JP2006064853A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device capable of displaying an image having high image quality using a simple optical system. <P>SOLUTION: A light emitting part 2 has a plurality of light emitting elements 32, 34 and 36 embedded in recessed parts corresponding to pixel elements. The recessed parts are formed by using a light shielding film 20. The plurality of light emitting elements 32, 34 and 36 correspond to three primary colors of R, G and B and are cyclically lit at a speed exceeding resolution of human visual time. A liquid crystal panel 10 changes alignment of liquid crystal molecules to control transmittance of light from the light emitting part 2 for each pixel. Transmittance of light of the plurality of colors emitted sequentially from each recessed part is controlled for each color in accordance with luminance to be realized in each pixel to form an image. Light putting out periods can be provided between cyclical lighting of the light emitting elements 32, 34 and 36. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display device such as a liquid crystal projector using a liquid crystal panel.

  In recent years, liquid crystal projectors have become widespread. Liquid crystal projectors can be made smaller and lighter than CRT (Cathode Ray Tube) projectors, and portable types have also been put into practical use. FIG. 1 of Patent Document 1 discloses a liquid crystal projector including an optical system and a liquid crystal panel for each of red, green, and blue (hereinafter referred to as R, G, and B).

FIG. 55 of Patent Document 1 discloses a display device in which three semiconductor lasers are sequentially turned on in a time division manner, and a liquid crystal panel modulates light generated in synchronization with the time division lighting.
International Publication No. 99/49358

  However, the display device disclosed in FIG. 55 of Patent Document 1 requires an array lens for converting into parallel rays and a deformed curved lens for uniformizing the luminance distribution, which increases the number of components and makes it complicated. An optical system is required. In addition, since three semiconductor lasers serving as light sources are arranged in parallel with the display surface for each pixel, it is difficult to increase the resolution.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a display device capable of displaying a high-quality image with a simple optical system.

  A display device according to an aspect of the present invention includes a light emitting unit in which a plurality of light emitting elements are provided for each pixel, and a light emission control unit that circulates and lights the plurality of light emitting elements, and the light emission control unit is realized by each pixel. The brightness of light of a plurality of colors emitted sequentially from the plurality of light emitting elements is controlled for each color according to the brightness to be increased. An organic EL element may be used as the “light emitting element”. The “plurality of light emitting elements” may be R, G, B light emitting elements.

  According to this aspect, an image can be obtained by rotating the light emitting elements of different colors according to the image data at high speed, for example, at a speed exceeding the human visual time resolution, thereby obtaining an image with high color purity. be able to.

  You may further provide the liquid crystal panel which controls the transmittance | permeability of the light from a light emission part by changing the orientation of a liquid crystal molecule, and the panel control part which controls the transmittance | permeability for every pixel. A ferroelectric liquid crystal may be used as the “liquid crystal”. The “transmittance” includes 0%, that is, a light shielding state.

  According to this aspect, the light emitting elements of different colors can be circulated and light-transmitted at a high speed, for example, at a speed exceeding human visual time resolution, and monochromatic light can be transmitted with different transmittances for each pixel to obtain an image. Therefore, an image with high color purity can be obtained. Further, since the wiring can be distributed between the light emitting unit and the liquid crystal panel, the structure of the light emitting unit and the liquid crystal panel can be simplified.

  Another embodiment of the present invention is also a display device. This device includes a light emitting unit in which a plurality of light emitting elements are embedded in a recess corresponding to a pixel, a light emission control unit that circulates and lights the plurality of light emitting elements in each recess, and a light emitting unit that changes the orientation of liquid crystal molecules. A liquid crystal panel that controls the transmittance of light from the light source, and a panel control unit that controls the transmittance for each pixel. The panel control unit controls the transmittance of light of a plurality of colors emitted sequentially from the plurality of light emitting elements for each color according to the brightness to be realized in each pixel. An LED or an organic EL element may be used as the “light emitting element”. The “plurality of light emitting elements” may be R, G, B light emitting elements. A ferroelectric liquid crystal may be used as the “liquid crystal”. The “transmittance” includes 0%, that is, a light shielding state.

