JPH0354437Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention is a strobe pulse generator used for purposes such as obtaining the sampling point when a high-speed repetitive signal is time-expanded by sampling and reshaped into a low-speed signal waveform. It is related to.

``Prior art'' As an example of a device that uses such sampling to reshape a high-speed repetitive signal into a low-speed signal waveform, we will explain the fluorescence analyzer shown in Figure 2 that uses laser light pulses. Constant period as shown in Figure 3 A from 1 to 3
T _r , for example, an extremely narrow pulse of 20 μs and a pulse width of 6 ns is supplied to the laser light source 2 as a driving pulse, and the laser light source 2 generates an extremely narrow pulse of laser light as shown in FIG. 3B. is input to the optical beam splitter 3.
In optical beam splitter 3, 9/10 of the incident optical pulse
1/10 of the remaining light amount passes through the filter 6 and enters the photodiode 7. As a result, the sample contained within the cell 5 emits fluorescent light, and the fluorescent light passes through the filter 8 and only the fluorescent components of the wavelength to be analyzed are input to the photomultiplier 9. The photomultiplier 9 converts the amount of input fluorescent light into the level of an electrical signal, and outputs a high frequency pulsed detection signal. This detection signal 16 corresponds to each laser pulse, for example, as shown in FIG. One sample at a time is sampled by strobe pulses 17 whose phases are sequentially shifted.

On the other hand, the laser light pulse input to the photodiode 7 is converted into an electric signal, and the synchronization signal generator 13 repeats the synchronization signal (fifth pulse) at a predetermined period.
Figure A) is created. This synchronization signal is transmitted to a strobe pulse generator 14, an LPF (low pass filter) 15,
It is used for a time axis reference such as the display 18. For example, the detection signal 16 is sampled with a strobe pulse 17 whose cycle is 97.6 picoseconds longer than the 20 μsec cycle of the synchronization signal in FIG. 3A. The detection signal 16 is a repetition of the same waveform, and the detection signal 16 having the same waveform is sequentially sampled by strobe pulses delayed by 97.6 picoseconds with respect to the synchronization signal pulse. In Fig. 3, the detection signal 16 is received at the same time as the laser pulse (Fig. 3B) is emitted, but since there is generally a time delay from the time the laser light enters the sample until the fluorescence is emitted, is detected with a delay depending on the type of

In this way, from the generation of laser pulses, e.g.
The detected signal for 200 nanoseconds is represented by 2048 samples as shown in FIG. 3D, resulting in a 200 nanosecond signal stretched to a length of 40.96 milliseconds. The detection signal time-expanded in this way is converted into a smooth signal through the low-pass waveform generator 15, and is further amplified by the DC amplifier 19 and displayed on the display 18.
is supplied to

In this way, a very short detection signal can be time expanded, received and displayed, and waveform processed.

In this way, in the time expansion circuit 15, the detection signal is sampled with the strobe pulse 17 whose phase is sequentially shifted with respect to the reference of the repetition for each repetition of the detection signal 16. It was as shown in Figure 4. That is, a reset signal is input from the input terminal 22 as shown in FIG. 5B in synchronization with the synchronization signal shown in _FIG . The transistor 23 is turned off during the period to be sampled, and the capacitor 24 is turned on during the other period.
Short-circuit to set the reset state. Therefore, this period
During T ₁ , the transistor 23 is non-conducting and the constant current circuit 25 charges the capacitor 24 with a constant current, and a sawtooth wave signal is obtained in the capacitor 24, which is amplified by the DC amplifier 26, as shown in FIG. C
A short sawtooth wave signal 27 as shown in FIG.

On the other hand, pulses from the terminal 22 are counted by a counter 28. For example, as mentioned earlier, the detection signal
When obtaining 2048 samples, counter 28 is
When 2048 is counted, the transistor 29 is made conductive for a certain period of time by the output of the counter 28, and the capacitor 31 is
short circuit to discharge its charge. Thereafter, while the counter 28 counts 2048, the transistor 2
9 becomes non-conductive, and the constant current circuit 32 charges the capacitor 31. In this case, the charging is done very slowly and gradually. The voltage of the capacitor 31 is amplified by a DC amplifier 33 to obtain a long sawtooth wave signal 34 whose level gradually increases as shown in FIG. 5D.

