JP2000329922A - Color wheel - Google Patents

Abstract

(57) [Summary] In a display technology using a color wheel, a decrease in brightness is prevented. SOLUTION: Color filters 20, 22, 24 and white filters 21, 23, 25 are arranged adjacent to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system of a color image display device, and more particularly, to a color wheel used in such a system.

[0002]

2. Description of the Related Art A color wheel as described above is arranged on an optical path in an optical system of an image display device, and is used to periodically generate a color change.

[0003] That is, a color wheel, in which several types of filters transmitting a specific wavelength of white light from a light source, are arranged, rotates at high speed along an optical path, so that a color change can be periodically generated. The light transmitted through the color wheel is projected to an image conversion device, and a continuous color image is projected on a screen so that it can be integrated in an observer's eyes, thereby generating a full color image.

A prior art color wheel is shown in FIG. Prior art color wheels typically have filters 120, 121, 12 configured to transmit RGB wavelengths on a fan-shaped glass substrate.
The mainstream is to arrange a color wheel by arranging two fan-shaped filters and fixing the respective fan-shaped filters to the rotation holding member 130 in a circular shape. Such a technique is known, for example, from Japanese Patent Application Laid-Open No. 06-347639.

[0005] In FIG. 11, reference numeral 123 schematically shows a light spot formed on a color wheel. Actually, the position of the light spot 123 in the optical system does not change, and the position of the filter with respect to the spot 123 changes as the color wheel rotates in the direction of the arrow 125. In other words, the spot position changes continuously in the direction of arrow 126 by the rotation of the color wheel.

In the color wheel constructed as described above, for example, in the section where the light spot crosses the adjacent color filters 121 and 122 from the position 123 and reaches the position 124, the light spot Are transmitted at the same time, and color mixing occurs in the transmitted light. That is, light transmitted through the two color filters is transmitted to the image conversion device, and this period is a blank period during which the image conversion device is not operated. That is, during this period, the luminous flux of the light source is discarded, which causes a decrease in the brightness of the screen. For example, when three color filters 120, 121, and 122 are arranged as in the conventional example, the color wheel is rotated, and there are three sections where the spot simultaneously straddles the two color filters.

FIG. 12 shows an operation time chart of an image conversion element with respect to rotation of a conventional color wheel. The horizontal axis of the graph indicates the rotation angle, and the vertical axis indicates ON / OFF. Here, OFF indicates a blank period, and will be expressed similarly in the following. Here, the outer diameter of the color wheel is 80 mm, and the diameter of the spot on the color wheel is 7 mm.
Is shown.

As can be seen from FIG. 11, the angle at which the spot covers the two segments, ie, the angle required to avoid color mixing, is about 11.5 degrees. Therefore, as shown in FIG. 12, when shifting from R to G, from G to B, and from B to R, the minimum OFF time of 11.5 degrees is required.

[0009]

In the above-described conventional color wheel, since the color filters are arranged side by side, there is a period in which the spot of light formed on the color filters extends between the two filters. In the case of the conventional example, the blank period is about 9.6% in one rotation, and that section corresponds to discarding light. Further, there may be a case where a margin is required in consideration of variations in components, variations in rotation speed, variations in switching timing of image conversion elements, and the like, and a blank period is further required.

[0010] Further, the structure in which the filter composed of the fan-shaped substrate is combined in a circular shape makes it easy to manufacture each filter. . For this reason, there is a drawback that air resistance occurs at the time of high-speed rotation, wind noise is generated, noise is caused, and a rotational load is generated.

Further, when a filter is formed on a single disk-shaped substrate, noise and the like are reduced since the aerodynamic resistance is smaller than when a fan-shaped filter is combined. However, since the color filters are arranged next to each other, a blank period is required similarly. Also, when placing the filter,
It is difficult to arrange them side by side without overlapping or overlapping.

It is an object of the present invention to provide a color wheel which solves the above problems, improves brightness and improves contrast.

