JPH0548399Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lighting device for a deuterium discharge tube used in a spectrophotometer.

[Conventional technology]

In order to obtain a continuous spectrum of ultraviolet rays, the deuterium discharge tube used in the spectrophotometer has a metal partition wall 6 having a recess 5 with a pinhole 4, as shown in the A-A cross-sectional view of FIGS. 4 and 5. is provided between the anode 2 and the cathode 1, and is configured so that a focused positive column that generates a continuous spectrum is formed near the pinhole 4. The cathode 1 is a thermionic emission cathode, and the cathode 1 and the anode 2 are partially covered with a metal shielding case 3 in order to remove the effects of arc spots on the cathode surface and anode glow on the anode surface that occur during discharge. A metal partition wall 6 with pinholes 4 arranged on the front surface of the anode 2 is electrically connected to the shielding case 3, and these are connected to deuterium gas and a quartz bulb 8 having an ultraviolet transmitting window 7. and the cathode heating lead wires 9 and 10, the anode lead wire 11 and the shielding case lead wire 1.
2 are led out of the quartz bulb 8, respectively.

The lighting device for the deuterium discharge tube with the above configuration is as follows:
As shown in FIG. 6, an AC power supply 13, a rectifier 1
4. A closed circuit consisting of a ballast 15, an anode 2 and a cathode 1 of a deuterium discharge tube 16, and a constant current device 17, connected in parallel with the deuterium discharge tube 16, and connected in parallel with a capacitor 19 and a resistor 20. A pulse generating circuit including a diode 18, a DC power source 21, and a cathode heating power source 22 are provided. In the figure, 23 indicates an on/off switch.

The cathode heating lead wires 9 and 10 and the anode lead wire 11 of the deuterium discharge tube 16 are connected to the cathode heating power source 22 and the anode terminal of the lighting device, respectively, and the shielding case lead wire 12 is connected to the cathode heating lead wire. 9 or 10, a pulse voltage is applied between the anode 2 and the cathode 1 of the deuterium discharge tube 16 by the power supply connection pulse circuit to start discharge, and the pinhole 4 Forms a shining pillar of focused sunlight near .

[The problem that the idea aims to solve]

The discharge starting voltage is determined by Patsien's law, but the relationship between the diameter of the discharge tube and the discharge starting voltage is
As shown in FIG. 7, as the diameter of the discharge tube becomes smaller, the discharge starting voltage increases. Figure 7 shows an example of discharge in air when the distance between the electrodes is 2.7 cm, and curves 24, 25, 26, 27, 28, and 29 have discharge tube diameters of 6.2 cm, 2.1 cm, 1.3 cm, and 0.95 cm, respectively. cm,
Cases of 0.5cm and 0.3cm are shown. However, since the deuterium discharge tube discharges through the pinhole 4 provided between the anode 2 and the cathode 1 as described above, the discharge path is partially constricted, and therefore the general structure is A discharge starting voltage higher than that of the discharge tube is required. this is,
This method has disadvantages in that the cathode 1 in the hot cathode discharge tube is greatly consumed, and it also has a disadvantageous effect on lighting circuits and pulse circuits using semiconductor elements, such as requiring a withstand voltage. Furthermore, as the deuterium discharge tube approaches the end of its life, abnormal discharge occurs due to deterioration of thermionic emission at the cathode and depressurization of the enclosed deuterium gas, and normal self-sustaining arc discharge does not occur, and the anode 2 and Glow discharge only occurs between the shielding case 3 or between the shielding case 3 and the cathode 1, and regular self-sustaining arc discharge does not start.

An object of the present invention is to obtain a lighting device for a deuterium discharge tube that has a low discharge starting voltage and operates stably.

[Means to solve the problem]

For the above purpose, a resistor having a resistance value of 5 kΩ or more and 5 MΩ or less is usually connected between the anode terminal and the shielding case terminal of the deuterium discharge tube lighting device in order to lower the discharge starting voltage. in series with this
A resistor with a resistance value of 50Ω or more and 500Ω or less,
This is achieved by connecting to a shared terminal point of the hot cathode filament.

