KR20020090388A - Color Scrolling Apparatus of Rear Projector - Google Patents

Color Scrolling Apparatus of Rear Projector Download PDF

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Publication number
KR20020090388A
KR20020090388A KR1020010028517A KR20010028517A KR20020090388A KR 20020090388 A KR20020090388 A KR 20020090388A KR 1020010028517 A KR1020010028517 A KR 1020010028517A KR 20010028517 A KR20010028517 A KR 20010028517A KR 20020090388 A KR20020090388 A KR 20020090388A
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KR
South Korea
Prior art keywords
light
lens
rotating
red
green
Prior art date
Application number
KR1020010028517A
Other languages
Korean (ko)
Other versions
KR100482318B1 (en
Inventor
강호중
최호영
김남식
Original Assignee
엘지전자 주식회사
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Application filed by 엘지전자 주식회사 filed Critical 엘지전자 주식회사
Priority to KR10-2001-0028517A priority Critical patent/KR100482318B1/en
Publication of KR20020090388A publication Critical patent/KR20020090388A/en
Application granted granted Critical
Publication of KR100482318B1 publication Critical patent/KR100482318B1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00Details of colour television systems
    • H04N9/12Picture reproducers
    • H04N9/31Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3102Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators
    • H04N9/3111Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying the colours sequentially, e.g. by using sequentially activated light sources
    • H04N9/3117Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] using two-dimensional electronic spatial light modulators for displaying the colours sequentially, e.g. by using sequentially activated light sources by using a sequential colour filter producing two or more colours simultaneously, e.g. by creating scrolling colour bands
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00Details of colour television systems
    • H04N9/12Picture reproducers
    • H04N9/31Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141Constructional details thereof

Abstract

PURPOSE: A color scrolling device of a backside projection system is provided to reduce costs and simplify the system by employing a rotary lens having diffractive optical elements formed by unit cells. CONSTITUTION: A color scrolling device of a backside projection system including a display device(56) has a rotary lens(48) and a field lens(50). The rotary lens includes a plurality of diffractive faces formed in micro-cell unit, rotates on paths of red, green and blue lights, and scrolls the red, green and blue lights. The field lens delays the image-formation points of the three-color lights scrolled by the rotary lens to the display device. The rotary lens rotates in a belt form. The rotary lens further includes at least one optical path converter.

Description

Color Scrolling Apparatus of Rear Projector}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection apparatus for expanding and projecting a small image implemented on a single liquid crystal display on a screen, and more particularly, to a color scrolling apparatus for a rear projection apparatus that simplifies a system while reducing costs.

The projector displays an image of the large screen by enlarging and projecting a digestive image implemented in an internal small display onto a large screen using a projection lens. This projector is divided into a front projection method in which an image is projected on the front of the screen and a rear projection method in which an image is projected on the rear of the screen. Among these, a projection television is mentioned as a typical example of the latter. In addition, a cathode ray tube (CRT) and a liquid crystal display (hereinafter referred to as "LCD") are used as a display for providing a small image from a projector. Recently, there is a growing interest in projectors using LCDs, which are advantageous for thinning projectors.

Typically, the display device includes an LCD for providing a fire extinguishing image, a projection lens system for expanding and projecting a fire extinguishing image displayed on the LCD, a light source for providing light to the LCD, and an illumination system for adjusting an optical path between the light source and the LCD. And a driving circuit section for signal processing.

Such display devices have a tendency to realize high brightness through efficient optical system configuration and lamp change, and to emphasize the simplicity of carrying and installation through miniaturization and light weight even though the brightness is somewhat lower. The display device uses three or one LCD for color implementation. Three LCDs are employed for the purpose of high brightness, but one LCD is generally employed for the purpose of miniaturization and light weight.

In order to implement a color, a single-plate projector employing a single display element uses a method of using a color filter, a method of separating three primary colors and entering them at a specific angle, and a method of sequentially sending three primary colors to the display element. Among them, a method of using a rotating prism as shown in FIG. 1 is typical of an image projecting device that sequentially sends three primary colors to a display device.

Referring to FIG. 1, an optical system of a single-plate projector including a conventional color scrolling device is schematically illustrated.

