Patent Description:
The invention relates to an optical element, a manufacturing method thereof, and a display device using the optical element, and more particularly to a wavelength conversion element, a manufacturing method thereof, and a projection device using the wavelength conversion element.

The type of light source used in the projection device has evolved from ultra-high pressure mercury lamp (UHP lamp), light emitting diode (LED) to laser diode (LD) with the market demand for brightness, color saturation, service life, non-toxic environmental protection and the like of the projection device.

At present, a cost of high-brightness red laser diodes and green laser diodes is too high. In order to reduce the cost, a blue laser diode is usually used to excite a phosphor on a phosphor wheel to generate yellow light and green light, then a desired red light is filtered through a filter wheel, and then a blue light emitted by the blue laser diode is used to form the three primary colors of red, green and blue required for a projection image.

The phosphor wheel is an extremely important element in projection devices that currently use laser diodes as a light source. However, the sintered phosphor layer of current phosphor wheels will generate pores, which affects the conversion efficiency and thermal conductivity of the phosphor wheels. In addition, due to the manufacturing process, when the phosphor layer is sintered, the two surfaces will warp due to stress imbalance, making the phosphor layer unable to fit on the wheel, which causes the conversion efficiency and thermal conductivity of the phosphor wheel to decrease.

The information disclosed in this "BACKGROUND OF THE INVENTION" section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this "BACKGROUND OF THE INVENTION" section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.

<CIT> describes a light source device which includes a light-emitting element; a base that includes a plurality of segment regions and that is controllable so that light from the light-emitting element sequentially enters the respective segment regions; a fluorescent member that is provided in at least one of the segment regions and that includes a fluorescent material that is excitable by light from the light-emitting element and configured to emit light with a different wavelength from the light emitted from the light-emitting element; and a filter that is provided so as to correspond to at least one of the fluorescent members, which is configured to transmit at least a part of light from the fluorescent material, and which is configured to transmit a part of light that is transmitted through the fluorescent member among the light from the light-emitting element.

<CIT> relates to a wavelength conversion element which includes a base material; a wavelength conversion layer supported by one surface of the base material and containing a wavelength conversion material and an inorganic binder; a light transmitting layer provided in a side of the wavelength conversion layer opposite to the base material and made of an inorganic material; and an antireflection film provided in a side of the light transmitting layer opposite to the wavelength conversion layer.

<CIT> describes a wavelength conversion module and a projection device. The wavelength conversion module comprises a substrate and a wavelength conversion layer. The substrate is provided with a rough surface, the rough surface comprises two first areas and a second area, and the second area is located between the two first areas in the radial direction of the substrate.

The wavelength conversion layer is located on the substrate and comprises a wavelength conversion material, a binding material and a plurality of diffuse reflection particles. The wavelength conversion material is dispersed in the bonding material. The plurality of diffuse reflection particles are located on the rough surface of the substrate and located between the wavelength conversion material and the substrate, and the density of the diffuse reflection particles in the second area range is larger than that of the diffuse reflection particles in each first area range, so that the wavelength conversion module can achieve the required reflectivity, heat conduction efficiency or reliability.

<CIT> relates to a wavelength conversion element which includes a wavelength conversion layer which has a first face on which an excitation light is incident and a second face facing the first face, a first layer which is provided facing the second face and contains a first inorganic oxide, a second layer which is provided facing the first layer and contains a first metal or a second inorganic oxide that is different from the first inorganic oxide, and a third layer which is provided facing the second layer, contains either silver or aluminum, and reflects the excitation light or a light obtained by wavelength conversion of the excitation light by the wavelength conversion layer.

<CIT> relates to a wavelength conversion element which comprises an alloy substrate, a wavelength conversion layer and a diffuse reflection layer. The wavelength conversion layer is disposed above the alloy substrate. The diffuse reflection layer is disposed between the alloy substrate and the wavelength conversion layer. The resulting wavelength conversion element can improve the mechanical property, the temperature resistance and the reflectivity.

<CIT> relates to a wavelength conversion element including: a base material including a light-reflecting surface; a dichroic film; and a wavelength conversion layer provided between the light-reflecting surface and the dichroic film. The dichroic film reflects portion of light in a wavelength band that the wavelength conversion layer absorbs, and has a reflectance distribution, with respect to the light along a predetermined direction.

