JP4606153B2 - Color filter and projector device - Google Patents

Description

  The present invention relates to a color filter having a plurality of regions each having a different color of transmitted light, and a projector device that projects a color image using the color filter.

  In the field of presentation or video projection, a projector device that enlarges and projects an image based on image data onto an external screen or the like is used. Such a projector apparatus is configured to form an image based on image data on an image device such as a liquid crystal panel or DMD (Didital Micromirror Device), and project the image on the image device to the outside by light from an internal light source. It has become. In addition, such a projector apparatus projects a color image with a three-plate system that includes image devices for each color of R (red), G (green), and B (blue), and synthesizes and projects the images of the respective colors. There is a single plate type that includes a single image device and projects a color image by projecting RGB images in a time division manner. The single-plate projector device has advantages in that it is low in cost and easy to miniaturize compared to a three-plate projector device including a plurality of image devices.

  FIG. 6 is a schematic diagram showing a main internal structure of a single-plate projector device. The projector device irradiates the image device 23 with the light from the light source 21 through the color wheel 22, and projects the light reflected on the image device 23 that formed the image to the outside through the projection optical system 24. An image on the image device 23 is projected onto an external screen or the like. In the figure, light is indicated by broken lines. The color wheel 22 is a color filter formed in a disk shape, and has a configuration in which three color filters each of which is formed in a fan shape and transmits light of each color of RGB are combined. The color wheel 22 is configured to rotate around the center of the disk at a predetermined rotational speed. As the light emitted from the light source 21 passes through the rotating color wheel 22, light of each color of RGB is irradiated onto the image device 23 in a time division manner. The image device 23 forms an image for each color in synchronization with the rotation of the color wheel 22, and an image for each color is projected.

  FIG. 7 is a schematic diagram illustrating an example of a color wheel. FIG. 7A shows a color wheel composed of RGB three-color filters. FIG. 7B shows a color wheel configured by four types of filters in which a W (white) filter that transmits white light is added to three RGB filters. FIG. 7C is composed of four types of filters obtained by adding an ND (Neutral Density) -G filter having a transmittance for transmitting G light lower than that of the G filter to three RGB filters. The color wheel is shown.

  Since each color filter of RGB transmits only about 1/3 of the wavelength component of visible light contained in white light, a color wheel composed of three color filters of RGB as shown in FIG. The projector device used has a problem that the amount of light used to project an image is small and the projected image is dark. Patent Document 1 discloses a projector device that can brighten a projected image by removing the color wheel from the light path as necessary. However, there is a problem that a mechanism for moving the color wheel is required. . Thus, by using a color wheel with a W filter as shown in FIG. 7B, the amount of light transmitted through the color wheel can be increased, and the image projected by the projector device can be brightened. Patent Documents 2 and 3 disclose a technique using a color wheel to which a W filter as shown in FIG. 7B is added.

  By the way, the projector apparatus can control the gradation of each color of the color image by controlling the length of time during which the light of each color is reflected by the image device. For example, if the time during which the R light that has passed through the color wheel is actually reflected on the imaging device is shortened, the intensity of red in the projected image will be reduced. If the time for reflecting the R light is increased, the intensity of red in the projected image increases. The conventional projector apparatus divides the time during which the monochromatic light is applied to the image device into a plurality of (for example, 8) sections having different time lengths, and controls whether light is reflected in each section. Thus, the color gradation is controlled by a signal having a bit number (for example, 8 bits) corresponding to the number of sections.

When the light that has passed through the ND-G filter included in the color wheel as shown in FIG. 7C is reflected by the imaging device, the G filter is reflected even if it is reflected for the same time as the light that has passed through the G filter. The intensity of green in the image is smaller than when the light that has passed is reflected. Therefore, using a color wheel to which an ND-G filter is added as shown in FIG. 7C, a G color image is projected with light that has passed through the ND-G filter in addition to light that has passed through the G filter. By doing so, the number of green gradations included in the projected image can be increased. Since G light is more sensitive to human eyes than RB light, the projector device increases the number of bits of the control signal of the image device by using a color wheel as shown in FIG. Therefore, it is possible to project an image having a larger number of gradations and more expressive power. Patent Document 4 discloses a technique that can increase the number of gradations of an image in the same manner by adjusting the amount of light to be projected.
JP 2003-241305 A JP 2000-152265 A JP 2002-6395 A Japanese Patent Laid-Open No. 2002-214697

