Patent Description:
A color wheel is a device used in an image display device, such as a projector, and may include a phosphor that converts a wavelength of incident light and emits it.

The color wheel may include a plurality of phosphors to convert incident light into various wavelength bands in order to improve the quality of an image to be displayed.

Japanese patent <CIT> discloses a phosphor color wheel for projector that includes a YAG:Ce phosphor and a LuAg:Ce phosphor. European patent application <CIT> discloses a color wheel with a cerium doped phosphor composition comprising YaCebAlcGadOz as a primary phosphor, the secondary phosphor comprises a nitride and/or oxynitride phosphor.

In the phosphor color wheel for projector, a light source radiates light to the phosphor wheel, and converts the light to which phosphor particles in the phosphor are irradiated into a specific wavelength and emit it.

However, the phosphor composition included in the phosphor color wheel for projector has a problem in that the emission intensity of phosphor is not good, and when a temperature is increased due to a high output, the emission intensity is decreased.

The technical problem to be solved by the present disclosure will be described as follows.

First, the present disclosure is to provide a color wheel having improved luminescence intensity.

Second, the present disclosure is to provide a color wheel in which a decrease in luminescence intensity due to an increase in temperature is reduced.

In addition, the present disclosure is to solve all problems that can be generated or predicted from the prior art in addition to the technical problems described above.

A color wheel according to the present disclosure includes a basic phosphor and a modified phosphor obtained by doping gallium into the basic phosphor.

Specifically, the basic phosphor includes Y3AI5O12, and the modified phosphor includes Y<NUM>(GaxAl(<NUM>-x))<NUM>O<NUM>:Ce in which gallium is doped into the basic phosphor.

The modified phosphor comprises a plurality of modified phosphors, and each of the plurality of modified phosphors has a different x value.

The modified phosphor forms a solid solution by substituting gallium with at least a portion of aluminum in the basic phosphor.

The color wheel further includes a substrate on which the basic phosphor and the modified phosphor are disposed, and the substrate is partitioned and includes a basic phosphor area on which the basic phosphor is disposed and a modified phosphor area on which the modified phosphor is disposed.

The number of the basic phosphor area and the modified phosphor area are equal to or greater than the number of types of the basic phosphor and the modified phosphor.

The basic phosphor area and the modified phosphor area are formed in a ring shape, based on a rotation axis of the substrate.

A sum of central angle of the basic phosphor area compared to a sum of central angles of the basic phosphor area and the modified phosphor area ranges from about <NUM>° to about <NUM>°, and a sum of central angle of the modified phosphor area compared to the sum of central angles of the basic phosphor area and the modified phosphor area ranges from about <NUM>° to about <NUM>°.

The modified phosphor includes a plurality of modified phosphors having different gallium contents, the modified phosphor area includes a plurality of modified phosphor small areas in which each of the plurality of modified phosphors having different gallium contents is disposed, and the modified phosphor small area has a different central angle according to a gallium content of the modified phosphor.

The modified phosphor comprises Y<NUM>(GaxAl(<NUM>-x))<NUM>O<NUM>: Ce(<NUM>≤x≤<NUM>) and Y<NUM>(GaxAl(<NUM>-x))<NUM>O<NUM>: Ce(<NUM>≤x≤<NUM>).

The effect of the color wheel in the present disclosure configured as described above is as follows.

The color wheel of the present disclosure includes a modified phosphor doped with gallium to not only improve the luminescence intensity, but also reduce the decrease in luminescence intensity due to an increase in temperature.

Advantages and features of the present disclosure and methods of achieving them will become apparent with reference to the embodiments described below in detail.

The present disclosure is defined by the scope of the claims.

The color wheel <NUM> of the present disclosure includes a basic phosphor <NUM> that converts incident light into a basic emission wavelength and emits it, and at least one modified phosphor <NUM> doped with gallium including at least one emission wavelength different from the basic emission wavelength.

In this regard, a color wheel <NUM> according to an embodiment of the present disclosure will be described with reference to <FIG> and <FIG>.

First, referring to <FIG>, the color wheel <NUM> includes a plate-shaped substrate <NUM> and a phosphor layer <NUM> disposed on the substrate <NUM>, and a reflective layer <NUM> disposed between the substrate <NUM> and the phosphor layer <NUM>.

Specifically, the substrate <NUM> forms a basic structure of the color wheel <NUM>, and may be a ring-shaped or circular-shaped member. The substrate <NUM> may rotate in one direction based on a central rotation axis, and the phosphor layer <NUM> to be described later may be rotated together by the rotation of the substrate <NUM>.

