KR20080025898A - Projector with one liquid crystal panel - Google Patents

Abstract

A projector with one liquid crystal panel is provided to reduce the size of the projector by employing a sequential light source device and a sequential liquid crystal display device. A projector with one liquid crystal panel includes a sequential light source device(50), a visual ray filter(24), an integrator lens(26), a condensing lens(28), polarizing plates(32,34), a field sequential liquid crystal display device(30), and a projection lens(12). The sequential light source device is composed of a white light source(2), a reflector(22), and a color selecting device(23). The reflector uniformly reflects light emitted from the white light source. The color selecting device sequentially filters the light emitted from the white light source into R, G, and B lights. The visual ray filter passes only the light of visual ray region among the light emitted from the color selecting device. The integrator lens uniformly emits the incident light. The condensing lens condenses the light emitted from the integrator lens to make the light enter the liquid crystal display device. The polarizing plates determine polarizing the axes of the light entering and leaving the liquid crystal display device. The projection lens projects the light emitted from the liquid crystal display device to a screen.

Description

Single plate type liquid crystal projection device {PROJECTOR WITH ONE LIQUID CRYSTAL PANEL}

1 is a configuration diagram of a conventional liquid crystal projection apparatus for sequentially sending three primary colors to a liquid crystal display device.

Fig. 2 shows a relationship between the effective screen size of the liquid crystal display element, the size of the entrance and exit surfaces of the optics, and the effective outer diameter size of the intake side of the projection lens.

3 is an operation timing diagram of a liquid crystal display cell of an embodiment for implementing a liquid crystal projection device of the present invention.

4 is a circuit diagram of a liquid crystal display cell of one embodiment for implementing a liquid crystal projection device of the present invention.

5 is a block diagram of a liquid crystal projection device of one embodiment according to the present invention;

6 is a plan view of one embodiment of a color filter used in the present invention.

7 is a modification of the color filter used in the present invention.

***** Explanation of the main symbols on the drawing *****

2: light source 22: reflection shade

23: color sorting device 24: visible light filter

26: Integrator 28: Condensing Lens

32, 34: polarizer 30: field sequential liquid crystal display device

12: projection lens 50: sequential light source device

60: light traveling direction

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-plate type liquid crystal projection apparatus, and more specifically, using a color screening device that sequentially irradiates R light, G light, and B light sequentially in time, and uses a liquid crystal display device of a sequential driving method. A single plate liquid crystal projection apparatus.

In general, the liquid crystal projection apparatus is classified into a single plate type using one liquid crystal display and a three plate type using three liquid crystal display elements as an image element.

In order to achieve high brightness, a three-plate type using three liquid crystal display elements is mainly used. However, in the case of miniaturization and light weight, a single plate type using one liquid crystal display element is mainly used. The single-plate type liquid crystal projection apparatus employing a single liquid crystal display element is a method of using a liquid crystal display element equipped with a color filter for color realization, (2) a method of separating three primary colors and incident at a specific angle, (3 ) The three primary colors are sequentially sent to the liquid crystal display device.

A liquid crystal projection device using a liquid crystal display device having a color filter is a method of irradiating a white light source to the liquid crystal display device and forming an image using the liquid crystal display device having R, G, and B color filters. Since the luminance is lowered and the high lumen light source is used, the color filter provided in the liquid crystal display device is deteriorated, resulting in a short lifespan. The liquid crystal projection device that separates the three primary colors and enters them at a specific angle uses a dichroic mirror that separates the three primary colors, and uses a microlens layer to accurately enter the separated light source into the liquid crystal display device. There is a problem that the manufacturing cost rises.

A liquid crystal projection apparatus that sequentially sends three primary colors to a liquid crystal display device is typically a method using a color wheel as shown in FIG. 1. Referring to FIG. 1, a conventional color separation apparatus using a color wheel includes a light source 2 for generating light, a curling wheel 4 for transmitting only specific color light from white light, and a condenser lens 6 for condensing light. ), A polarized beam splitter (PBS) 8 for reflecting and transmitting incident light, a reflective panel 10, and a projection lens 12 for expanding and projecting image light from the reflective panel 10. The use of such a reflective panel uses a complicated optical system, so that the optical loss in the optical element surface is inevitable.

