JPS6215749A - Variable-colored fluorescent lamp - Google Patents

Abstract

PURPOSE:To stabilize the discharge in discharge paths from the beginning of life to the end thereof, by emplacing a common cathode and paired anodes so that the discharge paths provided between a hot spot produced on the common cathode and the anodes do not contain the common cathode. CONSTITUTION:A common cathode 4 and paired anodes 3a-3d are emplaced so that discharge paths provided between a hot spot produced on the common cathode and the paired anodes do not contain the common cathode. Even if the position of the hot spot at the biginning of life differs from that of the hot spot at the end of life, the fluctuation in the ratio between the lengths of the discharge paths 12a-12c for colors and that of the discharge path 12d for pseudo-putting-out is reduced to fix the ratio between the luminance of the colors. Since the fluctuation in the length of each of the discharge paths is little, stable discharge is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a variable color fluorescent lamp used in a large color display device.

[Background Art] Conventionally, variable color fluorescent lamps of this type used in large color display devices have been shown in FIGS. 1IIi7 to 10. That is, this variable color fluorescent lamp has a U-shaped part 1a, 1 made up of three U-shaped glass tubes.
b, 1 c, and a rectangular parallelepiped part 2 formed from a lath plate.
and the U-shaped portion 18t 16. The inner surface of the IC is coated with phosphors of different emission colors (for example, red phosphor, green phosphor, and blue phosphor), and the U-shaped portions 1a of each are coated.

At one end of 1b and 1c is an anode 38t for controlling light emission.
3b and 3c are sealed. On the other hand, the rectangular parallelepiped part 2
On the front side, there are communication holes 5a, 5b, 5c that communicate with the other open ends of the U-shaped parts 18t1b, 1c.
A common cathode 4 made of a linear filament (coil) is provided in the rectangular parallelepiped portion 2 serving as a common discharge space and paired with each PIh electrode 3 at 3 b, 3C. In addition, a common cathode 4 provided in the common discharge space
An auxiliary anode 3d for starting and dimming that does not contribute to light emission is provided on the side of the anode. Here is the U-shaped part 1 at
The discharge space consisting of 1b, 1c and the rectangular parallelepiped part 2 is kept airtight with the outside, and the inside is filled with a rare gas.
A metal vapor gas such as mercury is sealed in the rectangular parallelepiped portion 2. The outer surface of the rectangular parallelepiped portion 2 is covered with a light shield (not shown).

FIG. 11 shows an example of a basic circuit of such a lighting control device for a variable color fluorescent lamp, in which a DC power supply 8 connects each anode 3 at 3 via a selection switch circuit 7 that switches the discharge path.
b, 3c and the auxiliary anode 3d, and by controlling the discharge switching timing, the emitted light color is changed. In addition, each anode 3 lit 3
Current limiting elements 6a to 6c are connected in series to the electrodes b, 3c and the auxiliary anode 3d, respectively, so that a constant lamp current flows therethrough. In the figure, a starter 9 generates high voltage at the time of starting.

The selection changeover switch circuit 7 is specifically formed of a switching transistor whose on/off duty is made variable by a control circuit, and connects the DC power supply 8 to each anode 3 at 3 b, 3 c and the auxiliary anode 3 at appropriate timing.
d to switch the discharge path. !
@14 and V Figure 15 is the anode 3a.

3b, 3c and the auxiliary anode 3d are time charts (shown by the operation of the switch contacts 78 to 7d) showing the timing at which the DC power source 8 is applied to the auxiliary anode 3d, and each repetition period T set by the clock pulse. A red light emitting period TR1, a green light emitting period Tc, and a blue light emitting period T are set within the red light emitting period TR, and the repetition period T is set so that flickering due to switching does not occur. Figure 14 shows the brightest luminescence! ! ! (Each light emission period T
It appears to emit light during the entire period of R, T,, T! ! This shows the different power supply conditions. Note that although the light emitting positions of each color are not at the same position, if viewed from a sufficiently long distance, or if the colors are mixed using a diffusing means, it will appear as if the light is emitting substantially white light. FIG. 15 shows a case where the actual light emitting period of each color is set to 1/2 of each possible light emitting period T,, T,, T, by the selection changeover switch circuit 7, and the brightness is as shown in FIG. 1 compared to the case
/2, and the light is in a 50% dimming state.

