KR20080028548A - Projector with one liquid crystal panel - Google Patents

Abstract

A projector with a single liquid crystal panel is provided to prevent an increase in the size of an LCD device by adopting a sequential light source device and the sequential driving LCD device, thereby miniaturizing the projector. An LED(Light Emitting Diode) light source(70) radiates RGB(Red, Green, Blue) light successively. A filed sequential LCD(Liquid Crystal Display) device(30) generates an image by using the light emitted from the LED light source, displays the image corresponding to the light of radiated color, and stores image data corresponding to the light of next sequential color simultaneously. A projection lens(12) enlarges and projects the image from the field sequential LCD device.

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.

2 is a configuration diagram of a conventional liquid crystal projection apparatus of a method of separating three primary colors and incident at a specific angle.

Fig. 3 is a relational view of the effective screen size of the liquid crystal display device, the size of the incident surface and the exit surface of the optical device, and the effective outer diameter size of the acquisition side of the projection lens in the conventional liquid crystal projection device.

4 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.

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

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

7 is a timing diagram of light emission of a three primary light emitting device light source;

8 is a configuration diagram of a liquid crystal projection device of another embodiment according to the present invention.

9 shows an embodiment of a three primary light emitting device light source 70.

10 is a configuration diagram of a liquid crystal projection apparatus using a reflective field sequential liquid crystal display device as another embodiment of the present invention.

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

24: visible light filter 26: integrator

28: condensing lens 32, 34: polarizing plate

30: filter sequential driving type liquid crystal display device

12: projection lens 60: light traveling direction

70: three primary light emitting device light source 73: G light emitting device light source

75: RB light emitting device light source

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single plate liquid crystal projection apparatus, and more particularly, to a single plate using a diode light source that sequentially irradiates R light, G light, and B light in sequence, using a liquid crystal display element of a sequential driving method. It relates to a type liquid crystal projection device.

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 conventional 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 magnifying and projecting an image formed 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.

Conventional liquid crystal projection apparatus of the method of separating the three primary colors and incident at a specific angle, it is common to use three dichroic mirrors (16R, 16G, 16B) as shown in FIG. In the embodiment of Figure 2 it can be seen that the device does not employ a color wheel while using a white light source. The light irradiated from the white light source 2 is irradiated to the front surface using the reflection shade 2a, and only the visible light wavelength band is transmitted by the visible light filter 24. Light passing through the visible light filter 24 is condensed by the condensing lens 28-1 and uniformly emitted by the fly's eye lenses 26-1 and 26-2. The light passing through the fly's eye lenses 26-1 and 26-2 reaches the R dichroic mirror 16R, the G dichroic mirror 16G, and the B dichroic mirror 16B and is spectroscopically. The R dichroic mirror 16R reflects only the R light from the incident white light and is polarized through the polarizing plate 32 before reaching the R pixel region of the liquid crystal display device 10. In the same manner, the G dichroic mirror 16G reflects only the G light from the incident white light to be polarized through the polarizing plate 32 to reach the G pixel region of the liquid crystal display device 10, and the B dichroic mirror 16B reflects only the B light from the incident white light and polarizes through the polarizing plate 32 to reach the B pixel region of the liquid crystal display device 10. Light reaching the R pixel area, the G pixel area, and the B pixel area, respectively, is converted into an image in the liquid crystal display device 10, and then enlarged in the projection lens 12 to be projected onto the screen 100. However, this driving method has the advantage of using a white light source and using only one liquid crystal display element. However, since three dichroic mirrors are used, the structure becomes complicated and the dichroic mirror is adjusted to adjust the liquid crystal display element. Spatial modulation must be used to reflect the exact position of the T-axis, which is difficult to control accurately.