  According to this aspect, the light emitting elements of different colors can be circulated and light-transmitted at a high speed, for example, at a speed exceeding human visual time resolution, and monochromatic light can be transmitted with different transmittances for each pixel to obtain an image. Therefore, an image with high color purity can be obtained. Further, since light is emitted from the light emitting element embedded in the concave portion for each pixel, light is not mixed and light with no unevenness can be obtained with a simple configuration. Furthermore, if a plurality of light emitting elements in the recess are three-dimensionally arranged, the area of the recess can be reduced, and the resolution can be increased.

  The recess may be formed by a conductive light shielding film. By using a conductive member such as tungsten or copper for the light-shielding film, it can be used as electrodes of a plurality of light-emitting elements, and wiring can be simplified. Moreover, the freedom degree of arrangement | positioning of the light emitting element in a recessed part can also be raised.

  The light emission control unit may provide an extinguishing period between the cyclic lighting of the light emitting elements. When black display is inserted, the same effect is obtained and the contrast ratio can be improved.

  The panel control unit may provide a period for shielding light from the light emitting unit. When black display is inserted, the same effect is obtained and the contrast ratio can be improved.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, etc. are also effective as an aspect of the present invention.

  According to the present invention, a high-quality image can be displayed with a simple optical system.

  FIG. 1 is a side sectional view of an image display device 1 according to the present invention. The light emitting unit 2 is mainly generated from the light shielding film 20, the first light emitting element 32, the second light emitting element 34, the third light emitting element 36, and the insulating film 40. The light shielding film 20 is formed of tungsten W, silicon tungsten WSi, copper Cu, aluminum Al, titanium Ti, or the like, and serves as a common electrode on the GND side of the first light emitting element 32, the second light emitting element 34, and the third light emitting element 36. Used.

  The light shielding film 20 is provided with a recess for each pixel. This recess is formed by etching or the like. The first light emitting element 32, the second light emitting element 34, and the third light emitting element 36 are embedded in each recess. The first light emitting element 32, the second light emitting element 34, and the third light emitting element 36 correspond to the three primary colors of R, G, and B. For these light emitting elements 32, 24 and 36, LEDs (Light Emitting Diodes) can be used. By using the LED, low power consumption can be achieved. Furthermore, heat generation can be suppressed, leading to a reduction in the cooling mechanism such as a fan, and miniaturization and noise reduction can be achieved. The lifetime is also semi-permanent.

  The three primary color light emitting elements 32, 34, and 36 can be arranged in arbitrary positions in the recess. Even among the light emitting elements that do not conform to the specification, the luminance can be adjusted by adjusting the distance of each light emitting element with respect to the display surface. In FIG. 1, the light emitting elements 32, 34, and 36 of the three primary colors in the recess are arranged side by side in a direction perpendicular to the display surface. One pixel can be made smaller and the resolution can be increased as it is linearly arranged in the direction perpendicular to the display surface.

Electrodes (not shown) are provided on the light emitting elements 32, 34, and 36 of the three primary colors embedded in the recesses, respectively. In the case where an electrode is provided at a position where light emitted from the light emitting elements 34 and 36 behind the display surface is blocked, a transparent electrode may be used. After the three primary color light emitting elements 32, 34, and 36 are provided with electrodes, an insulating film 40 is formed in each recess to fill the recess. The insulating film 40 may be a transparent silicon oxide SiO ₂ film. The silicon oxide SiO ₂ film can be formed by a plasma CVD (Chemical Vapor Deposition) method.

  The liquid crystal panel 10 transmits the light from the light emitting unit 2 with a predetermined transmittance and displays an image. The liquid crystal panel 10 may use a general TN (Twisted Nematic) liquid crystal, but may use a ferroelectric liquid crystal. The response time of a general ferroelectric liquid crystal is 10 to several hundreds [us], and some of them have been developed with several hundreds [ns]. Although the detailed operation of the display device 1 will be described later, the present invention switches the R, G, B single color display at a high speed and synthesizes the three colors in the human brain. A more accurate image can be generated by using. However, if the response time is about 5 [ms], it exceeds the human visual time resolution, so that it appears as an image in which three colors are combined.