  The color wheel to which the ND-G filter shown in FIG. 7C is added is created by pasting each filter of RGB and ND-G in a separate step and then affixing to the wheel. Since the G and ND-G filters are created in separate steps, it is difficult to make the wavelengths of light transmitted through the G and ND-G filters match each other. Accordingly, the wavelength characteristics of the filters indicating the wavelength region of the light passing through the filter are different from each other between the G and ND-G filters, and when the ND-G filter is used, the ND-G filter is not used. There is a problem that the color of the projected image is different. In addition, since it is difficult to match the wavelength characteristics of the filters to be created across all products, the difference in the wavelength characteristics of the G and ND-G filters differs from product to product, and the color of the projected image varies from product to product. There is a problem of variation.

  Further, as described above, the projector device expresses color by extracting light of each color of RGB from white light of the light source. However, the light transmitted by the W filter shown in FIG. 7B includes light of an intermediate wavelength of the light transmitted by the RGB filters and colors other than RGB. Therefore, when the W filter is used, the brightness of the projected image is improved, but there is a problem that the color reproducibility of the projected image is deteriorated due to the mixture of light of colors other than RGB. Brightness is important in the field of presentation, and color reproducibility is important in the field of video projection. Conventionally, a projector device that uses a W filter and a projector device that does not use a W filter are used separately for each field. There was a situation. Therefore, there is a need for a projector device that can improve brightness while maintaining good color reproducibility of the projected image so that it is not necessary to use the projector device for each field.

  The present invention has been made in view of such circumstances. The object of the present invention is to increase the number of gradations of an image and at the same time change the hue compared to the case of using RGB three-color filters. Another object of the present invention is to provide a color filter capable of suppressing variations in hues between products, and a projector device using the color filter.

  Another object of the present invention is to provide a projector device that can improve brightness while maintaining good color reproducibility of a projected image.

  Still another object of the present invention is to provide a projector apparatus that can be used without limiting the field of use.

The color filter according to the present invention is a color filter having a plurality of color regions that transmit light of different colors and a first white region that transmits white light, wherein the first white region transmits white light. and have a second white region for transmitting white light at a lower transmittance than the transmittance, the plurality of color areas respectively formed in a fan shape, a disc made of the first white area and the second white area It is formed on Jo and Oh, characterized in Rukoto.

  In the color filter according to the present invention, the plurality of color regions are regions that respectively transmit light of red, green, and blue colors.

  A projector apparatus according to the present invention includes a light source, the color filter according to any one of claims 1 to 3, means for sequentially causing light from the light source to enter each region of the color filter, and the means Means for projecting an image to the outside using light that has entered the color filter and passed through the color filter.

  The projector device according to the present invention further includes an optical filter, and the light transmittance of the light filter is a transmittance of a wavelength of light capable of transmitting each of a plurality of color regions of the color filter. In comparison, the transmittance of the intermediate wavelength of each of the wavelengths is low.

  The projector device according to the present invention is further characterized by further comprising means for allowing the light filter to enter and exit on a light path until light from the light source passes through the color filter and is projected to the outside.

  In the present invention, in addition to the plurality of color regions that transmit light of different colors and the first white region that transmits white light, the second white that transmits white light at a lower transmittance than the first white region. Using a color filter having a region, the projector device projects an image using light that has passed through each region of the color filter.

  In the present invention, the color filter is a color wheel formed in a disk shape in which the respective areas formed in a fan shape are combined.

  In the present invention, the plurality of color regions included in the color filter are regions through which light of each color of RGB is transmitted.

  In the present invention, the projector device includes an optical filter that transmits light transmitted through each color region of a color filter such as RGB and reduces the transmittance of light having an intermediate wavelength transmitted through each color region. Thus, light having a wavelength other than the wavelength transmitted by each color region is shielded.

  Furthermore, in the present invention, the projector device enables the light filter to enter and exit on the light path for projecting the image.

  In the present invention, a color filter such as a color wheel transmits white light at a lower transmittance than the W region in addition to a plurality of color regions such as RGB and the W region (first white region). Since it has an ND-W area (second white area), the image is projected using the light that has passed through this color filter, as in the case of using a color filter to which an ND-G filter is added. The number of gradations of the projected image can be increased without increasing the number of bits of the control signal of the image device. Compared to creating an ND-G filter so that it has the same wavelength characteristics as the G filter, an ND-W filter with a generally reduced white light transmittance can be created more easily. Therefore, the variation of the white light shade transmitted through the ND-W region for each product is smaller than when the ND-G filter is used. In addition, while the color of light transmitted through the G filter and the ND-G filter, in which the transmitted light is monochromatic light, varies depending on the shift in the wavelength characteristics of each other, the W region that transmits white light and the ND It is difficult to visually recognize the difference in color of light transmitted from the -W region. Therefore, the projector device can increase the number of gradations of the image and suppress a change in hue and a variation in hue for each product as compared to the case of using RGB three-color filters.

