JPS6015669B2 - fluorescent display tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to, for example, a fluorescent lamp for a low-speed electron beam that emits light from blue-green to red due to the impact of electrons at a low accelerating voltage of several V to several tens of V, and a fluorescent material using a light body. This relates to display tubes.

Recently, as a display device for various electronic and electrical equipment,
It can be driven at low voltage and has low power consumption.
Poppy light display tubes, which have the advantage of providing bright and easy-to-read displays, are increasingly being used. This optical display tube emits electrons emitted from a filament-shaped cathode that is heated by electricity onto the upper surface, and then strikes the anode, which is coated with a light layer and selectively given a positive anode voltage. The phosphor layer coated on the anode is made of a phosphor that can provide sufficient luminance to display at a low accelerating voltage. It is composed of a light body, a so-called phosphor for low-speed electron beams.

By the way, this poppy is a low-speed electron beam L-type for optical display tubes.
Conventionally, Zn○:Zn-based poppy and light bodies have been used exclusively as light bodies.

This Zn○:Zn-based poppy/light material has an extremely low luminescence threshold voltage, or so-called dead voltage, of 1 to 2 V, and generally an anode voltage of about 10 to 20 V is sufficient to obtain a display. Since it can provide luminance, it is extremely excellent as a phosphor excited by slow electron beams. However, this Zn0:Zn-based light material emits light in a greenish color due to the impact of an electron beam.
n○: The emitted light color of the Zn-based poppy, the poppy using a light body, and the light display tube is limited to green. On the other hand, as the field of application of poppy light display tubes expands, there are increasing demands from various quarters for diversification of display luminescent colors. For example, when performing a warning display, a red color display is preferable to green color in order to obtain a warning effect. In addition, when displaying multiple display objects using one or more poppies or light display tubes,
By changing the emitted light color of the display according to each display object, there are advantages such as making it extremely easy to discuss each display and eliminating the risk of misreading.

Thus, ZnS:Ag and ZnS:Cu-based poppies, light bodies, etc., which are used in well-known cathode ray tubes and the like, emit light in various colors when excited by the impact of electron beams accelerated by high acceleration voltages. (Zn, Cd)S: Ag-based poppy, light body,
Alternatively, efforts are being made to mix various conductive substances into the light body such as Y202S:Eu for low-speed electron beams, or to add rare earth elements such as Eu (europium) to Sn02 (tin oxide), which is originally a conductive substance. Proposals are being made to generate new poppies and light bodies.

However, with the poppies and luminous substances that have been obtained to date, for example, when a conductive substance is mixed, it is necessary to mix a large amount of the conductive substance, which is a non-luminescent substance, so the luminous area decreases and the luminous substance is not sufficient. There is a problem that luminance cannot be obtained, and if the mixture is not uniform, the luminescence tends to be uneven.

Further, Sn02 with Eu added exhibits saturation characteristics at low brightness, and sufficient brightness cannot be obtained, making it unsatisfactory as a light material for low-velocity electron beams.

Therefore, in order to cause different areas of one display section to emit light in different colors, when the above-mentioned phosphor layer for low-speed electron beams is provided in conjunction with the Zn○:Zn-based phosphor layer, There are problems such as the emission brightness of the two is different, making the display difficult to see, and the difference in the emission threshold, value voltage, and operating voltage complicates the drive circuit.
Furthermore, there were also problems in terms of lifespan and stability.

Here, a poppy for a low-speed electron beam and a light body refer to a poppy and a light body that emit light when excited with a voltage of 100 V or less, and have a secondary electron emission system number of 1 or less. The body refers to a light body that emits light when excited by a voltage of several hundred volts or more, and has a secondary electron emission system number of 1 or more.

Therefore, the light material itself must be made of a conductive material for low-speed electron beams, and if the light material itself is a conductive material, the surface of the light material will be charged all at once, making it impossible to emit light.
An insulating material is sufficient for the light body for high-speed electron beams.

In this way, phosphors and phosphors for low-speed electron beams and phosphors for high-speed electron beams and phosphors have completely different functions as chemical substances. I can't do that.