In this case, during the period when discharge is occurring between the common cathode 4 and the auxiliary anode 3d, the phosphor does not emit light, and the phosphor appears to be in an off state, which is a period in which the phosphor is off. In addition, this period when the luminous body is off is completely turned off! ! (discharge stop state), but if the completely turned off state is repeated, there is a problem that the temperature change of the common cathode 4 becomes severe and the life of the common cathode 4 is shortened. Therefore, during the period when the light emitter is off, a constant current is caused to flow through the common cathode 4 by causing discharge to occur between the light emitter and the auxiliary anode 3d, resulting in a so-called pseudo-light-off state. As described above, in this variable color fluorescent lamp, by switching the discharge path at high speed using the selection changeover switch circuit 7, an arbitrary emission color can be obtained, and the brightness can also be dimmed by using the auxiliary anode 3d. It has become.

By the way, when this variable color fluorescent lamp is used in a large color display device, it is necessary to downsize the display screen, but when the display screen is downsized, the proportion of the common cathode 4 that occupies the discharge space increases. Therefore, there are cases where the hot spot on the common cathode 4 made of a linear filament is located at the right end 4a as shown in FIG. 12, and when it is located at the left end as shown in FIG. Now, the discharge path 10a.

10a', 10b, 10b', 10c, 10c', 1
There will be a considerable difference in the discharge path lengths (0d and 10d'). Therefore, for example, if the current limiting elements 6 at 6 b, 6 et 6 d are designed under conditions such that the hot spot is at the position shown in FIG. When the spot gradually moves to the left and reaches the position shown in FIG. 13, the current limiting elements 6 a, 6 b, 6 et
6d would deviate considerably from the optimum value, causing problems such as poor circuit efficiency of the lighting control device and loss of color balance. In other words, due to the difference in the length of each discharge path between the beginning of life and the end of life, the balance of discharge is disrupted and the discharge becomes unstable, resulting in poor circuit efficiency, and the color balance of the colored light emitted by each discharge is also disrupted. was there.

In particular, an auxiliary anode 3d and a common cathode 4 for starting and dimming.
The difference in the discharge path length between the open and open discharge paths is remarkable. Further, as the lighting time becomes longer, the tube voltage during discharge corresponding to each color changes, and the circuit constant of the lighting control device may deviate significantly from the optimum value, making it impossible to maintain the discharge.

[Object of the Invention] The present invention has been made in view of the above points, and its object is to be able to stably perform discharge in each discharge path from the beginning of life to the end of life, An object of the present invention is to provide a variable color fluorescent lamp that can simplify the design of circuit constants of a lighting control device.

[Disclosure of the Invention j (Embodiment 1) Figures 1 and 2 show an embodiment of the present invention, in which one common cathode 4 made of a linear filament and a plurality of common cathodes 4 paired with the common cathode 4 are shown. Anode 3 at for controlling light emission of
3 b, 3 c and auxiliary anode 3 d are arranged in the discharge space, and the common cathode 4 and each anode 3 lit 3 b, 3 c are arranged in the discharge space.
In a variable color fluorescent lamp similar to the conventional example in which a discharge path is appropriately formed between the common cathode 4 and the anodes 3a and 3d to obtain different emission colors, a hot spot occurs on the common cathode 4 and the paired anodes 3a, 3d. The common cathode 4 is arranged so that the discharge path formed between the common cathode 4 and the common cathode 4 is not included in the discharge path formed between the
and anodes 3a, 3b, 3c, and 3d. Here, in the embodiment, the arrangement is such that an isosceles triangle is formed with the auxiliary anode 3d as the apex and the common cathode 4 as the base, and the common cathode 4 is arranged in the direction of its transverse direction (X direction in the figure). are three discharge paths 12a, 12b,
12c, and which discharge path 12a=12b, 12c.

