JPH09184823A - Analyzing device detection signal processing device - Google Patents

Abstract

(57) Abstract: An input signal having a large dynamic range can be detected with a simple configuration. An output of a preamplifier 2 is input to amplifiers 4-1 and 4-2 connected in parallel with different amplification factors,
The signal outputs amplified by the amplifiers 4-1 and 4-2 are input to 12-bit A / D converters 6-1 and 6-2, respectively, and converted into 12-bit digital signals. The outputs of the A / D converters 6-1 and 6-2 are the lower 12-bit input D ₀ of the DSP 8 having a 24-bit data input.
˜D ₁₁ and upper 12 bits of inputs D _{12 to} D ₂₃ , respectively, and are processed in the same manner. From the DSP 8, the measurement signal with the amplification factor n times in the amplifier 4-2 and the amplifier 4-
The measurement signal with the amplification factor of m times 1 is digitally processed and output, and the optimum one is used according to the range of the input signal, whereby the dynamic range of the input signal is expanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing device for processing a detection signal in an analyzer or measuring device such as a mass spectrometer, a gas chromatograph or a liquid chromatograph,
In particular, the present invention relates to a detection signal processing device which is convenient for processing a signal having a large dynamic range and noise.

[0002]

2. Description of the Related Art A detection signal processing device such as a mass spectrometer is
The output signal of the detector is amplified by an amplifier having a preset amplification factor, and then converted into a digital signal by an A / D converter for data processing.

[0003]

If the dynamic range of the input signal is too large with respect to the preset amplification factor, the output signal of the amplifier will be saturated and the correct output cannot be obtained. In that case, the amplification factor of the amplifier is lowered and the measurement is performed again, but for that purpose, the measurement time becomes long. In addition, when the sample has only one measurement, remeasurement cannot be performed.

Further, in the case of accurately detecting the noise level and performing the noise processing, it is necessary to set the amplification factor such that the noise level can be sufficiently amplified even if the signal level is saturated. In this case, noise level detection and correct signal detection cannot be performed simultaneously. The noise and the fluctuation component of the signal can be easily extracted by detecting only the AC component excluding the DC component, but the measuring device for detecting the measurement signal is not configured to detect only the AC component.

Therefore, a first object of the present invention is to enable detection of an input signal having a large dynamic range with a simple structure. A second object of the present invention is to be able to detect a signal component and a noise component at the same time.

[0006]

In order to detect an input signal having a large dynamic range with a simple structure, a plurality of parallel connected units for inputting a detection signal of an analyzer and amplifying the signals with different amplification factors. Equipped with an amplifier. Further, in the first aspect of the present invention, the same number of A / D converters respectively connected to the output side of the amplifier and the digital signal outputs of the plurality of A / D converters are input different from each other. , And a single high-speed processor dedicated to digital signal processing that is input simultaneously.

In the second aspect of the present invention, the same number of hold circuits connected to the output side of the amplifier and holding data, one A / D converter, and the hold circuit are further held. Switching means for switching respective data having different amplification factors by time division and leading to the A / D converter, and a digital signal output of the A / D converter are input 1
And a high-speed processor dedicated to digital signal processing.

In a third aspect of the present invention, the amplifier is further connected to the output side of the amplifier and performs an operation including a level shift operation so that the output of each amplifier becomes a signal extending from the negative region to the positive region. And the same number of operational amplifiers, and one A / D converter with bipolar inputs,
By switching the outputs of the plurality of operational amplifiers, the A / D
It is provided with a switch means for leading to the converter, and one digital signal processing dedicated high speed processor for inputting the digital signal output of the A / D converter. Then, the digital signal processing dedicated high-speed processor processes these plural input data.

In order to detect a signal component and a noise component at the same time, according to the present invention, a plurality of amplifiers connected in parallel for inputting and amplifying a detection signal of an analyzer,
An AC coupling capacitor provided on the input side of one of the plurality of amplifiers, the same number of A / D converters connected to the output side of the amplifier, and the plurality of A / D converters. The digital signal output of the converter is simultaneously input as mutually different inputs, and one digital signal processing dedicated high speed processor is provided, and the signal component and the noise component are processed by the digital signal processing dedicated high speed processor.

[0010]

FIG. 1A shows a first embodiment. For example, when applied to a mass spectrometer, a preamplifier 2 that amplifies a detection signal of a detector of the mass spectrometer is provided, and the preamplifier 2 is connected in parallel to amplify the output of the preamplifier 2 with different amplification factors. Amplifiers 4-1 and 4-2 are provided. The amplification factor of the amplifier 4-1 is m, and the amplification factor of the amplifier 4-2 is n (m <n), where m and n are 1, 16 and
Amplification factors such as 32, 64, 128, 256, 512 can be set. The signal outputs amplified by the amplifiers 4-1 and 4-2 are 12-bit A / D converters 6-, respectively.
It is input to 1 and 6-2 and converted into a 12-bit digital signal. Reference numeral 8 is a DSP (high-speed processor dedicated to digital signal processing) having a 24-bit data input, and the lower 12-bit inputs D _{0 to} D ₁₁ are A / D of the signal amplified n times by the amplifier 4-2. The converted output is input, and the A / D converted output of the m-fold signal in the amplifier 4-1 is input as the upper 12-bit inputs D _{12 to} D ₂₃ . The DSP 8 simultaneously processes the upper 12-bit and lower 12-bit input signals and outputs them to the host CPU.

