KR100352974B1 - Projector Using a Color Drum - Google Patents

Abstract

The present invention relates to an image projection apparatus capable of reducing the size of the entire optical system and improving image quality.

An image projection apparatus using a color drum of the present invention includes a light source for generating light, a first optical unit configured to condense light by at least one meniscus type convex lens, and at least one meniscus concave lens. A second optical unit configured to disperse the collected light so that the light distribution is uniform, a color drum in the form of a cylinder that sequentially transmits the color incident light from the second optical unit, and a video signal using the separated color light And an projection lens for enlarging and projecting the image.

Image projection apparatus according to an embodiment of the present invention can not only reduce the size of the system by using a color drum, but also improve the image quality by using an illumination optical system for reducing the unevenness of the bright or dark center on the screen.

Description

Projector Using a Color Drum {Projector Using a Color Drum}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image projection apparatus for expanding and projecting a small image display element onto a screen using an optical system, and more particularly, to an image projection apparatus capable of reducing the size of an entire optical system and improving image quality.

The image projection apparatus is a display apparatus that implements an image of a desired size on a large screen by projecting an internally implemented digest image using a projection lens. The image projection apparatus is divided into a front projection method and a rear projection method according to a method of projecting an image on a screen. A representative example of the projection apparatus using the rear projection method is a projection television.

An image projection apparatus has an advantage of allowing a large number of people to see one screen at a distant point by enlarging the image and displaying it in a large screen. Because of these advantages, projection apparatuses are used in various fields such as entertainment and video conferencing, and various kinds of image projection apparatuses are spread according to application fields.

A general front projection type image projecting device includes a small image display device that provides image information, a projection lens system that enlarges and implements an image of the implemented image on a screen, a lamp and a lighting device used as a light source, It is largely composed of an illumination lens system for adjusting the light propagation path and a circuit unit for signal processing. Currently, the research on image projection apparatus has a trend to realize high brightness through efficient optical system configuration or lamp change, and to emphasize the simplicity of carrying and installation through miniaturization and light weight even though the brightness is somewhat low. have.

Image projecting apparatuses can be divided into transmissive and reflective apparatuses according to the type of display elements used as image display elements therein. Projection apparatuses in which three or one image display elements are used are currently being developed. In most cases, image projection apparatuses using three sheets are being used for the purpose of realizing high brightness, while those using one sheet are being distributed for the purpose of small size and light weight.

Image projectors using one image display device use a color filter to realize color, a method of separating red, green, and blue, which are three primary colors of light, and incident them at a specific angle, and displaying three primary colors sequentially. The method of sending to a device is used. Among the above methods, the image projection apparatus that sequentially sends the three primary colors to the image display device uses a color wheel that separates the three primary colors (red, green, blue) in time. However, current color wheels have a large size, making it difficult to downsize the image projection apparatus.

Hereinafter, a conventional image projection apparatus using a color wheel will be described with reference to FIGS. 1 to 2D.

1 is a view showing the internal structure of an image projection apparatus using a conventional color wheel.

Referring to FIG. 1, a conventional image projection apparatus includes a lamp 2 for generating light, a reflector 4 for focusing light toward a front focus, and a first illumination lens 6 for narrowing the width of focused light. ), An optical filter of the color wheel 24 that transmits only specific color light of light, a field stopper 10 for blocking unnecessary light beams from the light beams passing through the optical filter, and second and second narrowing widths of emitted light. A third illumination lens (7,14), a total reflection mirror (16) that reflects all the light having a narrow divergence in different directions, and a fourth illumination lens that concentrates the reflected light to illuminate the reflective image display device (20) 18 and a reflection type image display device 20 for reflecting light passing through the fourth illumination lens according to an image signal to implement an image beam loaded with image information, and to enlarge and project the implemented image beam at an arbitrary distance. The projection lens 22 is provided. In the image projection apparatus of FIG. 1, the lamp 2 is positioned at a point corresponding to the first focus of the reflector 4 to generate light. The reflector 4 reflects and concentrates the light generated by the lamp 2 to the front second focal point. In this case, the first illumination lens 6 is provided in front of a predetermined distance of the point corresponding to the second focal point in order to narrow the width of the light concentrated by the reflector 4. Light whose width is reduced by the first illumination lens 6 is directed to the field stop 10. The color filter portion of the color wheel 24 positioned between the first illumination lens 6 and the field stop 10 transmits the red, green, and blue color lights sequentially as the color wheel 24 rotates. Of the light beams passing through the filter portion of the color wheel 24, the unnecessary light beams outside the predetermined width are removed from the field stop 10. The second and third illumination lenses 7 and 14 narrow the width of the light beam diverging through the second focal point so that all of them are incident on the predetermined area of the total reflection mirror 16. The light beams incident on the total reflection mirror 16 are all reflected and enter the reflective image display device 20 through the fourth illumination lens 18. The fourth illumination lens 18 causes the light beam reflected by the total reflection mirror 16 not to diverge, but is concentrated and incident on the reflective image display device 20 at a specific concentration angle. The image display element 20 transmits the image light containing the image information to the projection lens 22 by reflecting the incident light in accordance with the image signal. The projection lens 22 magnifies the image light and projects it on a screen installed in front of an arbitrary distance.