The invention provides a wavelength conversion element, in accordance with the appended claim <NUM>, which may improve conversion efficiency and thermal conductivity.

The invention provides a manufacturing method of a wavelength conversion element, in accordance with the appended claim <NUM>, which may improve conversion efficiency and thermal conductivity of the wavelength conversion element.

The invention provides a projection device, in accordance with the appended claim <NUM>, which may reduce the problem that the image brightness decreases.

Other advantages and objects of the invention, as defined by the appended dependent claims, may be further illustrated by the technical features broadly embodied and described as follows.

The object is solved by the features of the appended independent claims. Preferred embodiments are given in the appended dependent claims.

In order to achieve one or a portion of or all of the objects or other objects, a wavelength conversion element provided in an embodiment of the invention includes a substrate, a wavelength conversion layer, a first inorganic interstitial layer and a second inorganic interstitial layer. The wavelength conversion layer is disposed on the substrate. The wavelength conversion layer includes an inorganic adhesive and a wavelength conversion material, and the wavelength conversion material is mixed with the inorganic adhesive. The wavelength conversion layer has a first surface and a second surface relative to the first surface.

The first inorganic interstitial layer is disposed between the wavelength conversion layer and the substrate. The first inorganic interstitial layer is formed on the first surface and is configured to fill pores of the wavelength conversion layer. The wavelength conversion layer is disposed between the second inorganic interstitial layer and the first inorganic interstitial layer. A thickness of the second inorganic interstitial layer in a direction perpendicular to the substrate increases from a center toward an edge, or decreases from a center toward an edge. The second inorganic interstitial layer is formed on the second surface and is configured to fill pores of the wavelength conversion layer.

In order to achieve one or a portion of or all of the objects or other objects, a projection device provided in an embodiment of the invention includes an illumination system, a light valve and a projection lens. The illumination system is adapted to provide an illumination beam. The light valve is disposed on a transmission path of the illumination beam to convert the illumination beam into an image beam. The projection lens is disposed on a transmission path of the image beam. The illumination system includes an excitation light source and the wavelength conversion element described above. The wavelength conversion element is disposed on a transmission path of an excitation beam, and the wavelength conversion element is adapted to convert the excitation beam into a converted beam, and the illumination beam includes the converted beam.

Preferably, a material of any one of the inorganic adhesive and the first inorganic interstitial layer may comprise at least one of alumina, silica, ceramic, and aluminum nitride.

Preferably, a material of the second inorganic interstitial layer may comprise at least one of alumina, silica, ceramic, and aluminum nitride.

Preferably, a thickness of the second inorganic interstitial layer in a direction perpendicular to the substrate may be <NUM>~<NUM>.

Preferably, a thickness of the first inorganic interstitial layer and a thickness of the second inorganic interstitial layer in a direction perpendicular to the substrate may be the same or different.

Preferably, the wavelength conversion element may further comprise an adhesive layer, disposed between the first inorganic interstitial layer and the substrate.

Preferably, a volume-concentration ratio of the wavelength conversion material contained in the wavelength conversion layer may be <NUM>% to <NUM>%.

Preferably, a thickness of the first inorganic interstitial layer in a direction perpendicular to the substrate may be <NUM> ~ <NUM>.

Preferably, a thickness of the first inorganic interstitial layer in a direction perpendicular to the substrate may be uniformly distributed, increasing from a center toward an edge, or decreasing from a center toward an edge.

Preferably, a surface of the first inorganic interstitial layer facing the substrate may contact the substrate as a whole.

A projection device, is provided comprising: an illumination system, adapted to provide an illumination beam; a light valve, disposed on a transmission path of the illumination beam to convert the illumination beam into an image beam; and a projection lens, disposed on a transmission path of the image beam, wherein the illumination system comprises an excitation light source and a wavelength conversion element as recited in any one of the appended claims <NUM>-<NUM>, the excitation light source is adapted to provide an excitation beam, the wavelength conversion element is disposed on a transmission path of the excitation beam, and the wavelength conversion element is adapted to convert the excitation beam into a converted beam, and the illumination beam includes the converted beam.