On the other hand, the present inventor has discovered that zinc sulfide doped with Ag and AI, which has been known as a poppy light substance that emits light when excited by an electron beam accelerated at a voltage of several hundred V to several tens of KV, such as a cathode ray. Cadmium (hereinafter general formula (Zn, Cd)S
Focusing on the poppy and the light body (represented by Zn,C
d) 3 × 10-3 ~ needles that become donor impurities in the S matrix
A photon was obtained by adding 2.7×10-2 atoms/mol of poppy.

The conductivity of the phosphor is greatly improved due to N added at a higher concentration than Ag acting as a donor impurity, and the material is used for low-speed electrons applied to optical display tubes, etc. It has become a poppy and a light body that can be put to practical use as a line poppy and a light body.

However, this AI was added at high concentrations (Zn, C
d) S: Ag, AI poppy, even in the light body, for example, Z
n0:ZM has a higher luminescence threshold voltage of about 6 to 8V compared to the light body, and the luminance is inferior compared to the light body of Zn0:Zn poppy, and in one poppy light display tube, Z
When disposed in parallel with n0:Zn phosphor layer, the difference in the emission threshold and value voltage may require modification on the drive circuit side, or the difference in emission brightness may make the display difficult to see. There were problems such as:

The present invention was made in view of the above-mentioned circumstances, and
As a result of various studies in order to reduce the dead voltage of the light body and improve the luminance of the light emitting material, we have developed the above-mentioned invention of the present inventors, in which AI is added at a high concentration (Zn, Cd)S:Ag, AI. For example, ln203 is a good light body.
By mixing an appropriate amount of conductive metal oxides such as However, by using a light body, a light display tube was obtained.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

First, the poppy material used in the fluorescent display tube according to the present invention is made of (Zn, Cd)S:Ag, which is doped with AI at a high concentration.
One of the components is the N poppy and the light body.

This poppy, the matrix of the light body can be expressed as (ZnrxCdx)S when the mixed crystal ratio of Cd is x, but this (ZnMCd
x) S changes the band gap from 3.7 eV to 2.0 eV by changing the mixed crystal ratio x. It can be changed up to the umbrella V.

Therefore, a poppy light body using this (Zn, ˜Cdx)S as a matrix can emit light from blue to red.
In this case, if the Cd mixed crystal ratio × becomes smaller, the conductivity, which is a feature of the matrix itself, is lost, so the mixed crystal ratio ×
is set to be 0.25 or more, and the upper limit value of x is set to 0.95 as the range in which red light emission can be obtained.

That is, the crystalline ratio x is set to 0.25S x 0.95. Therefore, in this poppy, the phosphor is composed of (Zn, ~Cdx)S, which is the matrix of the phosphor, which is one of the constituent components.
was obtained as follows.

Powders of ZnS and CdS are weighed according to the mixed crystal ratio x, placed in a quartz boat together with NaCI as a flux for producing the mixed crystal, and heated and fired.

This firing is performed at 800 qo to 90 qo with N2 gas flowing.
Heat it to about 0:00 a.m. for about 1 hour, then let it cool naturally (
ZnrxCdx)S is obtained.

This (Zn, Cdx)S is the fluxing agent NaC
Since it contains NaCI, it is crushed in an agate mortar and washed with water to remove NaCI.

Next, Ag and N are added as impurities to (ZnMCdx)S as the base material obtained above.

Here, Ag and AI can be obtained in various forms, but in this example, A was added to the matrix as 03 and AI2(S04)3.

The amount of Ag and AI added is 10-5 to 10-
3 atoms/mol, AI is 3×10-3 to 2.7×10-2
The method of addition is as follows: the above (Z
nMCdx)S matrix is dried and coated after bonding, and this A
(Zn, ~Cdx)S coated with g and AI was placed in a quartz boat and heated at a temperature of about 600°C to 1000qo.
This was done by baking for about 1Q hours.