The products practically applied by applying the above three methods use a liquid crystal display device in which all the pixels for R, G, and B are provided in one liquid crystal display device. Therefore, under the assumption that the pixels have the same size as the external size of the liquid crystal display device, the resolution of the liquid crystal display device used in the single plate type by arithmetic calculation is only one third of the resolution of the liquid crystal display device used in the three plate type. do. In practice, the resolution will be 1/3 or less since there must be manufacturing margin between the pixels. The difference in resolution of the liquid crystal display has been a serious problem in reducing the size of the liquid crystal projection apparatus.

In addition, most liquid crystal projection apparatuses use one or more reflectors to refract or synthesize light emitted from a light source, and furthermore, use a PBS (Poralized Beam Splitter) or X-Cube between the liquid crystal display and the projection lens. Due to the use of such optics, the distance between the liquid crystal display element and the projection lens becomes far, which causes a problem in miniaturizing the liquid crystal projection device. In the conventional liquid crystal projection apparatus using the PBS of FIG. 1, the distance L between the projection lens 12 and the exit surface of the liquid crystal display device 10 is at least a diagonal length of the exit surface of the liquid crystal display device 10 due to the PBS. It is located farther away. The problem of the separation distance between the projection lens 12 from the exit surface of the liquid crystal display device 10 also occurs in optical devices such as X-cube, which is an obstacle in miniaturizing the liquid crystal projection device.

In addition to such a distance problem, there is a problem in that the size of the projection lens increases when using an optical device. The size of the projection lens is one of the biggest problems in miniaturizing the liquid crystal projection device.

In order for the image output from the liquid crystal display device to be incident on the optical device without loss, the size of the incident surface 9 of the optical device should be larger than that of the effective screen 11 of the liquid crystal display device. Also, for similar reasons, the inlet side effective outer diameter 13 of the projection lens should be larger than the size of the exit face 9 of the optics. FIG. 2 shows the relationship between the effective screen size 11 of the liquid crystal display element, the size of the entrance face 9 and the exit face 9 of the optics, and the size of the effective outer diameter 13 of the acquisition side of the projection lens. The effective screen of the liquid crystal display device is not the physical size of the liquid crystal display device but the screen on which the actual image is formed, and the effective outer diameter of the projection lens is the outer diameter area of the lens except the outer area 14 where aberration occurs. It is. Therefore, when the optical device is used between the liquid crystal display element and the projection lens, there is a problem that the outer diameter of the projection lens becomes large, which makes it difficult to miniaturize the liquid crystal projection device.

The present invention is to solve the above problems, while using the field-sequential liquid crystal display device to reach the projection lens in a straight line without reflecting the light emitted from the light source, a separate optical between the liquid crystal display device and the projection lens It is an object of the present invention to provide a liquid crystal projection apparatus which can be miniaturized without a device.

The above object of the present invention is a single-plate liquid crystal projection apparatus using a light source that is sequentially irradiated with light of a color including R light, G light, and B light by using a time difference, and is irradiated from a white light source and a white light source. A color screening device that sequentially emits white light as light having a color including R light, G light, and B light, and generates an image by using light incident from the color screening device, and emits light of the color to be irradiated. A field sequential liquid crystal display device for displaying an image corresponding to the light and simultaneously storing image data corresponding to light of a next sequential color, and a polarizer and a rear surface of the field sequential liquid crystal display devices installed at the front and rear of the field sequential liquid crystal display device. It can be achieved by a single-plate liquid crystal projection device characterized in that it comprises a projection lens provided on the rear of the polarizing plate provided in the.

The present invention will be more clearly understood from the following description, in comparison with the prior art, with reference to the accompanying drawings.

The liquid crystal projection apparatus according to the present invention uses the liquid crystal display element 30 driven in the field sequential frame method. The liquid crystal display device 30 driven in the field sequential frame method refers to a liquid crystal display device configured to sequentially display R, G, and B images using the same pixel electrode. In order to feel human being a natural moving image, an image of 60 frames or more per second (duration of one frame is 16 msec) must be displayed.In the case of a liquid crystal panel with a field-sequential frame driving method, R, G, and B subframes are used to form one frame. Should be displayed sequentially. However, if the 16msec is arithmetically divided into three, it becomes about 5msec. When the image data of one color is written after dividing the short duration, the display device cannot produce a commercially available display device. Therefore, the present invention uses a field sequential liquid crystal display in which image data of different colors is displayed while image data corresponding to one color is written. 3 is an operation timing diagram of a liquid crystal display cell of an embodiment for implementing a liquid crystal projection device of the present invention. The field sequential frame is composed of three subframes to form one image frame consisting of R, G, and B. The field sequential liquid crystal display will be described under the assumption that the light is sequentially irradiated in the order of R, G, and B light. The first subframe indicates a timing at which the R light is irradiated onto the liquid crystal display device 30 to output an image of the R light.