In order to achieve one or a portion of or all of the objects or other objects, a manufacturing method of a wavelength conversion element provided in an embodiment of the invention includes: providing a wavelength conversion layer, the wavelength conversion layer has a first surface and a second surface relative to the first surface; disposing a first inorganic interstitial layer on the first surface of the wavelength conversion layer, the first inorganic interstitial layer has a third surface and a fourth surface relative to the third surface, and the fourth surface faces the first surface; bonding the third surface of the first inorganic interstitial layer to a substrate to dispose the first inorganic interstitial layer between the wavelength conversion layer and the substrate.

Before bonding the third surface of the first inorganic interstitial layer to the substrate, the manufacturing method of the wavelength conversion element in accordance with the present invention further comprises disposing a second inorganic interstitial layer on the second surface of the wavelength conversion layer, wherein a thickness of the second inorganic interstitial layer in a direction perpendicular to the substrate increases from a center toward an edge, or decreases from a center toward an edge.

Preferably, the method of providing a wavelength conversion layer may comprise at least one of: providing a preformed substrate having a forming surface; mixing a wavelength conversion material with an inorganic adhesive and coating on the forming surface of the preformed substrate to form a wavelength conversion layer, and bonding the first surface of the wavelength conversion layer to the forming surface of the preformed substrate; heating the wavelength conversion layer; and separating the first surface of the wavelength conversion layer from the forming surface of the preformed substrate.

Preferably, the method of disposing the first inorganic interstitial layer on the first surface of the wavelength conversion layer may comprise forming the first inorganic interstitial layer on the first surface of the wavelength conversion layer by spraying.

Preferably, the method of disposing the first inorganic interstitial layer on the first surface of the wavelength conversion layer may comprise heating the wavelength conversion layer and the first inorganic interstitial layer.

Preferably, the method of bonding the third surface of the first inorganic interstitial layer to the substrate to dispose the first inorganic interstitial layer between the wavelength conversion layer and the substrate may comprise bonding the third surface of the first inorganic interstitial layer to the substrate through an adhesive layer.

Preferably, the method of bonding the third surface of the first inorganic interstitial layer to the substrate to dispose the first inorganic interstitial layer between the wavelength conversion layer and the substrate may comprise heating the wavelength conversion layer, the first inorganic interstitial layer and the substrate.

In the wavelength conversion element of the embodiment of the invention, the configuration of the first inorganic interstitial layer may reduce the pores generated during the preparation of the wavelength conversion layer, and stress may be applied to the wavelength conversion layer to reduce the warping phenomenon of the wavelength conversion layer during the preparation, thereby improving the conversion efficiency and thermal conductivity of the wavelength conversion element. In the manufacturing method of the wavelength conversion element of the embodiment of the invention, the first inorganic interstitial layer is disposed, so that the above-mentioned wavelength conversion element may be manufactured. Since the projection device of embodiment of the invention uses the above-mentioned wavelength conversion element, the problem that the image brightness decreases may be reduced.

Other objectives, features and advantages of the invention as defined by the appended claims will be further understood from the further technological features disclosed by the embodiments of the invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.

The accompanying drawings are included to provide a further understanding of the invention or if its context, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments, some of which are embodiments of the invention in accordance with the appended claims whereas others are not defining the present invention as claimed but are useful for understanding its context, and, together with the description, serve to explain the context and principles of the invention.

In the following detailed description of the preferred embodiments, some of which are embodiments of the invention as claimed, whereas others are not, but are illustrative embodiments being useful for understanding the context of the invention, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as "top", "bottom", "front", "back", etc., is used with reference to the orientation of the Figure(s) being described. The components of the invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention as defined by the appended claims. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of "including", "comprising", or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms "connected", "coupled", and "mounted" and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms "facing", "faces", and variations thereof herein are used broadly and encompass direct and indirect facing, and "adjacent to" and variations thereof herein are used broadly and encompass directly and indirectly "adjacent to". Therefore, the description of "A" component facing "B" component herein may contain the situations that "A" component facing "B" component directly or one or more additional components is between "A" component and "B" component. Also, the description of "A" component "adjacent to" "B" component herein may contain the situations that "A" component is directly "adjacent to" "B" component or one or more additional components is between "A" component and "B" component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.

