JP4834357B2 - Display device - Google Patents

Description

  The present invention relates to a display device, and more particularly, to a display device with improved light emission efficiency due to ultraviolet rays having a long wavelength.

  In recent years, as a large display device such as a road sign, a display device in which a coating material containing a phosphor is applied in a predetermined shape and irradiated with ultraviolet rays from a fluorescent lamp is widely used. It is coming. As a light source of such a display device, a fluorescent lamp that emits ultraviolet light having a long wavelength such as black light is used.

That is, when ultraviolet rays are used as a light source, ultraviolet rays having a wavelength of 300 nm or less harmful to the eyes are avoided, and ultraviolet rays having a long wavelength of around 330 to 380 nm are used. Specifically, fluorescent lamps using BaSi ₂ O ₅ : Pb phosphor (peak wavelength: 353 nm) and SrB ₄ O ₇ : Eu phosphor (peak wavelength: 370 nm) are used. FIG. 3 shows the emission spectrum distribution of these phosphors.

  Even in an LED lamp using a light emitting diode (LED), by applying blue, green and red light emitting phosphors on the surface of the LED chip, or by incorporating phosphor powders of each color light emitting in the resin constituting the LED. Attempts have been made to extract light of white or any intermediate color from one LED lamp. Even in such an LED lamp, the phosphor is excited by ultraviolet light having a long wavelength of about 370 nm emitted from the LED.

  For this reason, phosphors for display devices are required to emit visible light efficiently with long-wavelength ultraviolet light (around 330 to 380 nm). In addition, since display devices such as road signs are used outdoors, the phosphors are required to be chemically stable, such as excellent weather resistance.

An object of the present invention, by increasing the luminous efficiency by ultraviolet of the long wavelength of the phosphor is to provide a display apparatus capable of taking out each type of intermediate color light efficiency and accuracy.

The display device of the present invention has a resin layer containing a blue light-emitting phosphor, a green light-emitting phosphor and a red light-emitting phosphor as a light-emitting portion, and irradiates the light-emitting portion with ultraviolet rays having a long wavelength of 330 to 380 nm. In a display device that emits light,
The red light-emitting phosphor,
General _{formula: ((La, Y, Gd} ) 1-x-y Eu x Sm y) 2 O 2 S
(Wherein x and y are numbers satisfying 0.01 ≦ x ≦ 0.15 and 0.0001 ≦ y ≦ 0.03), and a part of La is derived from Y and Gd. A europium and samarium activated rare earth lanthanum oxysulfide phosphor substituted with at least one selected element;
And the blue light emitting phosphor is
General formula: (M1, Eu) ₁₀ (PO ₄ ) ₆ · Cl ₂
(Wherein M1 represents at least one element selected from Mg, Ca, Sr and Ba)
And a divalent europium-activated halophosphate phosphor substantially represented by the general formula: a (M2, Eu) O.bAl ₂ O ₃
(Wherein M2 represents at least one element selected from Mg, Ca, Sr, Ba, Zn, Li, Rb and Cs, and a and b are a> 0, b> 0, 0.2 ≦ a / (b ≦ 1.5)
In Ri least 1 Tanedea selected from divalent europium activated aluminate phosphor substantially represented,
It is characterized by obtaining any intermediate color light other than white light .

According to the display device of the present invention, it may be when excited by ultraviolet rays having a long wavelength of 3 30~380n m, obtained with each species efficiency and accuracy an intermediate color light.