  In the present invention, the projector device includes an optical filter that transmits light having a wavelength that is transmitted by each color region of RGB or the like, and that blocks light having an intermediate wavelength that is transmitted by each color region. Even when the light that has passed through the color filter W area and the ND-W area is used, as in the case where only each color area of the color filter is used, no extra color is mixed in the projection image. Deterioration of color reproducibility can be prevented. Further, since the W region and the ND-W region transmit more light than the light transmitted by each color region, the brightness of the projected image is improved as compared with the case where only each color region of the color filter is used. be able to. Therefore, the projector device can improve the brightness while maintaining good color reproducibility of the projected image.

  Further, according to the present invention, the projector device places more importance on color reproducibility when projecting an image by enabling the optical filter according to the present invention to enter and exit the light path for projecting an image. The present invention has an excellent effect, for example, when it is necessary to increase the brightness of a projected image such as when performing a presentation or when performing a presentation without limiting the field of use.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
FIG. 1 is a block diagram showing the main internal configuration of the projector apparatus of the present invention. The arrow in the figure indicates light. The projector device 1 includes a light source 11 such as a xenon lamp or an ultra-high pressure mercury lamp that emits white light, an optical filter 12 that transmits light from the light source 11, and a color wheel that transmits light that has passed through the optical filter 12. Filter) 13, an image device 14 for forming an image, and an optical system 15 for enlarging and projecting an image on the image device 14 to the outside. The color wheel 13 is configured to be rotatable. The image device 14 uses a liquid crystal panel, DMD (Didital Micromirror Device), or the like, and is configured to form images of RGB colors in a time-sharing manner. The optical system 15 includes a projection lens, a motor for adjusting the position of the projection lens, a drive circuit for driving the motor, and the like. The projector device 1 irradiates the image device 14 with light from the light source 11 through the optical filter 12 and the color wheel 13, and projects the light reflected on the image device 14 that has formed the image to the outside through the optical system 15. The image on the image device 14 is projected to the outside. In addition, it is good also as a structure which projects an image by making the light from the light source 11 permeate | transmit instead of reflecting on the image device 14. FIG.

  In addition, the projector apparatus 1 includes a color wheel driving unit 16 including a motor that rotates the color wheel 13 and a control circuit that controls the rotation speed of the color wheel, and a device driving unit 17 that causes the image device 14 to form an image. I have. The color wheel driving unit 16 and the device driving unit 17 are connected to a control unit 19 using a microcomputer or the like. The control unit 19 is connected to a receiving unit 18 that receives image data transmitted from an external device such as a personal computer (PC) or a video reproduction device. The control unit 19 processes the image data received by the receiving unit 18 and controls the operation of the color wheel driving unit 16 to appropriately drive the color wheel 13 so that an image based on the image data can be projected to the outside. Thus, the operation of the device drive unit 17 is controlled to perform processing for causing the image device 14 to form an appropriate image.

  Next, the color wheel that is the color filter of the present invention will be described. FIG. 2 is a front view schematically showing the configuration of the color wheel 13 which is the color filter of the present invention. The color wheel 13 is formed in a disk shape and is divided into five fan-shaped regions around the center of the disk. Three of the five areas are RGB filters (color areas) that transmit light of R, G, and B colors, respectively. One of the five regions is a W filter (first white region) that transmits white light. The last one of the five regions is an ND-W filter (second white region) in which the transmittance for transmitting white light is lower than that of the W filter. The color wheel 13 may be divided into five or more regions. In this case, the color wheel 13 has one or a plurality of R, G, B, W, and ND-W filters. This is a filter.