1 shows a light source 2 for generating light and first and second fly eye lenses disposed on an optical path between the light source 2 and the condenser lens 8. FEL ") (4, 6), Polarizing Beam Splitter Array (hereinafter referred to as" PBS array ") (7), and the first to fourth dikes for transmitting and reflecting light of a specific wavelength band The lower wing mirrors 10, 12, 24, and 26, the first to third rotating prisms 16, 18, and 20 that change the optical path according to the rotation angle, and the second dichroic mirror 10 and the first The first total reflection mirror 14 located between the three scrolling devices, the second total reflection mirror 22 located between the first scrolling device 16 and the third dichroic mirror 24, and the LCD 30. And a polarizing beam splitter (hereinafter referred to as "PBS") 28 positioned between the projection lens 31 and the projection lens 31.

The first and second FELs 4 and 6 divide the white light emitted from the light source 2 in units of cells to be focused on a specific portion of the PBS array 7. The PBS array 7 separates incident light into linearly polarized light having any one optical axis, that is, P wave and S wave so that the S wave is emitted as it is, and the P wave is half-wave plate partially attached to the rear surface of the PBS array 7 ( (Not shown) is converted into an S wave to be emitted. The condenser lens 8 prevents light from being emitted from the PBS array 7 and incident on the first dichroic mirror 10.

The first dichroic mirror 10 reflects and transmits incident light according to the wavelength band to separate the incident light. For example, the first dichroic mirror 10 reflects blue and red light of incident light and transmits green light. The green light separated by the first dichroic mirror 10 proceeds to the first rotating prism 16.

The second dichroic mirror 12 transmits blue light and reflects red light among blue and red light that are reflected by the first dichroic mirror 10 and are incident. The red light separated by the second dichroic mirror 12 proceeds to the second rotating prism 18.

The first total reflection mirror 14 passes through the second dichroic mirror 12 to reflect the incident blue light to the third rotating prism 20.

Each of the first to third rotating prisms 16, 18, and 20 is positioned on an optical path of green, red, and blue light. Each of the rotating prisms 16, 18, and 20 causes green, red, and blue light to form at different positions of the display element 30, and the rotation positions of the red, green, and blue light are scrolled by rotation. This is made possible by changing the angles of refraction of each light by varying the angles of rotation of each of the rotating prisms 16, 18, 20.

To this end, each of the rotating prisms 16, 18, and 20 are rotated sequentially at time intervals. As a result, red, green, and blue light are scrolled sequentially on the display element 30.

The green light transmitted through the first rotating prism 16 is totally reflected by the second total reflection mirror 22, and passes through the third and fourth dichroic mirrors 24 and 26 and enters the PBS 28. The red light transmitted through the second rotating prism 18 is reflected by the third dichroic mirror 24 and transmitted through the fourth dichroic mirror 26 to enter the PBS 28. The blue light transmitted through the third rotating prism 20 is reflected by the fourth dichroic mirror 26 and is incident on the PBS 28.

The PBS 28 reflects the blue, red, and green light of the incident S-wave component to the display element 30.

The display device 30 displays an image according to an image signal input to the tricolor light scrolled by the first to third rotating prisms 16, 18, and 20. The display device 30 is a reflective LCD that converts the light reflected from the PBS 28 into incident P-polarized light according to an image signal. The PBS 28 transmits the light emitted from the display element 30 as P-polarized light and enters the projection lens 31. The projection lens 31 enlarges and projects the light emitted from the PBS 28 onto the screen to implement an image.

As described above, the first to third rotating prisms 16, 18, and 20 of the rear projection apparatus are disposed in the paths of red, green, and blue light, and thus are positioned at different positions on the display element 30 as shown in FIG. Red, green, and blue light are formed. After a predetermined time Δt passes, the first to third rotating prisms 16, 18, and 20 rotate to sequentially scroll the red, green, and blue light formed in the display device 30 according to the rotation angle. .

In order to scroll red, green, and blue light sequentially on one display element, three rotating prisms and three motors for driving the same are required. In the case of using the rotating prism, the cost of the rotating prism is high and a large number of optical components are required to use the rotating prism. In addition, the control of the rotating prism is required to control each of the red, green, and blue light according to the driving signal of the display device, which causes a problem in that the system becomes complicated.

Accordingly, it is an object of the present invention to provide a color scrolling device of a rear projection apparatus which can simplify the system while reducing the cost.

1 is a view showing a rear projection device including a conventional color scrolling device.

2 is a view showing an optical path of the rotating prism shown in FIG.

3 illustrates a rear projection apparatus including a color scrolling apparatus according to an embodiment of the present invention.

