JPS588542B2 - fluorescent display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bar graph display fluorescent display device with a light emitting function, and an object of the present invention is to provide a device that vividly visually shows changes in the amount of information when the amount of information is displayed in analog form as a bar graph. This is the purpose.

Fluorescent display devices use zinc oxide phosphor, the only practical low-speed electron beam-excited phosphor, to display the characters of electronic desk calculators,
Widely used as a numerical display device.

Compared to display devices using other display elements such as light emitting diodes, liquid crystals, plasma displays, electroluminescent and electrochromic display elements, this fluorescent display device has (1) good visibility characteristics;
Due to its features such as 2) high brightness, (3) long life, (4) high degree of freedom in display patterns, and (5) low price, the range of applications has expanded beyond the character and number display of electronic desktop calculators. For displays on electronic registers, desks, and automobile clocks,
Recently, it has also been used to display the output of audio equipment and the time of timers in microwave ovens and washing machines.

In audio equipment, a bar graph display format is particularly used to display the output of an amplifier, and because this structure can visually appeal to various types of information in an analog display, it is also used as a display in a variety of other equipment. The value is high.

For example, it is ideal for analog display of automobile speedometers, fuel level meters, or water temperature gauges.

Recently, in addition to zinc oxide phosphors that emit blue-green light, phosphors that can emit red, blue, and yellow colors have been developed for fluorescent display devices, and multicolor technology has been established. A display device with an even richer amount of displayed information and easier viewing can be created.
If progress is made further, it has the potential to create a large color flat panel display that can replace the conventional cathode ray tube.

The present invention advances this color technology further by changing the mixing ratio of two or more types of phosphors with different emission colors in a stepwise manner in a series of anode segments to form a bar graph of a bar graph display device. The mixed phosphors are sequentially applied, and the emitted light color is changed stepwise in each segment.

As a result, when a certain amount of information is displayed in analog form as a bar graph, changes in the amount of information can be visualized vividly, and in particular, it is possible to display the transition process until reaching a certain noteworthy limit value in the display of certain information. suitable for

For example, when a bar graph is displayed on a fluorescent display device such as a car speedometer, it is green when the speed is 80 km/h or less;
m/h or more, the light is red, and in the middle, the anode segment can be made to emit light stepwise from green to red according to the present invention.

That is, since the proportion requiring attention can be displayed by changing the color tone of the light-emitting segments of the bar graph in stages, it can be said that the amount of transmitted information has increased.

Emitting multicolor light from intermediate colors between the two nine colors is,
This is not possible with other display elements such as light emitting diodes, and this is an advantage of fluorescent display devices, which have a high degree of freedom in display patterns not only in the structure of the segments but also in terms of functionality.

Next, a specific embodiment for realizing the bar graph display function of the present invention will be described.

EXAMPLE 1 A bar graph fluorescent display consisting of ten anode segments is shown in FIGS. 1 and 2.

FIG. 1 is a front view of the display device, and FIG. 2 is a side view thereof.

In these figures, G is a glass container with a vacuum inside, and a glass substrate S supporting an anode segment and a fluorescent film is housed in the container.
, a fluorescent film P is supported.

C is a mesh grid electrode, and H is a linear cathode whose surface is coated with an oxide for thermionic emission.

The circuit for causing the fluorescent film P coated on the anode segment A to emit light is described only for the first anode segment 1 in principle.

VH is a heater voltage, and a voltage of 2 to 3 V is applied to heat the cathode H, which is made of a tungsten wire whose surface is coated with oxide, to about 600°C.

Thermionic electrons are extracted from this cathode by a mesh grid C to which a voltage ■ is applied, and the electrons that have passed through the mesh are finally accelerated by the anode voltage VA and collide with the phosphor film P, causing the phosphor to emit light. Excite and emit light.

The mesh-like grid C functions to extract thermoelectrons and cause them to collide uniformly with the fluorescent film P.

Grid C also functions to control the excitation current density by changing VC.

In the bar graph fluorescent display device as described above, a red-orange-emitting europium-activated tin oxide phosphor SnO2:Eu and a green-emitting copper, aluminum-activated zinc sulfide fluorophore ZnS:Cu,Al are disposed on the anode segment. As will be described later, phosphors are mixed in appropriate proportions and applied.

SnO2:Eu phosphor has been recently developed as a phosphor that emits light at an excitation voltage as low as 5V.

ZnS:Cu, Al is often used as a green-emitting phosphor in cathode ray tubes of color televisions.

If this phosphor is applied alone, it will not emit light because it will be rapidly charged up at the moment of electron beam irradiation due to the powder's high electrical resistance when exposed to low-speed electron beams of 100 V or less.

However, due to the coexistence of the above-mentioned semiconductor powder SnO2:Eu, light can be emitted at a voltage of about 20 V without being charged up.

SnO2:Eu and ZnS:CusAl phosphors are mixed in the weight proportions shown in Table 1, and each is applied onto the anode segments numbered 1 to 10 shown in FIG.

Segments 1 to 5 have a mixing ratio of SnO2:Eu/ZnS:
Coat the same Cu and Al with 1/9, and the 6th one with 3/9
The mixing ratio is changed stepwise such as 5/5 for 7th and 7th, 9/1 for 8th, and the same mixing ratio of 9/1 is applied for 8th to 10th.