  The color wheel 13 is rotated at a constant speed by the color wheel driving unit 16 under the control of the control unit 19. The light emitted from the light source 11 and passed through the optical filter 12 passes through one of the R, G, B, W, and ND-W filters of the color wheel 13 according to the rotational position of the color wheel 13. The image device 14 is irradiated with light of a color corresponding to the passed filter. That is, the light from the light source 11 is sequentially incident on each filter by the rotation of the color wheel 13, and the light of each color is irradiated to the image device 14 in a time division manner. The color wheel driving unit 16 includes means for detecting the rotational position of the color wheel 13, and the control unit 19 determines which color of light is transmitted to the image device 14 at each time point according to the detection result of the rotational position of the color wheel 13. You can know if it is irradiated. The control unit 19 controls the operation of the device driving unit 17 in accordance with the timing of rotation of the color wheel 13, and displays an image for each color based on the image data on the image device 14 in a time division manner.

  The intensity of the light passing through the ND-W filter is smaller than that of the light passing through the W filter. Therefore, by projecting an image using the color wheel 13 having the ND-W filter, the number of bits of the control signal of the image device 14 is set as in the case of using the color wheel to which the ND-G filter is added. The number of gradations of the projected image can be increased without increasing it.

  Since the W filter is a filter that transmits white light without significantly limiting the wavelength of light that can be transmitted, the ND-W filter generally reduces the transmittance of light of each wavelength included in white light. Should be created. Compared to creating an ND-G filter so that it has the same wavelength characteristics as the G filter, an ND-W filter with a generally reduced white light transmittance can be created more easily. Therefore, the variation in the color of the white light transmitted through the ND-W filter for each product is smaller than that of the ND-G filter. In addition, since the G filter and the ND-G filter transmit monochromatic light, the color of the transmitted light differs depending on the difference in the wavelength characteristics of each other, whereas the W filter that transmits white light It is difficult to visually recognize the difference in color of light transmitted through the ND-W filter. Accordingly, when the image is projected using the color wheel 13 having the ND-W filter in addition to the RGBW filters, the number of gradations of the image is increased, and at the same time, when the RGB three-color filters are used. It is possible to suppress a change in hue and a variation in hue for each product.

  Next, the optical filter 12 will be described. The optical filter 12 is an optical filter formed in a plate shape. The light filter 12 is disposed on the light path until the light from the light source 11 reaches the color wheel 13, and the light from the light source 11 first passes through the light filter 12 and then is irradiated to the color wheel 13. Thus, the projector apparatus 1 is configured.

  FIG. 3 is a characteristic diagram showing the relationship between the wavelength of light passing through the optical filter 12 and the transmittance. In the figure, the horizontal axis indicates the wavelength of light, and the vertical axis indicates the transmittance of light of each wavelength. The region indicated by RGB in the drawing indicates the wavelength region of light transmitted by each of the RGB filters of the color wheel 13. The optical filter 12 transmits light of RGB colors transmitted by the RGB filters of the color wheel 13 with a transmittance close to approximately 1. On the other hand, the transmittance of light of each color of RGB at an intermediate wavelength is significantly lower than the transmittance of light of each color of RGB. That is, the optical filter 12 transmits light of each color of RGB that is transmitted by each of the RGB filters of the color wheel 13, while blocking light of an intermediate wavelength of B and G, and further, an intermediate wavelength of G and R To block the light.

  Therefore, when the light from the light source 11 passes through the optical filter 12, the color wheel 13 is irradiated with light composed of light of each color of the RBG and containing almost no light of other wavelengths. As a result, the light that has passed through the W filter and the ND-W filter of the color wheel 13 contains almost no light of colors other than RGB. Accordingly, the image projected by the projector apparatus 1 according to the present invention includes almost no colors other than RGB, as in the case of using a color wheel consisting of only three color filters of RGB. Sexual deterioration can be prevented. Further, since the W filter and the ND-W filter transmit about three times as much light as the light transmitted by each of the RGB filters, the projector device 1 of the present invention has only RGB color filters. The brightness of the projected image can be improved as compared with the case where the color wheel made of is used.

  In the present embodiment, the optical filter 12 is disposed between the light source 11 and the color wheel 13, but the present invention is not limited to this, and the light from the light source 11 is transmitted to the color wheel 13 and the image device. 14 may be arranged at any position in the path of light emitted from the optical system 15 via the optical system 15 to the outside. For example, the effect of the present invention is exhibited regardless of the position of the optical filter 13 on the light path, such as the light emission side of the optical system 15.