[0013]

In order to solve the above problems, a color wheel according to the present invention comprises a so-called color filter which can transmit a specific range of wavelengths and a so-called white filter which can transmit the wavelength of visible light. To place.

With this arrangement, the light flux is 2
Passing simultaneously between the two filters can be a combination of color and white filters. In the case of this filter combination, since the transmitted color is a combination with white, the color is only brightened, and the phenomenon of mixing two colors unlike the combination with other colors does not occur, and the color change Is also small. Therefore, by taking in the light in this section, the blank period can be shortened. That is,
Conventionally, at least two light spots on the color wheel
Although the rotation time corresponding to the individual is required as the blank period, the blank period can be shortened by arranging the white filter next to the blank period.

Further, when the filters are arranged on one disk-shaped substrate, the white filters are arranged next to the color filters, so that the color filters are not superimposed. Since there is no joint, aerodynamic drag can be reduced and noise can be reduced.

Further, when a fan shape is used, if the color filter and the white filter are arranged on one fan shape glass substrate, the number of fan shape glass substrates to be combined can be reduced. In addition, steps and gaps during assembly can be reduced.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of an embodiment of an image display device using a color wheel. White light emitted from the light source 1 is condensed on the color wheel 3 by the lens 2. The color wheel 3 is composed of R, G, B filters and a white filter that can transmit a specific wavelength. When the color wheel 3 rotates at a predetermined number of rotations, the white light of the light source 1 continuously passes through each filter, and is converted into light of three primary colors of R, G and B according to the filter characteristics. Is converted. The converted light beam passes through the lens 4 and the lens 5 and is transmitted to the image conversion device 6. The image conversion device 6 is a device that can convert input light into an image, such as a digital micromirror device or a liquid crystal panel. This embodiment shows an example in which a reflection type digital micromirror device is used. The light modulated by the image conversion device is enlarged and projected on a screen 8 by a projection lens 7.

Next, the configuration of the color wheel according to the present embodiment will be described in detail with reference to FIGS. FIG.
(A) is a top view of the color wheel, and (b) is a side view. In FIG. 2B, the disk-shaped substrate 15
It is coaxially fixed to the rotating member 30. The rotating shaft 31 is press-fitted into the rotating member 30 and the magnet 33 is fixed thereto. A coil 34 is fixed to the stator 32,
A ball bearing 35 is attached. The rotating shaft 31 is attached to the ball bearing 35 so as to be rotatable, and the rotating shaft 31 is controlled to a desired rotation speed by a driver circuit (not shown).

In FIG. 2A, 20, 22, and 24 are color filters, and 21, 23 and 25 are white filters.
In this embodiment, reference numerals 20, 22, and 24 denote filter films that respectively transmit the three primary colors of R, G, and B, and are formed on the disk-shaped substrate 15. A glass material or the like is typically used for the disk-shaped substrate, but the material is not particularly limited, and any material may be used as long as it can withstand a temperature rise due to a light spot and obtain desired transmission characteristics.

The white filter is, for example, 420n
It is formed so as to transmit a wavelength of m or more. Thus, by selecting the wavelength and cutting the ultraviolet rays, it is possible to reduce the temperature rise.

Next, the relationship between the color wheel and the spot according to the first embodiment will be described with reference to FIGS. FIG. 3 is a schematic view of a color wheel and light spots formed on the color wheel.
The white filters 43, 45, and 47 are arranged adjacent to each other. White filters 43, 4
The sizes of 5, 47 are set so that almost half of the light spot can be accommodated. With this setting, the light spot passes from the color filter to the white filter,
Pass through color filters. In a section that crosses the color filter and the white filter, the change in color is slight and the time is short, so that the influence of taking in light in this section is small. Therefore, by taking in the light in this section, the light can be used efficiently. On the other hand, the section where the light spot crosses the two color filters at the same time and the color mixture occurs is the section where the light spot moves from the position 41 to the position 42. This section is a blank period and the image conversion element is turned off.

