Patent Description:
The present invention relates to a phosphor wheel.

An apparatus which projects lights of different colors, such as a projector, includes an excitation light source configured to emit excitation light of a single color, and a phosphor wheel having a diffuser plate configured to receive the excitation light from the excitation light source and transmit therethrough while diffusing the excitation light and a phosphor layer configured to receive the excitation light and emit fluorescence of colors different from the color of the excitation light. The apparatus causes the excitation light source to irradiate the diffuser plate and the phosphor layer of the phosphor wheel rotating with excitation light and extracts light of a plurality of colors to form images to be projected (for example, refer to <CIT>). <CIT> relates to a wavelength conversion device with a transparent element. <CIT> relates to a luminescent wheel with a reflecing plate.

The phosphor wheel of <CIT> includes transmissive sections formed by fitting arc-shaped phosphor layers and arc-shaped diffuser plates in the same circumferential band of a wheel plate.

The phosphor wheel having the above-described structure has a problem that when the phosphor wheel rotates at high speed, the centrifugal force may cause misalignment or separation of transmissive members such as the diffuser plates, resulting in malfunction of the phosphor wheel.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a phosphor wheel capable of reducing or preventing misalignment and separation of transmissive members.

According to an aspect of the present invention, there is provided a phosphor wheel as defined in claim <NUM>.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Although the embodiment to be described below has some features which are technically advantageous in implementing the present invention, those features do not limit the scope of the present invention to the following embodiment and examples shown in the drawings.

<FIG> is a front view illustrating a phosphor wheel <NUM> which can be assembled in a light projection system of a projector, and <FIG> is an exploded perspective view illustrating the phosphor wheel <NUM>, and <FIG> is a cross-sectional view taken along a line V-V of <FIG>.

The phosphor wheel <NUM> is configured to convert excitation light of a predetermined color (a predetermined wavelength band) emitted from a light source of a projector into light of the same color having convergence lower than that of the excitation light and convert the excitation light into light of a different color (a different wavelength band).

The phosphor wheel <NUM> has a disk shape and includes a rotary shaft disposed in a center hole formed at a center thereof such that the rotary shaft can be rotated by a spindle motor. Torque is applied to the phosphor wheel <NUM> via the rotary shaft.

The phosphor wheel <NUM> includes a circular wheel plate <NUM>, a phosphor plate <NUM> disposed on one surface of the wheel plate <NUM>, a holding plate <NUM> disposed on the other surface of the wheel plate <NUM>, and a diffuser plate <NUM> disposed as a transmissive member in the wheel plate <NUM>.

With respect to the phosphor wheel <NUM>, the wheel plate <NUM>, the phosphor plate <NUM>, the holding plate <NUM>, and the diffuser plate <NUM>, surfaces on the front side of the drawing sheet of <FIG> are referred to as front surfaces, and surfaces on the opposite side to the front side are referred to as rear surfaces.

<FIG> is a front view illustrating the wheel plate <NUM>.

The wheel plate <NUM> is a circular plate formed of a metal such as copper, aluminum, or stainless steel.

The wheel plate <NUM> has a center hole <NUM> formed at a center thereof so as to extend from the front surface to the rear surface. The center hole <NUM> constitutes the above-mentioned center hole of the phosphor wheel <NUM>, and the rotary shaft is inserted therein during use of the phosphor wheel <NUM>.

The wheel plate <NUM> has through-holes <NUM>, <NUM> formed on one side of the center hole <NUM> so as to extend from the front surface to the rear surface in order to achieve a weight balance. One of the through-holes <NUM> is also used for alignment during assembling of the phosphor wheel <NUM>.

The wheel plate <NUM> has an opening <NUM> formed in an outer periphery side so as to extend from the front surface to the rear surface. The diffuser plate <NUM> is disposed inside the opening <NUM>.

The opening <NUM> has a structure which closes an outer side of a rotation radius direction of the phosphor wheel <NUM> for the diffuser plate <NUM> to be disposed inside the opening and has a blocking part <NUM> on the outer side of the diffuser plate in the rotation radius direction.

