KR100394015B1 - Optical device in projection-type display apparatus - Google Patents

Abstract

The present invention relates to an optical illumination device of a projection display device. In particular, a rod lens, which is an optical element for uniformly advancing color-separated light, has a propagation direction of a plurality of light incident by total internal reflection in an optical material of an optical switching device. And the changed plurality of light is emitted by a plurality of reflections from the light guide portion, and the optical means for changing the direction and the light guide portion is mechanically integrated, so that the set can be made smaller and thinner and the image quality can be improved.

Description

Optical device in projection-type display apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system configuration of a projection display system using a light source, and more particularly to an optical illumination device of a projection display device that makes light emitted from the light source homogeneous.

Recently, various types of products have been developed and marketed as an image projection apparatus called a projector is widely used. Such image projection apparatuses are being developed with the development of a form emphasizing the brightness and the development of a form emphasizing the compactness / light weight.

In general, an optical system of an image projector includes a lamp as a light source, an illumination unit for illuminating light emitted from the lamp to an image display element, and an image display element and a projection unit to enlarge and project the image displayed on the image display element on a screen. It is composed.

Currently, a high-pressure mercury lamp is used as a lamp, and a liquid crystal display device and a digital micromirror device (DMD) are widely used as an image display device. In such projection displays, single-type, two-, and three-plate optical systems are configured according to the number of image display elements used. In recent years, in the trend of miniaturization, light weight, and low cost, one image display element is used. have.

At this time, in order to make an image projection apparatus as a single display element, the display element has red, green, and blue color filters, or the red, green, and blue are separated from the outside and simultaneously illuminated on the display element or time. It should be illuminated sequentially with the difference.

As described above, in the case of illuminating red, green, and blue sequentially with an external time difference, the image display device requires at least three times the response speed than the three-plate type. As the image display element, there is a DMD ^™ .

1 shows an example of an optical system configuration using a single DMD sheet as a conventional image projection apparatus. Referring to the plan view of FIG. 1A, first, a light is focused on an incident surface of a rod lens 103 using a lamp 101 to which an elliptical reflector is attached. In this case, a color wheel 102 is disposed between the lamp 101 and the rod lens 103 to sequentially separate red, green, and blue, and the color wheel 102 rotates as shown in FIG. 1B. Red, green, and blue filters are attached to the motor in a disk shape, and colors are sequentially filtered out as the color wheel 102 rotates. That is, the area where the area of the filtering portion is minimized is a lamp. The color wheel 102 is disposed before the incident surface of the rod lens 103 because the light emitted from 101 is the portion to be focused on the incident surface of the rod lens 103.

When the light filtered by the specific color is incident on the rod lens 103, the light passes through the rod lens 103 while causing reflection several times therein, and at the exit surface of the rod lens 103, The light spreads out evenly. In other words, the light from the light source proceeds to the exit surface of the rod lens 103 so that the exit surface becomes a surface light source having a second homogeneous luminance distribution. Next, the light emitting surface of the rod lens 103 is formed to an appropriate size by the predetermined lenses 104 and the total reflection mirror 105 so that the light uniform on the display surface of the image display element. Provide a distribution. Here, the total internal reflection prism (TIR prism) 107 is two prisms are bonded with a small air gap so that the incident light is totally internally reflected at the boundary of the first prism is incident to the DMD (106). . Then, the DMD 106 outputs light at a different angle from the light incident by the tilt of the pixel mirrors in the white signal, thereby transmitting the TIR prism 107 without causing total internal reflection. The light thus output passes through the projection lens 108 and is enlarged and imaged on the screen.

On the other hand, in the case of black, since the pixel mirrors are tilted at different angles, the reflected light does not penetrate the projection lens 108 because the reflected light generates total internal reflection at the second prism boundary.

Here, the rod lens 102 is basically possible in two forms, one of which is empty and the inner boundary of the mirror is configured to operate to reflect the mirror, the other is a glass having a high refractive index There may be a configuration that operates by the total internal reflection.