<FIG> is a cross-sectional schematic diagram of a wavelength conversion element of one illustrative embodiment not forming part of the invention as claimed, but useful for understanding its context. Referring to <FIG>, a wavelength conversion element <NUM> of the embodiment includes a substrate <NUM>, a wavelength conversion layer <NUM>, and a first inorganic interstitial layer <NUM>. The wavelength conversion element <NUM> is, for example, a sheet-like element, but is not limited thereto. In other embodiments, the wavelength conversion element <NUM> may be a wavelength conversion wheel, and the substrate <NUM> is, for example, a turntable. The wavelength conversion layer <NUM> is disposed on the substrate <NUM>. The wavelength conversion layer <NUM> includes an inorganic adhesive <NUM> and a wavelength conversion material <NUM>, and the wavelength conversion material <NUM> is mixed with the inorganic adhesive <NUM>. The first inorganic interstitial layer <NUM> is disposed between the wavelength conversion layer <NUM> and the substrate <NUM>. The wavelength conversion material <NUM> is, for example, phosphor or quantum dot, but is not limited thereto. A material of the substrate <NUM> is, for example, metal, glass, or ceramic. The metal includes, for example, aluminum, aluminum alloy, copper, copper alloy, aluminum nitride, silicon carbide, and the like, and the glass surface can be plated with aluminum, silver, or electroplated film, but is not limited thereto.

A material of any one of the inorganic adhesive <NUM> and the first inorganic interstitial layer <NUM> includes, for example, at least one of alumina, silica, ceramic, and aluminum nitride, but is not limited thereto. Specifically, the material of the inorganic adhesive <NUM> is, for example, the same as that of the first inorganic interstitial layer <NUM>. In another embodiment, the inorganic adhesive <NUM> may be made of a different material from the first inorganic interstitial layer <NUM>.

The wavelength conversion element <NUM> further includes, for example, an adhesive layer <NUM> and a reflective layer <NUM>. The adhesive layer <NUM> is disposed between the first inorganic interstitial layer <NUM> and the substrate <NUM>. The reflective layer <NUM> is disposed between the adhesive layer <NUM> and the substrate <NUM>. A material of the adhesive layer <NUM> includes, for example, silica gel, epoxy resin, or thermally conductive adhesive. A material of the reflection layer <NUM> is, for example, metal. In another embodiment, the material of the reflective layer <NUM> may also be a mixture of reflective particles in the adhesive, so that the reflective layer <NUM> may have the functions of adhesion and reflection at the same time, so there is no need to dispose the adhesive layer <NUM>.

In the wavelength conversion element of the embodiment, the configuration of the first inorganic interstitial layer <NUM> may fill the pores generated during the preparation of the wavelength conversion layer <NUM>, so that a surface flatness of the wavelength conversion layer <NUM> may be improved, thereby improving the conversion efficiency and thermal conductivity of the wavelength conversion element.

A thickness T1 of the first inorganic interstitial layer <NUM> in a direction A perpendicular to the substrate <NUM> in <FIG> is, for example, uniformly distributed, but is not limited thereto. In other embodiments, for example, the thickness T1 of the first inorganic interstitial layer <NUM> may gradually increase from a center toward an edge as shown in <FIG>, or decrease from the center toward the edge as shown in <FIG>. The thickness T1 of the first inorganic interstitial layer <NUM> is, for example, <NUM> ~ <NUM>, and preferably <NUM> ~ <NUM>. In embodiments with different thickness distributions, the thickest part of the thickness is used as the measurement basis, such as at the edge of <FIG> or at the center of <FIG>.

<FIG> are cross-sectional schematic diagrams of a wavelength conversion element of other embodiments. Referring to <FIG>, not forming part of the present invention as claimed but useful for understanding its context, first, the wavelength conversion element 100a of the embodiment is similar in structure and advantages to the wavelength conversion element <NUM>, the only difference is that the wavelength conversion element 100a of the embodiment further includes a second inorganic interstitial layer <NUM>. The wavelength conversion layer <NUM> is disposed between the second inorganic interstitial layer <NUM> and the first inorganic interstitial layer <NUM>. A material of the second inorganic interstitial layer <NUM> includes, for example, at least one of alumina, silica, ceramic, and aluminum nitride, but is not limited thereto. Specifically, the material of the second inorganic interstitial layer <NUM> may be the same as or different from the inorganic adhesive <NUM> or the first inorganic interstitial layer <NUM>, for example. The function of the second inorganic interstitial layer <NUM> is the same as that of the first inorganic interstitial layer <NUM>. By disposing the second inorganic interstitial layer <NUM> on an upper surface and a lower surface of the wavelength conversion layer <NUM>, the above-mentioned advantages may be further enhanced.