Hereinafter, modes for carrying out the present invention will be described. The phosphor used in the display device of the present invention contains a blue light-emitting component (blue light-emitting phosphor), a green light-emitting component (green light-emitting phosphor), and a red light-emitting component (red light-emitting phosphor). The red light emitting component is a phosphor based on lanthanum oxysulfide (lanthanum oxysulfide phosphor),
The general _{formula: (La 1-xy Eu x} Sm y) 2 O 2 S ... (1)
(Wherein x and y are numbers satisfying 0.01 ≦ x ≦ 0.15 and 0.0001 ≦ y ≦ 0.03)
And trivalent europium and samarium activated lanthanum oxysulfide phosphors substantially represented by

  Here, trivalent europium (Eu) is an activator for enhancing the light emission efficiency of lanthanum oxysulfide as a phosphor matrix, and is contained in the range of 0.01 to 0.15 as the value of x in the above formula (1). When the value of x indicating the Eu content is less than 0.01, the effect of improving the light emission efficiency is small, and sufficient luminance cannot be obtained. On the other hand, when the value of x exceeds 0.15, the luminance is remarkably lowered due to concentration quenching or the like. More preferably, the value of x is in the range of 0.03 to 0.08.

  In addition to functioning as an activator, samarium (Sm) has an effect of shifting the shape of the excitation spectrum of a phosphor based on lanthanum oxysulfide to the longer wavelength side. As a result, for example, the absorption efficiency of ultraviolet light having a long wavelength of about 330 to 380 nm is improved, and the light emission efficiency at that time can be improved.

  Sm is contained in the range of 0.0001 to 0.03 as the value of y in the above formula (1). If the value of y indicating the Sm content is less than 0.0001, the effect of shifting the excitation spectrum wavelength to the long wavelength side cannot be sufficiently obtained. On the other hand, if the value of y exceeds 0.03, coloring tends to occur, and the luminance is significantly reduced due to concentration quenching or the like. The value of y is more preferably in the range of 0.001 to 0.01.

  In the lanthanum oxysulfide as the phosphor matrix, a part of the lanthanum (La) is at least one element selected from yttrium (Y) and gadolinium (Gd), specifically any one of Y, Gd, and Y + Gd. May be substituted. Y and Gd exhibit the effect of increasing the emission energy in the red region by being dissolved in the phosphor. However, if the amount of substitution of La by Y or Gd is too large, crystal distortion cannot be ignored, and conversely, the emission intensity decreases. Therefore, the amount of substitution by Y or Gd is preferably 30 mol% or less of La. . A more preferable substitution amount is in the range of 5 to 20 mol%.

  Such trivalent europium and samarium activated lanthanum oxysulfide phosphors as red light-emitting components efficiently absorb long-wavelength ultraviolet light having a wavelength of about 330 to 380 nm. Therefore, it is possible to efficiently obtain red light when excited by such a long wavelength ultraviolet ray.

  The trivalent europium and samarium activated lanthanum oxysulfide phosphors are produced, for example, as follows.

That is, first, raw material powders such as La ₂ O ₃ , Eu ₂ O ₃ , Sm ₂ O ₃ , and S are weighed in a predetermined amount so as to have the composition of the above-mentioned formula (1), and these are measured with Na ₂ CO ₃ Mix well with a flux such as Li ₃ PO ₄ using a ball mill or the like. The raw material mixture thus obtained is housed in an alumina crucible or the like and fired in the atmosphere at a temperature of about 1100 to 1400 ° C. for about 3 to 6 hours.

  Thereafter, the fired product obtained is washed with pure water to remove unnecessary soluble components. Further, for example, after washing with an acidic solution having a pH of 2 or more, washing with pure water about 3 to 5 times, filtering and drying, the desired red light-emitting phosphor can be obtained. Here, during acid cleaning, by maintaining the pH of the cleaning liquid at 2 or more, non-luminescent components mixed in the phosphor particles can be efficiently removed. More preferably, the pH of the cleaning solution during acid cleaning is kept in the range of 2-4.

  The phosphor used in the display device of the present invention contains a blue light-emitting component and a green light-emitting component in addition to the red light-emitting component made of the lanthanum oxysulfide phosphor described above. Here, as the phosphor as the blue and green light emitting components, a phosphor excellent in luminous efficiency by long wavelength ultraviolet rays is used.