In this case, the mixture may be fired at an elevated temperature while flowing H exchange as a reducing gas to remove CI present in the powder in the form of HCI. Further, the amount of the mountain added to the base is A
If it is about the same as g or about 120% of Ag, the acceptor Ag, the donor CI, and the peak will be charge-compensated, and no improvement in the conductivity of the light body can be expected, so AI will be reduced to the above 3× It needs to be selected within the range of 10-3 to 2.7 x 10-2 atoms/mol. In other words, the relationship between brightness and AI concentration is as shown in Figure 1, when the amount of N added is 3 x 10-3.
Good emission brightness can be obtained from around 1.0 x 10-2 atoms/mole, and if the amount of N added is further increased from this point, the emission brightness also increases in accordance with the increase in the amount of N added.
It reaches a peak per mole, and from this it reaches a peak of 2.7×10-2
Good luminescence brightness is maintained even though the luminance decreases to around atoms/mole. In this Figure 1, the horizontal axis shows the peak concentration (atoms/mole), and the vertical axis shows the luminance of the poppy and light body of the present invention at three acceleration voltages. In order to obtain red light emission, the concentration ratio x was selected to be 0.8, and the amount of Ag added was 1 x 10-4 atoms/mol.
Thus, a (Zn, -xCdx)S:Ag, AI poppy and light body, which is one of the constituent components of the poppy and light body used in the present invention, is obtained.

In this poppy/light body, the amount of added peaks is approximately one order of magnitude higher than the Ag concentration, and the concentration is relatively shallow (approximately 1
0 to heV) The conductivity is further improved by forming a donor level, and it emits light with sufficient brightness to obtain a display even when excited by a slow electron beam accelerated by a voltage of several volts to several tens of volts. It is.

In addition, the mixed crystal ratio x of the base material was set to 0.25 mix x SO. By changing it within the range of 95, it becomes a poppy, a luminous material that can be excited by a slow electron beam and emit light from blue to red. Here, the concentration of Ag is 1×10-5~
10-3 atoms/mol, and the mixed crystal ratio x of the base material was changed to 0.25SxSO. Even when the change is made within the range of 95, the state of change in the luminance of the light object according to the present invention has characteristics that are substantially parallel to the graph shown in FIG. 1 above and do not intersect. was confirmed through experiments.

That is, the peak value of the luminance of the light material used in the present invention and the range in which an effective luminance of at least 80% or more is obtained are related only to the concentration of AI in the constituent materials;
It has been confirmed that there is no alternating relationship between the concentration of g and the mixed crystal ratio x of the matrix.

Next, (Zn, -xCdx)S:Ag obtained above
, AI poppy, and the light body are mixed with an appropriate amount of a metal oxide having conductivity, which is the other component of the poppy poppy and the light body used in the present invention.

The metal oxide used here needs to be a dew-conducting substance that is chemically stable in itself and does not inhibit the light emission of the light body, and 1 to 03 or Sn02 are suitable.

Therefore, in one embodiment of the present invention, 1 to 03 are selected as the metal oxides, and (Zn, -xCdx)S:Ag,
Mixed with AI.

In this case, if the amount of ln203 mixed is too large,
and the luminous intensity of the light body decreases.

On the other hand, if the amount is too small, the effect of improving conductivity cannot be obtained. Therefore, the present inventors created poppy light display tubes, which will be described later, by varying the amount of 03 mixed per pile with respect to the poppy light body, and investigated the relative luminescence intensity and anode voltage-anode current characteristics at each mixture amount. , the optimum value of the mixing amount was selected.

Figures 2 and 3 are the measurement results.
The anode voltage was kept constant at 20V, and the ratio 03 was expressed in weight%.
This is a plot of the relative luminescence intensity at each mixing amount with respect to the luminous material.

That is, when ln203 is not mixed, the relative luminescence intensity is about 2.5 to 3, whereas when the mixing amount is in the range of about 1% to about 30%, the luminescence intensity is improved, A peak value is obtained at a mixing amount of around 10%. on the other hand,
In Fig. 3, curve a shows the anode voltage-anode current characteristics of the light material mixed with ln203 within the above range, and curves b, c, and d in the same figure show the conventional known characteristics for comparison. (Zn, Cd) S:A away, light body, (
These are curves showing the anode voltage versus anode current characteristics of the light body for Zn, ~Cdx) S:Ag, AI and Zn◯:Zn poppy. According to FIG. 3, when ln203 is mixed within the above-mentioned range, the anode voltage-anode current characteristic of the light body is Zn○.
:Zn? It becomes clear that the resistance is almost equal to that of the light body, and that the reduction in resistance is greatly promoted.