Configure the phosphor of the anode segment as above, apply 3V to VH, 20V to VC, and apply 30V and 60V to VA.
Table 1 shows the luminescent color of each segment when

The excitation current density of the phosphor film is 1.0 mA/cm2.

It can be seen from the table that the color of the emitted light changes somewhat depending on the excitation voltage η.

When the vA is 30V, the color changes from yellow-green to orange, and when the vA is 60V, the color changes stepwise from green to yellow for each segment of Nos. 5, 6, 7, and 8.

When VA=30v, the 6th and 7th segments are both yellow, but of course the 6th segment is greenish, and the 1st segment is orange, so their tones are different.

The brightness is 20 foot Lamberts for orange and 60 foot Lamberts for yellow-green when VA = 30 V and excitation current 1 mA/cm2, and 40 foot Lamberts for yellow and 70 foot Lamberts for green when VA = 60 V and excitation current 1 mA/cm2. Got Lambert.

These brightnesses are practically sufficient for ordinary character displays.

Example 2 Using the same bar graph display device as in Example 1, a blue-green-emitting zinc oxide phosphorescent ZnO:Zn and a yellow-emitting silver-activated zinc sulfide cadmium phosphor (Zn0.6Cd0.4)S:
Table 2 shows the results of coating various mixed Ag phosphors using the same method as in Example 1.

However, in Table 2, segments 5, 6, 7, and 8 with different mixing ratios
Only the numbers are listed.

The phosphors No. 5 and below and No. 8 and above are each coated with the same mixing ratio of phosphor.

(Zn0:6Cd0:4)S:Ag phosphor is ZnS:C
If it is used alone as a fluorescent film like u, Al, the electrical resistance of the powder is large, so it is immediately charged up at the moment of electron beam irradiation and does not emit light below 100V.

However, when semiconducting ZnO:Zn, which is created by heat treating zinc oxide in a reducing atmosphere, coexists, (Zn0.6Cd
0.4) The S:Ag phosphor can now emit light at 20V without causing a charge-up phenomenon.

Table 2 shows the emission color when VA=30V, but the emission color can be changed stepwise from green to yellow by changing the mixing ratio from 4/6 to 1/9.

The brightness is 50 foot Lamberts for green and yellow light emission at an excitation current density of 1.0 mA/cm2, which is sufficient for practical use as a character display.

Example 3 Using a bar graph display device similar to Example 1, an orange-emitting manganese-activated zinc sulfide phosphor, ZnS:Mn, and a green-emitting manganese-activated zinc silicate phosphor, Zn2SiO4:M
A mixture of 30% by weight of semiconducting In2O3 is used in addition to various mixed phosphors of n.

Table 3 shows the results of emitting light in the same manner as in Examples 1 and 2.

The brightness is 2 for both green and orange at an excitation current density of 1 mA/cm2.
It was more than 0 foot Lambert.

The same results in Table 3 can be obtained even if In2O3 is replaced with a semiconducting non-luminescent compound, zinc oxide.

That is, 25% by weight of Z was added to each of the various mixed phosphors in Table 3.
Almost the same results were obtained even when nO was added and allowed to coexist.

(2) The amount of n2O3 and ZnO may be appropriately changed depending on the combination of two or more types of phosphors to be combined, and the amount affects the brightness.

Therefore, it can be determined experimentally depending on the intended use.

However, in general, 20 to 30% by weight is suitable.

In addition to the combinations described in the above examples, at least one of the mixed phosphors may be SnO2:Eu phosphor or ZnO:Z
n phosphor, or mixed phosphor with In2O3
It has also been confirmed that a mixture containing ZnO can produce a mixed phosphor that can be excited at 100 V or less and is suitable for fluorescent display devices.

Furthermore, by changing the mixing ratio of these phosphors, it is possible to emit light with a stepwise change in color tone.

In this way, a fluorescent display device in which each successive segment of a bar graph is made to emit light using a phosphor whose color tone changes step by step allows you to see changes in the size of information that expands and contracts in a bar graph shape, and it is visually vivid. It has the effect of further improving information display and transmission functions.

[Brief explanation of the drawing]

The figures are schematic diagrams showing a bar graph fluorescent display device according to an embodiment of the present invention, with FIG. 1 being a front view and FIG. 2 being a side view. G... Glass container, S... Glass substrate, A... Anode segment, P... Fluorescent film, C... Grid electrode, H... Cathode.

Claims (1)

[Claims] 1. A method in which two or more types of phosphors with different luminescent colors are coated on a plurality of anode segments forming a bar graph while changing the mixing ratio in stages, and a part or all of a series of anode segments are coated. A fluorescent display device characterized by emitting light by changing the color tone in stages. 2. The fluorescent display device according to claim 1, wherein one of the two or more types of phosphors to be mixed is a europium-activated tin oxide phosphor. 3. The fluorescent display device according to claim 1, wherein one of the two or more types of phosphors to be mixed is a zinc oxide phosphor. 4. Claim 1, characterized in that the anode segment is coated with a phosphor obtained by adding indium oxide or zinc oxide to a mixed phosphor obtained by mixing two or more types of phosphors with different emission colors. Fluorescent display device as described in .