A rotation circumference direction of the wheel plate <NUM> matches the rotation circumference direction of the entire phosphor wheel <NUM>, and a rotation radius direction of the wheel plate <NUM> matches the rotation radius direction of the entire phosphor wheel <NUM>. In the following description, the rotation circumference direction of the wheel plate <NUM> will be simply referred to as the rotation circumference direction, and the rotation radius direction of the wheel plate <NUM> will be simply referred to as the rotation radius direction.

In the following description, when a rotation circumference direction and a rotation radius direction are referred to with respect to the diffuser plate, they refer to the rotation circumference direction of the wheel plate <NUM> and the rotation radius direction of the wheel plate <NUM> when the diffuser plate <NUM> is provided in the wheel plate <NUM> in the state of <FIG>.

In the following description, when a rotation circumference direction and a rotation radius direction are referred to with respect to the phosphor plate <NUM> and the holding plate <NUM>, they refer to the rotation circumference direction of the wheel plate <NUM> and the rotation radius direction of the wheel plate <NUM> in a state where the phosphor plate <NUM> and the holding plate <NUM> are concentrically assembled with the wheel plate <NUM>.

The opening <NUM> has a symmetrical shape in the left-right direction of the drawing sheet of <FIG>, and the edge of the opening includes a concave arc part <NUM> recessed outward in the rotation radius direction, a convex arc part <NUM> protruding outward in the rotation radius direction, a first straight part <NUM> and a second straight part <NUM> connected to both ends of the concave arc part <NUM>, respectively, and a third straight part <NUM> and a fourth straight part <NUM> connected to both ends of the convex arc part <NUM>, respectively.

The concave arc part <NUM> is formed along an arc having the same center as that of the wheel plate <NUM> and having a radius R1 slightly smaller than the outer circumference of the wheel plate <NUM>.

The convex arc part <NUM> is also formed along an arc, and the radius of the convex arc part may be equal to or larger than that of the concave arc part <NUM>, or may be smaller than that of the concave arc part. The convex arc part <NUM> may not have the same center as that of the wheel plate <NUM>.

The first straight part <NUM> and the second straight part <NUM> extend along a direction perpendicular to the tangent at the center of the concave arc part <NUM> in the rotation circumference direction.

The third straight part <NUM> and the fourth straight part <NUM> extend along a direction parallel with the tangent at the center of the concave arc part <NUM> in the rotation circumference direction.

<FIG> is a front view illustrating the diffuser plate <NUM>.

The diffuser plate <NUM> is configured to transmit excitation light therethrough while diffusing it. For example, the diffuser plate <NUM> is a light-transmissive plate formed of colorless and transparent glass or the like having particulates or fine pores distributed therein, or a colorless and transparent light-transmissive plate having fine irregularities on the front surface thereof. Therefore, convergence of excitation light having passed through the diffuser plate <NUM> is lower than that of the excitation light before passing through the diffuser plate.

Since the diffuser plate <NUM> is disposed inside the opening <NUM> of the wheel plate <NUM>, as shown in <FIG>, the shape of the outer edge of the diffuser plate <NUM> is similar to the shape of the inner edge of the opening <NUM>. The shape and dimensions of the diffuser plate <NUM> are set in view of the accuracy of machining of the diffuser plate such that a gap is formed around the diffuser plate in the state where the diffuser plate is disposed in the opening <NUM>.

The diffuser plate <NUM> has a symmetrical shape in the left-right direction of the drawing sheet of <FIG>, and the outer edge of the diffuser plate includes a convex arc part <NUM> protruding outward in the rotation radius direction, a concave arc part <NUM> recessed outward in the rotation radius direction, a first straight part <NUM> and a second straight part <NUM> connected to both ends of the convex arc part <NUM>, respectively, and a third straight part <NUM> and a fourth straight part <NUM> connected to both ends of the concave arc part <NUM>, respectively. All corners which are the boundaries between those parts are chamfered and thus the diffuser plate <NUM> is suppressed from cracking or being clipped.