(B) shows the bit configuration of the input signal to the DSP 8. Amplifier 4-1 from DSP8
When the signal of the amplification factor m by the signal A and the signal of the amplification factor n by the amplifier 4-2 are both output, and the signal level amplified n times exceeds the maximum input range of the A / D converter 6-2 and overflows. , A / D converter 6-1 for signals with amplification factor m
The output signal of the
If the data of the amplification factor n by 2 is the input range of the A / D converter 6-2, an n-fold signal can be used. In this way, of the two types of amplification factors, the output signal with the optimum amplification factor can be adopted as data, and the dynamic range for the input signal is expanded.

As another method of use, only the noise of the minimum level is evaluated from the n-fold data, and the signal component data is obtained from the m-fold signal. It can also be processed.

FIG. 2A shows the second embodiment. Similar to FIG. 1, the amplifiers 4-1 and 4- are connected in parallel to the output of the preamplifier 2 for amplifying the signal of the detector of the mass spectrometer.
2 are connected, and their amplification factors are m for the amplifier 4-1 and n (m <n) for the amplifier 4-2 as in FIG. Sample-and-hold circuits 10-1 and 10-2 are connected to the outputs of the amplifiers 4-1 and 4-2, respectively. The sample-and-hold circuits 10-1 and 10-2 switch the sample-and-hold signals and guide them to the A / D converter 6. Analog switches 12-1 and 12-2 are provided on the output sides of the circuits 10-1 and 10-2, respectively. The A / D converter 6 has 8, 10, 12,
It has an output of 14, 16, 20 or 24 bits. The output signal of the A / D converter 6 is input to the DSP 8a for data processing.

Sample and hold circuits 10-1 and 10-2
And analog switches 12-1 and 12-2 are controlled to switch between the sample hold of the amplified signal and the signal input to the A / D converter 6, the control signals T _{1 to} T ₄ are respectively supplied. It is input from the host CPU side.

The operation of this embodiment will be described with reference to FIG. The detector signal amplified by the preamplifier 2 is amplified m times and n times by the amplifiers 4-1 and 4-2, respectively. Sampled and held by control signals T ₁ and T ₂ ,
₃ and T ₄ , the analog switch 12-1 is turned on, 12-
2 is controlled to be off. At this time, the data of the amplification factor m by the amplifier 4-1 is input to the A / D converter 6, converted into a digital signal, and input to the DSP 8a.

Next, the analog switch is switched so that 12-1 is off and 12-2 is on, and the A / D
A signal having an amplification factor n by the amplifier 4-2 is input to the converter 6, converted into a digital value, and input to the DSP 8a.

As described above, the signals having the amplification factors of m and n are time-divided by the analog switches 12-1 and 12-2, respectively, A / D converted, and input to the DSP 8a for digital signal processing. . The DSP 8a can process both the signal having the amplification factor m and the signal having the amplification factor n with a time lag, and can employ a signal having an appropriate amplification factor. Further, the measurement signal can be read by the one with a low amplification factor and the noise can be evaluated by the one with a high amplification factor.

FIG. 3A shows a third embodiment. FIG.
The same parts as those in (A) are designated by the same reference numerals and the description thereof will be omitted. Comparing with the embodiment of FIG. 2A, an operational amplifier for performing an operation including a level shift operation so that the detection signals at the positions of the sample and hold circuits 10-1 and 10-2 respectively extend from the negative region to the positive region. 14-1, 14
-2 are provided. The A / D converter 6a has a bipolar input.

As shown in (B) of the operational amplifiers 14-1 and 14-2, output signals Va = -R ₃ (Vb / R ₂ + Vc / R ₁ ) are obtained as the output Va. Vb is an input signal and Vc is a reference signal. In the output signal Va, the input signal Vb is amplified by (R ₃ / R ₂ ) times as shown in (C), and the output signal Va is level-shifted by (R ₃ / R ₁ ) Vc. That is, the reference signal Vc causes A /
An offset component is added to the signal level input to the D converter 6, and the input signal Vb is converted so as to extend from the negative region to the positive region. Since the A / D converter 6a has a bipolar input, the input voltage range of the input signal is doubled, and the dynamic range is expanded accordingly.

