JPS6321309B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rapid start type fluorescent lamp.

Rapid start type fluorescent lamps usually have a NESA film (transparent conductive coating) formed on the inner surface of the fluorescent tube (glass tube) to obtain rapid lamp starting characteristics. However, this fluorescent lamp had the disadvantage that, as shown in FIG. 1, a peculiar deterioration phenomenon known as pockmarking (a phenomenon in which the lamp changes color to blackish brown in the form of spots) occurs as a result of long-term use. The cause of this phenomenon is thought to be as follows. That is, the position where the pock phenomenon A occurs is a position 10 to 20% of the length from both tube ends 1a and 1b of the fluorescent tube 1 (120
This is the coldest part of the tube wall of the phosphor tube 1 (10 to 30 cm for cm-long 40W type lamps), and is where the excess mercury sealed inside the tube condenses and adheres to the surface of the phosphor. This corresponds to the easy part. On the other hand, while the fluorescent lamp is lit, the mercury particles in the tube are subjected to a potential approximately corresponding to the discharge potential distribution in the tube, and the NESA membrane is at an approximately intermediate potential, and at the location where mercury aggregates, the mercury particles and the NESA A considerable potential difference is applied between the membrane and the phosphor. When the phosphor breaks down due to this potential difference, the heat of the discharge energy causes the phosphor to melt or scatter.
At the same time, it also releases impure gases such as oxygen. As a result, the mercury oxidizes, becomes amalgamated, or the phosphor is metamorphosed and becomes colored, and due to repeated discharge breakdown and occurrence of discharge breakdown in various parts of the mercury-attached area, it gradually becomes pockmarked as shown in Figure 1. It appears in the form of

On the other hand, when considering the startability of this rapid-start type fluorescent lamp, it changes depending on the state of the encapsulated mercury and the starting auxiliary conductor such as Nesa film. In other words, since the mercury that serves as the discharge material is used in a temperature-saturated form (most of it remains in liquid form and only a portion is gasified), its characteristics change greatly in response to changes in ambient temperature, and its startability is poor. As shown in FIG. 2, the problem worsens as the temperature becomes lower or higher. Moreover, this characteristic can be changed by changing the lamp design, for example by (1) making the tube diameter smaller, (2) changing the rare gas inside the tube to a heavier rare gas (e.g. krypton), or (3) increasing the rare gas pressure inside the tube. If you increase it, etc., it will shift to a worse direction, and eventually,
Startability will vary depending on the application, depending on the ambient temperature or design in which the lamp is used. However, regarding the other starting auxiliary conductor, compared to so-called external stripe type lamps in which conductive stripes are applied to the outer surface of the lamp, Nesa membrane has much better starting performance overall.
Due to the influence of the mercury state, the startability will deteriorate at low temperatures of 0° C. or lower or due to the above-mentioned design changes. In this case, it is conceivable that the resistance can be improved by lowering the resistance value over the entire length of the Nesa film coated on the entire inside of the pipe. Looking at the relationship between the Nesa membrane resistance and the starting voltage, as shown by curve It turns out that it is possible to improve startability regardless of the application. However, this resistance also has a great influence on the occurrence of the pock phenomenon described above, and as shown by the curve Y in Figure 3, the smaller the resistance, the greater the pock occurrence.
Below this, there is a tendency for the problem to become extremely poor, and even if it is desired to lower the Nesa membrane resistance in order to improve the starting performance, it is limited by the occurrence of pockmarking.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rapid start type fluorescent lamp that can prevent the occurrence of pockmarking and further improve startability.

In view of the above-mentioned causes of pock formation, this invention suppresses pock formation by forming depressions in a certain range on the surface of the phosphor layer, and reduces the resistance value of the Nesa film, thereby eliminating pock formation and improving startability. It was designed to make things better.

That is, first considering the cause of the pock occurrence, the degree of dissolution or scattering of the phosphor caused by dielectric breakdown depends on the degree of dielectric breakdown, that is, the breakdown discharge voltage. This breakdown discharge voltage is the fourth
As shown in Figure a, it depends on the layer thickness d1 of the phosphor 2. In the figure, 3 is a Nesa membrane and 4 is a mercury grain. Therefore, if the layer thickness d1 is made smaller, the voltage will decrease, but
This will result in a decrease in luminous flux, so if the depression 5 is formed as shown in FIG. This makes it possible to suppress the degree of dissolution and scattering of the phosphor, thereby suppressing pockmarking. Moreover, since the mercury grains 4 having a potential tend to fall and adhere to the bottom of the depressed portion 5 near the Nesa membrane 3, it is possible to suppress the decrease in luminous flux and prevent the occurrence of pockmarking. This depression 5 is based on the principle that
It is considered that the deeper the layer is (for example, 1/2 or more of the layer thickness), the wider the opening area (for example, 5 μ ² (square microns) or more), and the greater the number of depressions, the more effective it is at preventing pock marks. The manufacturing method for the depression is, for example, using phosphor powder with an average particle size of about 12μ,
It is obtained by cutting fine powder of about 5 μm or less by a sedimentation method, suspending it in an organic solvent such as amyl acetate, applying the solution to a glass tube using a conventional manufacturing method, drying it, and firing it. In particular, the condition of the depressed portion can be easily changed by adjusting the amount of thickener such as nitrocellulose mixed into the solvent.