In the conventional image projection apparatus having such a structure, as the large color wheel 24 is used as shown in FIGS. 2A to 2D, the space occupied by the color wheel 24 becomes large and the length of the lighting unit becomes long. The disadvantage is that the size of the system increases. In addition, the conventional image projection apparatus uses only the first illumination lens 6 in the illumination unit to inject the light into the field stop 10 so that the light distribution such as the amount of light increases due to concentration in the center after the incident light and the parallel light is incident. There is a disadvantage that the uniformity of the brightness of the final image is deteriorated because it is not uniform.

Accordingly, it is an object of the present invention to provide an image projection apparatus capable of reducing the size of the entire optical system and improving image quality.

1 is a diagram showing the configuration of a conventional image projection apparatus.

2A to 2D are three-dimensional views of a conventional image projection apparatus.

3 is a diagram showing the configuration of an image projection apparatus using a color drum according to an embodiment of the present invention.

Figures 4a to 4b is a view showing a comparison of the operating principle of the conventional illumination lens and the illumination lens used in the present invention.

5 is a view showing the configuration and operation principle of the color drum used in the present invention.

6A to 6D are three-dimensional views of the image projection apparatus shown in FIG.

7 is a diagram showing the configuration of an image projection apparatus according to another embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

2: lamp 4: reflector

6: first illumination lens 7, 8: second illumination lens

10: field aperture 12: color drum

13: color drum rotating body 14, 15: third illumination lens

16: total reflection mirror 18: fourth illumination lens

20: reflective image display element 21: transmissive image display element

22: projection lens 24; Collar wheel

In order to achieve the above object, an image projection apparatus using a color drum of the present invention comprises a light source for generating light, at least one meniscus type convex lens for condensing light and at least one A second optical part configured by the meniscus concave lens to uniformly disperse the collected light so that the light distribution is uniform, a cylindrical color drum which sequentially separates and transmits the light incident from the second optical part, and is separated from the second optical part An image display element for displaying an image according to an image signal using the color light, and a projection lens for enlarging and projecting the image.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 3 to 7.

3 is a view showing the internal structure of the image projection apparatus using a color drum according to an embodiment of the present invention.

Referring to FIG. 3, an image projection apparatus according to the present invention includes a lamp 2 for generating light, a reflector 4 for reflecting light toward a front focus, and a first illumination lens for concentrating the reflected light. 6) and a first illumination unit composed of a second illumination lens 8 for uniformly distributing the concentrated light, a field stop 10 for removing unnecessary light, and three primary colors of light by rotation A color drum 12 for transmitting, a third illumination lens 15 for preventing divergence of the light beam incident on the total reflection mirror 16, and a total reflection mirror for reflecting the incident light beam to change the traveling direction to another direction ( 16) a fourth illumination lens 18 which concentrates the light beam on the image display device 20 while suppressing divergence of the reflected light beam, and image light containing the image information by reflecting the illuminated light beam according to an image signal. An image display element 20 for generating a And a projection lens 22 for enlarging and projecting the image lights to any distance.

In the image projection apparatus of FIG. 3, the lamp 2 located near the first focal point of the reflector generates light. The reflector 4 reflects the light from the lamp 2 and focuses it toward the front second focal point. In the first lighting unit, the first illumination lens 6 is a meniscus-type convex lens having a convex shape toward the lamp 2 side in order to reduce the width of the light collected by the reflector 4 and corresponds to the second focal point. It is located in front of the predetermined distance in the direction of the lamp 2 from the point. The second illumination lens 8 provided between the first illumination lens 6 and the field stop 10 is a concave lens formed concave in the direction of the lamp 2 and prevents light from concentrating to the center. 4A to 4B, the conventional first illumination lens 6 is compared with the lens parts 6 and 10 formed in the first illumination part in the present invention.