12d is also arranged so as not to include the axis of the common cathode 4.

The operation of the embodiment will be described below. In the present embodiment, the discharge path formed between the hot spot generated on the common cathode 4 and the paired anodes 3 m, 3 b, 3 e, and 3 d does not include the common cathode 4. a common cathode 4 and each anode 3 a, 3 b, 3 c, 3
d, and even if the position of the hot spot moves between the beginning of life and the end of life, the discharge paths 12a, 12b, 12c of each color and the discharge path 12 when pseudo-extinguished
Fluctuations in the ratio of the lengths of the discharge paths d can be reduced, and the ratios of the brightness and brightness of each emitted color can be made constant. *In addition, since there is little variation in discharge path length, discharge is performed stably and circuit efficiency does not deteriorate.
The constant design of d is simplified. Especially when the hot spot moves, the auxiliary anode 3d
The difference in discharge path length between the common cathode 4 and the common cathode 4 becomes smaller, and the above effect becomes 'lX'! J.

(Example 2) Figures 3 to 6 show another example, in which the U-shaped portion 1 at 1 b = 1 c is arranged in a delta, and a common discharge space is formed in a hollow cylindrical portion 2a. The common cathode 4 is included in the plane of symmetry of the three U-shaped parts 1 at 1 b, 1 c, and the common cathode 4 has two parts with this as the base and the auxiliary anode 3 d as the apex. Located in the position of an equilateral triangle, the central part of the common cathode 4 has a communication hole 51Lt5b,
5 It is equidistant from c. As shown in FIGS. 5 and 6, the common cathode 4 in the embodiment is arranged at an angle so that the distances between the hot spot and each of the communicating holes 5 m, 5 b, and 5 c are approximately equal. There is.

Note that since the operation and effects are exactly the same as in the first embodiment, the explanation will be omitted.

[Effect of the Invention 1] As described above, the present invention includes one common cathode made of a linear filament and a plurality of anodes for light emission control that are paired with the common cathode, which are arranged in the discharge space, and the common cathode In a variable color fluorescent lamp, in which a discharge path is appropriately formed between a common cathode and each anode to obtain different emission colors, a discharge is formed between a hot spot that occurs on a common cathode and a paired anode. Since the common cathode and each anode are arranged so that the path does not include a common cathode, the discharge in each discharge path can be performed stably from the beginning of life to the end of life, and lighting control i
! This has the effect of simplifying the design of circuit constants for c positions.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of one embodiment of the present invention, Fig. 2 is a partially cutaway side view of the same as above, and Fig. tJ3 is a perspective view of another embodiment.
Figure 4 is a partially cutaway front view of the same as above, Figures 5 and 6 are partially cutaway side views of the same, Figure 7 is a perspective view of the conventional example, and Figure 8 is a partially cutaway front view of the same as above. 9 and 10 are partially cutaway side views of the same as the above, FIG. 11 is a block circuit diagram of the lighting control device of the same, and FIGS. 12 to 15 are diagrams for explaining the operation of the same. 3 at 3 b, 3 c, and 3 d are anodes, 4 is a common cathode, and 12a. 12b, 12e, and 12d are discharge paths. Agent Patent Attorney Ishi 1) Chief 7 Figure 4 Figure 8 Figure 13 μ) N)

Claims (2)

[Claims] (1) One common cathode made of a linear filament and a plurality of anodes for light emission control that are paired with the common cathode are arranged in a discharge space, and an appropriate discharge path is provided between the common cathode and each anode. In variable color fluorescent lamps that emit different colors by forming a hot spot on the common cathode,
A variable color fluorescent lamp characterized in that a common cathode and each anode are arranged so that a discharge path formed between the pair of anodes does not include a common cathode. (2) The variable color fluorescent lamp according to claim 1, wherein the difference in discharge distance between a hot spot generated on the common cathode and each anode paired therewith is minimized.