A thickness T2 of the second inorganic interstitial layer <NUM> in a direction A perpendicular to the substrate <NUM> in <FIG> is, for example, uniformly distributed, but is not limited thereto. Referring to <FIG> and <FIG>, in other embodiments being this time in accordance with the invention as defined by the appended claims, the thickness T2 of the second inorganic interstitial layer <NUM> either gradually increases from a center toward an edge as shown in <FIG>, or decreases from the center toward the edge as shown in <FIG>. The thickness T2 of the second inorganic interstitial layer <NUM> is, for example, <NUM> ~ <NUM>, and preferably <NUM> ~ <NUM>. The thickness T1 of the first inorganic interstitial layer <NUM> and the thickness T2 of the second inorganic interstitial layer <NUM> are, for example, the same or different. The first inorganic interstitial layer <NUM> in <FIG> and <FIG> may also gradually increase from a center to an edge as shown in <FIG>, or decrease from the center to the edge as shown in <FIG>. That is, the thickness distribution types of the first inorganic interstitial layer <NUM> and the second inorganic interstitial layer <NUM> may be used in combination according to different design requirements. The following will describe in detail how the wavelength conversion element <NUM> of the embodiment reduces the warping phenomenon during the preparation.

<FIG> is a schematic flowchart of a manufacturing method of a wavelength conversion element of one embodiment not forming part of the invention as claimed but useful for understanding the context of the invention. <FIG> is a schematic diagram of providing a wavelength conversion layer of one embodiment in the context of the invention. Referring to <FIG> and <FIG> first, a manufacturing method of the wavelength conversion element <NUM> of the embodiment includes the following steps. Step S101: Providing a wavelength conversion layer <NUM>, the wavelength conversion layer <NUM> has a first surface <NUM> and a second surface <NUM> relative to the first surface <NUM>.

Referring to <FIG>, specifically, the method for providing the wavelength conversion layer <NUM> includes: providing a preformed substrate <NUM> having a forming surface <NUM>. A wavelength conversion material <NUM> is mixed with an inorganic adhesive <NUM> and coated on the forming surface <NUM> of the preformed substrate <NUM> to form a wavelength conversion layer <NUM>. The first surface <NUM> of the wavelength conversion layer <NUM> is bonded to the forming surface <NUM> of the preformed substrate <NUM>. Next, the wavelength conversion layer <NUM> is heated, a so-called sintering process. After sintering, the first surface <NUM> of the wavelength conversion layer <NUM> is separated from the forming surface <NUM> of the preformed substrate <NUM>. During the separation process, due to factors such as a volume-concentration ratio of the wavelength conversion material <NUM>, a precipitation of the wavelength conversion material <NUM> in the wavelength conversion layer <NUM>, and a mold release from the edge of the wavelength conversion layer <NUM> during separation, the wavelength conversion layer <NUM> is warped due to a stress imbalance between the first surface <NUM> and the second surface <NUM>. If the wavelength conversion layer <NUM> after mold release is directly bonded to the substrate <NUM>, there will be a gap between the wavelength conversion layer <NUM> and the substrate <NUM>, which will affect the conversion efficiency and thermal conductivity of the wavelength conversion element <NUM>.

In the embodiment, by adjusting the volume-concentration ratio of the wavelength conversion material <NUM> contained in the wavelength conversion layer <NUM> to be <NUM>% to <NUM>%, and using the mold release agent to mold release the wavelength conversion layer <NUM>, the stress imbalance of the first surface <NUM> and the second surface <NUM> may be reduced initially. To further reduce the degree of warping, step S102 is then performed: disposing a first inorganic interstitial layer <NUM> on the first surface <NUM> of the wavelength conversion layer <NUM>, the first inorganic interstitial layer <NUM> has a third surface <NUM> and a fourth surface <NUM> relative to the third surface <NUM>, and the fourth surface <NUM> faces the first surface <NUM>.

