JPH0467758B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an electroluminescent lamp, and particularly to a light emitting layer that emits light upon application of an alternating electric field.

Conventional technology Organic electroluminescent lamps, which are used for displaying characters and figures, and as light sources for liquid crystal displays, are generally
As disclosed in Japanese Patent Publication No. 36-8479 and Japanese Patent Publication No. 40-8575, a back electrode such as aluminum, a high dielectric constant dielectric material such as cyanoethyl elrose, and a white high dielectric material such as barium titanate powder are used. An electroluminescent lamp element consisting of a reflective insulating layer made of a mixture of powdered derivatives, a light-emitting layer made of fluorescent particles dispersed in cyanoethyl cellulose, etc., a transparent electrode made of ITO, etc., and a laminate of transparent resin films with a resin outer film. Constructed by thermocompression sealing. When an AC voltage is applied between the back electrode and the transparent electrode, the phosphor particles in the light emitting layer are excited by the AC electric field and emit light.

The luminance, efficiency, and lifespan of such an electroluminescent lamp are greatly influenced by external conditions such as the magnitude and frequency of the voltage applied between the two electrodes, and especially by the internal conditions of the light emitting layer. In other words, if the particle sizes of the phosphor particles in the light-emitting layer are made larger, the lifespan will be extended, but leakage current will increase and the efficiency determined by the brightness per unit power will decrease, and the unevenness of the light-emitting layer will increase, causing luminescence spots. arise. On the other hand, if the particle size of the phosphor particles in the light-emitting layer is made small, the leakage current will be reduced, efficiency will increase, and luminescence spots will be reduced. is known to be shorter.

Therefore, in general electroluminescent lamps, the phosphor particles in the light-emitting layer are made of particles with a normal distribution of various particle sizes, that is, particles that are not classified based on particle size. I was getting something.

Problems to be Solved by the Invention Recently, the demand for electroluminescent lamps has been increasing in other directions, and there is a tendency for lamps with improved lifespan and efficiency to be improved. However, as mentioned above, products with long lifespans have poor efficiency, and increasing efficiency has a contradictory relationship with shortening lifespans. Therefore, products that are unsatisfactory in both lifespan and efficiency are used, and cannot fully meet the above requirements. The current situation was that I couldn't do it.

Means for Solving the Problems The present invention has been made in view of the increasing demand for electroluminescent lamps, and the need for a lamp with good longevity and efficiency. The layer is composed of large phosphor particles with an average particle size of 30 μm or more, and a mixture ratio of 1 wt% to 10 wt% of large phosphor particles with an average particle size of 3 μm.
It is formed by mixing pigment particles with a small particle diameter of m or less into a dielectric material.

Effect: According to the above technical means, since the phosphor particles contained in the light emitting layer have a large particle size, moisture deterioration of the phosphor particles is slow, and therefore the life of the electroluminescent lamp is extended. Furthermore, the small-sized pigment particles contained in the light-emitting layer exhibit the effect of suppressing leakage current, thereby improving the efficiency of the electroluminescent lamp. Furthermore, the small-sized pigment particles are intermixed between the large-sized phosphor particles to reduce the unevenness of the light-emitting layer, thereby reducing luminescent spots.

Embodiment The present invention will be explained based on an embodiment of FIG. 1. In FIG. 1, 1 is a back electrode, 2 is a reflective insulating layer, 3 is a light emitting layer, which is a feature of the present invention, 4 is a transparent electrode, and 5 is a reflective insulating layer. is a transparent resin film that serves as the base material of the transparent electrode 4. An electroluminescent lamp element is formed by laminating 1 to 5 above, and this electroluminescent lamp element is layered from above and below directly or through a moisture-absorbing film such as nylon 6. An electroluminescent lamp 7 is formed by sandwiching the resin outer films 6, 6 and sealing the resin outer films 6, 6 protruding from the periphery of the electroluminescent lamp element by thermocompression. The light-emitting layer 3 includes an organic dielectric material 8 such as cyanoethyl cellulose, phosphor particles 9 made to have a large particle size by classification, and the phosphor particles 9.
It is formed by mixing pigment particles 10 having a sufficiently smaller particle size in a desired weight ratio.