4 is a cross-sectional view showing in detail the unit diffraction surface of the rotating lens shown in FIG.

FIG. 5 is a view showing a rotation lens positioned on the light path shown in FIG. 3; FIG.

6 to 8 are views illustrating a process in which tricolor light is scrolled while the rotary lens shown in FIG. 5 rotates.

<Description of Symbols for Main Parts of Drawings>

2, 32: light source 4, 6, 34, 36: FEL

7, 37: PBS array 8, 38, 52: condenser lens

10, 12, 24, 26, 40, 42: dichroic mirror

14, 22, 44, 46, 60: total reflection mirror 48: rotating lens

28, 58: PBS 50: field lens

30, 56: display element

In order to achieve the above object, the color scrolling device of the rear projection apparatus of the present invention is a rear projection apparatus including a display element, comprising a plurality of diffractive surfaces formed in units of micro cells, red, green, blue light incident separately And a rotating lens for rotating red, green, and blue light on a light path, and a field lens for delaying an imaging point of three-color light scrolled by the rotating lens to the display element.

The rotating lens may be rotated in a belt shape in which a light incident surface and a light exit surface are positioned on the optical path of the tricolor light.

Other objects and features of the present invention in addition to the above object will be 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 6.

3 schematically illustrates an optical system of a rear projection apparatus including a color scrolling apparatus according to an embodiment of the present invention.

Referring to FIG. 3, an optical system of a rear projection apparatus according to an embodiment of the present invention may include a light source 32 that generates light, and an optical system disposed on an optical path between the light source 32 and the first condenser lens 38. The first and second FELs 34 and 36 and the PBS array 37, the first and second dichroic mirrors 40 and 42 for transmitting and reflecting light of a specific wavelength band, and for changing the path of the light. First to third total reflection mirrors 44, 46, and 60, a rotation lens 48 including a plurality of DOE surfaces, a field lens 50 for delaying focus of light, and a second condensing lens for focusing incident light 52, a PBS 54, a display element 56, and a projection lens 58 are provided.

The first and second FELs 34 and 36 divide the white light emitted from the light source 32 into units of cells to be focused on a specific portion of the PBS array 37. The PBS array 37 separates the incident light into linearly polarized light having one optical axis, that is, P wave and S wave, so that the S wave is emitted as it is, and the P wave is half-wave plate partially attached to the rear surface of the PBS array 37 ( (Not shown) is converted into an S wave to be emitted. The first condenser lens 38 prevents light from being emitted from the PBS array 37 and incident on the first and second dichroic mirrors 40 and 42.

The first and second dichroic mirrors 40 and 42 are arranged to intersect with each other, and reflect and transmit incident light according to a wavelength band to separate the incident light. For example, the first dichroic mirror 40 reflects red light of incident light and transmits blue light and green light. In addition, the second dichroic mirror 42 reflects blue light of incident light and transmits red light and green light. Thus, the first and second dichroic mirrors 40 and 42 separate incident light into tricolor light.

The first total reflection mirror 44 totally reflects the separated red light from the first dichroic mirror 40 toward the rotating lens 48 having a plurality of DOE surfaces. The DOE is a flat-panel lens with power. In addition to the DOE, the lens surface may be in the form of a fresnel lens. The second total reflection mirror 46 totally reflects the blue light from the second dichroic mirror 40 toward the rotating lens 48 having a plurality of DOE surfaces.

As shown in FIG. 4, the rotation lens 48 includes a diffractive optical element (hereinafter referred to as “DOE”) cell 48A formed in each unit cell to have diffraction characteristics of light on the aspherical lens surface. The DOE cell 48A changes the refractive angles of the tricolor light incident to one unit cell to form an image at different positions on the display element unit pixel 56A, and also rotates the DOE cell so that the image formation position of the tricolor light is scrolled. The DOE cell 48A is formed to correspond to the size of the display element unit pixel 56A. The rotating lens 48 is rotatable by manufacturing a plurality of unit cells in which the DOE cell 48A is formed in a belt form. Since the rotating lens 48 is in the form of a belt, tricolor light may be distorted through the light incident surface and the exit surface of the DOE cell 48A. In order to prevent this, at least two total reflection mirrors are disposed in the rotation lens 48. For example, by arranging the fourth and fifth total reflection mirrors 62 and 64 in the rotation lens 48, the red, green, and blue light that has passed through the DOE cell 48A at the entrance face is DOE cell 48A at the exit face. Do not penetrate.