  In the liquid crystal panel 10, data lines and scanning lines are arranged on a matrix, and a region surrounded by the lines corresponds to a pixel. This pixel corresponds to the pixel of the light emitting unit 2. In the liquid crystal panel 10, the data lines and the scanning lines are controlled by passive matrix driving or active matrix driving, and the molecular orientation of the liquid crystal is controlled for each pixel. With this molecular orientation, the light from the light emitting section 2 is transmitted with changing the transmittance for each pixel to generate an image. In the case of active matrix driving, a thin film transistor (TFT) may be used as a switching element of each pixel.

  FIG. 2 is a front sectional view of the light emitting unit 2. When viewed from the front, it is well understood that the light-shielding film 20 has a lattice-shaped recess corresponding to one pixel. As described above, the light emitting elements 32, 34, and 36 of the three primary colors can be arbitrarily arranged in the recess. The upper left pixel in FIG. 2 is an example in which the first light emitting element 32, the second light emitting element 34, and the third light emitting element 36 are arranged in this order in the direction perpendicular to the display surface as shown in FIG. is there. However, although it arrange | positions on the same surface of the light shielding film 20, it does not arrange | position on the same straight line, but arrange | positions so that it may not overlap on the same straight line. Depending on the size and type of the first light-emitting element 32 and the second light-emitting element 34, the light emitted from the second light-emitting element 34 and the third light-emitting element 36 that are distant from the display surface is blocked, and a light loss that cannot be ignored. May occur. In that case, the optical loss can be reduced by such an arrangement.

  As shown in FIG. 1, the pixel on the right of the pixel is arranged in the order of the first light emitting element 32, the second light emitting element 34, and the third light emitting element 36 on the same straight line in the direction perpendicular to the display surface. This is an example. When the size of the first light emitting element 32 and the second light emitting element 34 is sufficiently small or the light emitting part is transparent, it is preferable to arrange them on the same straight line. In that case, the size of the pixel can be minimized and the resolution can be increased.

  Further, the pixel on the right of the above pixel is an example in which the light emitting elements 32, 34, and 36 of the three primary colors are arranged on the bottom surface of the recess. Thus, even when they are arranged on the same surface facing the display surface, since the pixels are partitioned by the light shielding film 20, mixing of light between the pixels can be prevented.

  FIG. 3 is a side sectional view of an image display device 1 using an organic EL (ElectroLuminescent) according to the present invention. In the image display device 1 of FIG. 1, the example in which LEDs are used as the light emitting elements 32, 34, and 36 has been described. In this regard, in the image display device 1 in FIG. 3, an example in which organic EL elements are used as the light emitting elements 32, 34, and 36 will be described. The organic EL element has a configuration in which an organic layer is sandwiched between an anode and a cathode. In FIG. 3, when the light shielding film 20 is used as a common anode, the cathode 38 is provided at a position facing the organic layer. The cathode 38 is a transparent electrode formed of ITO (Indium Tin Oxide). The organic layer has a structure in which a hole transport layer, a light emitting layer, and an electron transport layer are laminated in this order from the bottom. Other configurations are the same as those described with reference to the LED in FIGS. 1 and 2.

  When organic EL is used for the light emitting elements 32, 34, and 36, the thickness can be reduced as compared with the case where an LED is used. Further, as will be described later, it is possible to perform control for performing luminance control on the light emitting unit 2 side.

  FIG. 4 is a block diagram of the display device 1 according to the first embodiment of the present invention. The liquid crystal panel 10 uses a region surrounded by a plurality of data lines provided at a predetermined interval in the column direction and a plurality of scanning lines provided at a predetermined interval in the row direction as pixels. This pixel corresponds to the pixel of the light emitting unit 2 partitioned by the light shielding film 20.