The short sawtooth signal 27 from the DC amplifier 26 and the long sawtooth signal 34 from the DC amplifier 33 are compared in a level comparator 35, and the short sawtooth signal 27 exceeds the level of the long sawtooth signal 34. The output of the comparator 35 becomes high level. Comparator 35
The rise of the output from the low level to the high level is detected by the differentiating circuit 36 and is obtained as a strobe pulse from the terminal 37 as shown in FIG. 4E.

Capacitor 24, constant current circuit 25, amplifier 26
The length T ₁ of each short sawtooth wave signal 27 generated in the short sawtooth wave signal generation circuit 38 consisting of
is the period of the detection signal 16 to be sampled,
In the example in Figure 2, this corresponds to a period of 200 nanoseconds,
The short sawtooth signal 27 in its period T ₁ is E ₁ to E ₂
capacitor 2 so that the level gradually increases until
A capacitance value of 4 and a constant current of the constant current circuit 25 were set. The constant current of the constant current circuit 25 is adjusted by a variable resistor 39.

Furthermore, in the long sawtooth wave circuit 41 consisting of the capacitor 31, the constant current circuit 32, and the DC amplifier 33, as shown in FIG. That is, a long sawtooth wave signal 34 whose output level gradually increases from E ₁ to E ₂ over a period 2048 times the period T _r of the synchronizing signal shown in FIG. 5A is generated. This is also determined by the constant current of the constant current circuit 32 and the capacitance value of the capacitor 31, and the constant current is adjusted by the variable resistor 4.
I was going by 2.

In this way, the long sawtooth signal 34 gradually rises, and the short sawtooth signal 27 is generated every fixed period T _r , and the point at which the short sawtooth signal 27 and the long sawtooth signal 34 coincide is reached. is a reference phase, that is, the phase is sequentially shifted by a constant value with respect to the repeated signal, in the above example, by 97.6 picoseconds, and a strobe pulse as shown in FIG. 5E or FIG. 3C is obtained.

Then, in the technique of detecting the intersection between the slope part of a short sawtooth wave signal as shown in Figure 5C and the slope part of a long sawtooth wave signal as shown in Figure 5D, a pulse is generated at this intersection. , the sawtooth wave signal was generated based on an analog circuit, that is, the waveform obtained by charging a capacitor.
-5189. Disclosed in Japanese Patent Publication No. 46-25593, etc., and also uses this sawtooth wave signal to convert the count value of the counter into AD.
JP-A-52-63774, JP-A-53-109462, etc., which generate signals based on signals obtained by conversion, are disclosed.

In addition, Japanese Patent Publication No. 59-34015 discloses a technique that uses a straight line portion with no blunt slope when generating a pulse by detecting an intersection point in a slope portion of a sawtooth wave.

``Problem to be solved by the invention'' In order to construct the above-mentioned strobe pulse generator simply and inexpensively, a short sawtooth wave signal is generated by an analog circuit, and a long sawtooth wave signal is generated by a counter. It is a good idea to configure combinations that are generated based on count values, but
Since each of these circuits is formed using active elements such as transistors, it is not possible to make the amplitude of each sawtooth wave signal uniform to a predetermined value, so adjustments must be made to make it operate according to a predetermined value. There is a need to do.

Therefore, there is a problem in how to configure and provide a circuit that can satisfactorily perform the above adjustment while maintaining stable generation of each sawtooth wave signal.

``Means for solving the problem'' This idea is based on the signal obtained by charging the capacitor as described above with a constant current circuit, and generates a sawtooth wave signal with a duration shorter than a predetermined period, that is, a short period. A sawtooth wave signal is created, and a signal obtained by DA converting the count value obtained by counting the signal at each predetermined period with a counter, that is, based on the AD conversion signal, a duration of multiple times the predetermined period described above is obtained. By creating a long sawtooth wave signal, that is, a long sawtooth wave signal with A strobe pulse generator that obtains pulse signals having intervals whose phases are sequentially shifted with respect to the above-mentioned predetermined period based on a signal obtained by detecting a point corresponding to a point where the sawtooth wave signal intersects with a slope portion. Non-adjustable short sawtooth wave generating means for generating the above short sawtooth wave signal using a sawtooth wave generating circuit having no variable adjustment portion, and varying the amplitude of the long sawtooth wave signal. In order to do this, the above DA conversion signal is passed through a variable resistor,
A long sawtooth wave input means is provided to the input side of the buffer circuit, and in order to change the DC level of the long sawtooth wave signal, the DC voltage obtained by the DC circuit separate from the above charging is connected to a variable resistor. DC level input means for applying the output signal of the buffer circuit to the input side of the buffer circuit through the buffer circuit; and comparison means for applying the output signal of the buffer circuit as the long sawtooth wave signal to the comparison circuit for comparison. By providing this, the above problem can be solved.

