KR102200450B1 - Image projection apparatus - Google Patents

Abstract

An image projection apparatus according to an embodiment includes a panel unit, a projection optical system that receives and refracts light rays from the panel unit, a reflection unit that receives and reflects the refracted light rays from the projection optical system, and the reflection unit And a screen unit configured to receive the reflected light beam from and to display an image according to the reflected light beam. A distance measured along a predetermined linear axis from the panel unit, the projection optical system, the reflective unit, and the screen unit to the reflection unit from the panel unit through the projection optical system is measured along the linear axis from the reflection unit to the screen unit. It is arranged to be longer than the measured distance.

Description

Image projection device {IMAGE PROJECTION APPARATUS}

The present invention relates to an image projection apparatus.

A beam projector, one of the image projection devices, is a device that enlarges and projects an image on a screen that is a certain distance away from itself. The beam projector is a light source that generates light rays that make up an image, a panel that generates an image by receiving a light source, and is located between the light source and the panel, and the light emitted from the light source is concentrated on the panel to create an image on the panel. It may include an illumination optical system to be configured, a projection optical system positioned between the panel and the screen to enlarge an image of the panel and project it onto the screen.

Such a beam projector is widely used for various purposes such as lectures, presentations, and watching videos in various places such as schools, companies, and homes. In addition, as the use of beam projectors is becoming more common, demand for ultra-small beam projectors that are small enough to be portable is also increasing in recent years.

1 and 2 are views showing a telecentric optical system. The telecentric optical system is characterized in that it is designed so that the chief ray angle (CRA) at each position on the panel and the normal line of the panel converges to zero. 1 and 2, the panel 30 exists between the illumination optical system 10 and the projection optical system 20 including a plurality of lenses 11 and 21, respectively. Among the plurality of light beams incident on the panel 30, those corresponding to the main light ray 40 are incident and radiated substantially perpendicular to the surface of the panel 30 as shown in the drawing.

Korean Patent Application Publication No. 10-2013-0019191 (published on February 26, 2013)

In recent years, interest in projectors that can project even at a very short distance, that is, a projection distance that is shorter than that of a general projector, is increasing. In the case of such a projector, astigmatism correction or chromatic aberration correction greatly affects performance.

Accordingly, the object to be solved of the present invention is to provide an image projection apparatus capable of having the effect of correcting astigmatism or chromatic aberration above a certain level even when the projection distance is short, and also securing an imaging magnification of more than a certain level. will be.

However, the problem to be solved of the present invention is not limited to the ones mentioned above, and another problem to be solved that is not mentioned can be clearly understood by those of ordinary skill in the art from the following description. will be.

An image projection apparatus according to an embodiment includes a panel unit, a projection optical system that receives and refracts light rays from the panel unit, a reflection unit that receives and reflects the refracted light rays from the projection optical system, and the reflection unit And a screen unit configured to receive the reflected light beam from and to display an image according to the reflected light beam. A distance measured along a predetermined linear axis from the panel unit, the projection optical system, the reflective unit, and the screen unit to the reflection unit from the panel unit through the projection optical system is measured along the linear axis from the reflection unit to the screen unit. It is arranged to be longer than the measured distance.

According to an embodiment, it is possible to provide an image projection apparatus capable of effectively correcting astigmatism or chromatic aberration even at a very short distance, and thus capable of projecting even at a very short distance.

1 and 2 are views showing a telecentric optical system.
3 is a diagram conceptually illustrating a configuration of an image projection apparatus according to an exemplary embodiment.
4 is a diagram illustrating the configuration of the projection optical system shown in FIG. 3 together with a panel portion and a reflective portion.
5 is a diagram illustrating a surface shape of a reflective portion illustrated in FIG. 3 by way of example.
6 is a diagram illustrating a configuration of an image projection apparatus according to an exemplary embodiment.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments make the disclosure of the present invention complete, and are common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims.

In describing the embodiments of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout this specification.