According to the invention, the convex arc part <NUM> is formed along an arc having a radius R2 larger than the radius R1 of the concave arc part <NUM> of the opening <NUM> of the wheel plate <NUM> (R1 < R2).

The radius of the arc of the concave arc part <NUM> may be selected to be an arbitrary value as long as the convex arc part <NUM> is not in contact with the convex arc part <NUM> in the disposition state of <FIG>.

The first straight part <NUM> and the second straight part <NUM> extend along a direction perpendicular to the tangent at the center of the convex arc part <NUM> in the rotation circumference direction.

The third straight part <NUM> and the fourth straight part <NUM> extend along the direction of the tangent at the center of the convex arc part <NUM> in the rotation circumference direction.

The width W of the diffuser plate <NUM> in a direction parallel with the tangent at the center of the convex arc part <NUM> in the rotation circumference direction is slightly narrower than the width of the opening <NUM> in the same direction in the disposition state of <FIG>.

The width H of the diffuser plate <NUM> in a direction perpendicular to the tangent at the center of the convex arc part <NUM> in the rotation circumference direction is slightly narrower than the width of the opening <NUM> in the same direction in the disposition state of <FIG>.

Therefore, in the case where the convex arc part <NUM> of the diffuser plate <NUM> is displaced toward the concave arc part <NUM> inside the opening <NUM> as shown in <FIG>, the outer circumference of the diffuser plate <NUM> comes into contact with the concave arc part <NUM> at two points P1, P2 of both ends of the convex arc part <NUM>.

In a direction perpendicular to the wheel plate <NUM>, the diffuser plate <NUM> is held centrifugal force acts on the diffuser plate <NUM> in the opening <NUM> of the wheel plate <NUM> in such a direction that the convex arc part <NUM> is displaced toward the concave arc part <NUM> of the opening <NUM>.

Therefore, if the diffuser plate <NUM> is disposed inside the opening <NUM> so as to come into contact with the concave arc part <NUM> at the two points P1, P2 of both ends of the convex arc part <NUM>, the position of the diffuser plate <NUM> can be kept more stably as compared to a state where the diffuser plate is in contact with the concave arc part <NUM> at one point.

The opening <NUM> of the wheel plate <NUM> has room where the diffuser plate <NUM> can be displaced in the rotation circumference direction. <FIG> shows a state where the diffuser plate <NUM> is displaced toward one side in the rotation circumference direction inside the opening <NUM>.

Even in this case, the diffuser plate <NUM> is in contact with the concave arc part <NUM> at the two points P1, P2 of both ends of the convex arc part <NUM> and a point P3 which is the border between the second straight part <NUM> and the fourth straight part <NUM>. Therefore, the position of the diffuser plate <NUM> can be kept more stable as compared to a state where the diffuser plate is in contact with the concave arc part <NUM> at one point.

Although <FIG> shows the case where the diffuser plate <NUM> is biased toward the right side of the drawing sheet, even in the case where the diffuser plate is biased toward the left side of the drawing sheet, the same effect is obtained.

As described above, the diffuser plate <NUM> is held from both sides by the phosphor plate <NUM> and the holding plate <NUM>. However, the diffuser plate <NUM> may be fixed by bonding a part of the surfaces of the diffuser plate <NUM> to one or both of the phosphor plate <NUM> and the holding plate <NUM>.

During bonding, it is advantageous to dispose the diffuser plate <NUM> inside the opening <NUM> such that the diffuser plate <NUM> is in contact with the edge of the opening <NUM> at two or more points as shown in <FIG>. In this case, even though the centrifugal force acts on the diffuser plate <NUM> during rotation, the adhesive is unlikely to peel off, and the amount of adhesive can be reduced.

Further, in this case, since the size of the bonding area where the diffuser plate <NUM> overlaps the phosphor plate <NUM> or the holding plate <NUM> can be reduced, it is possible to secure a large area of the diffuser plate <NUM> as an area where excitation light can enter.