Therefore, due to this, the emission threshold/value voltage is also Zn○:Z
It can be expected that it will decrease in the same way as the light body. Therefore, the mixing amount of ln203 was determined to be within the range of about 1 to 30%, (Zn, ~Cdx)S (where x is 0.25SxSO.95), and the amount of Ag added to the base was 10-5%. ~10-3 atoms/mol, and the amount of AI added is in the range of 3 x 10-3 to 2.7 x 10-2 atoms/mol, at a weight ratio of 1-03. 1-3
0% mixed, a shimmering light body is obtained according to the present invention.

As mentioned above, one of the constituent components of this poppy light body, (Zn.-xCdx)S:Ag,N, is a poppy light body that has a relatively low resistance by itself. As long as the amount of 1&03 as a conductive metal oxide mixed with this is small, it is possible to improve the luminous intensity, reduce the luminous threshold, and lower the value voltage. Takeshi becomes a light body. Next, a light display tube according to the present invention using the light material obtained as described above will be described.

FIG. 4a is a plan view of a main part showing a partially broken optical display tube that has been staggered by the present invention, and FIG. 4b is an enlarged sectional view of the main part. Here, 1 is a substrate made of an insulating material such as glass or ceramics, and furthermore, a wiring conductor is first adhered to this substrate 1, and then this wiring conductor 2 is placed in an insulating layer in which a through hole 3a is formed at a predetermined position. Cover with 3.

The insulating layer 3 is made of, for example, low-melting-point frit glass as a main component, mixed with a binder, an organic solvent, and, for example, a black pigment to form a paste, which is then printed and fired. 4 is an anode conductor formed on the insulating layer 3, for example, in a diagonal shape, and on this anode conductor, (ZnhCdx)S according to the present invention obtained through the above-mentioned process is applied.
: The anode 6 is formed by depositing a phosphor layer 5 made of a phosphor mixture of Ag, N and 1 03 by a suitable method such as a well-known screen printing method, an electroplating method, or a precipitation method. Ru.

Further, the anodes 6 are arranged in a Japanese character shape to form a single digit pattern display section 7. Further, 8 is a mesh-like control voltage disposed above facing the pattern display section 7, 9 is a filament-like cathode that emits electrons when heated, and 10 is formed, for example, in the shape of a flat-bottomed boat. , a front chamber which is sealed to the periphery of the substrate 1 to form a vacuum chamber together with the substrate 1, and which holds each electrode in a high vacuum atmosphere and has at least a transparent display window; This is an introduction terminal that airtightly penetrates the sealing portion between 1 and the front case 10, and is used to introduce a drive signal to each of the electrodes.

That is, the poppy and light display tube of the present invention shown in FIGS. ,-xCQ)S
: It is made of a mixture of Ag, N, and one pile of 03, and is made of a light material.

Next, a heating voltage is applied to the cathode 9 of the poppy light display tube of the present invention shown in FIGS. Describe the characteristics.

Here, the poppy of the present invention is a red-emitting poppy in which the mixed crystal ratio x of the (Zn.★Cdx)S:Ag,AI phosphor, which is one of the constituent components of the light body, is selected to be 0.85, The light emitting characteristics when the light body layer 5 is formed using a light body are shown in the fifth column.
As shown in the figure.

In FIG. 5, the horizontal axis represents the anode voltage, and the vertical axis represents the luminance of the anode 6 in footlambert (ft-L).As is clear from the figure, when the anode voltage is 3V, The anode 6 begins to emit red light when the temperature exceeds 10V, and by further increasing the anode voltage to about 12 to 15V, the luminance becomes around t-L.
Enables sufficient brightness for display.

That is, unlike the present invention, the light emission threshold value voltage of the optical display tube is extremely low at about 3 to 4 V, and the operating voltage required to obtain a display is about 10 to 20 V. ○: Almost the same luminance as a Zn-based poppy, a poppy using a light body, and a light display tube can be obtained.

This is because, as mentioned above, the amount of the poppy, the poppy that forms the light body layer 5, and the conductive metal oxide mixed in the light body is small, so there is little reduction in the light emitting area. It is something.

Furthermore, since the mixing amount may be small, an extremely high quality luminescent display can be obtained without causing uneven luminescence. Furthermore, there is no brightness saturation at low brightness, as seen in Sn02:Eu-based phosphors, and the conventional Z
n◯: Zn-based poppy, which makes it possible to obtain a display of red light emission that cannot be obtained with a luminous material.