3 is a diagram conceptually illustrating a configuration of an image projection apparatus 1000 according to an exemplary embodiment. However, since what is shown in FIG. 3 is only exemplary, the idea of the present invention is not limitedly interpreted through FIG. 3, and thus the image projection apparatus 1000 further includes other components other than those shown, Some of the illustrated components may not be included.

Referring to FIG. 3, the image projection apparatus 1000 includes a panel unit 110, a projection optical system 120, a reflective unit 130, and a screen unit 140. In addition, although not shown in FIG. 3, the image projection apparatus 1000 is a light source unit such as an LED that generates light by receiving power from a power supply unit and a power unit, and irradiates the panel unit 110 to form an image by receiving light rays from the light source unit. It may further include an illumination optical system composed of a plurality of lenses.

Here, since the panel unit 110 and the screen unit 140 themselves are known configurations, a description of each of them will be omitted. However, the projection optical system 120 will be described in detail in FIG. 4 and the reflective unit 130 in FIG. 5.

Hereinafter, a process of forming an image in the above-described image projection apparatus 1000 will be described. The light source unit supplied with power from the power supply unit generates light rays, and the generated light rays are transmitted to the panel unit 110 through an illumination optical system to form an image. The light rays forming the image in the panel unit 110 are transmitted to the reflecting unit 130 through the projection optical system 120 and reflected, and the light rays reflected from the reflecting unit 130 are transmitted to the screen unit 140. Then, an image is formed on the screen unit 140.

In this case, since the image projection apparatus 1000 is a projector, the size of the image formed on the screen unit 140 is larger than the image formed on the panel unit 110. Accordingly, as shown in FIG. 3, the panel unit 110 may be referred to as a “reduced side” and the screen unit 140 may be referred to as a “enlarged side”.

Hereinafter, a position at which each component of the image projection apparatus 1000 is disposed will be described with reference to the panel unit 110.

First, the power supply unit, the light source unit, and the illumination optical system described above may be disposed near the panel unit 110 of FIG. 3 although not shown in the drawings, but are not limited thereto.

The projection optical system 120 is disposed along a predetermined linear axis (y-axis in FIG. 3) (in a direction parallel to the linear axis), and at a position separated by a first distance (shown in FIG. 3) from the panel unit 110 do.

The reflective unit 130 is disposed at a position spaced apart from the panel unit 110 by a second distance (shown in FIG. 3) along the y-axis described above. At this time, the second distance is longer than the first distance.

The screen unit 140 is disposed at a position spaced apart from the panel unit 110 by a third distance (shown in FIG. 3) along the above-described y-axis. At this time, the third distance is shorter than the second distance. Accordingly, the fourth distance (shown in FIG. 3), which is a distance from the reflective unit 130 to the screen unit 140 along the y-axis, is shorter than the aforementioned second distance.

Here, the second distance is referred to as a'total length distance', and the fourth distance is referred to as a'projection distance' in that it is a distance through which light rays reflected from the reflector 130 are projected to the screen unit 140. Looking at this as a basis, in the image projection apparatus 1000 according to an embodiment, the ratio of the projection distance to the total length is less than 1. This is, even though the ratio of the projection distance to the total length is less than 1, that is, even when projecting at an ultra-short distance, various configurations of the image projection apparatus 1000, for example, the projection optical system 120 to the reflection unit 130 This means that an image can be properly formed. That is, the image projection apparatus 1000 according to an embodiment is a device capable of projecting even at a very short distance.

In addition, referring to FIG. 3, the length of the optical path from the reflecting unit 130 to the upper end of the screen unit 140 is defined as a first length (shown in FIG. 3 ), and the screen unit 140 from the reflecting unit 130 Let the length of the optical path to the lower end of) be defined as the second length (shown in FIG. 3). In the case of a general projector, the distance from the reflector to the screen is relatively much longer than the distance from the panel to the reflector. That is, the ratio of the projection distance to the total length is greater than 1. Therefore, the ratio of the second length (refer to the one shown in Fig. 3) in the general projector to the first length (refer to the one shown in Fig. 3) in such a general projector is less than 1, but will have a value close to 1. I can.