The timing of the first subframe for irradiating the R light will be described, and the remaining G light and B light are irradiated in a similar manner. During the 't1' addressing time, the liquid crystal cell stores image data of light G irradiated in the next subframe in the liquid crystal cell. The 't2' hold time is a time for maintaining the stored image data for the light G irradiated in the next subframe. The 't3' reset time is a time for resetting image data on the light source currently being irradiated from the liquid crystal cell. After that, the input data is input for the 't1' time during the 't4' write time, and then image data of the light G irradiated from the subframe is written in the liquid crystal cell. It can be seen from the timing diagram of FIG. 3 that the operation of storing the image data irradiated in the next subframe during the time t1 + t2 is irradiated partially overlaps.

4 is a circuit diagram of a liquid crystal display cell of an embodiment for implementing a liquid crystal projection device of the present invention. In FIG. 4, it can be seen that the liquid crystal cell is provided in an area where the gate line 101 and the data line 103 cross each other. During the 't1' time, the first switch SW1 is turned on to store image data for the light G irradiated from the data line 103 to the next subframe in the memory M-NXT. At this time, the second switch SW2 and the third switch SW3 maintain the OFF state. During the 't2' time, the first switch SW1, the second switch SW2, and the third switch SW3 maintain the OFF state. Image data for the light source R to be irradiated is stored in the sustain memory M-SUS and the liquid crystal memory M-CL during the 't1 + t2' time.

At the 't3' reset time, the third switch SW3 is turned on, and the image data of the light source R under irradiation that has been stored in the sustain memory M-SUS and the liquid crystal memory M-CL is reset. At this time, the remaining switches are turned off. During the 't4' write time, the second switch SW2 is turned on so that the image data for the light G irradiated to the next subframe stored in the memory M-NXT is stored in the sustain memory M-SUS and Stored in the liquid crystal memory (M-CL). 3 and 4 are various embodiments of the field sequential driving method, and thus the present invention is not limited to the embodiment shown in FIGS. 3 and 4.

5 is a configuration diagram of a liquid crystal projection apparatus of an embodiment according to the present invention. The liquid crystal projection device according to the present invention includes a sequential light source device 50, a reflector 22, a color screening device 23, a visible light filter 24, an integrator lens 26, a condensing lens 28, and a polarizing plate ( 32, 34, field sequential liquid crystal display elements 30, and projection lenses 12. As shown in FIG.

The sequential light source device 50 is composed of a white light source 2, a reflector 22, and a color screening device 23, and is a light source device that sequentially projects R, G, and B light. The reflector 22 is a device that uniformly reflects the light emitted from the white light source 2 to the front, and the color screening device 23 sequentially sequentially converts the light emitted from the white light source 2 into R, G, and B light. Device for filtering. UHF or a halogen lamp is usually used as the white light source.

Although the color screening device 23 is illustrated in FIG. 5 as being installed after the white light source 2, the color screening device 23 is not limited to the position shown in FIG. It can be installed at any position in the previous stage.

The visible light filter 24 is a filter for passing only the visible light region in the light emitted from the color screening device 23, and may be provided between the light source 2 and the color screening device 23 in the configuration of FIG. 5. .

An integrator lens 26 is a lens that uniformly emits incident light. Lenses that emit incident light uniformly include fly's eye light integrator lenses and rod types. The fly's eye lens type has a form in which a plurality of spherical or aspherical small lenses are formed on a substrate, and the rod type has a circular or columnar lens shape. The rod type can be subdivided into solid type and hollow reflection type (hollow rod). In FIG. 5, a fly's eye lens type is applied, and two fly's eye lenses are installed to face each other. It consists of a first integrator lens 26-1 and a second integrator lens 26-2, each integrator lens 26 having a plurality of spherical or aspherical small lenses formed on a substrate. Since the first and second integrator lens 26-1 and the second integrator lens 26-2 are each independently aligned, it is necessary to precisely align both. desirable. In order to avoid the alignment problem of the integrator lens 26, spherical or aspherical lenses for primary and secondary integrator lenses may be formed on both surfaces of one substrate. The adoption of these integrator lenses simplifies alignment and reduces the size of the overall optical engine.

