JPH0524192B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a phosphor that emits light when excited by a slow electron beam, and a fluorescent display tube using this phosphor. The present invention relates to a phosphor having a spectrum and a fluorescent display tube that uses this phosphor as an anode and displays light emitted from the anode through a color filter. [Prior Art] Phosphors for fluorescent display tubes are called phosphors for low-speed electron beams (hereinafter simply referred to as phosphors) because they emit light when excited by a low-speed electron beam emitted from a linear cathode. Traditionally, this phosphor has been
ZnO: Zn phosphor is often used. this
ZnO: Zn phosphor can generally achieve sufficient luminance with an anode voltage of about 10 to 20 V, and its peak emission wavelength
The emission spectrum of 505nm is blue-green, so it can be used in clocks, car instrument panels, measuring instruments, and VTRs.
It has been used in fluorescent display tubes as display devices. However, recently, as the field of use for fluorescent display tubes has expanded, there has been a trend toward color display methods, from the traditional blue-green color to display in various colors such as blue, green, yellow, and red. Ta. Further, there are two methods of color display using a fluorescent display tube: a method in which the emitted color of the phosphor is directly displayed through a transparent envelope, and a method in which the emitted color of the phosphor is passed through a color filter to display the desired color. The present invention concerns a phosphor used in the latter display method. The phosphor observed through this color filter desirably contains all components from the blue emission spectrum to the red emission spectrum. As a conventional example of such a phosphor, there is a patent application published in 1983-
There is an invention of a ``fluorescent display tube'' that was filed in No. 181844 and published in Japanese Patent Application Laid-Open No. 84884/1984. This conventional example consists of a red-emitting ZnCdS:Ag phosphor, a green-emitting ZnS:Cu,Al phosphor, and a blue-emitting ZnCdS:Ag phosphor.
ZnS: Composed of a phosphor that is a mixture of Ag phosphor and conductive powder that provides conductivity. [Problem to be solved by the invention] As can be seen from the graph of lighting time and relative brightness shown in Figure 4, the ZnS:Ag phosphor used as a blue phosphor emits blue-green light when the lighting time exceeds 500 hours. ZnO: Zn phosphor or red-emitting (ZnCd)S:
Compared to Ag and Cl phosphors, the brightness is significantly lower, and the brightness balance with other colors is disrupted. As a result, the chromaticity also deviates from the initial value, resulting in the problem that the color does not become the same even under the same conditions as the initial conditions. In addition, the ZnS:Ag blue phosphor, ZnS:Cu,
The Al green phosphor has _a band gap of about 3.7eV (room temperature) of its base material ZnS, and ( _{Zn 0.7} Cd _0.3 )
The band gap was larger than that of S (2.9 eV) and CdS (2.4 eV), and the resistance value was therefore high, so unless a conductive material such as indium oxide was mixed in, the resistance could not be lowered and it would not emit light at low voltage. This conductive material does not emit light by itself, but has the effect of blocking light emission, so it has the problem that it serves as a protection against damage in order to increase brightness. Furthermore, in ZnS:Ag blue phosphor, the base material sulfide (ZnS) decomposes during energization and scatters S, SO, SO ₂ , etc., which react with the linear cathode. reduce the emission capacity of
As a result, there was also the problem that the service life was shortened. The present invention was made to solve the above-mentioned problems, and has a broad emission spectrum from blue to red, and when combined with a color filter, can display colors, and can be used for long periods of time. Another object of the present invention is to provide a fluorescent display tube using a mixed type phosphor that is free from chromaticity deviation and has a long life. [Means for Solving the Problems] The present invention provides a blue-green luminescent ZnO:Zn phosphor;
Red-emitting (Zn _1-x , Cdx)S: Ag, Cl (however, x
= 0.7 to 1.0) A low-speed electron beam phosphor mixed with phosphors at a weight ratio of 9:1 to 4:6 is deposited on the anode conductor to form an anode, and the electrons are ejected from the linear cathode. This is a fluorescent display tube characterized by displaying light emitted by a color filter through a color filter. [Function] The phosphor of the present invention focuses on a broad ZnO:Zn phosphor containing components from blue to green and even yellow.
As the missing red component, (Zn _1-x , Cdx) S: Ag, Cl (x = 0.7 ~
1.0) was mixed at 10 to 60 wt%. Therefore, the mixed phosphor of the present invention is a phosphor containing all color components from blue to red. By mounting this mixed phosphor in a fluorescent display tube and combining it with a desired color filter, the desired color display becomes possible. Furthermore, one pixel is divided into three primary colors of blue, green, and red, and by mixing these three colors, it is possible to display all colors from white to various colors. [Example] A known ZnO:Zn phosphor and a red-emitting phosphor (Zn _1-x Cdx)S:Ag,Cl (x=0.7 to 1.0) are thoroughly stirred in powder form. The mixing ratio is ZnO:Zn
A ratio of phosphor to red-emitting phosphor in the range of 90:10 to 40:60 is good. If the red-emitting phosphor is less than 10wt%, the intensity of the red component will be weak and there will be no effect. Moreover, if the red-emitting phosphor is more than 60 wt%, the brightness will be significantly lowered, which is not preferable. Preferably as a red phosphor (Zn _1-x Cdx)
S: When using Ag, Cl (x = 0.7 to 1.0),
A highly preferred range of this red-emitting phosphor is 20 to 40 wt%. The mixed phosphors mixed at various mixing ratios were mixed with a vehicle to form a phosphor paste. This mixture paste was printed on an anode conductor of a glass substrate by a well-known screen printing method, and then baked, and a fluorescent display tube was produced by a general fluorescent display manufacturing process. For comparison, 100% ZnO:Zn phosphor and 100% (ZnCdx)S:Ag,Cl phosphor were also mounted on a fluorescent display tube and data were collected. FIG. 1 is a diagram showing the emission spectrum distribution of phosphors at various mixing ratios. The mixing ratio is shown in Table 1 below.