In the embodiment shown in FIG. 3 as well, the number of A / D converters 6a is one.
In order to lead to the D converter 6a, the analog switch 12-
1, 12-2 are provided.

FIG. 4 shows a fourth embodiment. Compared to the embodiment of FIG. 1, amplifiers 4-1 and 4-2
Respectively amplify m times and n times, and m and n may be the same or different. m and n are 1, 2, 4, 8, 16, 32, 64, 128, 256,
An amplification factor such as 512 can be selected. In this embodiment, the AC coupling capacitor 16 is provided on the input side of the amplifier 4-2.

Now, the operation of this embodiment will be described with m <n. The amplifier 4-1 inputs to the A / D converter 6-1 as a signal Sn obtained by multiplying the output signal of the preamplifier 2 by m, and the amplifier 4-2 cuts the DC component and multiplies only the AC component by n. Create Sa and input it to the A / D converter 6-2. The output signals of the A / D converters 6-1 and 6-2 are input to the DSP 8 and processed at the same time as in FIG.

The DC component of the signal Sa of the AC component is cut and becomes a signal of only the noise component and the fluctuation component of the signal. The result of digital processing of this signal component can be used for noise removal and signal processing in addition to the digital processing after the A / D conversion of the measurement signal Sn multiplied by m. It is also possible to perform noise evaluation using the digitally converted signal Sa. The embodiment of FIG. 4 does not expand the dynamic range, but is effective for noise processing and signal fluctuation processing.

[0024]

According to the present invention, a plurality of amplifiers connected in parallel for inputting the detection signal of the analyzer and amplifying them with different amplification factors are provided, and the outputs of these amplifiers are A / D converted into one amplifier. Since it is input to the DSP for digital processing, a plurality of output signals having different sensitivities can be taken out with a simple configuration, and the dynamic range of the input signal can be expanded. The present invention also includes a plurality of amplifiers connected in parallel for inputting and amplifying the detection signal of the analyzer, and an AC coupling capacitor is provided on the input side of any one of the amplifiers, and the output of those amplifiers is provided. Since A / D conversion is performed and input to one DSP for digital processing, a signal component and a noise component can be extracted with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment, (A) is a circuit diagram, and (B) is a diagram showing a bit configuration of an input signal to a DSP.

FIG. 2 is a diagram showing a second embodiment, (A) is a circuit diagram, and (B) is a timing diagram showing an operation.

FIG. 3 is a diagram showing a third embodiment, (A) is a circuit diagram, (B) is a circuit diagram showing an operational amplifier portion therein.
(C) is a waveform diagram showing the operation of the operational amplifier portion.

FIG. 4 is a circuit diagram showing a fourth embodiment.

[Explanation of symbols]

 4-1 and 4-2 amplifier 6,6-1,6-2,6a A / D converter 8,8a DSP

Claims (4)

[Claims] 1. A plurality of amplifiers connected in parallel for inputting a detection signal of an analyzer and amplifying them with different amplification factors, and the same number of A / A connected to the output sides of the amplifiers respectively.
A D converter and one digital signal processing dedicated high speed processor for simultaneously inputting the digital signal outputs of the plurality of A / D converters as mutually different inputs, and the digital signal processing dedicated high speed processor A detection signal processing device, which processes a plurality of input data. 2. A plurality of amplifiers connected in parallel for inputting a detection signal of an analyzer and amplifying them with different amplification factors, and the same number of hold circuits each connected to the output side of the amplifier and holding data. An A / D converter, switch means for switching the respective data held by the hold circuit and having different amplification factors in a time division manner and leading the data to the A / D converter, and the A / D converter And a single high-speed processor dedicated to digital signal processing for inputting the digital signal output of (1), wherein the plurality of input data are processed by the high-speed processor dedicated to digital signal processing. 3. A plurality of amplifiers connected in parallel for inputting the detection signal of the analyzer and amplifying them with different amplification factors, and the amplifiers respectively connected to the output side of the amplifiers. Switching the outputs of the same number of operational amplifiers as the above-mentioned amplifiers for performing the operation including the level shift operation, the A / D converter having a bipolar input, and the outputs of the plurality of operational amplifiers so as to obtain a signal over the range The above A / D
The digital signal processing dedicated high-speed processor for inputting the digital signal output of the A / D converter is provided with the switch means for leading to the converter, and the digital signal processing dedicated high-speed processor converts the plurality of input data. A detection signal processing device characterized by processing. 4. A plurality of amplifiers connected in parallel for inputting and amplifying a detection signal of an analyzer, an AC coupling capacitor provided on an input side of any one of the plurality of amplifiers, The same number of A / s connected to the output side of the amplifier
A D converter and a single high-speed processor dedicated to digital signal processing for simultaneously inputting digital signal outputs of the plurality of A / D converters as mutually different inputs. A detection signal processing device characterized by processing a noise component.