The phosphor particles 9 are normally distributed phosphor particles represented by the chemical formula ZnS:Cu, which are classified to have a uniform particle size of 30 μm or more. The pigment particles 10 are either Basic Cred-1 (Chemical Substance No. (5)-1947) or Solvent Yellow-44 (Chemical Substance No. (5)-3050).
General pigments with a particle size of 3 μm or less are used. The mixing weight ratio of the phosphor particles 9 and the pigment particles 10 is 10 to 100 of the phosphor particles 9 to 1 part of the pigment particles.
Setting 0 to about 1 brings about good results in terms of characteristics.

Next, examples of various experimental results that clarify the characteristic improvement effect of the present invention will be explained with reference to FIGS. 2 to 5. In addition, A of the graph in Fig. 2 to Fig. 4 is
B is a product of the present invention in which 3 wt% of the weight of the phosphor is mixed with pigment particles of 3 μm or less into large phosphor particles of 30 μm or more; The first conventional product has no pigment, and C is a general second conventional product in which the phosphor particles in the light emitting layer have a normal distribution, that is, they are not classified and have various particle sizes.
D is 3wt of pigment of 3μm or less in the luminescent layer of the second conventional product.
% of the third conventional product for comparison with the present invention. This experiment was conducted at an ambient temperature of 50°C and humidity of 90%.
These are the results obtained by applying a voltage at a frequency of 400 Hz under the following conditions.

Figure 2 shows the results of a life test in which the lamps were turned on at the same initial brightness and the reduction in brightness was investigated. However, in order to make the initial brightness the same, for graphs A and B, the applied voltage is
140V, and those in graphs C and D were applied with an applied voltage of 130V. Generally, when lighting the same electroluminescent lamp, it is known that the brightness deteriorates more when the applied voltage is increased. Approximately 200 items
While the brightness is halved before and after time, Clubs A and B, which use large-diameter fluorescent particles, and Clubs 1
With the conventional product, it took more than 600 hours for the brightness to halve, even though the applied voltage was increased. This shows that the product of the present invention has a long life almost as long as the first conventional product.

Figure 3 is a graph showing the results of examining the brightness-power consumption characteristics. Figure 3 shows that when a pigment is mixed into the light-emitting layer, the power consumption required to turn on the light at the same brightness is lower than when no pigment is mixed. It can be seen that efficiency increases.

Figure 4 is a graph showing the results of examining the voltage-current density characteristics. This figure shows that when the same voltage is applied, the current flowing in the case with pigment is less than that without pigment. Even so, the efficiency improvement effect of the present invention is demonstrated.

Figure 5 shows the results of investigating the luminance deviation between the product of the present invention and the first conventional product shown in graph B in each of the above experiments.
with the reference position (0 point) and move the photodetector 1mm to the left and right.
This was done by moving it at intervals and measuring the brightness of each point. Graph A' in Figure 5 shows the luminance deviation of the product of the present invention, and graph B' shows the luminance deviation of the first conventional product.As a result, the luminance deviation of the product of the present invention is approximately 1/2 smaller than that of the first conventional product. It can be seen that lighting with fewer luminescent spots is possible.

Effects of the Invention According to the present invention, it is possible to provide a long-life, high-efficiency electroluminescent lamp that eliminates the disadvantage of low efficiency of conventional long-life electroluminescent lamps that use large-diameter fluorescent particles in the light-emitting layer. .

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view including a partially enlarged sectional view showing one embodiment of the present invention, and FIGS. 2 to 5 are characteristic diagrams showing experimental results of the product of the present invention and the conventional product. 3...Light emitting layer, 8...Drivative layer, 9...Large diameter phosphor particles, 10...Small diameter pigment particles.

Claims (1)

[Claims] 1 The mixing ratio of large-sized phosphor particles with an average particle size of 30 μm or more and the large-sized phosphor particles is
An electroluminescent lamp characterized in that a light-emitting layer is formed by mixing 1wt% to 10wt% of pigment particles with an average particle size of 3 μm or less into a dielectric material.