In addition, a polarization conversion element may be added to the front or rear of the integrator lens as needed to increase the light efficiency. In the embodiment of FIG. 5, a polarization conversion element may be added between two fly's eye lenses.

The condensing lens 28 is a lens that functions to collect light emitted from the integrator lens 26 and to enter the liquid crystal display device 30.

The polarizing plates 32 and 34 have polarization axes perpendicular to each other, and determine polarization axes of light incident on the liquid crystal display device 30 and emitted light, and the projection lens 12 projects from the liquid crystal display device 30. It consists of a series of lens groups for projecting the light to the screen.

In the embodiment of FIG. 5, a visible light filter 24, an integrator lens 26, and a condensing lens 28 are illustrated between the sequential light source device 50 and the liquid crystal display device 30. Of course, it can be modified to any lens combination by commercial modification. As shown in FIG. 5, it can be seen that the liquid crystal projection apparatus of the present invention is designed without a separate optical device such as an X-cube or PBS between the liquid crystal display device 30 and the projection lens 12. have. Therefore, there is an advantage in that the effective outer diameter of the projection lens 12 needs to be made larger than the effective screen size of the liquid crystal display element 30. In addition, since a separate optical device such as an X-cube or PBS is not provided between the field sequential liquid crystal display device 30 and the projection lens 12, the projection lens 12 from the exit surface of the field sequential liquid crystal display device 30 is provided. ) Has an advantage that can be shorter than the diagonal length of the exit surface of the liquid crystal display device (30).

In addition, as shown in FIG. 5, the liquid crystal projection device of the present invention includes a liquid crystal display element of one sequential driving method, and does not use optical instruments such as PBS and X-cube, so that light does not need to be refracted. . Therefore, in the liquid crystal projection apparatus of the present invention, since the light propagation direction 60 emitted from the light source reaches the projection lens without refraction, it can be seen that all the components are disposed perpendicular to the light propagation direction 60.

The color screening device 23 that color-codes light emitted from the white light source 2 sequentially into R, G, and B light is usually composed of a rotating color filter. 6 is a plan view of one embodiment of a color filter used in the present invention. In the color filter of FIG. 6 (a), the circular color filter is divided into an R light transmission region, a G light transmission region, and a B light transmission region, and the reflection region 33 shown as a shaded region between the transmission regions of each light includes: Characterized in that it is provided. The reflection area 33 is an area for reflecting the light irradiated from the white light source 2 back to the reflection shade 22. The reflective region 33 can be formed by various methods such as forming a metal layer by sputtering. The transmission region is rotated at an angular velocity synchronized with 't1 + t2' (addressing time + hold time) in the timing diagram of FIG. 3, and the reflection region is rotated at an angular velocity synchronized with 't3 + t4' (reset time + write time). do. Alternatively, there is a method of fixing the angular velocity constantly and adjusting the area of each part of the color wheel, that is, the angle of the corresponding part, according to the ratio of 't1 + t2' and 't3 + t4'. When using the color screening apparatus, the 't1 + t2' time corresponding to the R light, the G light, and the B light in the timing diagram shown in FIG. An embodiment in which the reflective region 33 is removed from the color filter is shown in FIG. 6 (b). As shown in FIG. 6B, when the reflection region is removed from the color screening apparatus 23, the brightness is better than the color filter of FIG. 6A, but the color purity is lowered.

When the R light transmitting region, the G light transmitting region, and the B light transmitting region are constituted by color filters, the color filters use dyes, and thus have a disadvantage of reducing luminance. For example, when light is incident on the R transmission color filter region, G and B light are absorbed by the color filter, and only R light is passed through. Therefore, the color filter is deteriorated by the light absorbed in this manner, which causes a problem of shortening the life of the liquid crystal projection apparatus. In order to solve this problem, the transmission region may be configured as a dichroic mirror. That is, the dichroic mirror which transmits only the R light and reflects the G light and the B light is made of the R light transmitting region and transmits only the G light and reflects the R and B light. It consists of a dichroic mirror which transmits only B light and reflects R light and G light. When the dichroic mirror is used, light that does not transmit can be reflected back to the reflector 22 and used again. Therefore, the luminance reduction effect generated when the color filter is used does not appear.