As shown in <FIG>, the holding plate <NUM> is fixed to the rear surface of the wheel plate <NUM> by bonding.

The holding plate <NUM> is a circular plate formed of a metal such as copper, aluminum, or stainless steel, and has an outside diameter approximately equal to that of the wheel plate <NUM>.

The holding plate <NUM> has a center hole <NUM> formed at the center so as to extend from the front surface to the rear surface. The center hole <NUM> constitutes the above-mentioned center hole of the phosphor wheel <NUM>, and the rotary shaft is inserted therein during use of the phosphor wheel <NUM>. The center hole <NUM> of the holding plate <NUM> has the same diameter as that of the center hole <NUM> of the wheel plate <NUM>, and the holding plate <NUM> and the wheel plate <NUM> are bonded so as to be concentric.

Both end parts of the holding plate <NUM> in a diameter direction of the holding plate <NUM> passing through the center of the center hole <NUM> have arc-shaped cutouts <NUM>, <NUM>, respectively.

Both of the cutouts <NUM>, <NUM> are formed with a predetermined width in the rotation radius direction from the outer circumference of the holding plate <NUM> toward the center in a predetermined angle range in the rotation circumference direction. Since the cutouts <NUM>, <NUM> are the same as each other in the formation width and the formation angle range, a weight balance during rotation is achieved.

The holding plate <NUM> and the wheel plate <NUM> are assembled with each other such that one cutout <NUM> and the opening <NUM> of the wheel plate <NUM> overlap as seen from the direction of the center axis.

The angle range of the cutout <NUM> in the rotation circumference direction is narrower than the angle range of the opening <NUM> in the rotation circumference direction.

In a state where the holding plate <NUM> and the wheel plate <NUM> are assembled, due to the cutout <NUM>, the holding plate <NUM> blocks both end parts of the opening <NUM> in the rotation circumference direction and does not block the center part of the opening <NUM> in the rotation circumference direction, as seen from the direction of the center axis.

Therefore, when the diffuser plate <NUM> is disposed inside the opening <NUM>, both outer parts of the cutout <NUM> of the holding plate <NUM> in the rotation circumference direction which block both end parts of the opening <NUM> in the rotation circumference direction support both end parts of the diffuser plate <NUM> in the rotation circumference direction from the rear surface side.

Both outer parts of the cutout <NUM> of the holding plate <NUM> in the rotation circumference direction and both end parts of the diffuser plate <NUM> in the rotation circumference direction may be bonded with an adhesive.

As shown in <FIG>, the phosphor plate <NUM> is fixed to the front surface of the wheel plate <NUM> by bonding.

The phosphor plate <NUM> is a circular plate formed of a metal such as copper, aluminum, or stainless steel, and has an outside diameter slightly smaller than that of the wheel plate <NUM>. The front surface of the phosphor plate <NUM> is a reflective surface produced by mirror finishing such as mirror polishing or silver deposition.

The phosphor plate <NUM> has a center hole <NUM> formed at the center thereof so as to extend from the front surface to the rear surface. The center hole <NUM> constitutes the above-mentioned center hole of the phosphor wheel <NUM>, and the rotary shaft is inserted therein during use of the phosphor wheel <NUM>. The center hole <NUM> of the phosphor plate <NUM> has the same diameter as that of the center hole <NUM> of the wheel plate <NUM>, and the phosphor plate <NUM> and the wheel plate <NUM> are bonded so as to be concentric.

The outer periphery of the phosphor plate <NUM> has an arc-shaped cutout <NUM>. The cutout <NUM> is formed with a predetermined width in the rotation radius direction from the outer circumference of the phosphor plate <NUM> toward the center, in a predetermined angle range in the rotation circumference direction.

The opposite side of the center hole <NUM> to the cutout <NUM> has an arc-shaped through-hole <NUM> formed closer to the center hole <NUM> than the cutout <NUM> is, so as to extend from the front surface to the rear surface. The through-hole <NUM> is formed to achieve a weight balance with respect to the cutout <NUM> during rotation.