[Table] The curve in Figure 1 is a spectrum of 100% ZnO:Zn, which has a peak at 505 nm and contains a blue component around 450 nm, a green component around 500 nm, and a yellow component around 550 nm. However, it can be seen that almost no orange-emitting components around 600 nm or red components around 650 nm are included. Therefore, we added a red-emitting ZnCdS:Ag,Cl phosphor to the ZnO:Zn phosphor at 90:
The curve shows the emission spectrum of the phosphor mixed at a mixing ratio of 10. The peak is slightly shifted to the longer wavelength side and is located around 510 nm. This means that it contains a lot of red components. Also
From around 600 nm, the curve becomes gentler compared to , and some red components are included. Furthermore, 30% of red-emitting ZnCdS:Ag,Cl phosphor was added.
% mixing results in a curve shown as , which shows that the red component around 650 nm is contained even more. The peak shifted slightly to the longer wavelength side and reached 525nm.
Although it is nearby, it also contains a sufficient amount of blue components. The curve shown is the red-emitting ZnCdS:Ag,Cl
This is the case when the phosphor is 60% more than the ZnO:Zn phosphor, and peak wavelengths appear both near 520 nm and near 680 nm, clearly indicating that each component from blue to red is contained. For comparison, the curve shown is for red light emission.
This is the case where ZnCdS: Ag, Cl phosphor is 100%. As described above, the emitted light color of the phosphor of the present invention, which is composed of a ZnO:Zn phosphor and a red phosphor mixed at a weight ratio of 9:1 to 4:6, is determined by the x value of chromaticity Y depending on the mixing ratio. Although the values are different and the emission colors are slightly different, as can be seen from the emission spectrum, it was found that all the components from blue to red were contained. It is a graph showing the relationship between the luminance of the phosphor and the anode voltage. Light emission conditions are cathode voltage 1.7Vac, grid voltage
The anode voltage was varied from 0 to 40V at 12Vdc. The emission starting voltage is as low as 4V, and the luminance is more than 1000Cd/m ² at an anode voltage of 10V or more, making it suitable for use in fluorescent display tubes. Also, the anode voltage can be changed from 20V to 100V, 150V, 200V
Even if the value is increased, the x value and y value of the chromaticity coordinate table showing chromaticity as shown in Table 2 do not change. Therefore, it is different from a so-called color-shifting phosphor, in which the color of the emitted light does not change depending on the voltage, but the color of the emitted light changes depending on the voltage.

〔effect〕

As explained above, the present invention emits blue-green light.
ZnO: Zn phosphor to red phosphor e.g. ZnCdS:
Since the Ag and Cl phosphors are mixed at a ratio of 9:1 to 4:6, the following effects are achieved. (1) ZnO: Zn phosphor (Zn _1-x Cdx) S: Ag, Cl
((x = 0.7 to 1.0) The phosphor of the present invention, which is a mixture of phosphors in a ratio of 9:1 to 4:6, has low resistance and a low emission starting voltage even without a conductive material.
It has the effect of being able to obtain sufficient brightness to be used as a fluorescent display tube at low voltage. (2) Since the emission spectrum of the phosphor of the present invention includes components of all colors in the visible range from blue to red, it has the effect of making it possible to display all colors by combining it with a color filter. (3) Even if the anode voltage applied to the anode changes, for example from 20Vdc to 200Vp-p, the chromaticity deviation of the emitted color of only the phosphor without a filter will be the X value and Y value of the chromaticity coordinate table. Both values are within 0.05, and considering measurement errors, no deviation in chromaticity occurs. Therefore, the emission spectrum of this phosphor does not change and always includes components of all colors from blue to red. (4) No shift in chromaticity occurs even after the lighting time elapses. For example, the deviation in chromaticity is within 0.04 for both the X value and the Y value during the lapse of 1000 hours from the initial lighting stage, and considering measurement errors and the like, it can be said that no deviation in chromaticity occurs. Therefore, even if the lighting time changes, all color components from blue to red are always included. (5) Not only can the same objective be achieved by mixing two types of phosphors compared to the conventional mixture of three types of phosphors, but also without using the ZnO:Ag phosphor as the blue phosphor. , ZnO: Since the Zn phosphor can emit a blue component, there is no deterioration in the brightness of the blue-based phosphor, and it has the effect of providing a fluorescent display tube with excellent brightness balance.

[Brief explanation of the drawing]

Figure 1 is an emission spectrum diagram of the phosphor of the present invention, Figure 2 is a diagram showing the relationship between anode voltage and brightness of the phosphor of the present invention, and Figure 3 is a diagram showing the mixing ratio of the phosphor of the present invention. A graph showing the relationship between relative brightness, Figure 4, shows a conventional blue-green-emitting ZnO:Zn phosphor, a red-emitting (Zn _1-x Cdx) S:Ag,Cl phosphor, and a blue-emitting ZnS:Ag phosphor. It is a graph showing the relationship between continuous lighting time and relative brightness of the body.

Claims (1)

[Claims] 1 Blue-green-emitting ZnO: Zn phosphor and red-emitting (Zn _1-x , Cdx) S: Ag, Cl (x = 0.7 to 1.0)
A phosphor for low-speed electron beams, which is a mixture of phosphors at a weight ratio of 9:1 to 4:6, is deposited on an anode conductor to form an anode, and light is emitted by the bombardment of electrons from a linear cathode. A fluorescent display tube that displays images through a color filter.