At this time, the rod lens 101 outputs a homogeneous light that is positioned to maximize the incident light focused and reflected from the ellipsoidal mirror of the lamp 101 so that the output surface is accurately formed on the display surface of the image display element. Therefore, it is important to be positioned to maximize the light utilization efficiency. This is because the change in the position of the rod lens lowers the light efficiency or causes a phenomenon that light is not irradiated to a part of the outer surface of the image display surface. At this time, in the case of the mirror type rod lens, the optical lens does not lose optically even when the external body is contacted to fix the rod lens mechanically. As a result, light loss occurs.

On the other hand, another optical system configuration may be considered in the single-type projection optical system, which is basically the same as the case of FIG. 1 described above, and has a color drum instead of the color wheel structure in the method of color illumination. Here, the color drum refers to a glass tube having a cylindrical tube shape as shown in FIG. 2b, and dichroic coating is performed to transmit light of red, green, and blue, respectively, according to the rotation of the motor. It means a color separation device for separating the desired color by rotating the color drum.

Referring to FIG. 2B, the color drum includes a cylindrical color filter 303 for transmitting only a light beam having a wavelength corresponding to each color among white light beams, a coupler 302 attaching the color filter 303, and a coupler ( A motor 301 is attached to the 302 and generates a rotational force. That is, in the color drum, color filters of R, G, and B are formed in a cylindrical shape.

When the color drum is used as a color separation element, the color purity (or brightness) of red, green, and blue can be increased with respect to the case of using the color wheel, and the color that can influence the size (that is, the height) of the projector set is used. It has the advantage that the size (ie diameter) of the separation element can be made small.

3 is a diagram conceptually comparing these phenomena, FIG. 3A shows the color purity reduction and the size of the color wheel, and FIG. 3B shows the color purity reduction and the size of the color drum. That is, for the same illumination spot size on the dichroic filter surface of the color separation element, the angle representing the purity deterioration area of each color due to the interval between the colors is smaller than that of the color wheel. w> d) can be seen. In addition, even in the size of the element, the diameter of the color drum does not increase because the illumination spot is located on the circumferential surface, while the diameter of the color wheel increases because it is located in the radial direction.

2A shows an example of the optical system configuration of the image projection apparatus using the color drum described above, wherein a color drum 202 is disposed between the lamp 201 and the rod lens 203. That is, the light beam generated by the lamp 201 proceeds to the color drum 202. In this case, the color drum 202 sequentially separates the white light beam. The light beam color separated by the color drum 202 proceeds to the rod lens 203. The rod lens 203 distributes the color-separated light beam uniformly on the screen. Next, the output surface of the rod lens 203 is formed to an appropriate size on the surface of the image display element 206 due to the predetermined lenses 204 and the total reflection mirror 205. It provides a homogeneous light distribution on the display surface.

The light beam displaying the image on the display surface of the image display element 206 is reflected by the TIR prism 207 to travel to the projection lens 208. The projection lens 208 causes an image to be enlarged and displayed on a screen (not shown).

At this time, unlike in the case of FIG. 1, due to the mechanical limitations of the color drum 202 and the rod lens 203, the optical axis from the lamp 201 and the optical axis of the rod lens 203 exiting side are difficult to be aligned. . Accordingly, the rod lens 202 has a reflecting means that allows the light paths of the lamp 201 and the rod lens 203 to be different from each other while changing optical paths without changing optical characteristics.

Fig. 4 shows an example of a rod lens having the reflecting means described above in the color drum using optical system including the light path changing means.

4A is an example of a rod lens in a mirror configuration, and FIG. 4B is an example of a rod lens in a glass configuration.

That is, FIG. 4A is a case in which the inner surface is composed of a tubular mirror having a reflective surface, and since the outside does not have an optical effect, mechanical fixation is easy, whereas an elliptical reflector is provided at the mirror surface for switching paths even if a small amount of light is absorbed from the mirror reflective surface. Since the focused light is incident from the coating, the coating on the mirror surface is damaged or broken.

Figure 4b has a structure of a block filled with the same glass inside, even if there is a small amount of light self-absorption of light due to the operation by the total internal reflection has a volume (volumn) is strong to breakage, while the entire optical path surface Because of this, there is an optical problem such as loss of brightness or uneven light output due to total internal reflection cracking of the mechanical contact area.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical system lighting apparatus of a projection display device that can prevent thermal damage and fix a mechanism of a rod lens, which is an optical element, in a projection display device using a color drum. In providing.