However, the shape of the substrate <NUM> is not limited to the description and the shape shown in drawing, and may include a shape applicable to a color wheel shape by a person skilled in the art.

The substrate <NUM> may include at least one of aluminum Al, iron Fe, and copper Cu, and may include aluminum having good thermal conductivity because, for example, high energy light is irradiated to increase the temperature.

However, the constituent material of the substrate <NUM> is not limited to the above description, and may include all materials applicable to the color wheel <NUM> by a person skilled in the art within a range having good thermal conductivity and reflectivity.

A reflective layer <NUM> may be disposed between the substrate <NUM> and the phosphor layer <NUM>.

The reflective layer <NUM> may have an adhesive property so that the phosphor layer <NUM> can be firmly coupled to the substrate <NUM>, and at the same time, have a reflective property to improve light conversion efficiency of the phosphor layer <NUM>.

Specifically, the reflective layer <NUM> may include at least one of resin, silver Ag, and titanium oxide TiO2.

For example, a reflective layer composed of titanium oxide powder and resin may be applied, or a substrate having a surface deposited with silver may be applied as the reflective layer.

However, the constituent material of the reflective layer <NUM> is not limited to the above description, and may include a constituent material within a range that can be easily design-changed by a person skilled in the art.

The color wheel <NUM> according to the embodiment of the present disclosure can implement the effect of excellent luminescence intensity and reduced luminescence intensity degradation at high temperatures, by adjusting the composition of the phosphor included in the phosphor layer <NUM>.

In this regard, the phosphor layer <NUM> will be described in detail with reference to <FIG>, <FIG> and <FIG>.

The phosphor layer <NUM> may be irradiated by a light source, and each of the phosphors <NUM> and <NUM> included in the phosphor layer <NUM> may absorb incident light, convert it to a specific wavelength, and then emit it.

Specifically, the phosphor layer <NUM> may include a basic phosphor <NUM> having a basic emission wavelength and at least one modified phosphor <NUM> having at least one emission wavelength different from the basic emission wavelength.

First, the basic phosphor <NUM> may be a phosphor including YAG:Ce including yttrium, aluminum Al, and garnet to which cerium Ce is added.

In detail, the empirical formula of the basic phosphor <NUM> may be Y3AI5O12, and <NUM>, <NUM>, and <NUM> in the empirical formula means at% which is the number of elements occupied by each element in comparison with the total number of atoms. Cerium is included in a very trace amount, and may be, for example, <NUM> at% as about <NUM> at% or less.

In the present specification, the fact that the basic phosphor <NUM> is a phosphor including Y3AI5O12 (YAG:Ce) may mean that it is a phosphor obtained by mixing and hardening Y3AI5O12 phosphor powder with a resin.

In addition, the phosphor including Y3AI5O12 included in the basic phosphor <NUM> may have an average particle size of about <NUM> to about <NUM>.

The basic phosphor <NUM> absorbs incident light, converts it to a basic emission wavelength, and emits it, for example, emits yellow-series light.

Meanwhile, the color wheel <NUM> according to the embodiment of the present disclosure may include not only the basic phosphor <NUM> but also at least one modified phosphor <NUM> having at least one emission wavelength different from the basic emission wavelength.

Specifically, the color wheel <NUM> according to the embodiment of the present disclosure may include a plurality of modified phosphors <NUM> having different gallium contents, and the emission wavelength is also varied because the content of gallium included in each of the plurality of modified phosphors <NUM> is varied.

That is, the color wheel <NUM> includes at least one modified phosphor <NUM> together with the basic phosphor <NUM>, thereby emitting light having a basic emission wavelength and an emission wavelength different from the basic emission wavelength.

A detailed description of the composition of the plurality of modified phosphors <NUM> will be described later.

The modified phosphor <NUM> may include Y3(GaxAl(<NUM>-x))5O12:Ce in which the basic phosphor <NUM> is doped with gallium Ga.

In the present specification, the fact that the modified phosphor <NUM> is a phosphor including Y3AI5O12 doped with Ga may mean that it is a phosphor obtained by mixing and hardening Y3AI5O12 phosphor powder doped with Ga with a resin.

In addition, the phosphor including Y<NUM>Al<NUM>O<NUM> doped with Ga included in the modified phosphor <NUM> may have an average particle size of about <NUM> to about <NUM>.

Specifically, the modified phosphor <NUM> may be in a state in which gallium Ga is substituted with at least a portion of aluminum of the basic phosphor <NUM> to form a solid solution.

