JP2003307609A - Color wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the warp of a glass plate owing to difference in film thickness between films formed on one face of the glass plate and films on the other face thereof. <P>SOLUTION: A color wheel has a 1st dichroic film which transmits only blue-wavelength light in one filter area and a 3rd dichroic film which transmits only green-wavelength and red-wavelength light beams in the remaining two filter areas on one side face of the glass plate 2 and also has a 2nd dichroic film which transmits only the red-wavelength light in one filter area and a 4th dichroic film which transmits only green-wavelength and blue-wavelength light beams in the remaining two filter areas on the other side face of the glass plate 2. The color wheel transmits white light incident on the glass plate 2 in a manner such that the 1st and 2nd dichroic film formation part 35B transmits only the blue light, the 1st and 4th dichroic film formation part 35G transmits only the green light, and the 3rd and 4th dichroic film formation part 35R transmits only the red light. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter for separating white light, and more particularly to a color filter having a dichroic film formed on both sides of a glass plate. 2. Description of the Related Art Conventionally, a color wheel of this type splits white light emitted from a light source into blue light, red light and green light. For example, FIG. 9 and FIG. 10 are diagrams illustrating the color wheel 100 that splits white light emitted from the light source 110. FIG. 10 is a side view of the color wheel 100, and FIG. 9 is a view of the color wheel 100 as viewed from above. In FIG. 9, a color wheel 100 includes a rotating shaft 101, a support 102, a holding ring 103, and a color filter 104. The color filter 104 held by the rotating shaft 101, the support 102, and the holding ring 103 includes three types of filters, a blue light filter 104B, a red light filter 104R, and a green light filter 104G. Among these three types of filters, the blue light filter 104B transmits only the blue wavelength light out of the white light, the red light filter 104R transmits only the red wavelength light, and the green light filter 104G transmits only the green wavelength light. And has the property of reflecting other wavelengths. This color wheel 100 has a color filter 10
4 is rotated at a high speed, and white light is incident from a light source to separate the light into three primary colors. [0003] The above-described color filter 104 is similar to that shown in FIG.
As shown in the figure, the red filter 111R, the green filter 111G, and the blue filter 1
11B is formed by forming an antireflection film 112 on the back surface. The red filter 111R, the green filter 111G, and the blue filter 111B
On top of 0, alternating high and low index materials, 4
It is formed by forming zero or more layers. The antireflection film 112 is a film formed on the opposite side of the glass plate 110 from the filter forming surface. The anti-reflection film 112 includes a red filter 111R, a green filter 11
Unlike the 1G and blue filters 111B, they are formed with a small number of films of about four layers. [0004] Incidentally, since the above-mentioned glass plate 110 is formed very thin in order to reduce the weight due to high-speed rotation, the glass plate 110 is formed on the front and back surfaces. If the number of layers differs greatly, there is a problem that warpage occurs. That is, 40 or more layers of the red filter 111R, green filter 111G, and blue filter 111B are respectively formed on the front surface with the glass plate 110 therebetween, and about four layers of the antireflection film 112 are formed on the back surface. ing. For this reason, the glass plate 11
Thus, a difference in film thickness occurs on both surfaces of No. 0, and as a result, warpage occurs on the outer peripheral portion on the surface side. [0005] As described above, when the glass plate 110 is warped, rotation blur occurs when the color wheel 100 is rotated. In other words, the driving force for rotating the rotating shaft 101 is constant, but the glass plate 110 is warped, so that the color wheel 100 is rotated. As described above, if the glass plate 110 is warped, there is a problem that when the color wheel 110 is rotated, buoyancy is generated in the direction in which the glass plate 110 is warped. As a result, the color wheel 1
At the time of rotation of 00, noise such as wind noise is generated. Further, depending on the number of rotations of the color wheel 100, there is a problem that the warpage of the color wheel 100 is promoted to cause cracks or a large load is applied to the rotating shaft. SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a color wheel in which a glass plate does not warp when a color filter is laminated on the glass plate. In order to achieve the above-mentioned object, a color wheel according to the present invention has a first surface on one side of a transparent disk which transmits only blue and green wavelength light. A dichroic film is formed in two filter regions, and a third dichroic film that transmits only red wavelength light is formed in one filter region.