A product practically applied by the above three methods should use a color wheel or use a liquid crystal display device having a pixel for R, G, and B in one liquid crystal display device. In the case of using a liquid crystal display device in which all the pixels for R, G, and B are provided in one liquid crystal display device, a single plate is formed by arithmetic calculations on the assumption that the liquid crystal display device has pixels having the same size as the external size of the liquid crystal display device. The resolution of the liquid crystal display element used in the equation is only one third of the resolution of the liquid crystal display element used in the three-plate type. In practice, the resolution will be 1/3 or less since there must be a manufacturing margin between the pixels. The resolution difference of the liquid crystal display device is a serious problem to reduce the size of the liquid crystal projection device.

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, dichroic mirror, etc., 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 becomes larger when using optics. The size of the projection lens is one of the biggest problems in miniaturizing the liquid crystal projection device.

In order for an image output from the liquid crystal display device to be incident on the optical device without loss, the size of the incident surface of the optical device should be larger than that of the effective screen of the liquid crystal display device. Also for similar reasons, the effective outer diameter of the intake side of the projection lens should be larger than the size of the exit surface of the optics. FIG. 3 shows the relationship between the effective screen 11 size of the conventional liquid crystal display device, the size of the incident surface 9 and the exit surface 9 of the optical device, and the size of the effective outer diameter 13 of the acquisition side of the projection lens. . The effective screen 11 of the liquid crystal display device refers to a screen on which a substantial image is formed, not the physical external size of the liquid crystal display device. The effective outer diameter 13 of the projection lens is an outer region 14 in which aberration occurs in the lens. It means the outer diameter area excluding. 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, to provide a liquid crystal projection apparatus that can be miniaturized without using a separate optical device between the liquid crystal display element and the projection lens while using the liquid crystal display element of the field sequential drive method. The purpose.

The above object of the present invention is a single-plate liquid crystal projection apparatus using a light emitting element light source that is sequentially irradiated with R light, G light, and B light by using time difference, and sequentially irradiating R light, G light and B light. Field sequence for generating an image using a light emitting device light source and light emitted from the light emitting device light source, displaying an image corresponding to light of an irradiated color, and simultaneously storing image data corresponding to light of a next sequential color A liquid crystal display device, a polarizing plate provided on the front and rear of the field sequential liquid crystal display device, and a projection lens provided on the rear of the polarizing plate provided on the rear of the field sequential liquid crystal display device are achieved by a single-plate liquid crystal projection device It is possible.

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 having a field-sequential frame driving method, R, G, and B subframes are used to compose 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. 4 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 liquid crystal display of the field sequential driving method 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 during the 't1' time during the 't4' write time, and then image data of the light G emitted from the subframe is written in the liquid crystal cell. In the timing diagram of FIG. 4, it can be seen that the operation of storing the image data irradiated in the next subframe during the time t1 + t2 of R light irradiation is partially overlapped.

In the present invention, the R, G, and B lights sequentially irradiated mean that the time when only the R light is irradiated, the time when only the G light is irradiated, and the time when only the B light is irradiated are sequentially. Therefore, even if there is a time when white light is irradiated between the time when only R light is irradiated with only G light, it means that R, G, and B light are sequentially irradiated. In this manner, when there is a time when white light is irradiated between the times when only each light source is irradiated, the luminance increases, and the frame diagram of FIG. 4 should be changed accordingly.

5 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. 5, 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). 4 and 5 are embodiments of the field sequential driving method can be modified in various ways, the present invention is not limited to the embodiment shown in FIGS.

6 is a configuration diagram of a liquid crystal projection apparatus of an embodiment according to the present invention. The liquid crystal projection apparatus according to the present invention includes a three primary light emitting device light source 70, a visible light filter 24, an integrator lens 26, a condensing lens 28, polarizing plates 32 and 34, a field sequential liquid crystal display device ( 30) and projection lens 12.

The tri-color light emitting device light source 70 is a light source consisting of an R light emitting diode (LED) emitting red light, a G light emitting device emitting green light, and a B light emitting device emitting blue light.