The method of disposing the first inorganic interstitial layer <NUM> on the first surface <NUM> of the wavelength conversion layer <NUM> includes forming the first inorganic interstitial layer <NUM> on the first surface <NUM> of the wavelength conversion layer <NUM> by spraying. During the spraying process, an interstitial material used by the first inorganic interstitial layer <NUM> fills the pores of the wavelength conversion layer <NUM>, increase the density and the surface flatness of the first surface <NUM>, and help to improve the conversion efficiency and thermal conductivity of the wavelength conversion element <NUM>.

Further, in one embodiment, the method of disposing the first inorganic interstitial layer <NUM> on the first surface <NUM> of the wavelength conversion layer <NUM> further includes after forming the first inorganic interstitial layer <NUM> by spraying, the above-mentioned wavelength conversion layer <NUM> having the warping phenomenon and the first inorganic interstitial layer <NUM> disposed on the first surface <NUM> are heated and sintered, which is also the second sintering of the wavelength conversion layer <NUM>. During the sintering process, the first inorganic interstitial layer <NUM> applies a stress to the wavelength conversion layer <NUM> that generates the warping phenomenon, so that the degree of the warping phenomenon is reduced, and the third surface <NUM> of the first inorganic interstitial layer <NUM> facing the substrate <NUM> may contact the substrate <NUM> as a whole, for example. That is, the conversion efficiency and thermal conductivity of the wavelength conversion element <NUM> would not be affected due to the gap between the wavelength conversion layer <NUM> and the substrate <NUM>. If the degree of warping phenomenon is serious, in another embodiment, a curved substrate may also be used, and the degree of bending of the substrate <NUM> corresponds to the warping phenomenon of the wavelength conversion layer <NUM> so that the wavelength conversion layer <NUM> may contact the substrate <NUM> as a whole. In addition, in the embodiment in which other layers such as the adhesive layer <NUM> and the reflective layer <NUM> are disposed between the first inorganic interstitial layer <NUM> and the substrate <NUM>, the case where the wavelength conversion layer <NUM> contacts the substrate <NUM> as a whole means that the wavelength conversion layer <NUM> may contact other layers such as the adhesive layer <NUM> or the reflective layer <NUM> on the substrate <NUM> as a whole to indicate that no gap is generated between the wavelength conversion layer <NUM> and the substrate <NUM> or the layers above it.

Depending on the degree of the warping phenomenon generated by the wavelength conversion layer <NUM>, the first inorganic interstitial layer <NUM> may be selected to be disposed with different thickness distributions, for example, disposed as shown in <FIG>. Taking <FIG> as an example, the warping phenomenon of the wavelength conversion layer <NUM> is that the edge is warped away from the forming surface <NUM> of the preformed substrate <NUM> (warped upward), so that the thickness T1 of the first inorganic interstitial layer <NUM> may be disposed to gradually increase from the center to the edge as shown in <FIG>. Generally speaking, the first inorganic interstitial layer <NUM> having a thicker thickness is usually disposed in a place with a large degree of warping phenomenon, and the first inorganic interstitial layer <NUM> having a thinner thickness is usually disposed in a place with a small degree of warping phenomenon.

In another embodiment, the warping phenomenon may not occur in the wavelength conversion layer <NUM> after the first heating and sintering in step S101, but the warping phenomenon may occur in the second sintering performed in step S103. In such a situation, the thickness distribution of the first inorganic interstitial layer <NUM> needs to be adjusted in step S102 to reduce the degree of warping phenomenon caused by secondary sintering.

Next, step S103: bonding the third surface <NUM> of the first inorganic interstitial layer <NUM> to a substrate <NUM> to dispose the first inorganic interstitial layer <NUM> between the wavelength conversion layer <NUM> and the substrate <NUM>. The method of bonding the third surface <NUM> of the first inorganic interstitial layer <NUM> to the substrate <NUM> to dispose the first inorganic interstitial layer <NUM> between the wavelength conversion layer <NUM> and the substrate <NUM> includes, for example, bonding the third surface <NUM> of the first inorganic interstitial layer <NUM> to the substrate <NUM> through an adhesive layer <NUM>, but is not limited thereto. In another embodiment, for example, the first inorganic interstitial layer <NUM> formed by spraying and not yet heated and sintered is directly bonded to the substrate <NUM>, and then the wavelength conversion layer <NUM>, the first inorganic interstitial layer <NUM> and the substrate <NUM> are heated and sintered together to achieve a stable bonding effect. However, in this case, the material of the substrate <NUM> is preferably ceramic, which has higher temperature resistance than metal.