On the other end surface of the transparent disk, a second dichroic film that transmits only blue wavelength light is formed in one filter region, and a fourth dichroic film that transmits only green and red wavelength lights is formed in two filter regions. Wherein the second dichroic film and the third dichroic film are formed in mutually different filter regions with a transparent disk interposed therebetween. A color wheel according to the present invention will be described below with reference to the drawings. FIG. 1A is a diagram of the color wheel 1 according to the present embodiment as viewed from above, and FIG. 1B is a cross-sectional view of a contour portion of the color wheel 1. In FIG. 1A, on one side surface of a glass plate 2, a first dichroic film 31 transmitting only blue and green wavelength light is formed in two filter regions, and one filter region has a red dichroic film. A third dichroic film 33 that transmits only light of a wavelength is formed. On the other end surface of the glass plate 2, a second dichroic film 32 for transmitting only the blue wavelength light is formed in one filter region, and only the green and red wavelength lights are transmitted for the two filter regions. A fourth dichroic film 34 to be formed is formed. The second dichroic film 32 and the third dichroic film 33 are formed in mutually different filter regions with the glass plate 2 interposed therebetween. The color wheel 1 thus formed
Is that white light incident from the first and second dichroic film forming portions 35B of FIG. 1A transmits only blue light, and white light incident from the first and fourth dichroic film forming portions 35G is green. Only light is transmitted, and white light incident from the third and fourth dichroic film forming portions 35R transmits only red light. As described above, as shown in FIG.
The reason why each color is transmitted in the 5G and 35R regions will be described. FIG. 2 shows the first dichroic film 3 shown in FIG.
FIG. 3 is a diagram showing spectral transmittances of a first dichroic film 32, a third dichroic film 33, and a fourth dichroic film 34. In the figure, the horizontal axis indicates the wavelength, and the vertical axis indicates the spectral transmittance. Here, blue light is approximately 500 nm.
It is light having the following wavelengths, and green light is approximately 500 to 55
It is light having a wavelength of 0 nm, and red light is approximately 550 nm.
It is light having the above wavelength. FIG. 2A shows the spectral transmittance of the first dichroic film 31. The first dichroic film 31 is a filter that transmits only light having a wavelength of approximately 550 nm or less. As is clear from FIG. 7A, the first dichroic film 31 is approximately 500 n
m and a wavelength of approximately 500 nm to 55 nm
Green light having a wavelength of 0 nm is transmitted, but approximately 550 n
Red light having a wavelength of m or more is not transmitted. Next, (b) shows the spectral transmittance of the second dichroic film 32. The second dichroic film 32 is a filter that transmits only light having a wavelength of approximately 500 nm or less. As is apparent from FIG. 7B, the second dichroic film 32 is a filter that transmits only blue light and does not transmit green light and red light. Next, (c) shows the spectral transmittance of the third dichroic film 33. The third dichroic film 33 is a filter that transmits only light having a wavelength of approximately 550 nm or more. As is apparent from FIG. 7C, the third dichroic film 33 is a filter that does not transmit blue light and green light but transmits red light. Finally, (d) shows the spectral transmittance of the fourth dichroic film 34. The fourth dichroic film 34 is a filter that transmits only light having a wavelength of about 500 nm or more. As is apparent from FIG. 4D, the fourth dichroic film 34 is a filter that does not transmit blue light but transmits green light and red light. The first dichroic film 3 as described above
1, the second dichroic film 32, the third dichroic film 33, and the fourth dichroic film
1A, the first and second dichroic film forming portions 35B, the first and fourth dichroic film forming portions 35G, and the third and fourth dichroic film forming portions 35R of FIG. Indicates the spectral transmittance as shown in FIG. That is, in the first and second dichroic film forming portions 35B formed with the first dichroic film 31 transmitting blue and green and the second dichroic film 32 transmitting only blue, the white light incident from the light source is , Only blue light is transmitted. Next, in the first and fourth dichroic film forming portions 35G forming the first dichroic film 31 transmitting blue and green and the fourth dichroic film 34 transmitting green and red, only green light is transmitted. Is done. Finally, the third and fourth dichroic film forming portions 35R, which form the fourth dichroic film 34 that transmits green and red and the third dichroic film 33 that transmits only red, emit white light incident from the light source. Is
