15. 4 obtained like this
Since the largest data among the data is used, it is possible to reduce the chance of missing a peak.

The frequency division ratio of the frequency divider 10 is determined by turning the changeover switch 8 to the counter 9 side only during the first sweep period, and counting the number of sampling clock pulses, in other words, the number of sampling data, with the counter 9 during the first sweep period. It can be set by dividing the obtained count value 1536 by the output 384 of the raster number signal generator 11 in the division circuit 12 and sending the obtained "4" to the frequency divider 10. Therefore, no waveform display is performed during the first sweep period, but this does not pose any problem since the sweep is repeated.

Further, in this embodiment, since a zoom circuit 4 is attached, it is possible to easily enlarge and display any part of the spectrum. That is, the zoom circuit 4 combines a plurality of one-shot circuits with variable pulse widths to create a pulse with an arbitrary width t at an arbitrary position during the sweep period, as shown in FIG. Therefore, the spectrum signal obtained during the period t will be written into the memory 15, and if it is read out and displayed as a waveform on the CRT, the spectrum signal obtained during the period t will be as shown in Figure 4a. The image will be enlarged to fill the entire width of the CRT screen. FIG. 4b shows a spectral waveform over the entire sweep range displayed on the CRT when the zoom circuit 4 is not used, and naturally corresponds to the spectral signal a shown in FIG. 3b.
It goes without saying that by changing the width of the period t and the position during the sweep period, it is possible to enlarge and display any range within the sweep range.

As detailed above, according to the present invention, waveforms can be displayed on the CRT in real time during sweeping, so there is no delay and it is effective during high-speed sweeping.Since digitized data is displayed, it is easy to hold, and the sweep time is It is also effective even during long periods. Furthermore, unlike an oscilloscope, a sweep signal is not required, and a sweep state signal only needs to be provided, so that the configuration is simplified.

It is also possible to perform the functions of each component shown in the above embodiment by a computer program, and in this case, the configuration after the A-D converter 2 can be replaced with a computer, resulting in a simple configuration. becomes.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a device for carrying out the method according to the present invention, FIG. 2 is a diagram showing a display state of a CRT, and FIG. 3 is a waveform diagram for explaining the operation of the embodiment. FIG. 4 is a diagram showing a spectrum waveform displayed on a CRT. 1: Mass spectrometer, 2: A-D converter, 3: Digital peak hold circuit, 4: Zoom circuit,
5: AND gate, 6, 8: Changeover switch, 7:
Oscillator, 9, 17: Counter, 10: Frequency divider, 1
1: Raster number signal generator, 12: Division circuit, 1
3: CRT, 14: CRT control device, 15: memory.

Claims (1)

[Claims] 1 In a data display method in which data stored in memory corresponding to each scanning line is sequentially sent to a cathode ray tube that performs raster scanning at a fixed period and displayed, the signal to be displayed is sampled at a fixed period. From the sequentially obtained sampling data,
A data display method characterized in that the maximum value for each predetermined number is determined and the maximum values are sequentially stored in the memory.