FIG. 4 shows an operation time chart of the image conversion element with respect to the rotation angle of the color wheel in the present embodiment. Here, the horizontal axis of the graph indicates the rotation angle of the color wheel, and the vertical axis indicates ON / OFF of the image conversion element. Here, the outer diameter of the color wheel is 80 mm, and the diameter of the spot on the color wheel is 7 mm. As described above, since the size of the white filter is set to half of the spot, from the position 41 where the spot is half of the white filter and the color filter, the spot is half that of the next color filter and the white filter 42. By setting the OFF time to the position, it is possible to avoid color mixture that straddles two color segments. With this setting, the angle at which the switch is turned off is about 5.7 degrees. That is, as shown in FIG.
To G, G to B, and B to R, the minimum OFF time of 5.7 degrees is required. However, this is half of the OFF time compared to the conventional example, which is efficient. Indicates that light can be used.

Next, the relationship between a color wheel and a spot according to the second embodiment will be described with reference to FIGS. FIG. 5 shows a light spot 8 formed on the color wheel.
6 is a diagram schematically showing the state of the color filters 80 and 8;
White filters 81, 83, 85 are arranged adjacent to 2, 84, respectively. Light spot 87, 8
8 shows a part of a state in which the position of the light spot 86 with respect to the color wheel has been moved by the rotation of the color wheel. The white filters 81, 83, 85 are set larger than the spot 86. With this setting, the spot 86 does not straddle two color filters at the same time. That is, the simultaneous passage of the light spot between the two filters is always a combination of the color filter and the white filter.

FIG. 6 shows an operation time chart of the image conversion element with respect to the rotation of the color wheel in the present embodiment. The horizontal axis of the graph is the rotation angle, and the vertical axis is ON /
OFF is shown. As described above, in the present embodiment, the size of the white filter is set to the size of the spot. With this setting, no color mixing occurs,
Considering only the OFF time to avoid color mixing,
The FF time becomes zero. That is, it is only necessary to consider a margin in consideration of variations in components, variations in rotation speed, variations in switching timing of image conversion elements, and the like.

Therefore, the blank period required conventionally can be shortened or eliminated, the light amount of the light source can be used with high efficiency, and a bright image can be provided, so that the contrast can be improved. it can.

Next, the assembling structure of the color wheel filter will be described with reference to FIGS.

FIG. 7 shows a case where a color filter and a white filter are respectively formed on a fan-shaped glass substrate.
The color filters 52, 54, 56 and the white filters 51, 53, 55 are bonded and fixed to the rotating member 50. In this case, in this case, it is only necessary to separately form the filter layers on the fan-shaped glass substrate, so that operations such as masking are not required in manufacturing. However, there is a drawback that it is difficult to connect the individual filters, and furthermore, a step is formed between the filters, causing aerodynamic resistance and causing noise.

FIG. 8 shows that one fan-shaped glass substrate 61
This is an example in which a color filter and a white filter are formed. The fan-shaped glass substrates 61, 62, 63 on which the color filter and the white filter are arranged are fixed to the rotating member 60.
With this configuration, the place where the step is generated can be reduced by half, and the aerodynamic characteristics can be improved.

FIG. 9 shows an example in which one disk substrate is used. A color filter and a white filter are formed on one disk substrate 71, and are fixed to the rotating member 70. With this configuration, it is possible to realize a color wheel with little aerodynamic resistance without any step between the filters. Furthermore, since a white filter is arranged next to the color filter, when forming a filter layer, two
There is no problem that two color filters overlap.

Next, a third embodiment will be described with reference to FIG.

