JPH0295221A - Spectrophotometer - Google Patents

Abstract

PURPOSE:To synchronize the measurement output sampling period of the spectrophotometer with a source alternating current without using any circuit means by converting a source AC waveform and obtaining a pulse signal having the same period with the source alternating current, and using this signal as an interrupt signal at the time of measurement output sampling by a CPU. CONSTITUTION:A waveform shaping circuit 2 outputs a rectangular wave obtained by shaping the source AC waveform to an input/output device 1. When a rectangular wave rises, the input/output device 1 outputs the pulse signal, which is inputted directly to the interrupt signal input terminal of the CPU. The CPU performs specific interrupting operation when the signal is inputted to the input terminal. In such interrupting operation, the output sampling of a photodetector D and storing operation for a RAM are carried out. Thus, the pulse signal obtained by converting the current AC waveform is used as an interrupt signal, so the data sampling operation is synchronized with the source alternating current automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sampling device for measurement output in a spectrophotometer.

(Prior art) When the measured output of a spectrophotometer is processed by a CPU, the measured output is sampled at regular time intervals and
It is necessary to perform D conversion and input the measurement output into the CPU as digital data. In this case, since commercial AC is used as the power source for the spectrophotometer, the measurement output contains hum noise at the same frequency as the AC power supply and noise due to harmonic components of the AC power supply, so it is necessary to prevent the effects of these noises. Therefore, the sampling operation of the measurement output is synchronized with the frequency of the AC power supply. A conventional example of such a synchronous sampling method is Japanese Patent Application Laid-Open No. 63-1349.
There is No. 25. In this conventional example, circuit means are used to synchronize the measurement output sampling operation with the frequency of the AC power source. That is, this conventional example has a conversion period timer circuit means that determines the period of A/D conversion, and this timer circuit means is supplied with a power supply AC voltage and responds to a predetermined phase in a predetermined cycle of the power supply AC voltage to perform an old conversion. The end of the period and the start of a new conversion period are determined.

(Issues to be Solved by the Invention) If a circuit means such as the above-mentioned conventional example is used to synchronize the sampling period of the measurement output with the frequency of the AC power source in a spectrophotometer, the spectrophotometer The price of photometers will rise.

Therefore, the present invention seeks to synchronize the measurement output sampling period of a spectrophotometer with the mains alternating current without using the circuitry described above.

(Means for Solving the Problems) The power supply AC waveform was converted to obtain a pulse signal having the same period as the power supply AC, and this signal was used as an included signal at the time of measurement output sampling in the CPU.

(effect) The CPU performs A/D conversion of the measurement output of the spectrophotometer.

In addition to data sampling operations such as storing A/D converted data in memory, it processes measurement data, controls the spectrophotometer, and performs other operations, and data sampling operations interrupt other CPU operations. Therefore, for data sampling, an interrupt signal is sent to the CPU to interrupt other operations and then start the data sampling operation. In the present invention, a pulse signal obtained by converting a power supply AC waveform is used as the included signal, so the data sampling operation is automatically synchronized with the power supply AC waveform.

(Embodiment) FIG. 1 shows an apparatus according to an embodiment of the present invention. D is a photodetector whose output is sent via an amplifier A to an A/D converter A/D. C is a CPU that performs operations such as controlling the spectrophotometer and processing data. Ro is a ROM in which these operating programs are written, Ra is a RAM that stores photodetector output and other various data, and 1 is an input/output device. ROM,
RAM, input/output device 1, etc. are connected to the CPU via path line B.
It is connected to the. 2 is a waveform shaping circuit to which AC power is input. A rectangular wave obtained by shaping the power AC waveform is output from the waveform shaping circuit 2 and input to the input/output device 1 . The input/output device 1 outputs a pulse signal at the rise of the input rectangular wave, and directly inputs it to the interrupt signal input terminal IRQ of the CPU. The CPU performs a predetermined interrupt operation when a signal is input to the IRQ terminal. In this case, this interrupt operation is the sampling of the output of the photodetector and the storage operation in the RAM.

FIG. 2 is a time chart of the above-mentioned sampling operation. AC is a power supply alternating current waveform, and B is a rectangular wave shaped by the waveform shaping circuit 2 from the above waveform. The input/output device 1 outputs the pulse signal C to the IRQ terminal of the CPU at the rising edge of the waveform B. When a signal enters the IRQ terminal, the CPU
During the period shown in the figure, the output of the photodetector is sampled, the A/D converter AD is controlled, A/D conversion is performed, and the next E
RA the digital data of the photodetector output at the timing of
Store in M. In the time chart shown in Fig. 2, the CPU samples the photodetector output immediately upon receiving the interrupt signal, but by including a timing operation within the interrupt operation, the CPU performs the sampling operation, A/D conversion, and A/D conversion after a certain period of time from the interrupt signal. It is also possible to store data or the like.

(Effect of the invention) According to the present invention, as long as a signal synchronized with the power source AC is generated, C
The PU performs sampling of the measurement output by interrupt operation.
/D conversion, etc., and the adjustment of the phase relationship with the power supply AC can be adjusted by the CPU software, and it is also possible to change the data import format such as thinning out data or integrating the data of the number of steps. This simplifies the circuit configuration and improves the degree of freedom in operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a time chart of the main operations of the embodiment. D...Photodetector, AD...A/D converter, B...
Pass line, 1... input/output device, 2... waveform shaping circuit. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] It has a CPU that takes in the photometric output and processes the data, and a means for converting the power AC waveform to obtain a signal synchronized with the power AC waveform, and applies the signal to the CPU as an interrupt signal, and the CPU receives the interrupt signal. A spectrophotometer characterized in that the photometric output is captured by the following.