As a blue light emitting component (blue light emitting phosphor),
General formula: (M1, Eu) ₁₀ (PO ₄ ) ₆ · Cl ₂ (2)
(Wherein M1 represents at least one element selected from Mg, Ca, Sr and Ba)
In the divalent europium activated halophosphate phosphor substantially represented, and the general formula: a (M2, Eu) O · bAl 2 O 3 ... (3)
(Wherein M2 represents at least one element selected from Mg, Ca, Sr, Ba, Zn, Li, Rb and Cs, and a and b are a> 0, b> 0, 0.2 ≦ a / b ≦ 1.5)
At least one selected from divalent europium activated aluminate phosphors substantially represented by the formula:

In addition, as a green light emitting component (green light emitting phosphor),
General formula: a (M2, Eu, Mn ) O · bAl 2 O 3 ... (4)
(Wherein M2 represents at least one element selected from Mg, Ca, Sr, Ba, Zn, Li, Rb and Cs, and a and b are a> 0, b> 0, 0.2 ≦ a / b ≦ 1.5)
It is preferable to use a divalent europium and manganese activated aluminate phosphor substantially represented by

  Both the blue light-emitting phosphor and the green light-emitting phosphor described above are excellent in absorption efficiency of long-wavelength ultraviolet light having a wavelength of about 330 to 380 nm. Therefore, when excited with long-wavelength ultraviolet light, blue light and green light Light can be obtained efficiently.

  As described above, the phosphor used in the display device of the present invention efficiently absorbs ultraviolet light having a long wavelength of about 330 to 380 nm and efficiently emits visible light of each color of blue, green, and red. Therefore, by appropriately selecting the combination of each color component, it is possible to efficiently extract white light of any color temperature and intermediate color light such as purple, pink, and blue-green, and greatly improve the color reproducibility of each color. Can be improved.

  The mixing ratio of the blue, green, and red light emitting components can be appropriately set according to the target light emission color. For example, when obtaining white light, it is preferable that the blue light-emitting component is 65% or less, the green light-emitting component is in the range of 5 to 65%, and the red light-emitting component is in the range of 15 to 95%. According to such a mixing ratio, for example, white light having a color temperature of about 2700 K to about 8000 K can be arbitrarily obtained, and furthermore, brightness comparable to that of a conventional three-wavelength phosphor excited at a wavelength of 254 nm can be obtained. . The ratio of each color component is more preferably 50% or less for the blue light emitting component, 15 to 45% for the green light emitting component, and 30 to 80% for the red light emitting component.

  As described above, the phosphor used in the display device of the present invention is excellent in luminous efficiency with respect to ultraviolet rays having a long wavelength of about 330 to 380 nm. Therefore, it is suitable for a display device having such a light source that emits ultraviolet light having a long wavelength.

  The display device of the present invention is configured to irradiate the light emitting unit including the phosphor for display device of the present invention as described above with ultraviolet light having a long wavelength from a light source, thereby obtaining visible light from the light emitting unit. Is. Specifically, the LED lamp which has arrange | positioned the resin layer as a light emission part containing the fluorescent substance for display devices to the outer peripheral side of the light emitting chip which irradiates light, such as long wavelength ultraviolet-rays, to this light emission part is mentioned. In such an LED lamp, the phosphor is excited by long-wavelength ultraviolet light having a wavelength of around 370 nm emitted from the LED.

  Next, specific examples of the present invention and evaluation results thereof will be described.

Example 1
First, a red light emitting phosphor represented by La ₂ O ₂ S: Eu _0.06 , Sm _0.002 and a blue light emitting phosphor represented by (Sr _0.73 Ba _0.22 Ca _0.05 ) ₁₀ (PO ₄ ) ₆ · Cl ₂ : Eu Then, a green light emitting phosphor represented by 3 (Ba, Mg) O.8Al ₂ O ₃ : Eu _0.20 and Mn _0.40 was prepared. These phosphors of each color emission are weighed so that the red light emission component is 60.5%, the blue light emission component is 18.0%, and the green light emission component is 21.5% by mass ratio. A phosphor for a display device was obtained.

  The phosphor (mixed phosphor) thus obtained was measured for the emission spectrum distribution when excited with ultraviolet light having a wavelength of 380 nm. The result is shown in FIG.