The field lens 50 delays the position of the focal point F of the red, green, and blue light from the rotating lens 48 having a plurality of DOE surfaces, thereby causing the image to be reimaged on the display element 56. The third total reflection mirror 60 totally reflects the tricolor light incident from the field lens 50 to the second condensing lens 52. The second condenser lens 52 is provided to prevent the light distribution from widening as the light path becomes longer.

The PBS 54 reflects the blue, red, and green light of the incident S-wave component to the display element 56.

The display element 56 displays an image in accordance with an image signal input to the tricolor light scrolled by the rotary lens 48. The light reflected by the PBS 54 is incident and converted into P-polarized light according to the video signal to be emitted. The PBS 54 transmits the light emitted from the display element 56 as P-polarized light and enters the projection lens 58. The projection lens 58 enlarges and projects the light emitted from the PBS 54 onto the screen to implement an image.

5 to 8 are views showing the operation principle of the rotating lens.

Referring to FIG. 5, all of red, green, and blue light are incident on the DOE cell 48A of the rotating lens 48 on which the plurality of DOE cells 48A are formed. The DOE cell 48A is formed to be imaged at different positions on the display element unit pixel 56A by varying the angles of refraction of the incident red, green, and blue light.

Subsequently, referring to FIG. 6, when the rotation lens 48 is rotated in the y-axis direction (clockwise), a part of the blue light of the three-color light incident on the DOE cell 48A of the rotation lens enters the next unit cell. Will be. Accordingly, the red, green, and blue light incident on the DOE cell 48A are formed at the first focal point F, and the partial light of the blue light incident on the next unit cell is formed at the second focal point F '. Will be separated. As a result, the imaging area of the blue light located above the display element unit pixel 56A is reduced by the amount of blue light separated from the DOE cell 48A, and separated from the first focal point F to separate the second focal point F '. The blue light condensed at is formed in the lower portion of the display element 56. As the rotation lens 48 is further rotated in the y-axis direction, red, green, and blue lights formed on the LCD unit pixels 56A are sequentially scrolled as shown in FIGS. 7 and 8.

As a result, the rotating lens 48 is allowed to scroll on the display element 56 by varying the refraction angles of the red, green, and blue light. The same applies to the case where other display elements are used in addition to the LCD.

As described above, the color scrolling device of the rear projection apparatus according to the present invention can reduce the cost by using a rotating lens having a diffractive optical element formed in unit cell units compared to conventional three rotating prism. It can simplify the system.

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 (5)

  1. In the rear projection device comprising a display element,
    A rotating lens for rotating red, green, and blue light, having a plurality of diffraction planes formed in units of micro cells, rotating on an optical path of red, green, and blue light incident thereto;
    And a field lens for delaying the imaging point of the tricolor light scrolled by the rotating lens to the display element.
  2. The method of claim 1,
    And the rotating lens is rotated in the form of a belt in which a light incident surface and a light exit surface are positioned on the optical path of the tricolor light.
  3. The method of claim 2,
    The rotating lens further comprises at least one light path converting means in the rotating lens to prevent the light transmitted through the diffraction surface from the light incident surface from passing through the diffraction surface at the light exit surface. Color scrolling device.
  4. The method of claim 1,
    And the size of the unit diffraction surface of the rotating lens corresponds to the size of the unit cell of the display element.
  5. The method of claim 1,
    And a color separation means for allowing the color-separated trichromatic light to be incident on all of the unit diffraction surfaces of the rotating lens.
KR10-2001-0028517A 2001-05-23 2001-05-23 Color Scrolling Apparatus of Rear Projector KR100482318B1 (en)

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KR10-2001-0028517A KR100482318B1 (en) 2001-05-23 2001-05-23 Color Scrolling Apparatus of Rear Projector

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Application Number Priority Date Filing Date Title
KR10-2001-0028517A KR100482318B1 (en) 2001-05-23 2001-05-23 Color Scrolling Apparatus of Rear Projector

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KR20020090388A true KR20020090388A (en) 2002-12-05
KR100482318B1 KR100482318B1 (en) 2005-04-13

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100965877B1 (en) * 2003-06-13 2010-06-24 삼성전자주식회사 High efficiency projection system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100965877B1 (en) * 2003-06-13 2010-06-24 삼성전자주식회사 High efficiency projection system

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