The phosphor plate <NUM> and the wheel plate <NUM> are assembled with each other such that the cutout <NUM> and the opening <NUM> of the wheel plate <NUM> overlap as seen from the direction of the center axis.

Further, the angle range of the cutout <NUM> in the rotation circumference direction is slightly smaller than the angle range of the opening <NUM> in the rotation circumference direction. The cutout <NUM> of the phosphor plate <NUM> has a width in the rotation radius direction and an angle range in the rotation circumference direction approximately equal to those of the cutout <NUM> of the holding plate <NUM>.

Therefore, in a state where the phosphor plate <NUM> and the wheel plate <NUM> have been assembled, due to the cutout <NUM>, the phosphor plate <NUM> blocks both end parts of the opening <NUM> in the rotation circumference direction and does not block the center part of the opening <NUM> in the rotation circumference direction, as seen from the direction of the center axis.

Therefore, when the diffuser plate <NUM> is inside the opening <NUM>, both outer parts of the cutout <NUM> of the phosphor plate <NUM> in the rotation circumference direction which block both end parts of the opening in the rotation circumference direction support both end parts of the diffuser plate in the rotation circumference direction, from the front surface side.

Both outer parts of the cutout <NUM> of the phosphor plate <NUM> in the rotation circumference direction and both end parts of the diffuser plate <NUM> in the rotation circumference direction may be bonded with an adhesive.

The phosphor plate <NUM> has an arc-band-shaped phosphor layer <NUM> formed on the outer periphery of the front surface over an angle range in the rotation circumference direction except for the cutout <NUM>. The phosphor layer <NUM> is formed on a circumferential zone which is almost the same as a circumferential zone where the cutout <NUM> is formed, as seen from the direction of the center line of rotation.

The phosphor layer <NUM> is a layer formed by dispersing a phosphor in a transmissive binder (such as a ceramic binder, a resin binder, or a silicon binder).

The phosphor layer <NUM> may be formed inside an arc-band-shaped recess formed in the front surface of the phosphor plate <NUM> over the formation range of the phosphor layer <NUM>. In this case, mirror finishing may be necessary on the bottom of the recess.

If excitation light of the predetermined color (the predetermined wavelength band) emitted from the light source enters the phosphor layer <NUM>, the phosphor layer <NUM> is excited by the excitation light to emit fluorescence of a color different from that of the excitation light. Although the wavelength band of the excitation light is not particularly limited, it is advantageous that the excitation light is visible light of a single color. As long as the color of fluorescence which is emitted from the phosphor layer <NUM> is different from the color of the excitation light, the wavelength band of the fluorescence is not particularly limited. However, it is advantageous to select a phosphor capable of emitting visible light of a single color. For example, the color of the excitation light is any one color of the three primary colors of light, and a phosphor is selected such that the color of fluorescence which is emitted from the phosphor layer <NUM> is another color of the three primary colors of light. For example, in the case where the excitation light is light of the wavelength band of blue, a phosphor may be selected such that fluorescence which is emitted from the phosphor layer <NUM> is light of the wavelength band of green.

Although the phosphor layer <NUM> is formed over the circumferential zone expect for the cutout <NUM>, it may be formed in a partial range of the circumferential zone except for the cutout <NUM>.

In this case, it is advantageous to form an antireflection layer on the front surface of the phosphor plate <NUM> over the circumferential zone except for the cutout <NUM> and the phosphor layer <NUM>.

As shown in <FIG>, the phosphor layer <NUM> may be divided into two phosphor layers 34A, 34B in the rotation circumference direction, and phosphors may be selected such that the color of fluorescence of the first phosphor layer 34A is different from the color of fluorescence of the second phosphor layer 34B. As seen from the direction of the center line of rotation, the first phosphor layer 34A and the second phosphor layer 34B are arranged on the same circumferential zone having the center line of rotation as the center and are arranged so as not to overlap each other in the rotation circumference direction. If the color of fluorescence which is emitted from each of the phosphor layers 34A, 34B is different from the color of the excitation light, the wavelength band of the fluorescence is not particularly limited. However, it is advantageous that the fluorescence is visible light of a single color.