"Example" An example will be described below with reference to FIG.

In the figure, a short sawtooth signal generator 43 charges a constant current of a constant current circuit 44 to a capacitor 45, and the output of the capacitor 45 is transferred to a DC amplifier 36.
to obtain a sawtooth wave signal. In this case, the resistor used in the constant current circuit 44 is, for example, a metal film resistor, which has a small temperature coefficient and is extremely stable against changes in ambient temperature and changes over time. Also capacitor 4
As the capacitor 5, a highly stable material such as a styrene capacitor is used. capacitor 45
The charge is discharged periodically, that is, in synchronization with the repetitive signal. For example, the repetitive signal shown in FIG. 5A is input from the terminal 61 and supplied to the inverter 47 through the delay circuit 46. The input of this inverter 47 is at a low level during a certain period of the repetitive signal, for example, as shown in _{FIG .}
In the example above, it is longer than 200 nanoseconds, e.g.
It is said to be about 3 times as large. Therefore, the output of the inverter 49 is at a high level during this period, and at a low level during the other periods, and the charge in the capacitor 45 is discharged.
During _the period _T3 , the capacitor 45 is charged by the constant current circuit 44, and as shown _{in FIG} . It is obtained as the output of the DC amplifier 36. During the period T ₁ in the middle of this period T ₃ , the level rises from level E ₄ to E ₅ , and this level difference is made to be approximately equal to the level difference between E ₁ and E ₂ in Figure 5C. .

On the other hand, in the long sawtooth signal generating circuit 48, the clocks from the terminal 45 are counted by a counter 49. The clock supplied to the counter 49 is obtained by frequency-dividing the output of a stable oscillator, such as a crystal oscillator. This counter 49 is set so that when it counts the required number of samples, 2048 in the previous example, it becomes a full count. Preferably, the value of the full count can be changed as necessary. The count value counted by this counter 49 is converted into an analog signal by a DA converter 51. Therefore, the level of the output of the DA converter 51 gradually increases step by step, and for example, at a count value of 2048, the level reaches H in FIG.
As shown in the figure, it changes from approximately E ₄ to E ₅ .

The output of this DA converter 51 is supplied to an adjustment circuit 52. In the adjustment circuit 52, the output of the DA converter 51 is supplied to a buffer circuit 54 which also performs addition through a gain adjustment variable resistor 53, and the set level from the level setting circuit 55 is supplied to the buffer circuit 54. That is, in the level setting circuit 55, a level setting variable resistor 5 is connected in series between the power supply terminals.
6 is provided, a set level is obtained from the output of the mover of the variable resistor 56, and the set level is supplied to the non-inverting input side of the buffer circuit 54 through a resistor 57 and further through a resistor 58. . A connection point between resistors 57 and 58 is grounded through resistor 59. The level set by the level adjusting variable resistor 56 is divided by resistors 57 and 59 and supplied to the buffer circuit 54 through the resistor 58. Further, this adjustment circuit 52 can adjust the gain, and the gain adjustment is performed using the variable resistor 5.
3, the amplitude of the output of the DA converter 51 is controlled. That is, by adjusting the variable resistor 56, the DC level E _d can be adjusted with respect to the reference potential E ₀ in FIG. 5, and by adjusting the gain adjusting variable resistor 53, the sawtooth The difference ΔE between wave change amplitudes E ₄ and E ₅ can be adjusted.

The comparator 35 compares the short sawtooth signal 61 from the short sawtooth signal generation circuit 43 with the long sawtooth signal 62 from the long sawtooth signal generation circuit 48, and generates a short sawtooth signal. When the level of signal 61 exceeds the level of long sawtooth signal 62, the output of comparator 35 is inverted to high level, and the rising edge of the high level is output from terminal 37 as a strobe pulse from differentiation circuit 36. In the short sawtooth wave signal generation circuit 43, no adjustment is made to the short sawtooth wave signal 61. Therefore its level E ₃
The slope between E6 and _E6 is not constant and may deviate slightly from the set value. However, the DC level E ₀ superimposed so that the long sawtooth wave signal 62 crosses the short sawtooth wave signal 61 approximately at the center thereof is adjusted by the level adjustment variable resistor 56.
and also the required number of samples, in this example 2048
is obtained with a period T ₁ of the long sawtooth signal 6
The gain of 2, that is, the amplitude ΔE, is adjusted by the gain adjustment variable resistor 53. In this way, the desired strobe pulse can be obtained.