The visible light filter 24 is a filter for passing only the visible light region in the light emitted from the light source 70, and is provided at any position between the three primary color light emitting device light source 70 and the polarizing plate 32 in the configuration of FIG. It may be.

An integrator lens 26 is a lens that uniformly emits incident light. The integrator lens 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 in the substrate. Since it has a shape configured on the phase, the two integrator lenses 26-2 and the second integrator lens 26-2 can be aligned independently. It is preferable to have a. 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. Lenses that uniformly emit incident light include a solid rod integrator, a hollow rod integrator (hollow rod), and a fly eye lens.

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.

Since the polarizing plates 32 and 34 use a light emitting element as a light source, they may be directly fixed to the entrance and exit surfaces of the field sequential liquid crystal display element with an adhesive. The polarization axis of the light incident on the liquid crystal display device 30 and the light emitted from the liquid crystal display device 30 are determined, and the projection lens 12 is composed of a series of lens groups for projecting the light projected from the liquid crystal display device 30 onto the screen.

In the embodiment of FIG. 6, a visible light filter 24, an integrator lens 26, and a condensing lens 28 are illustrated between the three primary color light emitting device light source 70 and the field sequential liquid crystal display device 30. It is possible, of course, to be modified in any lens combination by various commercial modifications. As shown in FIG. 6, it can be seen that the liquid crystal projection device of the present invention is designed without a separate optical device such as 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 a PBS is not provided between the field sequential liquid crystal display device 30 and the projection lens 12, the projection lens 12 is separated from the exit surface of the field sequential liquid crystal display device 30. There is an advantage that the distance to is shorter than the diagonal length of the exit surface of the liquid crystal display device 30.

In addition, as shown in Fig. 6, the liquid crystal projection device of the present invention is provided with one field-sequential liquid crystal display element, and does not use optical devices 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 field sequential liquid crystal display device 30 reaches the projection lens without refraction, all the components are disposed perpendicular to the light propagation direction 60. It can be seen.

FIG. 7 illustrates a light emission timing diagram of the three primary light emitting device light source 70. Referring to FIG. 7, it is understood that the R light emitting device, the G light emitting device, and the B light emitting device are sequentially emitted and then turned off. At this time, there is a blank time until one light emitting device is turned off and the next light emitting device is turned on.

The time for keeping one light emitting device ON is set equal to the time interval of the sum of the addressing time t1 and the holding time t2 of the field sequential liquid crystal display device 30, and the blank time is the field sequential liquid crystal display device. The reset time t3 and the write time t4 of (30) are set to the sum of time intervals. When the light emission times of the R light emitting device, the G light emitting device, and the B light emitting device are adjusted to be 3: 6: 1, the operation timing of the field sequential liquid crystal display device 30 must be adjusted accordingly.

8 is a configuration diagram of a liquid crystal projection device of another embodiment according to the present invention. The liquid crystal projection device according to FIG. 8 includes a G light emitting element light source 73, an RB light emitting element light source 75, a visible light filter 24, an integrator lens 26, a condensing lens 28, and polarizing plates 32 and 34. ), The field sequential liquid crystal display element 30 and the projection lens 12.

In comparison with the liquid crystal projection device shown in FIG. 6, the liquid crystal projection device shown in FIG. 8 includes a G light emitting device light source 73 in which the three primary color light emitting device light sources 70 are composed of only green light emitting devices, and a red and blue light emitting device. There is a difference in that the dichroic mirror 80 is provided between the RB light emitting element light sources 75, which are provided therebetween. The dichroic mirror 80 uses a dichroic mirror that transmits green light and reflects the remaining red and blue light. In this case, the light incident on the field sequential liquid crystal display device 30 is preferably configured such that G: B: R emits light with a luminance of 6: 1: 3. In the case of the liquid crystal projection device shown in Fig. 8, the G light reaches the straight field liquid crystal display device 30 in a straight line, but the R light and the B light are sequentially turned after being turned vertically in the dichroic mirror 80. It can be seen that the field liquid crystal display device 30 is reached. 8 illustrates an example in which a light source that emits G light is independently configured, and in some cases, R light or B light may be independently configured.