For example, the color of the excitation light, the color of fluorescence which is emitted from the first phosphor layer 34A, and the color of fluorescence which is emitted from the second phosphor layer 34B are the three primary colors of light, and phosphors different from each other are selected. For example, in the case where the excitation light is light of the wavelength band of blue, for the first phosphor layer 34A, a phosphor may be selected such that fluorescence which is emitted is light of the wavelength band of green, and for the second phosphor layer 34B, a phosphor may be selected such that fluorescence which is emitted is light of the wavelength band of red.

As shown in <FIG>, the phosphor layer <NUM> may be divided into three or more phosphor layers in the rotation circumference direction (<FIG> shows an example of the case where the phosphor layer <NUM> may be divided into three phosphor layers). In this case, for phosphor layers 34D to 34F, phosphors different from one another in the colors of fluorescence may be selected. Even in this case, as seen from the direction of the center line of rotation, the phosphor layers 34D to 34F are arranged on the same circumferential zone having the center line of rotation as the center, so as not to overlap one another in the rotation circumference direction. Although the wavelength of fluorescence which is emitted from each of the phosphor layers 34D to 34F is not particularly limited, it is advantageous that the fluorescence is visible light of a single color different from the color of the excitation light.

Assembling of the phosphor wheel <NUM> will be described.

First, in a state where the phosphor plate <NUM> is placed such that the rear surface faces upward, the wheel plate <NUM> with the rear surface facing upward is overlapped such that the phosphor plate and the wheel plate are concentric and the opening <NUM> and the cutout <NUM> are placed at appropriate positions in the rotation circumference direction, and the rear surface of the phosphor plate <NUM> and the front surface of the wheel plate <NUM> are bonded.

Subsequently, inside the opening <NUM> of the wheel plate <NUM>, the diffuser plate <NUM> with the rear surface facing upward is disposed. At this time, the diffuser plate is disposed such that the convex arc part <NUM> of the diffuser plate <NUM> is biased toward the concave arc part <NUM> of the opening <NUM> and the convex arc part <NUM> comes into contact with the concave arc part <NUM> at the two points P1, P2 of both end parts of the convex arc part <NUM> (see <FIG>). If necessary, both end parts of the front surface of the diffuser plate <NUM> in the circumference direction and both end parts of the rear surface of the phosphor plate <NUM> in the circumference direction are bonded.

Subsequently, on the wheel plate <NUM> with the rear surface facing upward, the holding plate <NUM> with the rear surface facing upward is overlapped such that the holding plate and the wheel plate are concentric and the cutout <NUM> and the opening <NUM> are placed at appropriate positions in the circumference direction, and the rear surface of the wheel plate <NUM> and the front surface of the holding plate <NUM> are bonded.

If necessary, both end parts of the rear surface of the diffuser plate <NUM> in the circumference direction and both end parts of the cutout <NUM> of the front surface of the holding plate <NUM> are bonded.

In this manner, assembling of the phosphor wheel <NUM> is performed.

Although the case where the phosphor plate <NUM>, the wheel plate <NUM>, and the holding plate <NUM> with the rear surfaces facing upward are stacked in the order of the phosphor plate <NUM>, the wheel plate <NUM>, and the holding plate <NUM> has been described as an example, assembling is not limited thereto.

For example, the phosphor plate <NUM>, the wheel plate <NUM>, and the holding plate <NUM> with the front surfaces facing upward may be stacked and be assembled in the order of the holding plate <NUM>, the wheel plate <NUM>, and the phosphor plate <NUM>.

The operation of the phosphor wheel <NUM> during use will be described. During use of the phosphor wheel <NUM>, as described above, the rotary shaft is fixed in the center hole and is rotated by the spindle motor. The excitation light is radiated onto a predetermined irradiation position S (see <FIG>) of the phosphor wheel <NUM> which is rotating along an optical axis along a direction perpendicular to the front surface of the phosphor plate <NUM>. The irradiation position is in the band-shaped circumferential zone including the phosphor layer <NUM>.