On the other hand, as Comparative Example 1 with the present invention, a known three-wavelength phosphor [red light emitting phosphor = Y ₂ O ₃ : Eu34.0%, blue light emitting phosphor = (Sr, Ba, Ca) ₁₀ (PO ₄ ) ₆ · Cl ₂ : Eu 36.0%, green light emitting phosphor = (La, Ce) (P, B) O ₄ : Tb 30.0%] is excited with ultraviolet light having a wavelength of 254 nm. Shown in The color temperature of the white light emitted from each of these mixed phosphors is about 5000K.

  As a result of obtaining the respective areas from the spectral distributions shown in FIG. 1 and FIG. 2 and comparing the emission luminance, assuming that the three-wavelength phosphor of Comparative Example 1 is 100%, the mixed phosphor of Example 1 has a long wavelength ultraviolet ray. It was found that the brightness was 80% despite being excited by the light, and that the brightness was practically satisfactory.

Further, as Comparative Example 2, a red light-emitting phosphor represented by Y ₂ O ₂ S: Eu _0.05 was 80.0%, and (Sr _0.73 Ba _0.22 Ca _0.05 ) ₁₀ (PO ₄ ) ₆ · Cl ₂ : blue represented by Eu. A phosphor (mixed fluorescence) in which a green phosphor expressed by 8.5%, 3 (Ba, Mg) O.8Al ₂ O ₃ : Eu _0.20 and Mn _0.40 is mixed at a ratio (mass ratio) of 11.5%. ) Was measured for the emission spectrum distribution when excited with ultraviolet light having a wavelength of 380 nm. Assuming that the mixed phosphor of Comparative Example 2 is 100%, the brightness of the mixed phosphor of Example 1 is 216%, and the brightness (efficiency) when excited with long-wavelength ultraviolet light is significantly improved. .

  From each measurement result mentioned above, it turns out that the mixed fluorescent substance by Example 1 is very useful for the display apparatus which uses long wavelength ultraviolet rays (around 330-380 nm) as an excitation source.

Example 2
_{La 2 O 2 S: Eu 0.06} , 64.5% of the red light-emitting phosphor represented by _{Sm 0.002, 3 (Ba, Mg} ) O · 8Al 2 O 3: 12.5% blue emitting phosphor represented by Eu _0.20, 3 (Ba, Mg) O.8Al ₂ O ₃ : The green fluorescent material represented by Eu _0.20 and Mn _0.40 is sufficiently mixed at a ratio (mass ratio) of 23.0% to achieve the desired fluorescence for a display device. Got the body.

  The phosphor (mixed phosphor) thus obtained was measured for the spectral distribution of light emission when excited with ultraviolet light having a wavelength of 380 nm. The emission color at this time was white light having a color temperature of about 5000K.

  The area was obtained from the obtained emission spectrum distribution and compared with the emission spectrum distribution by the phosphor of Comparative Example 1 described above. Assuming that Comparative Example 1 was 100%, the mixed phosphor of Example 2 was 85% despite being excited by ultraviolet light having a long wavelength, and had a brightness that was practically satisfactory. Furthermore, if the mixed phosphor of Comparative Example 2 described above is 100%, the brightness of the mixed phosphor of Example 2 is 232%, and the brightness (efficiency) when excited with long-wavelength ultraviolet light is significantly improved. Was.

  From the measurement results described above, it can be seen that the mixed phosphor according to Example 2 is very useful for a display device using a long wavelength ultraviolet ray (about 330 to 380 nm) as an excitation source.

Example 3
La ₂ O ₂ S: Eu _0.06 , red emitting phosphor represented by Sm _0.01 , 61.0%, (Sr _0.80 Ba _0.15 Ca _0.05 ) ₁₀ (PO ₄ ) ₆ · Cl ₂ : blue emitting phosphor represented by Eu 22.0%, 2 (Ba, Mg) O.5Al ₂ O ₃ : Eu _0.20 , Mn _0.40 and the green light emitting phosphor represented by Mn _0.40 are sufficiently mixed at a ratio (mass ratio) of 17.0%. A phosphor for a display device was obtained.