Furthermore, the ratio of the element of substituted gallium to the total element of aluminum, the x value in the empirical formula of the modified phosphor <NUM> may be about <NUM> to about <NUM>.

The modified phosphor <NUM> may be doped with gallium so that the x value in the empirical formula is about <NUM> to about <NUM>, thereby changing the emission wavelength and the emission intensity of the modified phosphor <NUM>.

As a result, the emission intensity of the color wheel <NUM> including the basic phosphor <NUM> and the modified phosphor <NUM> can be remarkably improved, and as the output of the incident light increases, the decrease in the emission intensity can be effectively reduced even when the temperature increases.

Meanwhile, as described above, since the color wheel <NUM> may include a plurality of modified phosphors <NUM>, the modified phosphor <NUM> included in the embodiment of the present disclosure may be composed of a plurality of modified phosphors <NUM> having different x values when x ranges from <NUM> to <NUM>.

For example, the modified phosphor <NUM> may be composed of a plurality of modified phosphors <NUM> having different gallium ratios such as Y<NUM>(Ga<NUM>, Al<NUM>)<NUM>O<NUM>:Ce(x=<NUM>), Y<NUM>(Ga<NUM>, Al<NUM>)<NUM>O<NUM>:Ce(x=<NUM>), Y<NUM>(Ga<NUM>, Al<NUM>)<NUM>O<NUM>:Ce(x=<NUM>).

In the modified phosphor <NUM>, as the x value in the empirical formula increases within the range of about <NUM> to about <NUM>, the emission wavelength can move from the yellow series to the green series.

The color wheel <NUM> according to the embodiment of the present disclosure includes at least one modified phosphor <NUM> having a different gallium doping ratio, thereby improving the quality of an image finally implemented by the projector by diversifying the wavelength band of light that can be implemented through the color wheel <NUM>.

In addition, the color wheel <NUM> according to the embodiment of the present disclosure includes a plurality of modified phosphors <NUM> having different gallium doping ratios, thereby further improving the luminescence intensity, and more effectively reducing a decrease in luminescence intensity due to a rise in temperature.

For example, when the color wheel <NUM> includes a first modified phosphor <NUM> having x in the range of about <NUM> to <NUM> in the empirical formula and a second modified phosphor <NUM> having x in the range of about <NUM> to <NUM>, the luminescence intensity can be further improved, in comparison with a case of including only one type of modified phosphor <NUM>.

Next, the disposition structure of the basic phosphor <NUM> and at least one modified phosphor <NUM> will be described.

Referring back to <FIG>, the substrate <NUM> may be partitioned to have a certain central angle with respect to the rotation axis of the substrate, and the partitioned substrate may include a basic phosphor area <NUM> on which the basic phosphor <NUM> is disposed, and a modified phosphor area <NUM> in which the modified phosphor <NUM> is disposed.

Since the basic phosphor <NUM> or the modified phosphor <NUM> may be spaced apart from each other and disposed in plurality on the substrate, the number of the basic phosphor area <NUM> and the modified phosphor area <NUM> may be the same as or more than the number of the types of the basic phosphor <NUM> and the modified phosphor <NUM> (in the case of the modified phosphor <NUM>, the modified phosphor <NUM> having the same x value in the empirical formula is determined as one type, and the modified phosphor <NUM> having a different x value is determined as another type).

A plurality of the basic phosphor <NUM> or the modified phosphor <NUM> having the same type may be respectively disposed on the substrate, and may be disposed in contact with each other or spaced apart from each other when a plurality of basic phosphors <NUM> or modified phosphors <NUM> having the same type are disposed on the substrate.

For example, the basic phosphor area <NUM> and the modified phosphor area <NUM> may be formed of each part of an annular shape based on the rotation axis of the substrate <NUM>. That is, an annular area of a certain width is formed around the rotation axis of the substrate <NUM>, and the annular area is partitioned and divided to have a certain central angle to become the basic phosphor area <NUM> and the modified phosphor area <NUM>.

However, the shapes of the basic phosphor area <NUM> and the modified phosphor area <NUM> are not limited to the above description and the structures shown in drawing, and as long as the shape can surround the central axis based on the rotation axis of the substrate <NUM>, it can be said that it includes a shape or structure that can be easily designed and changed by a person skilled in the art.