If the excitation light passes through the cutout <NUM> of the phosphor plate <NUM> during rotation of the phosphor wheel <NUM>, the excitation light enters the diffuser plate <NUM> and passes through the diffuser plate <NUM> while diffusing. Therefore, the excitation light is converted into transmitted light having convergence and directivity lower than those of the excitation light by the diffuser plate <NUM>. The optical axis of the transmitted light (the optical axis of the transmitted light is a virtual line extending from the diffuser plate <NUM> in a direction in which the light intensity is maximum) is an extension of the optical axis of the excitation light. In this case, the color of the transmitted light is the same as the color of the excitation light (for example, blue).

If the excitation light enters the phosphor layer <NUM> during rotation of the phosphor wheel <NUM>, the phosphor layer <NUM> is excited by the excitation light and fluorescence of a color different from that of the excitation light is emitted from the phosphor layer <NUM> (for example, green). Even though a part of the excitation light has passed through the phosphor layer <NUM>, the excitation light having passed through the phosphor layer is reflected by the front surface of the phosphor plate <NUM>, and the reflected light excites the phosphor layer <NUM>, and the phosphor layer <NUM> emits fluorescence. Therefore, the excitation light is converted into fluorescence of a color different from that of the excitation light by the phosphor layer <NUM>. The fluorescence which is emitted from the phosphor layer <NUM> is diffused light having low convergence and low directivity, and the optical axis of the fluorescence (the optical axis of the fluorescence is a virtual line extending from the phosphor layer <NUM> in a direction in which the light intensity is maximum) is perpendicular to the phosphor wheel <NUM> and the direction thereof is opposite to the direction of the optical axis of the excitation light.

As described above, the excitation light enters each of the phosphor layer <NUM> and the diffuser plate <NUM> of the phosphor wheel <NUM> rotating, and thus it is possible to extract fluorescence of a different color.

In the phosphor wheel <NUM>, since the outer periphery of the diffuser plate <NUM> on the outer side in the rotation radius direction is in contact with the edge of the opening <NUM> of the wheel plate <NUM> at the two points or a plurality of points including them to be supported, as compared to the case where the diffuser plate is in contact with the edge of the opening at one point, the position of the diffuser plate <NUM> can be kept more stably, and it is possible to effectively suppress occurrence of misalignment or clipping of the diffuser plate <NUM> during high-speed rotation of the phosphor wheel <NUM>.

Since it is possible to reduce occurrence of misalignment or clipping of the diffuser plate <NUM>, even in the case of fixing the diffuser plate <NUM> by bonding or the like, it is possible to reduce the amount of adhesive. In this case, it is possible to reduce the transmitted light of the diffuser plate <NUM> from being affected by the adhesive, and thus it becomes possible to obtain appropriate transmitted light. Further, since the reduction in the amount of adhesive allows to reduce the size of the bonding area where the diffuser plate <NUM> overlaps the phosphor plate <NUM> or the holding plate <NUM>, it is possible to secure a large area of the diffuser plate <NUM> as an area where excitation light can enter.

Since the opening <NUM> of the wheel plate <NUM> has the blocking part <NUM> on the outer side for the diffuser plate <NUM> in the rotation radius direction, it is possible to more effectively reduce occurrence of misalignment and clipping of the diffuser plate <NUM>.

Further, since the opening has the blocking part <NUM> on the outer side for the diffuser plate <NUM>, it is possible to protect the diffuser plate <NUM> from the outside and reduce occurrence of misalignment and clipping of the diffuser plate.

The edge of the opening <NUM> of the wheel plate <NUM> has the arc-shaped concave arc part <NUM> on the outer side for the diffuser plate <NUM> in the rotation radius direction of the wheel plate <NUM>, and the edge of the diffuser plate <NUM> has the arc-shaped convex arc part <NUM> on the outer side in the rotation radius direction of the wheel plate <NUM>, and the convex arc part <NUM> of the diffuser plate <NUM> has an arc shape having a diameter larger than that of the concave arc part <NUM> of the opening <NUM>.