However, the presence of the depressions 5 may cause uneven brightness due to a partial reduction in luminance, and if the number of depressions increases, the layer thickness of the phosphor becomes smaller on average, which may lead to a reduction in luminous flux.

Therefore, we first used an ordinary fluorescent tube, and
A NESA film of about 50KΩ was formed, a phosphor was coated with a coating amount of about 3mg/cm ² using the above manufacturing method, a fluorescent lamp was made with the amount of mercury sealed in about 30mg, and this fluorescent lamp was used to create a cavity. We investigated the feeling of uneven brightness with respect to the number of copies. The results are shown in Figure 5.
On the vertical axis of the figure (the feeling of uneven brightness), a is the position where the uneven brightness is felt greatly, b is the position where it is felt normally, c is the position where it is felt slightly, and d is the position where it is unknown or not felt at all.
It is plotted against the number of depressions (×10 ⁵ /mm ² ) on the horizontal axis. From this figure, the number of depressions is approximately 10 ⁶ /
It was found that no brightness unevenness occurs when the thickness is mm ² (=10 pieces/(100μ×100μ)) or more. Next, using the same fluorescent lamp as above, the number of depressions was set to about 10 ⁶ /mm ² ,
The luminous flux (%) and the degree of occurrence of pockmarks (%) with respect to the area ratio of the total area of the depression to the inner surface of the phosphor were investigated. The results are shown in Figure 6.
In the figure, S is a luminous flux curve, and V is a pockmark curve. That is, in the area ratio range of 1/200 to 1/20,
It has been found that this method can be put to practical use without causing pockmarks or reducing the luminous flux.

To summarize the above, the number of depressions is
By limiting the area to 10 ⁶ /mm ² or more and 1/200 to 1/20 in terms of area ratio, the luminous flux does not decrease compared to conventional ones without depressions, there is no uneven brightness, and there is no pock phenomenon. The result is that it is suitable for practical use.

Furthermore, using a fluorescent lamp with such a recessed part, we investigated the relationship between the resistance of the Nesa film and the degree of occurrence of pockmarks. The results are shown in Figure 7.
In the figure, Q1 has the number of depressions approximately 3 (pieces/100μ×100μ),
The comparison curve when the area ratio is 1/500 or less (equivalent to almost no depressions), and Q2 is the curve when the number of depressions is approximately 10 (pieces/100μ x 100μ) and the area ratio is approximately 1/200 ( (equivalent to the condition of the depressed area mentioned above)
It is. From this figure, it is possible to reduce the resistance value of the NESA film to 50KΩ or less for the phosphor layer having the depressions, and as a result, the startability can be further improved compared to the conventional method. However, the lower limit of the Nesa membrane resistance value is preferably about 10KΩ. This is because the Nesa membrane is in parallel with the discharge path of the phosphor tube, and when the Nesa membrane resistance value drops below 10KΩ, the power consumption in the Nesa membrane cannot be ignored and the loss increases. For example, in the case of a 40W fluorescent lamp, when the Nesa membrane resistance value is 10KΩ, the resistance value of the discharge path is approximately 0.23KΩ.

As described above, the rapid start type fluorescent lamp of this invention has a resistance of about 10K of the conductive transparent film.
Ω or more and approximately 50KΩ or less, and depressions with an area ratio of 1/200 to 1/20 are formed on the surface of the light layer at 10 ⁶ or more/mm ² , so that luminous flux is reduced without uneven brightness. Moreover, it has the effect of improving startability without causing pockmarking.

[Brief explanation of the drawing]

Figure 1 is a bottom view of a conventional rapid-start type fluorescent lamp, Figure 2 is a characteristic diagram of starting voltage versus temperature, Figure 3 is a characteristic diagram of starting voltage versus resistance of the full length of the Nesa membrane, and Figure 4 is a diagram of starting voltage versus temperature. An enlarged cross-sectional view of the main part of the optical lamp. Figure 5 is a characteristic diagram of uneven brightness against the number of depressions. Figure 6 is a characteristic diagram of luminous flux (%) and degree of pockmarking against the area ratio of depressions. Figure 7 is a characteristic diagram of NESA. FIG. 2 is a characteristic diagram of the degree of pock occurrence versus the resistance value of the entire length of the film. 1... Fluorescent tube, 2... Fluorescent body, 3... Nesa membrane, 4... Mercury grain, 5... Recessed part.

Claims (1)

[Scope of Claims] 1. A fluorescent tube, a conductive transparent film having an electrical resistance of about 10KΩ or more and about 50KΩ or less, which is coated all around the inner surface of the fluorescent tube, and this conductive transparent film. A phosphor layer coated on the inner surface of the phosphor layer, with 10 ⁶ particles/mm ² or more formed on the inner surface of the phosphor layer and 1/200 of the total area of the inner surface of the phosphor layer.
A rapid start type fluorescent lamp equipped with a bottomed depression for reducing breakdown discharge voltage formed at an area ratio of ~1/20. 2. The rapid start type fluorescent lamp according to claim 1, wherein the depth of the depressed portion is 1/2 or more of the thickness of the phosphor layer, and the surface area thereof is 5 μ ² or more. .