In the manufacturing method of the wavelength conversion element <NUM> of the embodiment, by disposing the first inorganic interstitial layer <NUM> on the first surface <NUM> of the wavelength conversion layer <NUM>, the first inorganic interstitial layer <NUM> applies a stress to the wavelength conversion layer <NUM> that generates the warping phenomenon, so that the degree of the warping phenomenon is reduced, thereby improving the conversion efficiency and thermal conductivity of the wavelength conversion element <NUM>. In the invention, the degree of warping phenomenon is defined as a spacing difference between the highest and the lowest points of the curved surface formed by bending. Taking <FIG> as an example, the degree of warping phenomenon of the wavelength conversion layer <NUM> is a spacing D difference between the edge and the center of the first surface <NUM>. If the spacing D is larger, the degree of the warping phenomenon is higher, and vice versa. Specifically, the degree of warping phenomenon of the wavelength conversion layer when the first inorganic interstitial layer is not disposed is <NUM> ~ <NUM>. After the first inorganic interstitial layer <NUM> is disposed in the wavelength conversion element <NUM> of the embodiment, the degree of warping phenomenon of the wavelength conversion layer <NUM> is reduced to <NUM> ~ <NUM>.

<FIG> is a schematic flowchart of a manufacturing method of a wavelength conversion element of an embodiment of the invention. Referring to <FIG> and <FIG>, a manufacturing method of the wavelength conversion element 100a of an embodiment includes the following steps. Step S201: Providing a wavelength conversion layer <NUM>, the wavelength conversion layer <NUM> has a first surface <NUM> and a second surface <NUM> relative to the first surface <NUM>. Next, step S202: disposing a first inorganic interstitial layer <NUM> on the first surface <NUM> of the wavelength conversion layer <NUM>, the first inorganic interstitial layer <NUM> has a third surface <NUM> and a fourth surface <NUM> relative to the third surface <NUM>, and the fourth surface <NUM> faces the first surface <NUM>. Steps S201 and S202 are the same as steps S101 and S102 in the manufacturing method of the wavelength conversion element <NUM>, and will not be repeated hereinafter.

Next, step S203: disposing a second inorganic interstitial layer <NUM> on the second surface <NUM> of the wavelength conversion layer <NUM>. The second inorganic interstitial layer <NUM> is, for example, also formed on the second surface <NUM> of the wavelength conversion layer <NUM> by spraying. In accordance with the present invention as claimed, the second inorganic interstitial layer <NUM> is disposed with different thickness distributions like the first inorganic interstitial layer <NUM>, in the manner shown in <FIG> or <FIG>. The thickness distribution types of the first inorganic interstitial layer <NUM> and the second inorganic interstitial layer <NUM> may be used in combination according to different design requirements, and the invention is not particularly limited, as long as falling under the scope of the appended claims. After step S203, step S204 is performed: bonding the third surface <NUM> of the first inorganic interstitial layer <NUM> to a substrate <NUM> to dispose the first inorganic interstitial layer <NUM> between the wavelength conversion layer <NUM> and the substrate <NUM>.

<FIG> is a block diagram of a projection device of one embodiment of the invention. Referring to <FIG>, in the embodiment, the above-mentioned wavelength conversion element <NUM>, resp. 100a in accordance with the present invention, is, for example, a wavelength conversion wheel, and the substrate <NUM> is, for example, a turntable. A projection device <NUM> of the embodiment includes an illumination system <NUM>, a light valve <NUM> and a projection lens <NUM>. The illumination system <NUM> is adapted to provide an illumination beam L1. The illumination system <NUM> includes an excitation light source <NUM> and the wavelength conversion element <NUM>. The excitation light source <NUM> is, for example, a diode module including a light emitting diode or a laser diode chip or a matrix composed of a plurality of diode modules to provide the excitation beam Le, but is not limited thereto. The wavelength conversion element <NUM> is disposed on a transmission path of the excitation light beam Le and includes a wavelength conversion region (not shown). The wavelength conversion region includes the wavelength conversion layer <NUM> and the reflective layer <NUM>. The wavelength conversion region of the wavelength conversion element <NUM> is adapted to convert the excitation beam Le into a converted beam Lp, and the illumination beam L1 includes the converted beam Lp, but is not limited thereto. The illumination system <NUM> may further include other optical elements, such as a light combining element, a color wheel, a light homogenization element, and a condensing lens, so that the illumination beam L1 may be transmitted to the light valve <NUM>. The light valve <NUM> is disposed on the transmission path of the illumination beam L1 to convert the illumination beam L1 into an image beam L2. Depending on the design architecture, the quantity of light valve may be one or more. The projection lens <NUM> is disposed on the transmission path of the image beam L2 and is adapted to project the image beam L2 out of the projection device <NUM>.

