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Difference between revisions of "Philips HPL-N"
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== History == | == History == | ||
HPL-N lamps are high pressure mercury vapour lamps that have been produced, with somewhat similar properties, since the 1950s. The lamp's fluorescent coating technology dates back to around the end of 1930s while modern lamps were essentially manufactured as early as 1970s and are a result of subsequent improvements up until that time. The market for these lamps grew as industry and commercial activity recovered after the Second World War, meaning that research was justified by large sales. | HPL-N lamps are high pressure mercury vapour lamps that have been produced, with somewhat similar properties, since the 1950s. The lamp's fluorescent coating technology dates back to around the end of 1930s while modern lamps were essentially manufactured as early as 1970s and are a result of subsequent improvements up until that time. The market for these lamps grew as industry and commercial activity recovered after the Second World War, meaning that research was justified by large sales. | ||
The lamp technology was an improvement of previous lamps that used a clear envelope and had an alumino-silicate glass where the mercury discharge was constrained. Colour reproduction was nonexistant, being so low as to render people and everything natural around them as being dead. Increasing the pressure and temperature of the mercury vapour gas discharge to emit more useful light was possible only with the advent of quartz discharge tubes. Colour reproduction was only slightly improved but lower wattage lamps were much more efficient. Up until late in production, the clear lamp was avoided except for street lighting and some industrial applications. Subsequently, mercury vapour lamps were heavily used in street lighting and industry. Colour rendering was the highest barrier to market success. Improvements focused on colour reproduction but energy efficiency and reliability increases were areas with best results. | |||
Development of fluorescent coatings that emit red light made the lamp more desirable although good flourescent powders were mass produced and cheap only in late 1970s. The lamps itself were running hot so fluorescent powders had to withstand temperature and UV-C exposure stress for many years while also emitting more light than the coating powder absorbed. The first generation powders had mild colour improvements but Yttrium Vanadate ones were highly successful and durable, making the lamp suited even for some indoor illumination, especially for deluxe lamps. Near the end of production deluxe lamps were very common and standard lamps such as the HPL-N were incorporating most developments specific to these top-of-the-line lamps. These improvements made high pressure mercury vapour lamps suited for industrial, commercial, street-lighting and even some occasional residential use. | |||
The energy crisis meant that clients demanded improvements and they were focused on improving these lamps, giving rise to derivatives such as metal-hallide lamps, with much better colour reproduction and lower energy consumption. Sodium lamps were improved, culminating in the high-pressure sodium lamps that, with their yellow-orange or golden glow, dominated exterior lighting. By late 1980s mercury vapour lamps where on a market share decline that lasted more than 25 years. This can be attributed mostly to inertia in replacing fixtures that had a lifetime of around 15 years because new installations were not done after mid 1990s due to availability of compact or linear fluorescent lamps. | |||
These lamps were not intended for home or office use and they were seldomly used as such. Tungsten lamps had perfect colour reproduction and electric energy costs were very low. Even after the oil crisis of the early 1970s, tungsten lamps were still cheap enough and convenient to be used for general lighting. Also, these lamps did no require any gear. | |||
These lamps were not intended for home or office use and they were seldomly used as such. Tungsten lamps had perfect colour reproduction and electric energy costs were very low. Even after the oil crisis of the early 1970s, tungsten lamps were still cheap enough and convenient to be used for general lighting. Also, these lamps did no require any gear | |||
== Manufacturing specificities == | == Manufacturing specificities == | ||