1A is a diagram showing an example of a general DMD single-sheet projection optical system

Figure 1b is a view showing the configuration of the color wheel of Figure 1a

Figure 2a is a diagram showing another example of a typical DMD single-sheet projection optical system

Figure 2b is a view showing the configuration of the color drum of Figure 2a

3A is a conceptual diagram showing an example of color purity degradation and size of a color wheel

3B is a conceptual diagram showing an example of color purity degradation and size of a color drum

4A shows an example of a rod lens of a general mirror configuration

4B is a view showing an example of a rod lens having a general glass configuration

5A is a view showing an example in which a rod lens applied to the present invention is formed by adhering a tubular mirror to a glass block;

5B is a view showing an example in which a rod lens applied to the present invention is mirror-bonded to a glass block

5c is a view illustrating an example in which a rod lens applied to the present invention is mirror coated on a glass block and configured

Explanation of symbols for main parts of drawings

201: lamp 202: color drum

203: rod lens 204: lens

205: total reflection mirror 206: image display element

207: TIR prism 208: projection lens

301: motor 302: coupler

303: cylindrical color filter

The optical illumination device of the projection display device according to the present invention for achieving the above object, the rod lens, which is an optical element for uniformly advancing color separated light to the total internal reflection in the optical material of the optical means for switching direction By changing the traveling direction of the plurality of light incident by the light, the changed plurality of light is emitted by a plurality of reflections are emitted from the light guide portion, the optical means for switching direction and the light guide portion is characterized in that the mechanically integrated do.

Preferably, the light guide portion has at least one portion of the mirror reflection.

Preferably, all or part of the part having the mirror reflection is in contact with the mechanical fixing means.

Preferably, the light guide portion is characterized in that the interior is composed of a combination of mirrors having a mirror reflection surface.

Preferably, the light guide portion is filled with an optical medium instead of air, and reflection on most surfaces is performed by total internal reflection, and some surfaces are in optical contact with a total reflection mirror.

Preferably, the light guide portion is filled with an optical medium instead of air, and reflection on most surfaces is performed by total internal reflection, and a part of the surfaces is totally mirror coated.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is applied to an optical system in which a color drum is used, and in particular, relates to a structural example and a conceptual fixing method of a rod lens, which is an optical element which can be minimized or minimized.

That is, in the case of using the color separation element of the color drum, the rod lens used after the color drum has a problem that the output light passes through the color drum again when the optical axis matches the optical axis of the lamp by the shape of the color drum. In addition, mechanically causing a problem of colliding with the color drum, in order to avoid this, the direction of the light after the color drum exit part should be changed so that the rod lens exit part is different from the light incident direction of the color drum. In this case, when a mirror is used to switch the light path, light is focused on the mirror surface, which causes the mirror to be broken.

In order to solve this problem, in the present invention, a glass block having a high heat resistance and a relatively high refractive index is optically bonded to the light incident part of the rod lens, so that light incident by total internal reflection may be mirror reflected.

In addition, a hollow mirror tube or glass block may be used for the construction of a practical rod lens requiring a homogeneous output of light. In this case, the direction change function and the function of the homogeneous light output may be implemented by an integrated shape as in the case of FIG. 4B, but in this case, as described above, it is difficult to precisely fix mechanically without loss of optical characteristics. there is a problem.

Therefore, the rod lenses shown in Figs. 5A to 5C are proposed to solve this problem.

Summarizing the features of FIGS. 5A-5C, total internal reflection means in the optical material are used as the optical means for turning in the path of the light output through the color separation element. In addition, as a means for making the output light uniform in angle and luminance without loss, a light guide type element is used which causes a plurality of reflections without losing light to the outside. These two functions are performed by a mechanically integrated rod lens, and the outside of a portion of the rod lens is configured to be independent of the optical optical path of light inside even if there is a mechanical or joint contact.