The light valve <NUM> may be a reflective light valve or a transmissive light valve, in which the reflective light valve may be a digital micro-mirror device (DMD), a liquid crystal display (LCD), a liquid crystal on silicon panel (LCoS panel), a transparent liquid crystal panel, an electro-optical modulator, a magneto-optic modulator, an acousto-optic modulator (AOM), and the transmissive light valve may be a transmissive liquid crystal panel, but is not limited thereto.

The projection lens <NUM> includes, for example, a combination of one or more optical lenses having diopter, such as various combinations of non-planar lenses including biconcave lenses, lenticular lenses, meniscus lenses, convex and concave lenses, plano-convex lenses, and plano-concave lenses. In one embodiment, the projection lens <NUM> may also include a planar optical lens. The invention does not limit the type and kind of the projection lens <NUM>.

In <FIG>, the wavelength conversion element <NUM> of <FIG> is taken as an illustrative example, not forming part of the invention as claimed but useful for understanding its context. In accordance with the present invention, the wavelength conversion element <NUM> is to be replaced with the wavelength conversion element 100a of any of the above embodiments of the invention as claimed.

Since the projection device <NUM> of the embodiment uses the wavelength conversion elements <NUM>, 100a capable of improving the conversion efficiency, the image brightness may be improved. For example, the wavelength conversion element <NUM> disposed with the first inorganic interstitial layer <NUM> of an illustrative embodiment not forming part of the invention and the current wavelength conversion element without the first inorganic interstitial layer <NUM> are measured by integrating sphere brightness, the wavelength conversion element <NUM> of this illustrative embodiment may improve the brightness by <NUM>% to <NUM>% compared with the current wavelength conversion element.

In summary, in the wavelength conversion element of the embodiment of the invention, the configuration of the first inorganic interstitial layer may reduce the pores generated during the preparation of the wavelength conversion layer, and stress may be applied to the wavelength conversion layer to reduce the warping phenomenon of the wavelength conversion layer during the preparation, thereby improving the conversion efficiency and thermal conductivity of the wavelength conversion element. In the manufacturing method of the wavelength conversion element of the embodiment of the invention, the first inorganic interstitial layer is disposed, so that the above-mentioned wavelength conversion element may be manufactured. Since the projection device of embodiment of the invention uses the above-mentioned wavelength conversion element, the problem that the image brightness decreases may be reduced.

Claim 1:
A wavelength conversion element (100a) comprising:
a substrate (<NUM>);
a wavelength conversion layer (<NUM>), disposed on the substrate (<NUM>), wherein the wavelength conversion layer (<NUM>) includes an inorganic adhesive (<NUM>) and a wavelength conversion material (<NUM>), and the wavelength conversion material (<NUM>) is mixed with the inorganic adhesive (<NUM>), wherein the wavelength conversion layer (<NUM>) has a first surface (<NUM>) and a second surface (<NUM>) relative to the first surface;
a first inorganic interstitial layer (<NUM>), disposed between the wavelength conversion layer (<NUM>) and the substrate (<NUM>), wherein the first inorganic interstitial layer (<NUM>) is formed on the first surface (<NUM>) and is configured to fill pores of the wavelength conversion layer (<NUM>); and
a second inorganic interstitial layer (<NUM>), wherein the wavelength conversion layer (<NUM>) is disposed between the second inorganic interstitial layer (<NUM>) and the first inorganic interstitial layer (<NUM>), and
wherein a thickness (T2) of the second inorganic interstitial layer (<NUM>) in a direction perpendicular to the substrate (<NUM>) increases from a center toward an edge, or decreases from a center toward an edge, and
wherein the second inorganic interstitial layer (<NUM>) is formed on the second surface (<NUM>) and is configured to fill pores of the wavelength conversion layer (<NUM>).