9 illustrates one embodiment of light emitting device light sources 70, 73, 75. In order to implement a small liquid crystal projection apparatus, a small size liquid crystal display device is required, and it is preferable to keep the diagonal length less than 1 inch as the size of the liquid crystal display device so as not to cause inconvenience to carry. Currently, the diagonal length of the liquid crystal display device is 0.7 to 0.9 inches in the mainstream of the market, but considering the case of carrying with electronic devices such as mobile phones for personal use, the size should be smaller. In consideration of this use, the diagonal length of the liquid crystal display device is reduced to 0.2 inches to 0.7 inches, which is equivalent to 0.5 cm to 1.8 cm (5 mm to 18 mm) in terms of the metric method.

In the present invention, a surface mounted light emitting diode is used as a light source suitable for a liquid crystal display device having a diagonal length of 5 mm. The surface-mounted light emitting device is a square light source having a horizontal and vertical size of about 1 mm in one light emitting device, and is suitable as a light source of a rectangular liquid crystal display device. 9 illustrates various types of surface mounted light emitting devices used as a light source.

When the same luminance and the same number of R, G, and B light emitting elements are irradiated for the same time, the human eye does not recognize it as white. In order to be able to perceive near white, it is preferable to maintain the luminance ratio of R light: G light: B light at 3: 6: 1. For this reason, the light emitting device light sources 70, 73, 75 are (1) the number of the R light emitting device, the G light emitting device, and the B light emitting device having the same brightness is set to 3: 6: 1, or (2) The number of R light emitting devices, G light emitting devices, and B light emitting devices having the same brightness is the same, and the light emission time of the R light emitting devices, the G light emitting devices, and the B light emitting devices is 3: 6. It is preferable to adjust the luminance of each light emitting device by adjusting it to be: 1, or (3) the amount of current flowing through the R light emitting device, the G light emitting device, and the B light emitting device.

9 (a) and 9 (b) show an example of the three primary color light emitting device light source 70 of FIG. 6, and FIG. 9 (a) shows a single cold substrate 77 made of metals having good heat transfer characteristics. Four surface mounted light emitting devices 79 were provided on the top surface, and two of the four surface mounted light emitting devices were provided with the G light emitting device and the other one as the R light emitting device and the B light emitting device, respectively. 9 (b) shows an example in which six surface mount light emitting devices are provided on one cold substrate 77, and two R light emitting devices, G light emitting devices, and B light emitting devices are used. The three primary color light emitting device light source 70 of FIG. 9A has a square shape having one side of about 2 mm in size, and the three primary color light emitting device light source 70 of FIG. 9 (B) has a width of about 3 mm and a length of about 2 mm. Will have a rectangular shape.

9 (c) and 9 (d) show examples used as the G light emitting element light source 73 and the RB light emitting element light source 75 of the liquid crystal projection device of FIG. Both of them used a light source provided with four surface mount light emitting elements 79 on one cold substrate 77. At this time, the RB light emitting device light source 75 is arranged to minimize the unevenness of the irradiation light due to the luminance difference between each light emitting device by arranging the R light emitting device and the B light emitting device to cross each other, as shown in Fig. 8 (d). .