However, in the case of the image projection apparatus 1000 according to an exemplary embodiment, the ratio of the projection distance to the total length is less than 1. Therefore, the ratio of the second length to the first length has a smaller value than that of a general projector.

Meanwhile, the imaging magnification is also referred to as reduction ratio (RED), and is calculated as a ratio of the height of the image (image) formed on the enlarged side to the height of the image (image) formed on the reduction side. 3, the ratio of the first height (shown in FIG. 3) to the second height (shown in FIG. 3) is an imaging magnification. While a typical projector has an imaging magnification of 0.02 or less, an imaging magnification of the image projection apparatus 1000 according to an exemplary embodiment is greater than 0.04. This means that although the imaging magnification has a larger value than that of a general projector, the image projection apparatus 1000 according to an exemplary embodiment can properly form an image.

Meanwhile, as described above, the image projection apparatus 1000 according to an exemplary embodiment is a device capable of properly forming an image despite projecting from a very short distance. This means that in the image projection apparatus 1000 according to an exemplary embodiment, astigmatism or chromatic aberration is effectively corrected despite projecting at a very short distance. This means that the projection optical system 120 and the reflector 130 shown in FIG. ) Through. Hereinafter, the projection optical system 120 will be described in more detail.

4 is a diagram illustrating the configuration of the projection optical system 120 shown in FIG. 3 together with the panel unit 110 and the reflecting unit 130. However, since FIG. 4 is merely an example, the configuration of the projection optical system 120 is not limited to that illustrated in FIG. 4.

Referring to FIG. 4, the projection optical system 120 includes at least one aspherical lens 122 or at least one meniscus lens 121. Compared to the aspherical lens 122, the meniscus lens 121 may be disposed at a farther side (a distance measured along a direction parallel to the y-axis in FIG. 4) from the panel unit 110. It is not limited thereto.

The aspherical lens 122 and the meniscus lens 121 may improve an imaging magnification according to a projection distance, and may play an effective role in correcting astigmatism. In particular, when at least three meniscus lenses 121 are included, they may be continuously adjacently disposed along a predetermined linear axis (y-axis in FIG. 4). In this case, the effect of improving the imaging magnification according to the projection distance is maximized. Can be.

Meanwhile, when a plurality of aspherical lenses 122 are included in the projection optical system 120, the focal length and absolute values of these aspherical lenses 122 may have the following relationship. Of course, depending on the embodiment, the meniscus lens 121 may also have the following relationship, but hereinafter, it is assumed that the aspherical lens 122 has the following relationship.

-On the premise that two adjacent lenses among a plurality of lenses are viewed as a pair,

-The signs of the focal lengths of the lenses constituting the same pair are opposite to each other

-The difference between the absolute value of the focal length between the lenses constituting the same pair is within 10% based on the absolute value of the focal length of any one of the paired lenses.

For example, as illustrated in FIG. 4, lenses constituting the projection optical system 120 may be paired as follows, and in this case, the focal length and sign of each pair may be as follows.

(G3,G4) = (-10.3, 10.7)

(G5,G6) = (4.4,-5.7)

(G7,G8) = (7.0,-7.1)

(G9,G8) = (3.2,-3.5)

When the lenses constituting the projection optical system 120 are configured to have a focal length and a sign according to the above-described relationship, an effect of improving an imaging magnification according to the projection distance can be maximized, and chromatic aberration can also be effectively corrected.

Next, the reflection part 130 will be described.

5 is a diagram illustrating a surface shape of the reflective unit 130 shown in FIG. 3 by way of example. However, since FIG. 5 is only an example, the shape of the surface of the reflective unit 130 is not limited to that illustrated in FIG. 5.

Referring to FIG. 5, the reflector 130 has a curved surface (sag) having a predetermined curvature. When the distances to each point of the reflector 130 are measured based on the second axis shown in FIG. 5, the measured distances form a line symmetry with respect to the first axis shown in FIG. 5. In addition, each measured distance may be displayed or calculated by Equation 1 below.