That is, when looking at the path of the light input to the rod lens, first, most of the incident light changes the light propagation direction by reflection, and then a plurality of reflections are emitted from the light guide part, and the light is emitted. Most of the operation of changing the direction of is performed optically by the principle of total internal reflection in the medium, and at least one portion of the configuration of the light guide portion which serves to cause the multi-sided reflection of the light beam has mirror reflection.

All or part of the portion with the mirror reflection is in contact with the mechanical fastening means.

FIG. 5A is an optical bonding with a part of the hollow tube mirror by minimizing the light guide part (eg, the glass block) of FIG. 4B, and it can be seen that the aforementioned problems are solved by the mechanical contact of the outside of the hollow tube. . That is, the inside of the light guide portion, which serves to cause the multi-sided reflection of the light beam, is composed of a combination of mirrors having mirror reflective surfaces.

5B and 5C have a role of turning and light guide as shown in FIG. 3B, which is a mechanical contact means, which gives an optical contact by an element or a coating having a total reflection mirror property to a part of the outer surface of the glass block. This mechanical contact will be used.

That is, in FIG. 5B, the light guide portion, which causes the reflection of the multi-sided light beams, is filled with an optical medium instead of air, and reflection on most surfaces is performed by total internal reflection, and some surfaces are optically contacted by the total reflection mirror. Is fulfilling.

In addition, in the case of FIG. 5C, the light guide part, which plays a role of causing the multi-sided reflection of the light beam, is filled with an optical medium instead of air, and the reflection on most of the surfaces is performed by total internal reflection, and a part of the surface is a total reflection mirror coating. have.

On the other hand, the total internal reflection optically has a reflectance of 1 for light having an angle of incidence greater than or equal to the critical angle, and the total reflection mirror is about 0.9 to 0.95 for aluminum mirror and 0.99 for Siflrex ^™ (Unaxis), and thus the total reflection mirror part in the configuration of the present invention. The amount of reflected light is slightly lower than that of total internal reflection. However, the loss is negligible when the mirror surface is smaller than the total reflection surface. The mechanical fixing means of the rod lens may be, for example, bonding by the adhesive between the mirror outer surface and the mechanism, or close contact by the spring structure.

On the other hand, the present invention can be mainly applied to the method of separately illuminating the red, green, blue in sequence with a color difference from the outside.

As described above, according to the optical system illuminating device of the projection display device according to the present invention, the optical means as an optical means for changing the direction of the rod lens for homogeneously outputting light so that the color drum can be used as the color separation element. It uses total reflection means and uses a light guide type device that causes a plurality of reflections without loss of light to the outside as a means of making the output light homogeneous without loss of angle, and these two functions are mechanical By integrating into the unit, there is an effect of reducing the size / thinness of the set and improving image quality (eg, improving brightness, improving color).

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (6)

A projection display device comprising a color drum for sequentially separating colors from light focused at a light source, and an optical element for uniformly advancing color separated light. The optical element changes the traveling direction of the plurality of light incident by the total internal reflection in the optical material of the optical means for switching direction, the plurality of changed light is emitted by a plurality of reflections in the light guide portion, And the optical means for changing the direction and the light guide part are mechanically integrated to constitute the optical system illuminator of the projection display device. The method of claim 1, The optical guide device of the projection display device, characterized in that the light guide portion for causing the reflection of the multi-sided light has at least one portion of the mirror reflection. The method of claim 2, All or part of the portion having the mirror reflection is in contact with the mechanical fixing means. The method of claim 1, The light guide portion causing the multiple surface reflection of the light Optical system illumination device of a projection display device, characterized in that the interior is composed of a combination of mirrors having a mirror reflection surface. The method of claim 1, The light guide portion causing the multiple surface reflection of the light An optical illumination device of a projection display device, characterized in that it is filled with an optical medium rather than air, and reflection on most surfaces is carried out by total internal reflection and some surfaces are in optical contact with a total reflection mirror. The method of claim 1, The light guide portion causing the multiple surface reflection of the light An optical illuminator of a projection display device, characterized in that it is filled with an optical medium rather than air, and reflection on most surfaces is carried out by total internal reflection, and some of the surfaces are totally mirror-reflective.