9 (e) and 9 (f) show examples used as the G light emitting element light source 73 and the RB light emitting element light source 75 of the liquid crystal projection device of FIG. 7, respectively. Both of them used a light source provided with six surface mount light emitting elements 79 on one cold substrate 77. In this case, the RB light emitting device light source 75 has an R2 light emitting device next to the R1 light emitting device, a B3 light emitting device next to the R2 light emitting device, and a B2 light emitting device next to the B1 light emitting device. And the R3 light emitting device were placed next to the B2 light emitting device. For wiring, connect R1 light emitting device, R2 light emitting device, and R3 light emitting device in series, or connect them all in parallel, or connect R1 light emitting device, R2 light emitting device in series, and R3 light emitting device in parallel. It was done. When all of them are connected in series, a voltage drop occurs in each light emitting device, so that the R1 light emitting device emits higher luminance than the R3 light emitting device. When all of them are connected in parallel, the brightness can be maintained most similarly among the three methods. There is a problem to increase the power supplied to the light source. Therefore, as a compromise, it is most preferable to connect the R1 light emitting devices and the R2 light emitting devices in series and the R3 light emitting devices in parallel. Wiring of the B1 light emitting device, the B2 light emitting device, and the B3 light emitting device was performed in the same manner.

In the arrangement example of the light source of FIG. 9, the maximum number of light emitting elements disposed on one cold substrate 37 is illustrated as six, but this is only an example. As described above, the small liquid crystal display device has a 0.5 cm to 1.8 cm (5 mm to 18 mm) diagonal length, but when the number of light emitting devices becomes too large, the cross-sectional area of the light source becomes large, thereby increasing the lens structure such as agglomerated lenses. Will cause problems. In order to maintain etendue without the addition of such a lens structure, the number of light emitting devices that can be installed depending on the angle of the light source incident on the liquid crystal display device is limited.

The number of light emitting devices that can be used in a small liquid crystal display device having a diagonal length of 1.8 cm and a aspect ratio of 4: 3 will be calculated. The etendue is determined as in Equation 1.

Where E is etendue, A _l is the area of the exit face of the light source, θ is the exit angle of the light emitting device, Ap is the area of the entrance face of the liquid crystal display device, and Fnum is the F value.

The F value is expressed as the ratio f / D of the focal length f of the lens to the effective aperture D (aperture aperture) D (where D / f is the mouth ratio). In the case of the liquid crystal display device, the F value does not exist since the plane is flat, but the F value is determined by the lens existing between the liquid crystal display device and the light source.

In the case of a 1.8 cm small liquid crystal display device, the F value is about 1.5 (which can be changed according to the design of the optical engine, and any one value is arbitrarily selected), and Ap is 155.5 mm 2, so the etendue is Using the rightmost equation of 1, the calculation yields 54.2. In addition, since the average emission angle of the light emitting device can be calculated as an average of 120 degrees, it is possible to calculate the A _l value using the obtained etendue and the emission angle of the light emitting device 120 degrees, where A _l is 23 ㎜, so that the light emitting device It can be seen that up to about 24 can be provided.

When using a maximum of 24 surface mount light emitting devices, it is preferable that six surface mount light emitting devices are provided on a substrate made of metals having good heat transfer, and four surface mount light emitting devices are provided vertically. That is, the light source that can be used in the present invention is provided with 4 to 24 surface mount light emitting devices on a substrate made of metals having good heat transfer, and the light emitting devices provided on the substrate can be uniformly maintained to maintain uniform brightness. Preferred.

10 is a configuration diagram of a liquid crystal projection apparatus using a reflective field sequential liquid crystal display device as another embodiment of the present invention. The liquid crystal projection device according to FIG. 10 includes a three primary light emitting device light source 70, a visible light filter 24, an integrator lens 26, a condensing lens 28, a PBS 8, and a reflective field sequential liquid crystal display device ( 35) and projection lens 12. The liquid crystal projection apparatus of FIG. 10 uses a reflective field sequential liquid crystal display element 35 and has a PBS between the liquid crystal display element 35 and the projection lens as compared with the liquid crystal projection apparatus shown in FIG. have. In addition, the use of the PBS 8 eliminates the need to employ a separate polarizing filter. In the case of using the reflective panel, PBS is used to send the image reflected from the liquid crystal display device to the projection lens. Of course, the reflected image can be sent to the projection lens without using PBS. It gets complicated.