  Further, the projector device 1 may be in a form provided with a mechanism that allows the optical filter 12 to enter / exit manually or mechanically at a position on the light path. FIG. 4 is a schematic diagram showing an example of a mechanism that enables the optical filter 12 to enter and exit a position on the light path. The optical filter 12 can be inserted into the housing 10 of the projector device 1, and the optical filter 12 includes a groove 121 that is positioned on the light path when the optical filter 12 is inserted. In the drawing, the light path is indicated by a broken line, and the optical filter 12 inserted in the groove 121 is indicated by a two-dot chain line. By inserting or removing the optical filter 12 with respect to the groove 121 manually or using mechanical means (not shown), the optical filter 12 can be made to enter and exit at a position on the light path. The optical filter 12 may be configured to be removable in any direction, and the optical filter 12 is positioned on the light path by a rotation mechanism having an axis parallel to the optical axis of the light from the light source 11 as a rotation axis. It is also possible to use a configuration using other mechanisms such as enabling entry / exit.

  When the brightness of the projected image is more important than color reproducibility, such as when giving a presentation, the light in the wavelength region blocked by the optical filter 12 is imaged by removing the optical filter 12 from the light path. Is added to the light for projecting, so that the projected image becomes brighter. Therefore, by allowing the optical filter 12 to enter and exit the light path, the projector apparatus 1 can adjust the brightness of the projected image when giving importance to color reproducibility when projecting video and when giving presentations. It can be used together when it needs to be larger.

  In the present embodiment, the color filter of the present invention is the color wheel 13, and the light from the light source 11 is incident on each region of the color wheel 13 in a time division manner by rotating the color wheel 13. Although shown, it is not restricted to this, The light from the light source 11 is incident on each area | region of a color filter by a time division by changing the incident path of the light from the light source 11 by a time division using a movable mirror etc. Form may be sufficient. In this case, the shape of the color filter of the present invention is not limited to the color wheel 13 shown in FIG. 2, and may be other shapes such as a rectangular flat plate.

  FIG. 5 is a front view schematically showing another configuration example of the color filter of the present invention. The color filter shown in FIG. 5A is formed in a rectangular shape, and R, B, G, ND-W, and W filters formed in a strip shape are arranged side by side in the long side direction. . The color filter shown in FIG. 5B is configured by arranging R, B, G, ND-W, and W filters formed in a strip shape in the short-side direction. In the color filter shown in FIG. 5C, one region divided by a line substantially parallel to the short side direction is a G filter, and the other region is further divided into four regions in a lattice shape. The region is configured as a W, ND-W, R, B filter. By sequentially entering light from the light source into the R, B, G, ND-W, and W filters of the color filters having these shapes, a projector device can be realized using these color filters.

  In the present embodiment, the projector apparatus 1 of the present invention shows a form in which an image is projected onto an external screen or the like. However, the projector apparatus 1 may be a form that constitutes a part of a rear projection type image display apparatus. Good. This rear projection type image display device includes an internal configuration of the projector device 1 and a screen, and displays an image on the screen by projecting an image from the back side of the screen using the function of the projector device 1. To do.

It is a block diagram which shows the main internal structures of the projector apparatus of this invention. It is a front view which shows typically the structure of the color wheel which is a color filter of this invention. It is a characteristic view which shows the relationship between the wavelength of the light which passes an optical filter, and the transmittance | permeability. It is a schematic diagram which shows the example of the mechanism which enables an optical filter to enter / exit to the position on the path | route of light. It is a front view which shows typically the example of another structure of the color filter of this invention. It is a schematic diagram showing a main internal structure of a single-plate projector device. It is a schematic diagram which shows the example of a color wheel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projector apparatus 11 Light source 12 Optical filter 13 Color wheel (color filter)
14 Imaging device

Claims (5)

In a color filter having a plurality of color regions that transmit light of different colors and a first white region that transmits white light,
And have a second white region for transmitting white light at a lower transmittance than the transmittance of the first white area is transmitted through the white light,
Wherein the plurality of color areas respectively formed in a fan shape, the first white area and the second color filter and said Oh isosamples a disk shape formed of a white area. The color filter according to claim 1, wherein the plurality of color regions are regions that transmit light of red, green, and blue colors, respectively. A light source;
The color filter according to claim 1 or 2 ,
Means for sequentially making the light from the light source incident on each region of the color filter;
And a means for projecting an image to the outside by using the light incident on the color filter and passing through the color filter. An optical filter;
The transmittance of light in the optical filter is such that the transmittance of the intermediate wavelength of each of the wavelengths is higher than the transmittance of the wavelength of light that can pass through each of the plurality of color regions of the color filter. The projector device according to claim 3 , wherein the projector device is low. The projector device according to claim 4 , further comprising means for allowing the light filter to enter and exit on a light path until light from the light source passes through the color filter and is projected to the outside.

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