The case of performing machining such that the outer diameter of one of the concave arc part <NUM> and the convex arc part <NUM> facing each other is larger as described above is easier than the case of performing machining such that the outer diameter of the concave arc part <NUM> is the same as the outer diameter of the convex arc part <NUM>.

Therefore, it is possible to obtain the structure in which the outer circumference of the diffuser plate <NUM> is in contact with the edge of the opening <NUM> of the wheel plate <NUM> by easy machining, and thus it is possible to make it easier to manufacture the phosphor wheel <NUM>.

Since the diameter of the convex arc part <NUM> of the diffuser plate <NUM> is larger than the diameter of the concave arc part <NUM> of the opening <NUM>, it is possible to reduce the width H of the convex arc part <NUM> in the direction perpendicular to the tangent at the center in the circumference direction, and thus it is possible to obtain more diffuser plates from a diffuser plate formation material. Therefore, it becomes possible to reduce the manufacturing cost.

Further, since the phosphor wheel <NUM> has the phosphor layer <NUM> formed on the phosphor plate <NUM> disposed on the front surface of the wheel plate <NUM>, if the excitation light enters the front surface side of the phosphor wheel <NUM>, it is possible to obtain fluorescence of a different color.

The inventive concept of present invention can be applied to other embodiments without being limited to the above-described embodiment and can be appropriately modified without departing from the scope of the present invention.

For example, the color of the excitation light and the color of the fluorescence which is emitted from the phosphor layer <NUM> are examples and may be other colors. For example, it is advantageous that the color of the excitation light and the color of the fluorescence which is emitted from the phosphor layer <NUM> are different colors of the three primary colors of light.

Similarly, the color of the excitation light, the color of the fluorescence which is emitted from the first phosphor layer 34A, and the color of the fluorescence which is emitted from the second phosphor layer 34B may also be other colors. For example, it is advantageous that the color of the excitation light, the color of the fluorescence which is emitted from the first phosphor layer 34A, and the color of the fluorescence which is emitted from the second phosphor layer 34B are the three primary colors of light and are different from each other.

Also, in the above-described embodiment, as an example of the transmissive member, the diffuser plate <NUM> for transmitting while diffusing the excitation light has been taken; however, even in the case where a transmissive member formed of a transmissive material having no diffusing function, such as glass, is used in a phosphor wheel, the shape, the structural features, and the features of the surrounding support structure described in the embodiment can be applied.

Claim 1:
A phosphor wheel comprising:
a wheel plate (<NUM>) which has an opening (<NUM>) formed in an outer periphery side of the wheel plate (<NUM>) and extending from one surface to the other surface thereof and is to be used in a rotating state;
a transmissive member (<NUM>) which is disposed inside the opening (<NUM>),
a phosphor plate (<NUM>) disposed on the one surface of the wheel plate (<NUM>); and a holding plate (<NUM>) disposed on the other surface of the wheel plate (<NUM>),
wherein the transmissive member (<NUM>) is in contact with an edge of the opening (<NUM>) of the wheel plate (<NUM>) at two points (P1, P2) of an end part of an outer periphery of the transmissive member on an outer side in a rotation radius direction of the wheel plate to be supported,
wherein the opening (<NUM>) includes a blocking part (<NUM>) on the outer side of the transmissive member (<NUM>) in the rotation radius direction,
the opening (<NUM>) has room where the transmissive member (<NUM>) can be displaced in a rotation circumference direction,
the edge of the opening (<NUM>) includes a concave arc part (<NUM>) recessed outward in the rotation radius direction and having a radius (R1), and
an outer edge of the transmissive member (<NUM>) includes a convex arc part (<NUM>) protruding outward in the rotation radius direction and having a radius (R2) larger than the radius (R1) of the concave arc part (<NUM>).