Light sequentially emitted from the three primary light emitting device light sources 70 is filtered by the visible light filter 24 only to the visible light region, and then converted into parallel light by the integrator lens 26. Thereafter, the light is collected by the condensing lens 28 and then reflected by the PBS 8 to be incident on the reflective field sequential liquid crystal display 35. The image formed by the reflective field sequential liquid crystal display element 35 is reflected and then re-entered into the PBS 8, and then is magnified and projected by the projection lens 12 to form an image on the screen.

The reflective field sequential liquid crystal display device 35 may be configured by forming a reflecting plate on the emission surface side of the projection field sequential liquid crystal display, or by replacing a lower substrate with a silicon wafer instead of a glass substrate and forming a circuit portion and a reflecting plate thereon. It can also be implemented in LCOS form. In the embodiment of FIG. 10, the position is changed when the optical axis 60 enters and exits the PBS image. However, for convenience of description, the position of the optical axis 60 is different from the incident axis and the exit axis. It is partly emitted. In addition, the three primary color light emitting device light source 70 of FIG. 10 may be replaced with the G light emitting device light source 73 and the RB light emitting device light source 75 used in the liquid crystal projection device of FIG. 8.

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 liquid crystal projection apparatus of the present invention can be designed to reach the projection lens without refraction from the image projected from the field-sequential liquid crystal display device, it is not necessary to provide a separate optical device such as X-cube or PBS, so the size of the projection lens It is possible to provide a small liquid crystal projection apparatus by reducing the

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

Claims (13)

A single plate liquid crystal projection apparatus using a light emitting element light source sequentially irradiated with R light, G light, and B light by using a time difference, Light emitting device light source for sequentially irradiating R light, G light and B light; A field sequential liquid crystal display for generating an image using the light emitted from the light emitting 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 from said field sequential liquid crystal display element. The method of claim 1, And the field sequential liquid crystal display device is provided in a reflective type. The method of claim 1, The R, G and B light emitted from the light emitting element light source is emitted in the same direction, and the same direction is perpendicular to the incident surface of the field sequential liquid crystal display device. The method of claim 1, And the distance between the exit surface of the field sequential liquid crystal display device and the projection lens is smaller than the diagonal length of the exit surface of the liquid crystal display device. The method of claim 1, Light emitting device light source A single plate comprising a dichroic mirror disposed between each of the light sources and a light source composed of only one light emitting element selected from R, G, and B light emitting elements, and a light source composed of light emitting elements of the remaining colors; Liquid crystal projection device. The method according to any one of claims 1 and 3 to 5, Between the light emitting device light source and the field sequential liquid crystal display device An integrator for uniformly emitting light incident from the light source; Polarizing plates provided on the front and rear surfaces of the field sequential liquid crystal display device; And And a condensing lens for condensing light incident from the integrator. The method of claim 6, And the integrator lens is formed of a plurality of small lenses formed on both surfaces of one substrate. The method according to any one of claims 1 to 5, 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 8, And said field sequential liquid crystal display device comprises a second switch between said subsequent memory and said liquid crystal memory. The method of claim 8, The light emitting device light source is sequentially turned on and off in the order of R light, G light and B light, and there is a blank period in which all light emitting devices are turned off until the light source of one color is turned on after the light source of one color is turned off. And the period is equal to the sum of the time for resetting image data stored in the field sequential liquid crystal memory and the writing time for storing image data stored in the subsequent memory in the liquid crystal memory. The method according to any one of claims 1 to 5, The light emitting device light source is a single-plate liquid crystal projection device, characterized in that provided with four or more light emitting devices (LEDs) on a thermally conductive metal substrate. The method of claim 11, The light emitting device is provided in an even number, characterized in that provided in less than 24 single-panel liquid crystal projection device. The method of claim 11, The light emitting device is a single-plate liquid crystal projection device characterized in that the serial and parallel connection is provided in a mixture.

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