As described above, the basic phosphor <NUM> may be disposed in the basic phosphor area <NUM> and the modified phosphor <NUM> may be disposed in the modified phosphor area <NUM>. Meanwhile, in the color wheel <NUM> according to the embodiment of the present disclosure, the basic phosphor area <NUM> and the modified phosphor area <NUM> may be configured at a certain ratio.

Specifically, the sum of the central angle θ11 of the basic phosphor area compared to the sum of the central angle θ11 of the basic phosphor area and the central angle θ12 of the modified phosphor area may be about <NUM>° to about <NUM>°, and the sum of the central angle θ11 of the modified phosphor area compared to the sum of the central angle θ11 of the basic phosphor area and the central angle θ12 of the modified phosphor area may be about <NUM>° to about <NUM>°.

That is, the ratio occupied by the basic phosphor area <NUM> in <NUM>° may be about <NUM>/<NUM> to about <NUM>/<NUM>, and conversely, the ratio occupied by the modified phosphor area <NUM> may be about <NUM>/<NUM> to about <NUM>/<NUM>.

In the color wheel <NUM> according to the embodiment of the present disclosure, the basic phosphor area <NUM> and the modified phosphor area <NUM> are configured in the above ratio, thereby improving the luminescence intensity of the color wheel <NUM>.

Furthermore, as described above, the modified phosphor <NUM> may include a plurality of modified phosphors having different gallium contents, and the modified phosphor area <NUM> may be disposed by classifying modified phosphors having different gallium contents by type.

Specifically, the modified phosphor area <NUM> may include a plurality of modified phosphor small areas 12a and 12b in which a plurality of modified phosphors having a different gallium content are disposed respectively.

In the present specification, the number of the modified phosphor small areas 12a and 12b is not limited to the description and the contents disclosed in drawing, but includes a range that can be easily designed and changed by a person skilled in the art.

For example, the modified phosphor small area 12a may be one, may be two 12a and 12b, or may be plural, e.g., three or more. When there are a plurality of modified phosphor small areas, e.g., three or more modified phosphor small areas, reference numerals may be denoted as 12a, 12b, 12c.

The modified phosphor small area 12a, 12b may have a different central angle depending on the gallium content of the modified phosphor <NUM>, and the modified phosphors <NUM> of the same type having the same gallium content may have the same central angle of the modified phosphor small area 12a.

When a plurality of modified phosphors <NUM> having different gallium contents are included, the central angle of the modified phosphor small area 12a, 12b is differently configured according to the content of gallium, thereby implementing a difference in color characteristics such as color coordinates and brightness ratio and a difference in emission intensity between each of the basic phosphors <NUM> and the modified phosphors <NUM>, and implementing a color wheel that effectively satisfies the required color characteristics due to such a difference, while having an excellent luminous intensity.

Next, the characteristics and effects of the color wheel <NUM> according to the embodiment of the present disclosure will be described in detail with reference to Tables <NUM>, <NUM>, and <NUM> below.

Referring to Tables <NUM> and <NUM>, in contrast to Comparative examples, embodiments <NUM> to <NUM> include one or two modified phosphors <NUM> doped with gallium together with the basic phosphor <NUM>.

At the same time, when two modified phosphors <NUM> are included, the modified phosphor area 12b in which the modified phosphor <NUM> having a high gallium content (x value is relatively high in the empirical formula) is controlled to have a greater central angle than the modified phosphor area 12b in which the modified phosphor <NUM> having a low gallium content.

As a result, it can be checked that the luminescence intensity of embodiments <NUM> to <NUM> are significantly increased compared to comparative example <NUM>.

Furthermore, when different types of modified phosphors <NUM> having different gallium contents are included, the luminescence intensity can be further improved by controlling the respective gallium content (x value of the empirical formula) and the angle of the modified phosphor small area 12a, 12b.

Meanwhile, in <FIG>, embodiment <NUM> and comparative example <NUM> are compared for luminescence intensity according to the output (POWER) of the incident light.

Referring to <FIG>, in comparative example <NUM>, as the output of the incident light increases, the temperature of the phosphor also increases, so that the emission intensity of the phosphor decreases to a certain level or lower.

Claim 1:
A color wheel (<NUM>) comprising:
a basic phosphor (<NUM>) having a basic emission wavelength; and
at least one modified phosphor (<NUM>) having at least one emission wavelength different from the basic emission wavelength,
wherein the basic phosphor (<NUM>) comprises Y<NUM>Al<NUM>O<NUM>, and
wherein the modified phosphor (<NUM>) comprises Y<NUM>(GaxAl(<NUM>-x))<NUM>O<NUM>:Ce in which gallium is doped into the basic phosphor.