Only red light is transmitted. By forming the above filters on both surfaces of the glass plate 2, the incident white light can be color-separated into blue light, green light and red light. Hereinafter, a manufacturing process of the above-described color wheel 1 will be described. FIG. 4 is a diagram in which the first dichroic film 31 is laminated on the glass plate 2. In FIG. 4A, first, an aluminum film 90 is laminated on the glass plate 2 for use as a mask. Next, in 4B, of the aluminum films 90 stacked by film formation using a mask,
The two filter regions are peeled and removed. Next, 4C
In step (1), the first dichroic film 31 is laminated while the aluminum film 90 for the remaining one filter region is laminated. At this time, in the state of 4C, the first dichroic film 31 is laminated on one surface of the glass plate 2 for two filter regions, and the aluminum film 90 is laminated on the remaining portion. Has a first dichroic film 31 laminated thereon. Finally, the aluminum film 90 laminated on the glass plate 2 and the first dichroic film 31 laminated on the aluminum film 90 are peeled off, as shown in FIG.
The first dichroic film 31 for two filter regions can be laminated on one surface. FIG. 5 is a diagram in which the second dichroic film 32 is laminated on the surface of the glass plate 2 opposite to the surface on which the first dichroic film 31 is laminated. FIG. 5A is a diagram in which an aluminum film 90 is laminated on the glass plate 2. Next, as shown in FIG. 5B, one filter region of the laminated aluminum film 90 is removed by etching. Next, in such a state, the second dichroic film 32 is laminated on the whole. Finally, the aluminum film 9
0 and the second dichroic film 3 laminated thereon
By peeling off the second dichroic film 2, a first dichroic film 31 is laminated on one surface of the glass plate 2, and a second dichroic film 32 is laminated on the other surface. FIG. 6 is a diagram in which a third dichroic film 33 is laminated on the same surface of the glass plate 2 on which the first dichroic film 31 is laminated. FIG. 6A is a diagram in which the aluminum film 90 is further laminated on the surface on which the third dichroic film 31 is laminated from the state of 5D. Next, FIG. 6B is a diagram in which one filter region of the laminated aluminum film 90 is removed by etching. Next, FIG. 6C shows a state in which the third dichroic film 33 is laminated in such a state. Finally, by peeling off the aluminum film 90 and the third dichroic film 33 laminated thereon, the first dichroic film 3 is formed on one surface of the glass plate 2 as shown in 6D.
The first and third dichroic films 33 are stacked, and the second dichroic film 32 is stacked on the opposite surface. FIG. 7 is a diagram in which a fourth dichroic film 34 is laminated on the surface of the glass plate 2 opposite to the surface on which the first dichroic film 31 is laminated. FIG. 7A is a diagram in which the aluminum film 90 is further laminated on the surface on which the second dichroic film 32 is formed from the state of 6D. Next, 7B is the aluminum film 90 from the laminated aluminum film 90.
FIG. 5 is a diagram in which two filter regions are separated and removed. Next, FIG. 7C shows a state in which the fourth dichroic film 34 is laminated in such a state. Finally, by peeling and removing the aluminum film 90 and the fourth dichroic film 34 laminated thereon, as shown in 7D,
On one surface of the glass plate 2, a first dichroic film 31 and a third dichroic film 33 are stacked, and on the other surface, a second dichroic film 32 and a fourth dichroic film 33 are stacked. The color wheel 1 is formed by laminating as described above. Here, since the color wheel 1 is a circular member, it is difficult to position the color wheel 1 in the rotation direction at the time of etching and forming the dichroic film. For this purpose, as shown in FIG. 8, the glass plate is a square, particularly preferably a square plate body 60 until the first to fourth dichroic films are formed. Thereby, at the time of film formation, the positioning can be performed accurately by bringing the positioning pins 61 into contact with at least two positions on each of two sides adjacent to each other.