In addition to the R, G, and B colors as shown in FIG. 7B, a color screening device may add a white area to increase luminance. Of course, in order to increase the color range, color regions other than the R, G, and B colors and the white region may be added. In this case, the field sequential liquid crystal display must drive one frame divided into four frames.

The color screening apparatus 23 shown in FIGS. 6 and 7 (a) is configured to display one frame when rotated 360 °. However, as shown in FIG. 7A, the color screening apparatus 23 may irradiate light corresponding to several frames while rotating 360 °.

The liquid crystal display device used in the conventional single-plate type liquid crystal projection device had to include all the pixels for expressing R, G, and B. Therefore, the size of the liquid crystal display device is increased, thereby increasing the size of the liquid crystal display device. In the liquid crystal projection device of the present invention, since the size of the liquid crystal display device is not increased by adopting the light source device and the liquid crystal display device of the sequential driving method, the liquid crystal projection device can be miniaturized.

In addition, since the light projected from the light source can be designed to reach the projection lens without refraction, an optical device such as a reflector is unnecessary, and a separate X-cube or PBS, such as a field-sequential liquid crystal display device and the projection lens, is unnecessary. It is possible to reduce the size of the projection lens because it is not necessary to provide an optical device to provide a compact liquid crystal projection device.

While the preferred embodiments of the present invention have been described using specific terms, such descriptions are for illustrative purposes only, and various changes and modifications may be made without departing from the spirit and scope of the following claims. It must be understood.

Claims (11)

A single plate liquid crystal projection apparatus using a light source that is sequentially irradiated with light of a color including R light, G light, and B light by using a time difference, White light source; A color screening device which emits the white light emitted from the white light source sequentially over time into light having a color including R light, G light, and B light; A field sequential liquid crystal display for generating an image using light incident from the color screening device, displaying an image corresponding to light of an irradiated color, and simultaneously storing image data corresponding to light of a next sequential color; And And a projection lens for magnifying and projecting an image emitted from the field sequential liquid crystal display device. The method of claim 1, And the light emitted from the field sequential liquid crystal display is projected in a straight line without being reflected to the projection lens. The method of claim 1, A reflection shade installed at a rear side of the white light source and reflecting the light reflected from the white light source to the rear side to the front side; An integrator for uniformly emitting light incident from the light source; Polarizers disposed on the front and rear surfaces of the field sequential liquid crystal display; And And a condensing lens for condensing light incident from the integrator. The method of claim 3, wherein And the integrator lens is formed of a plurality of small lenses formed on both surfaces of one substrate. The method according to claim 1 or 2, And the field sequential liquid crystal display device comprises a liquid crystal memory for storing image data corresponding to a light source currently irradiated, and a subsequent memory for storing image data corresponding to a next sequential light source. The method of claim 5, And said field sequential liquid crystal display device comprises a second switch between said subsequent memory and said liquid crystal memory. The method according to claim 1 or 2, The color screening apparatus includes an R transmission region for projecting only R light, a G transmission region for projecting only G light, and a B transmission region for projecting only B light, and a reflection region for reflecting light irradiated therebetween. A single-plate liquid crystal projection apparatus comprising a. The method of claim 7, wherein The color screening device is a single-plate liquid crystal projection device, characterized in that formed by a color filter provided in a circular shape. The method according to claim 1 or 2, The color screening device includes an R transmission region that projects only R light, a G transmission region that projects only G light, and a B transmission region that projects only B light, and includes the R transmission region, the G transmission region, and the B transmission region. It is formed with this dichroic mirror, The single-plate type liquid crystal projection device characterized by the above-mentioned. The method according to claim 1 or 2, The color screening apparatus includes an R transmission region for projecting only R light, a G transmission region for projecting only G light, and a B transmission region for projecting only B light, and a reflection region for reflecting light to be irradiated therebetween. Equipped, And the reflection area is operated in synchronization with a sum of a time for resetting image data stored in the liquid crystal memory and a writing time for storing image data stored in the subsequent memory in the liquid crystal memory. The method of claim 2, And the distance between the exit surface of the liquid crystal display device and the projection lens is smaller than the diagonal length of the exit surface of the liquid crystal display device.

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