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L6999 Scheda tecnica(PDF) 6 Page - Hamamatsu Corporation |
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L6999 Scheda tecnica(HTML) 6 Page - Hamamatsu Corporation |
6 / 7 page Figure 6 shows the external view and internal construction of a deuterium lamp. The anode has a unique structure covered with ceramic to prevent abnormal discharge, and the cathode has a highly durable electrode. Since a deuterium lamp uses the positive column flash of arc discharge, the cathode is shifted sideways and an aperture is located immediately in front of the anode so that high intensity is obtained. The aperture plate placed between anode and cathode may be used as an auxiliary elec- trode for lamps designed for low voltage lighting. 1Solarization 4Life 3Output stability 2Discharge starting voltage Transmittance of UV glass and fused silica drops when they are used over a long period. This is caused by a drop in transparency of the glass resulting from dirt on the glass and the influences of ultraviolet rays. In the worst case, the glass becomes cloudy and its life is short- ened. This is called solarization, and transmittance drops, particularly in short wavelength region. This phenomenon is hardly ever seen with synthetic silica. When the cathode is sufficiently heated and ready for arc discharge, a pulse trigger voltage is applied between anode and cathode, and dis- charge starts. The discharge starting voltage of 30 W deuterium lamps is approx. 350 V (400 V max.). However, since the discharge starting voltage rises according to the prolongation of operation time, it is rec- ommended that a voltage of approx. 500 V be applied to assure dis- charge. (The maximum applied voltage for trigger is 650 V.) The dis- charge starting voltage varies depending on the trigger method and trigger constant. (1) Drift Drift refers to variation of output over a long period caused as a result of the change in thermoelectron discharge characteristic of the cathode, change in gas pressure or dirt on the window. It is expressed in variation per hour. In the case of deuterium lamps, it takes 10 to 15 minutes until the inside of the lamp reaches thermal equilibrium after start of discharge, so a warm-up period of 20 to 30 minutes is required. (2) Fluctuation Fluctuation refers to variation of output caused by deterioration of the cathode or fluctuation of discharge position. Light output fluc- tuates approx. 0.05 % at intervals between a few minutes and a few hours. In addition, the position of the arc point also fluctuates. (1)Fluctuation of light output Life is determined by the point at which fluctuation combining fluctuation and shift exceeds 0.05 %p-p. (2)Drop of light output Life is determined by the point at which the total emitted energy drops to 50 % of the initial level. As described earlier, decrease in light output is caused mainly by solarization and dirt inside the window. The life specified is 2000 hours for L2-2000 series, and 4000 hours for L2-4000 series. 9 L2D2 Lamps (Deuterium Lamps ) OPERATING TEMPERATURE PRECAUTION AND WARRANTY 10 Table1: Allowable Operating Temperature Range for Deuterium Lamps Lamp Type +290 °C Max. +245 °C to +280 °C +10 °C to +50 °C (+20 °C to +30 °C)* L2D2 Lamp Cathode Type All Cathode type Ambient temperature: Ta Bulb wall temperature: Tb Maximum allowable bulb wall temperature: Tb Max. *Temperature enclosed by ( ) indicates the optimum ambient temperature. Warranty Optimum Operating Temperature As the ambient temperature (Ta) rises, cathode tem- perature increases, resulting in evaporation of the cathode. If the ambient temperature (Ta) drops, the gas pressure inside the bulb is reduced increasing the kinetic energy of the gas and ions causing sputtering of the cathodes thermionic coating. In both cases, the gas inside the bulb is rapidly consumed. This deterio- rates the stability and intensity. Thereby drastically shortening the operating life. For stable operation of deuterium lamps, care should be paid to the installation of the lamps so that the bulb wall temperature (Tb) does not exceed +290 °C. Precautions When Using Deuterium Lamps To obtain high stability and long operating life, ade- quate care must be paid to operating conditions includ- ing the operating temperature of the lamp. Although the lamp,s bulb wall temperature (Tb) rises as the ambient temperature (Ta) rises, the bulb wall temperature of conventional deuterium lamps normal- ly rises to approx. +200 °C (direct-heated cathode type) to 240 °C (SQ cathode type) when the ambient temperature is +25 °C. Moreover, the bulb wall tem- perature of the L2D2 lamps rises even further by +50 °C reaching +280 °C due to the way in which the elec- trode is constructed. (Bulb wall temperature (Tb) also differs depending on the lamp type and heater voltage as well as lamp housing.) Although the operating tem- perature of Hamamatsu L2D2 lamps has been designed based on lamps operated under normal tem- perature, the temperature range given in the table below is recommended as the allowable operating temperature range enabling the use of the lamps over a long period of time with high stability. Deuterium lamps emit ultraviolet rays which can be harmful to your eyes and skin. Never look directly at the emitted lights, nor should you allow it to come into contact with your skin. Always wear protective goggles and clothing when operating the lamps. Since the bulb wall reaches a very high tempera- ture (over +200 °C) when the lamp is on, do not touch it with bare hands or bring flammable objects near it. Do not exert mechanical vibration or shock on the lamp, otherwise the stability will deteriorate. Silica glass graded sealing. In the case of bulbs using silica glass, the window is formed by connecting different glass sections hav- ing slightly different expansion rates. Since the mechanical strength of these seams is low, the bulb fixing method should be so arranged that no force is exerted on these seams during fixing or opera- tion. Before turning on the lamp, wipe the bulb and win- dow gently with alcohol or acetone. Dirt on the win- dow will cause deterioration of the UV transmission, so always wear gloves when handling the lamp. High voltage is used to operate the lamp. Use extreme caution to prevent electric shocks. 1. 2. 3. 4. 5. 6. The warranty period will be one year after our ship- ment to original purchaser or guaranteed life time whichever comes first. The warranty is limited to replacement of the faulty lamp. Faults resulting from natural disasters and incorrect usage will also be excluded from warranty. Ta: Temperature measured at a position 2.5 cm (1 inch) away from the bulb wall Tb: Temperature on the bulb wall (cathode side) 2.5 cm (1inch) Ta Tb Construction Figure 6: External View and Electrode Construction APERTURE ANODE CATHODE BULB CERAMIC ELECTRODE (CENTER PIECE) CERAMIC ELECTRODE (REAR PIECE) LIGHT OUTPUT TLSOC0030EA Construction External view Terminology Discharging the L2D2 Lamps Figure 7: Example Circuit Diagram 300mA CONSTANT- CURRENT POWER SUPPLY (150 to 160 V dc) RT (5 k Ω) R (<3 k Ω) TRIGGER SWITCH TRIGGER POWER SUPPLY (500 to 600 V dc) CT (>0.1 µF) ANODE DEUTERIUM LAMP CATHODE HEATER POWER SUPPLY TLSOC0019EB TLSOC0020EB •Auxiliary electrode operation •Conventional circuit 300mA CONSTANT- CURRENT POWER SUPPLY (150 to 160 V dc) RT (1 to5 k Ω) TRIGGER SWITCH CT (0.2 to 0.5 µF) ANODE DEUTERIUM LAMP CATHODE HEATER POWER SUPPLY In deuterium lamps, an aperture electrode is placed between cathode and anode to compress the discharge, so that high light intensity is obtained. This required, a high voltage trigger discharge across cathode and anode. In general, a typical power supply for deuterium lamps consists of the follow- ing three power supplies. G Constant current power supply of 300 mA (open voltage about 150 V) G Trigger power supply of 500 to 600 V peak G Power supply for the heater (about 10 W) However, in view of the need for cost reduction, safety and downsizing, lamp manufactures are evaluating methods that eliminate the trigger power sup- ply. One of these is the use of an auxiliary electrode. In this approach, the electrical energy from a constant current power supply of 150 V/300 mA (main power supply) is stored in a trigger capacitor and then is discharged between lamp shield box and cathode. This generates ions and momentarily reduces the impedance between anode and cathode, leading to the main dis- charge. However, because this trigger discharge occurs only at a restricted point near the cathode, it is a less reliable triggering method. In the L2D2 lamp, ceramic insulators are used as part of the electrode sup- port, so that the aperture potential is isolated from the shield box potential. Since this aperture electrode is used as an auxiliary electrode, the trigger dis- charge can be guided to the aperture, allowing operation at a voltage 40 to 50 V lower than that of a conventional lamp. This also results in higher reli- ability of the triggering operation. Thus, the greatest advantage of the auxili- ary electrode is that no trigger power supply is necessary. The circuit shown on the below, resulting both a cost reduction and downsizing of the power supply. When the L2D2 lamp series with an aperture size of 0.5 mm diameter will be operated by the circuit as shown above, it is recommended to employ CR constant as RT=1 k Ω and CT=0.5 µF to obtain the reliable lamp ignition. ELECTRODE BULB LEAD WIRE TECHNICAL INFORMATION |
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