[Effect]

A closed circuit consisting of an AC power supply, a rectifier, a ballast, an anode and a cathode of a deuterium discharge tube, a constant current control device, a diode connected in parallel with the deuterium discharge tube, a capacitor and a counter, and a DC power supply. In a deuterium discharge tube lighting device that includes a pulse generation circuit and a cathode heating power source, a 5kΩ resistance is applied between the anode terminal and the shield terminal of the lighting device.
The discharge starting voltage is lowered by connecting a resistor with a resistance value of 5MΩ or less, but in the above method, if the resistance value is 5kΩ or less, the glow discharge becomes large, and the glow discharge is emitted from the heated metal. As the electrons transfer to arc discharge, it becomes difficult to discharge between the filament and the filament.In addition, if the resistance value is 5MΩ or more, the glow discharge generated is too small to assist lighting, and from the viewpoint of pressure and electron radiation, it is difficult to discharge between the filament and the filament. It can be said that a resistance value in the vicinity is optimal. In series with the above resistor,
In the present invention, a resistor having a resistance value of 50Ω or more and 500Ω or less is connected to the cathode common terminal of the cathode filament terminal, so that the shielding case of the deuterium discharge tube and one terminal of the cathode filament are electrically connected,
Produce a preliminary discharge between the pinhole and the anode,
It is designed to discharge at a low discharge starting voltage. The electron emission characteristics of the cathode oxide in the above deuterium discharge tube have a saturation current value around 20V, and an optimum value of 150Ω has been determined through experiments. As the deuterium discharge tube approaches the end of its life, the deterioration of thermionic radiation and the depressurization of the deuterium gas sealed inside the tube cause the deuterium discharge tube's pressure curve to change, resulting in a gap between the anode and the shielding case. Although a glow discharge is generated as a preceding discharge, the discharge does not migrate to between the cathodes. Therefore, in series with the resistor between the anode terminal and the shield terminal, a resistor having a resistance value of 50Ω or more and 500Ω or less is connected to the common terminal point of the hot cathode filament to apply a potential to the electron emitting part, and The glow discharge between the shielding case and the cathode is arranged to transfer to between the cathode and the shielding case.

Assuming that the above resistor does not exist, the glow discharge between the anode and the shielding case remains as a glow discharge between the shielding case and the cathode, and does not progress to a regular arc discharge. It turns out.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a circuit diagram showing an embodiment of the deuterium discharge tube lighting device according to the present invention, Fig. 2 is a diagram showing the relationship between the cathode heating voltage and the discharge starting voltage, and Fig. 3 is a diagram showing the relationship between the cathode heating voltage and the discharge starting voltage. It is a partial sectional view showing an example.
As shown in FIG. 1, the deuterium discharge tube lighting device according to the present invention comprises an AC power source 13, a rectifier 14, a ballast 15, an anode 2 and a cathode 1 of a deuterium discharge tube 16, and a constant current control device 17. a diode 1 connected in parallel with the deuterium discharge tube 16 and connected in parallel with a capacitor 19 and a resistor 20;
8, a pulse generation circuit including a DC power source 21, and a cathode heating power source 22, between the anode terminal 30 of the lighting device to which the deuterium discharge tube 16 is connected and the shielding case terminal 31, 5kΩ or more
Connect a resistor 32 having a resistance value of 5MΩ or less,
And in series with this, between the shielding case terminal 31 and the lead wire 10 of the cathode filament, there is a resistance of 50Ω or more.
A resistor 33 having a resistance value of 500Ω or less is connected. In the figure, 23 is an open/close switch for the closed circuit and the cathode heating power source 22. When the cathode 1 is heated and the AC power source 13 is connected, a pulse voltage is applied between the anode 2 and the cathode 1 of the deuterium discharge tube 16 by the pulse generating circuit, but the cathode 1 is electrically connected to the shielding case 3. Since the potential difference between the pinhole 4 and the anode 2 is smaller than that between the anode 2 and the cathode 1, a preliminary discharge is first generated between the anode 2 and the pinhole 4. During this time, the cathode 1 has already been heated and a floating state of thermoelectrons has been formed in the vicinity of the cathode 1. Therefore, following the preceding discharge, the discharge moves between the anode 2 and the cathode 1, and the pin A beam of focused sunlight is formed near the front of the hole 4. However, as the end of its life approaches, the Patsien curve gradually changes compared to its initial state due to deterioration of thermionic radiation and depressurization of deuterium gas. If there is a resistance of 50Ω or more between the shielding case 3 and the lead wire 10 of the cathode filament 1,
Assuming that there is no resistor 33 with a resistance value of 500Ω or less, the floating state of thermionic electrons near the cathode 1 will change as the thermionic radiation deteriorates, and the relationship between the anode 2 and pinhole 4 will change. It remains a glow discharge which is a preliminary discharge between the anode 2 and the cathode filament 1, and does not progress to an arc discharge between the anode 2 and the cathode filament 1. Furthermore, as the pressure of deuterium gas decreases, the potential between the shielding case 3 and the cathode filament 1 is different, and the potential between the anode 2 and the pinhole 4 is lower than that between the shielding case 3 and the cathode filament 1. Only a glow discharge is generated, and the anode 2
There is no transition to arc discharge between the cathode filament 1 and the cathode filament 1. In Fig. 2, curve A shows the relationship between the cathode heating voltage and the discharge starting voltage when the resistance value of the resistor 32 is 50 kΩ and the resistance value of the resistor 33 connected in series with this resistor 32 is 200Ω. The curve B shows the shielding case 3 as the cathode 1.
The conventional lighting device shown in FIG. 6 is connected to the conventional lighting device shown in FIG.
It was found that when the cathode heating voltage was 5 V or more, the deuterium discharge tube lighting device of this example discharged at a lower firing voltage even at the end of its life compared to other lighting devices. As shown in FIG.
It is also possible to connect between the anode lead wire 11 and the shielding case lead wire 12 within the flare of the stem 8' that supports the resistors 32, 33. quartz valve 8
Since it is located outside of the deuterium discharge tube 16, it is possible to avoid being directly affected by the high temperature caused by the lighting of the deuterium discharge tube 16.