In FIG. 4A, the light emitted from the lamp 2 is reflected by the reflector 4 and is incident on the first illumination lens 6. At this time, the direction of incidence of light travels in parallel with the optical axis concentrating toward the first illumination lens 6 and the light is distributed between the light incident on the first illumination lens 6. However, in the conventional lighting unit, when the light is incident on the field stop 10 using only the first illumination lens 6, the light distribution of the concentrated light and the parallel light is not uniform, and the uniformity of the brightness on the actual screen is not good. On the other hand, in the first lighting unit of the present invention shown in FIG. 4B, a second illumination lens 8, which is a concave lens, is installed between the first illumination lens 6 and the field aperture 10 to adjust the focal length of the concave lens. By adjusting the light distribution difference according to the concentrated light and parallel light can be reduced. As a result, the uniformity of brightness on the screen can be secured. In other words, the light incident on the center of the second illumination lens 8 does not change its direction even though it passes through the lens. However, the light propagating in the outside is changed in the outward direction by the diverging refractive power of the concave lens. By using this principle, the degree of light concentration in the center can be adjusted by changing the refractive power of the concave lens, so that the image projection apparatus of the present invention can show a more homogeneous screen than the conventional image projection apparatus. The field stop 10 blocks the unnecessary light of the light from the first lighting unit so that only the effective light is directed to the color drum 12. The color drum 12 sequentially changes the incident light into a specific color light by rotation. In detail, as shown in FIG. 5, the color drum 12 is configured to allow the drum in the form of a cylinder to rotate by the rotating body 13. The color drum 12 is an optical filter which is divided into three parts to transmit red, green, and blue light, and whose surface is coated or colored. Alternatively, the color drum 12 may be separated into four parts, including a part that transmits light as it is, in addition to the red, green, and blue coatings. The color drum 12 transmits only the color light suitable for the characteristics of the optical filter corresponding to the incidence surface among the light incident from the outside as shown in FIGS. 6A to 6C, and sequentially color light as the color drum 12 rotates. To be transmitted. Specific color light transmitted through the color drum 12 is incident on the third illumination lens 15 corresponding to the second illumination unit. The third illumination lens 15 suppresses the emission of the incident color light so as to be incident on all of the predetermined region of the total reflection mirror 16. The total reflection mirror 16 reflects the color light whose divergence is suppressed in a direction different from the incident propagation direction and enters the fourth illumination lens 18. The fourth illumination lens 18 is incident on the image display element 20 while suppressing the divergence of the reflected color light. The image display device 20 reflects the color light incident by the fourth illumination lens 18 according to the image signal to generate image light containing image information, and causes the image light to enter the projection lens 22. The projection lens 22 enlarges and projects the color light reflected from the image display element 20 at an arbitrary distance.

As described above, the image projection apparatus according to the embodiment of the present invention can be miniaturized as shown in FIGS. 6A to 6D by using the color drum 12 having a small size.

7 shows an image projection apparatus using a color drum according to another embodiment of the present invention. The image projection apparatus of FIG. 7 uses the transmissive image display element 21 unlike the image projection apparatus shown in FIG. 3 uses the reflective image display element 20.

In FIG. 7, the light generated from the lamp 2 passes through the reflector 4, passes through the first illumination unit and the field aperture 10, and the incident direction of the incident light is changed by the color drum 12 and the second illumination unit so that the image display device ( 21 is the same as the image projection apparatus shown in FIG. In this way, the color light emitted from the second lighting unit is incident on the transmissive image display element 21 to be modulated into image light having image information. Image light is incident on the projection lens 22, and the projection lens 22 enlarges and projects the image light at an arbitrary distance.

As described above, the image projection apparatus of the present invention can reduce the size of the image projection apparatus by using a small color drum instead of the color wheel. In addition, the image projection apparatus of the present invention uses a meniscus-shaped convex lens and a concave lens together in the first lighting unit to uniformly distribute the light, thereby reducing unevenness in the center of the screen.

As described above, the image projection apparatus according to the embodiment of the present invention can reduce the size of the entire system of the image projection apparatus by using a color drum that occupies a relatively small space than the conventional color wheel.

In addition, the image projection apparatus of the present invention can improve the image quality by using an illumination optical system for reducing the unevenness of the center of light or dark on the screen.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (4)

A light source for generating light, A first optical unit configured to condense at least one light having at least one meniscus convex lens; A second optical part composed of the at least one meniscus concave lens to disperse the focused light so that light distribution is uniform; A color drum in the form of a cylinder that sequentially transmits the color incident light from the second optical unit, and An image display element for displaying an image according to an image signal using the separated color light; And a projection lens for enlarging and projecting the image. The method of claim 1, A third optical unit for preventing an incident angle of color light transmitted through the color drum from increasing; A total reflection mirror for changing an incident light propagation direction of color light illuminated by the third optical unit to another direction; An image projection apparatus using a color drum, further comprising a fourth optical unit for condensing the color light with the image display device. The method of claim 1, The color drum is formed in a cylinder shape and a color filter for separating the red, green, blue color light sequentially; An image projection device using a color drum, characterized in that consisting of a rotating body for rotating the color filter. delete