After the first to fourth dichroic films are formed, the color wheel 1 is formed by cutting the film into a circle as indicated by the imaginary line in FIG. As described above, in this embodiment,
By forming a filter as shown in FIG. 1 on both surfaces of the glass plate 2, the incident white light can be color-separated into blue light, green light and red light. In this embodiment, since filters having substantially the same number of layers are formed on both surfaces of the glass plate 2, the glass plate 2 can be prevented from warping. Therefore, it is possible to prevent a warp caused by forming a filter having a number of layers that are greatly different between the front surface and the rear surface with the glass plate 2 interposed therebetween. Here, in the present embodiment, the antireflection film described in the related art is not provided. This is due to the characteristic that dichroic films such as the first dichroic film 31, the second dichroic film 32, the third dichroic film 33, and the fourth dichroic film 34 have a function as an antireflection film. If three types of filters, that is, a filter that transmits only blue light, a filter that transmits only green light, and a filter that transmits only red light, are formed on both sides of the glass plate 2, blue and green are obtained. At the same time as dispersing red light, it is possible to prevent the occurrence of bending.
However, when the filter is formed as described above, the film must be formed three times on one surface of the glass plate 2 and three times on the opposite surface, that is, a total of six times. In the present embodiment, the glass plate 2
It is only necessary to perform the film formation four times on both sides, so that the time for forming the film is reduced. Furthermore, compared to the case where three types of filters, a filter transmitting only green light, a filter transmitting only green light, and a filter transmitting only red light, are formed on one surface of the glass plate. In the embodiment, only two types of filters are formed on one surface, so that a stable filter can be formed. As described above, according to the present invention, it is possible to form a color wheel in which a glass plate does not bend.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view and a cross-sectional view of a color wheel according to the present invention as viewed from above. FIG. 2 is a graph showing the spectral transmittance of each dichroic film in the present invention. FIG. 3 is a graph showing the spectral transmittance of each dichroic film forming portion in the present invention. FIG. 4 is a diagram for forming a first dichroic film in the present invention. FIG. 5 is a diagram illustrating a process of forming a second dichroic film according to the present invention. FIG. 6 is a diagram illustrating a process of forming a third dichroic film according to the present invention. FIG. 7 is a view for forming a fourth dichroic film in the present invention. FIG. 8 is a view showing a square glass plate in the present invention. FIG. 9 is a diagram of a conventional color wheel viewed from above. FIG. 10 is a side view of a conventional color wheel. FIG. 11 is a detailed view of each dichroic film and a glass plate of a conventional color wheel. [Description of Signs] 1 Color wheel 2 Glass plate 31 First dichroic film 32 Second dichroic film 33 Third dichroic film 34 Fourth dichroic film 35B First and second dichroic film forming portions 35G Fourth dichroic film forming part 35R Third and fourth dichroic film forming parts 61 Positioning pin 90 Aluminum film 100 Color wheel 101 Rotating shaft 102 Support 103 Holding ring 104 Color filter 104B Blue light filter 104G Green light filter 104R Red light Filter 105 Light source 110 Glass plate 111B Blue filter 111G Green filter 111R Red filter 112 Anti-reflection film

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hidenobu Ishihara             700 Konakacho, Sano City, Tochigi Prefecture Sano Fujimitsu             Machine Co., Ltd. F term (reference) 2H048 AA15 AA16 AA19 AA22 AA24                       FA15 FA24

Claims (1)

Claims: 1. A color wheel in which three filter regions transmitting blue, green, and red wavelength light are formed on a transparent disk, wherein one side surface of the transparent disk includes: A first dichroic film that transmits only blue and green wavelength light is formed in two filter regions, and a third dichroic film that transmits only red wavelength light is formed in one filter region. On the other end surface of the disk, a second dichroic film that transmits only blue wavelength light is formed in one filter region, and a fourth dichroic film that transmits only green and red wavelength lights is formed in two filter regions. A dichroic film is formed, and the second dichroic film and the third dichroic film are different in filter area from each other with the transparent disc interposed therebetween. Color wheel, characterized in that a configuration of forming a.