In addition, each parameter in Equation 1 above may be defined as follows.

-z: Sag value parallel to the first axis

-c: curvature

-k: conic constant

-r: radial distance (sqrt(x^2+y^2))

-ARn: coefficient of r^n (1<= n <= 30)

The reflector 130 having such a curved surface is referred to as'rotational symmetry'. When the reflective unit 130 is rotationally symmetric, an effect of improving the imaging magnification according to the projection distance may be maximized.

6 is a diagram illustrating a configuration of an image projection apparatus 1000 according to an exemplary embodiment. However, since FIG. 6 is only an example, the configuration of the image projection apparatus 1000 is not limited to that illustrated in FIG. 6.

Referring to FIG. 6, the image projection apparatus 1000 includes a panel unit 110, a reflective unit 130, and a screen unit 140. In addition, although not shown in FIG. 6, the image projection apparatus 1000 may include components generally provided in a projector, for example, a power supply unit, a light source unit, a projection optical system (same as illustrated in FIG. 3 ), and an illumination optical system. . In addition, the image projection apparatus 1000 may include a case 200 in which the above-described components are mounted. In this case, some of the cases 300 may be formed of a transparent material to form an empty space 310, and the screen unit 140 may be disposed in the empty space 310. Accordingly, the user can recognize the screen unit 140 and an image formed on the screen unit 140 through the case 300 made of such a transparent material.

Looking at the process of forming the image, the light rays forming the image in the panel unit 110 are not shown in FIG. 6, but are transmitted to the reflecting unit 130 through the projection optical system, and reflected by the reflecting unit 130. The light rays form an image in the screen unit 140.

In this case, in the case of the image projection apparatus 1000, as described above, the ratio of the projection distance to the total length is less than 1. This means that even though the ratio of the projection distance to the full length distance is less than 1, that is, even when projecting at an ultra-short distance, an image can be properly formed on the image projection apparatus 1000. That is, one embodiment The image projection device 1000 according to is a device capable of projecting even at an ultra-short distance.

In addition, although the image projection apparatus 1000 projects at a very short distance, the astigmatism or chromatic aberration may be effectively corrected in the image projection apparatus 1000.

In addition, although the image projection magnification of the image projection apparatus 1000 has a larger value than that of a general projector, the image projection apparatus 1000 may properly form an image.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential quality of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

According to an embodiment, it is possible to provide an image projection apparatus capable of projecting even in a very short distance.

1000: image projection device

Claims (6)

A panel part,
A projection optical system disposed at a position spaced apart from the panel part by a first distance along a first linear axis and refracting by receiving light rays from the panel part,
A reflector receiving and reflecting the refracted light rays from the projection optical system,
And a screen unit that receives the reflected light from the reflection unit and displays an image according to the reflected light,
The panel part, the projection optical system, the reflective part, and the screen part,
A second distance measured along the first linear axis from the panel unit to the reflection unit through the projection optical system is longer than a third distance measured along the first linear axis from the panel unit to the screen unit, and the reflective unit It is arranged to be longer than the fourth distance measured along the first linear axis from the to the screen part,
The projection optical system includes at least a pair of lenses,
Between the lenses constituting the pair,
The sign of the focal length is opposite, and the ratio of the difference between the absolute value of the focal length relative to the absolute value of the focal length of one of the lenses constituting the pair is within 10%.
Image projection device. The method of claim 1,
The projection optical system,
Comprising at least one aspherical lens and at least two meniscus lenses
Image projection device. The method of claim 2,
The at least two meniscus lenses,
A distance measured from the panel part along the linear axis is disposed farther than the at least one aspherical lens
Image projection device. The method of claim 1,
The projection optical system,
Including at least three meniscus lenses continuously adjacently disposed along the linear axis
Image projection device. delete The method of claim 1,
The curved surface of the reflective part,
Rotationally symmetric
Image projection device.

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