Note that when the count value of the counter 49 changes in the DA converter 51, whisker-like noise is superimposed on the output, causing so-called glitches, and in order to avoid malfunctions caused by this, the count in the counter 49 is performed in a short sawtooth shape. The delay amount of the delay circuit 46 is set so that it changes between the end of the wave signal 61 and the beginning of the next short sawtooth wave signal 61. Also, the level is adjusted so that the first strobe pulse is obtained with the leading edge of the reference repetition signal as a reference. Therefore, the reset signal of this short sawtooth wave signal, that is, the output of the delay circuit 46 (FIG. 5F), is produced with a corresponding phase shift from that of the repetition signal.

If the input of the comparator 35 becomes too high, it will not operate correctly. When such a fear occurs, the diode 71 becomes conductive, the output of the comparator 72 becomes low level, the transistor 73 becomes non-conductive, and the high voltage is absorbed by the capacitor 74.

"Effects of the invention" According to this invention, as mentioned above, the sawtooth wave signal generation circuit 43 for the short sawtooth wave signal is made into a circuit that does not require adjustment, so the circuit can be constructed easily and inexpensively, and the circuit elements Since the circuit is simple, it is easy to obtain a device that operates stably, and even if the amplitude of the short sawtooth wave signal becomes asymmetric due to the asymmetry of the circuit elements, it is easy to obtain a device that operates stably. The amplitude of the long sawtooth wave signal can be adjusted by the gain adjustment variable resistor 53 to adjust the amplitude relationship of each sawtooth wave signal to a predetermined relationship, and the level adjustment variable resistor 56 can adjust the amplitude of the long sawtooth wave signal. Since the position of the wave signal can be adjusted to match the part with good linearity in the middle of the slope part of the short sawtooth wave signal, it is simple to provide the adjustment means only on the side of the long sawtooth wave signal generation circuit. It has the advantage of being able to provide a strobe pulse generation operation balanced to the target value with an inexpensive configuration.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing an example of a strobe pulse generator according to this invention, FIG. 2 is a block diagram showing an example of a pulsed laser fluorescence analyzer using the strobe pulse generator, and FIG. A time chart for explaining the operation, FIG. 4 is a connection diagram showing a conventional strobe pulse generator, and FIG. 5 is a time chart for explaining the operation of the strobe pulse generator of FIGS. 1 and 4. It is. 35: Comparator, 36: Differential circuit, 43: Short sawtooth signal generation circuit, 44: Constant current circuit, 45:
Clock input terminal, 46: Integrating capacitor, 4
8: Long sawtooth signal generation circuit, 49: Counter, 51: DA converter, 52: Adjustment circuit, 53:
Variable resistor for gain adjustment, 55: Level setting circuit,
56: Variable resistor for level adjustment.

Claims (1)

[Claims for Utility Model Registration] Based on the signal obtained by charging a capacitor, a sawtooth wave signal having a duration shorter than a predetermined period (hereinafter referred to as a short sawtooth wave signal) is generated, and the predetermined period is The signal obtained by DA converting the count value obtained by counting each signal with a counter (hereinafter referred to as
A long sawtooth wave signal (hereinafter referred to as a long sawtooth wave signal) having a duration multiple times the predetermined period is generated based on the AD conversion signal), and the short sawtooth signal and the long sawtooth wave signal are generated. The predetermined period is determined based on a signal obtained by comparing the signals with a comparison circuit to detect a time point corresponding to a point where the slope portion of the short sawtooth wave signal and the slope portion of the long sawtooth wave signal intersect. A strobe pulse generator that generates pulse signals having intervals whose phases are sequentially shifted from each other, the strobe pulse generator comprising: (a) generating the short sawtooth wave signal by a sawtooth wave generation circuit having no variable adjustment part; adjusting short sawtooth wave generating means; b. passing the DA conversion signal through a variable resistor in order to change the amplitude of the long sawtooth wave signal;
a long sawtooth wave input means to be applied to the input side of the buffer circuit; d. a direct current level input means for supplying the output signal to the input side through the buffer circuit; and d comparison means for supplying the output signal of the buffer circuit as the long sawtooth wave signal to the comparator circuit for comparison. Strobe pulse generator.