[Effect of idea]

As described above, the deuterium discharge tube lighting device according to the present invention has a closed circuit consisting of an AC power source, a rectifier, a ballast, an anode and a cathode of the deuterium discharge tube, and a constant current control device, and a closed circuit that is connected in parallel to the deuterium discharge tube. connected,
In a deuterium discharge tube lighting device that is equipped with a pulse generation circuit including a diode and a DC power source connected in parallel with a capacitor and a resistor, and a cathode heating power source, there is a resistance of 5 kΩ or more between the anode terminal of the lighting device and the shielding case. By connecting a resistor with a resistance value of 5MΩ or less, and connecting a resistor with a resistance value of 50Ω or more and 500Ω or less in series to the common terminal point of the hot cathode filament, the deuterium discharge tube can be shielded. After generating a preliminary discharge between the pinhole electrically connected to the case and the anode,
It is possible to shift the discharge to between the anode and the cathode and operate stably at a low discharge starting voltage until the end of its life, and furthermore, by incorporating the above-mentioned lighting device, it is possible to downsize the spectrophotometer. .

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the deuterium discharge tube lighting device according to the present invention, Fig. 2 is a diagram showing the relationship between the cathode heating voltage and the discharge starting voltage, and Fig. 3 is a diagram showing the relationship between the cathode heating voltage and the discharge starting voltage. FIG. 4 is a partial cross-sectional view of a deuterium discharge tube, FIG. 5 is a cross-sectional view taken along line A-A in FIG. 4, and FIG. 6 is a circuit diagram showing a conventional lighting device. FIG. 7 is a diagram showing the relationship between discharge tube diameter and discharge starting voltage. 1... cathode, 2... anode, 3... shielding case,
13... AC power supply, 14... Rectifier, 15... Ballast, 16... Deuterium discharge tube, 17... Constant current control device, 18... Diode, 19... Capacitor, 20... Resistor, 21... DC power supply, 22...
...Cathode heating power supply, 32, 33...Resistor.

Claims (1)

[Scope of utility model registration request] A closed circuit consisting of an AC power supply, a rectifier, a ballast, the anode and cathode of the deuterium discharge tube, a constant current control device, a diode connected in parallel with the deuterium discharge tube, a capacitor and a resistor, and a DC power supply. In a deuterium discharge tube lighting device equipped with a pulse generation circuit and a cathode heating power source,
A resistor with a resistance value of 5 kΩ or more and 5 MΩ or less is connected between the anode terminal of the lighting device and the shielding case terminal, and a resistor with a resistance value of 50 Ω or more and 500 Ω or less is connected in series with the hot cathode. A lighting device for a deuterium discharge tube, characterized in that it is connected to a common terminal point of a filament.