  The phosphor (mixed phosphor) thus obtained was measured for the spectral distribution of light emission when excited with ultraviolet light having a wavelength of 380 nm. The emission color at this time was white light with a color temperature of around 6500K.

On the other hand, as Comparative Example 3 with the present invention, a known three-wavelength phosphor [red light-emitting phosphor = Y ₂ O ₃ : Eu 32.0%, blue light-emitting phosphor = (Sr, Ba, Ca) ₁₀ (PO ₄ ) ₆ · Cl ₂ : Eu42.0%, green light emitting phosphor = (La, Ce) (P, B) O ₄ : Tb26.0%] was excited with ultraviolet light having a wavelength of 254 nm, and the emission spectrum distribution at that time was It was measured.

  As a result of obtaining the respective areas from the spectrum distributions of Example 3 and Comparative Example 3 and comparing the emission luminance, assuming that the three-wavelength phosphor of Comparative Example 3 is 100%, the mixed phosphor of Example 3 is a long wavelength ultraviolet ray. It was 83% despite being excited by the light, and had a brightness that was practically satisfactory. Therefore, it can be seen that the mixed phosphor according to Example 3 is very useful for a display device using a long wavelength ultraviolet ray (around 330 to 380 nm) as an excitation source.

It is a figure which shows the emission spectrum distribution at the time of exciting the fluorescent substance for display apparatuses by Example 1 of this invention with the ultraviolet-ray with a wavelength of 380 nm. It is a figure which shows the emission spectrum distribution at the time of exciting the three wavelength fluorescent substance by the comparative example 1 with the ultraviolet-ray with a wavelength of 254 nm. It is a figure which shows the typical light emission spectrum distribution of the fluorescent substance used for a ultraviolet light-emitting lamp.

Claims (4)

In a display device having a resin layer including a blue light emitting phosphor, a green light emitting phosphor and a red light emitting phosphor as a light emitting portion, and emitting light by irradiating the light emitting portion with ultraviolet rays having a wavelength of 330 to 380 nm .
The red light-emitting phosphor,
General _{formula: ((La, Y, Gd} ) 1-x-y Eu x Sm y) 2 O 2 S
(Wherein x and y are numbers satisfying 0.01 ≦ x ≦ 0.15 and 0.0001 ≦ y ≦ 0.03), and a part of La is derived from Y and Gd. A europium and samarium activated rare earth lanthanum oxysulfide phosphor substituted with at least one selected element;
And the blue light emitting phosphor is
General formula: (M1, Eu) ₁₀ (PO ₄ ) ₆ · Cl ₂
(Wherein M1 represents at least one element selected from Mg, Ca, Sr and Ba)
And a divalent europium-activated halophosphate phosphor substantially represented by the general formula: a (M2, Eu) O.bAl ₂ O ₃
(Wherein M2 represents at least one element selected from Mg, Ca, Sr, Ba, Zn, Li, Rb and Cs, and a and b are a> 0, b> 0, 0.2 ≦ a / (b ≦ 1.5)
In Ri least 1 Tanedea selected from divalent europium activated aluminate phosphor substantially represented,
A display device characterized by obtaining any intermediate color light other than white light . The display device of claim 1 Symbol placement,
The green light emitting phosphor is:
General formula: a (M2, Eu, Mn) O.bAl ₂ O ₃
(Wherein M2 represents at least one element selected from Mg, Ca, Sr, Ba, Zn, Li, Rb and Cs, and a and b are a> 0, b> 0, 0.2 ≦ a / (b ≦ 1.5)
A display device characterized by being a divalent europium and manganese activated aluminate phosphor substantially represented by The display device according to claim 1 or 2 ,
A display device, wherein 30 mol% or less of La of lanthanum oxysulfide as a phosphor matrix of the red light emitting phosphor is substituted with at least one element selected from Y and Gd. The display device according to any one of claims 1 to 3 ,
A display device that emits light by irradiating ultraviolet rays comprises an LED lamp.

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