FIG. 10 shows an example in which RGB color filters are arranged twice each. Such a filter configuration is a method adopted when color switching is performed at high speed. 10, 100 is an R filter, 101 is a G filter.
A filter, 102 is a B filter, and 106 is a white filter. Also in this configuration, the same effect can be obtained by disposing the color filter and the white filter side by side. In the case where the filter is divided into many parts as in the example of this embodiment, and in the case where the white filter is not arranged as in the conventional example, a blank period is required for each connecting portion of the filter, so that the same as in the previous examples. If the outer diameter of the color wheel is 80 mm and the outer diameter of the light spot is 7 mm, about 20% of the light must be discarded. On the other hand, according to the present invention, the blank period can be reduced or eliminated by disposing the white filter.

In the above embodiment, as a result of combining the filters, it is sufficient that the outer diameter is circular, and the same effect can be obtained even if the inner part is polygonal. The shape is not limited.

In the present embodiment, the color filter
Although an example is shown in which one or two RGB filters are arranged, the type and number of filters are not particularly limited. Also, the order of the filter arrangement is not limited.

The blank period in the present embodiment is an example and is not limited.

[0036]

As described above, according to the color wheel of the present invention, by arranging the white filter next to the color filter, the light spot formed on the color wheel simultaneously straddles the two color filters. The so-called color mixing time can be reduced or eliminated. Therefore, it is possible to reduce or eliminate the time required for the conventional spot to cross the two color filters, that is, the blank period, to use the light source light amount with high efficiency, and to provide a bright image. Further, the contrast can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an outline of a display device according to a first embodiment of the present invention.

FIG. 2 is a structural diagram of a color wheel according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a relationship between a color wheel and a light spot according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a timing chart of the operation of the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between a color wheel and a light spot according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a timing chart of the operation of the second embodiment of the present invention.

FIG. 7 is a perspective view showing an assembly configuration of a color wheel according to the embodiment of the present invention.

FIG. 8 is a perspective view showing an assembly configuration of a color wheel according to the embodiment of the present invention.

FIG. 9 is a perspective view showing an assembly configuration of a color wheel according to the embodiment of the present invention.

FIG. 10 is a relationship diagram between a color wheel and a light spot according to a third embodiment of the present invention.

FIG. 11 is a diagram illustrating a relationship between a color wheel and a light spot according to a conventional example.

FIG. 12 is a diagram showing a timing chart of the operation of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Lens 3 ... Color wheel 6 ... Image conversion device 7 ... Projection lens 8 ... Screen 15 ... Disc-shaped glass substrate 20 ... Color filter 21 ... White filter

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Nobuyuki Kaku 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Digital Media Development Division, Hitachi, Ltd. (72) Masahiko Yatsu 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Digital Media Development Division (72) Inventor Satoshi Ouchi 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. Digital Media Development Division (72) Inventor Nobuo Masuoka Yoshida, Totsuka-ku, Yokohama, Kanagawa Prefecture F-term (reference) 2H048 AA01 AA11 AA12 AA19 AA24 2H091 FA02X FB07 FD26 LA15 LA17 LA18 5C058 AA05 AA06 BA05 BA08 EA01 EA11 EA26 EA27

Claims (5)

[Claims] 1. A color wheel having a filter capable of transmitting light of a desired wavelength disposed on a disk-shaped substrate made of a material capable of transmitting light, wherein the filter is capable of transmitting at least a wavelength in a specific range of visible light. A color wheel comprising two or more types of color filters and a white filter capable of transmitting visible light. 2. A color wheel in which a filter capable of transmitting light of a desired wavelength is disposed on a disk-shaped substrate made of a material capable of transmitting light, said filter comprising at least a filter capable of transmitting a specific range of wavelengths of visible light. A color wheel comprising two or more types of color filters and a white filter capable of transmitting visible light, wherein the color filters and the white filters are arranged adjacent to each other. 3. The color foil according to claim 1, wherein the filter is arranged on one circular glass substrate. 4. The color wheel according to claim 1, wherein the filters are arranged in a plurality of fan-shaped glass substrates and are combined in a circular shape. 5. The color foil according to claim 4, wherein a color filter and a white filter are arranged on the fan-shaped glass substrate.