JPH0710267Y2 - Spectrophotometer photometric circuit - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a control system initialization device for controlling a dynode voltage of a photomultiplier tube of a spectrophotometer.

[Prior art]

The emission energy of the light source varies greatly depending on the wavelength.Therefore, in the spectrophotometer, an automatic control system that automatically adjusts the voltage applied to the dynode of the photomultiplier tube up and down to keep the photometric output at a constant value. (Dynode feedback system) and manual control system are usually provided,
It can be switched arbitrarily. In the conventional spectrophotometer, the automatic control system is always set in the initial setting after the power is turned on, but when the lamp burns out or the lamp fails to light, the incident light amount becomes extremely small. , The automatic control system tries to raise the signal intensity output from the photomultiplier tube to a certain set value and applies the maximum voltage to the dynode, which causes deterioration of the photomultiplier tube. there were.

[Problems to be solved by the device]

The purpose of the present invention is to extend the life of the high electron multiplier tube by eliminating unnecessary high voltage in the photoelectron multiplier tube in the spectrophotometer to eliminate the situation of promoting deterioration of the high electron multiplier tube. And

[Means for Solving the Problems]

In a photometric circuit of a spectrophotometer equipped with an automatic control system of a dynode feedback system and a manual control system, a lighting detection means for detecting a light source lighting state, and a light measurement circuit if the light source lighting state is normal by the detection means. Switching to an automatic control system is provided with switching means for switching the photometric circuit to a manual control system if the light source lighting state is defective by the detection means.

[Action]

According to the present invention, in the initial setting after the power supply of the spectrophotometer is turned on, the lighting state of the light source is confirmed before switching the photometric circuit to the automatic control system or the manual control system,
When the lighting condition is normal, the automatic control system is set, and when the lighting condition is abnormal, the manual control system is set, so that the photoelectron multiplication caused by the defective lighting condition in the initialization operation at the start of the spectrophotometer It was possible to prevent high voltage application to the tube, prevent deterioration of the photomultiplier tube, and extend the life of the photomultiplier tube.

【Example】

FIG. 1 shows an embodiment of the present invention. In FIG. 1, 1
Is a lighting monitor that monitors the lighting status of the light source, 2 is a CP
If the signal from the lighting monitor 1 indicates a good lighting state at U, connect the detector (photomultiplier tube) 6 and the automatic control system 5 with the changeover switch 3, and the signal from the lighting monitor 1 is in a poor lighting state. In the case of, the changeover switch 3 controls to connect the detector 6 and the manual control system 4. This control operation is also performed when the light source is broken or other accidents occur during the spectroscopic measurement. FIG. 2 shows details of essential parts of the above-described embodiment. In FIG. 2, L is a power source for the light source, and when the light source is turned on, the k point is at a low level, and when not turned on, it is at a high level. The high and low signals at the k points are input to the CPU via the input / output circuit I / O. When the spectrophotometer is powered on, the CPU switches the slider of the volume V to the 0 potential position and switches SW1 and SW2 to the contact a side, respectively. In this connection state of the switches SW1 and SW2, the output of the photomultiplier tube P goes through the preamplifier A and the comparator C.
Is input to the high voltage generating circuit H, the output of the high voltage generating circuit H is applied to the dynode of the high electron multiplication tube P, Dynode feedback is provided. If the light source is not lit, the CPU detects the state through the I / O and switches the switches SW1 and SW2 to the contact b side, respectively. In the connection state of the switches SW1 and SW2, the slider voltage of the volume V is applied to one terminal of the comparator in the manual control state, and the output voltage of the high voltage generation circuit H is applied to the + terminal of the voltage dividing resistor R. The voltage divided by is applied. Initially, the slider of the volume V is moved to the 0 potential position,
The 0 potential and the divided voltage of the high voltage generating circuit are compared by the comparator, and the dynode voltage of the photomultiplier tube becomes 0 and moves. Then, by manually operating the volume V, the output of the high voltage generating circuit H can be manually set arbitrarily. SW1 and SW2 can be switched from contact side a to side b by giving a command to the CPU.

【effect】

According to the present invention, when the light source lighting condition is normal, the photomultiplier tube control system is automatically connected to the automatic control system, and when the light source lighting condition is poor, the photomultiplier tube control system is connected to the manual control system. As a result, unnecessary high voltage is not applied to the photomultiplier tube, and the life of the detector can be extended. Also, if it is only for extending the life of the photomultiplier tube, when the light source of the spectrophotometer is turned on, the photometric circuit may always be in the manual control state, and after the light source is turned on, it may be manually switched to automatic control. The starting operation of the spectrophotometer is troublesome. According to the present invention, if the lighting state is normal, the measurement efficiency is not lowered because the automatic control system is automatically set.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a detailed view of essential parts in the above embodiment. 1 ... Lighting monitor, 2 ... CPU, 3 ... Changeover switch, 4 ... Manual control system, 5 ... Automatic control system, 6 ... Detector.

Claims (1)

[Scope of utility model registration request] 1. In a photometric circuit of a spectrophotometer equipped with a dynode feedback type automatic control system and a manual control system, lighting detection means for detecting a lighting state of a light source, and the lighting state of the light source is normal when said detection means. If so, the photometric circuit is switched to an automatic control system, and a switching means is provided for switching the photometric circuit to a manual control system if the light source lighting state is defective by the detection means, and the photometric circuit of the spectrophotometer.