In addition, the poppy seeds used in the present invention, one of the constituent components of the light body, containing AI added at a high concentration (Zn. to Cdx) S:A
The conductive metal oxide mixed in the light body is ln
Similar effects can be obtained not only with 2Q but also with SnQ. Furthermore, the transfer ratio x of the matrix of the light body is set to 0.
By varying the value within the range of 25 to 0.95, any luminescent color from blue line color to red can be obtained.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

As described above, the poppy and light bodies used in the present invention are made of chemically stable materials such as 1&03 and Sn02 in addition to the S:Ag, mountain poppy, and light bodies doped with a high concentration of N (Zn, ★Cdx). A conductive metal oxide is used, and the weight ratio to the light body is 1 to 3.
This is a mixture of 0% and is intended to lower the resistance of the light body.

However, since one of the constituent components of the metal oxide mixture, the phosphor, has a lower resistance than the other phosphor, the amount of metal oxide mixed is small. The resistance of the light body is sufficiently reduced without reducing the light emitting area, and the light emission threshold voltage is about 3 to 4 V, and a low voltage of about 10 to 20 V is sufficient for display. This material has a high brightness and is extremely suitable for use with low-speed electron beams.

Moreover, since the amount of metal oxide, which is a non-luminescent substance, mixed in the poppy light body used in the present invention is small, uneven light emission does not occur, and sufficient brightness can be obtained by being excited by the low-speed electron beam. , has the excellent feature of being able to selectively emit light of various colors from blue to red by changing the mixed crystal ratio of the matrix.

Therefore, according to the present invention using a light body as described above, the light display tube can easily display multiple colors, and the display effect can be greatly improved in, for example, alarm display or multi-item display. In addition, it can be expected that a color flat display device can be realized in place of the conventional color cathode ray tube, and the effects obtained in terms of diversification and multifunctionality of display devices are extremely large.

Furthermore, the light emission threshold, value voltage, and operating voltage of the poppy and light body used in the present invention are almost the same as those of conventional Zn○:Zn-based poppy and light bodies. In the optical display tube of the present invention, it is extremely easy to manufacture a drive circuit for driving each display section that emits light of a different color, and there is almost no variation in malt between each display section, and the display The effects obtained from the use of pipes are also extremely large.

[Brief explanation of the drawing]

Figure 1 shows poppies used in the present invention, (Zn, ★Cdx) S:Ag, AI poppies used in one embodiment of the light body, and AI of the light body.
Figure 2 is a diagram showing the concentration characteristics, Figure 2 is a diagram showing the relationship between the mixing amount of ln2Q and the relative luminescence intensity in the example of the poppy light material used in the present invention, and Figure 3 is the anode voltage in the same example. - A diagram showing anode current characteristics in comparison with other poppy and light bodies; Figures 4a and 4b are partially cutaway plan views showing an embodiment of the light display tube according to the present invention; FIG. 5, an enlarged cross-sectional view of the main part, is a diagram showing the anode voltage-brightness characteristic in the same example. 4... Anode conductor, 5... Poppy, light layer, 6... Anode, 9... Cathode. Figure 1 Figure 4 Figure 4 Figure 2 Figure 3 Figure 5

Claims (1)

[Scope of Claims] 1. A method of obtaining a display by causing electrons emitted from a filament-like cathode to strike an anode, on which a phosphor layer is attached, to excite the phosphor layer to emit light. In the light display tube, the phosphor layer has the general formula (Zn_1_-
_xCdx)S (where x is 0.25≦x≦0.95
Zinc cadmium sulfide represented by a number selected from the range of 1×10^-^5~
10^-^3 atoms/mol, 3 x 10^-^3~2 Al
．． Slow electrons made by mixing a phosphor with 7×10^-^2 atoms/mol added and a metal oxide having conductivity of 1 to 30% by weight relative to the phosphor. A fluorescent display tube comprising a line fluorescent material. 2. The fluorescent display tube according to claim 1, wherein the metal oxide is In_2O_3. 3. The fluorescent display tube according to claim 1, wherein the metal oxide is SnO_2.