  The panel control unit 50 includes a data line driving circuit 52 and a scanning line driving circuit 54, and receives image data and a synchronization signal. The panel control unit 50 processes the input image data, and applies the R, G, B image data from the data line driving circuit 52 to the data lines (not shown) of the liquid crystal panel 10 in a predetermined order. The predetermined order corresponds to the cyclic lighting control of the light emitting unit 2 by the light emission control unit 60. Each of the R, G, and B image data is 8-bit digital data to express 256 gradations, and the data line driving circuit 52 performs PWM (Pulse Width Modulation) control on the digital data, and the data line To give. Each image data may be composed of other bits such as 6 bits.

  The scanning line driving circuit 54 controls to output the image data given to the liquid crystal panel 10 by the data line driving circuit 52 from the pixels of the specific scanning line in accordance with the synchronization signal. For example, when the light emission control unit 60 performs the cyclic lighting control of the light emitting device 2 within 1/60 [s], the scanning line driving circuit 54 switches the scanning line at the same timing. Corresponding to this, the data line driving circuit 52 gives the R, G, B image data to be output from the pixels of the scanning line to the data line. Those pixels of the liquid crystal panel 10 transmit the light from the light emitting unit 2 with the transmittance according to each image data. As a result, the R, G, B three-color image data is displayed within 1/60 [s] from the specific scanning line, but the human visual time resolution is exceeded. It looks like a color-synthesized image. Note that when the liquid crystal panel 10 having a slow response time is used, the subjective image quality deteriorates.

  As described with reference to FIGS. 1 to 3, in the light emitting unit 2, pixels configured by an assembly of a plurality of light emitting elements 32, 34, and 36 are formed in the respective concave portions partitioned by the light shielding film 20. The light emission control unit 60 circulates and lights the plurality of light emitting elements 32, 34, and 36 of each pixel of the light emitting unit 2. A synchronization signal for synchronizing with the control of the liquid crystal panel 10 is given from the synchronization generation circuit 70 to the light emission controller 60. The light emission control unit 60 turns on the light emitting elements 32, 34, and 36 in the order of R, G, and B within 1/60 [s], for example, in accordance with the synchronization signal. Instantaneously, one of R, G, and B is turned on.

  The pixel to be lit is based on the wiring of the light emitting elements 32, 34 and 36. When all the light emitting elements 32, 34, and 36 of the light emitting unit 2 are connected by the same power line for each color, the entire surface is controlled to emit light for each color. In this case, the power supply control system can be simplified. In addition, when each color is connected by the same power supply line in the row direction corresponding to the scanning line of the liquid crystal panel 10 and power control is possible in units of rows, the row corresponding to the scanning of the scanning line, or the number before and after the row A row may be lit. In this case, power consumption can be reduced.

  The synchronization generation circuit 70 supplies a synchronization signal to the panel control unit 50 and the light emission control unit 60. The circulation lighting control of R, G, and B by the light emitting unit 2, the supply of image data to the data line of the liquid crystal panel 10, and the scanning line control must be synchronized. The synchronization generation circuit 70 generates a signal for achieving this synchronization and supplies it to both.

  As described above, according to the first embodiment, it is possible to obtain an image with high color purity by switching the monochromatic display of R, G, and B at a high speed that cannot be recognized by humans. Further, in order to improve the contrast ratio, a turn-off time may be provided for each of the R, G, and B monochrome displays. Specifically, the light emission control unit 60 may insert an extinguishing period when the light emitting elements 32, 34, and 36 are switched when the three primary color light emitting elements 32, 34, and 36 are turned on. As another method, when the scanning line driving circuit 54 selects one scanning line, a light shielding period may be inserted each time R, G, and B colors are displayed. According to these, there is an effect equivalent to inserting a black display, and the contrast ratio is improved.

  FIG. 5 shows a block diagram of the display device 1 in the second embodiment of the present invention. Unlike the display device 1 in the first embodiment, the display device 1 in the second embodiment is an example in which the image data is written by the light emitting unit 2 instead of the liquid crystal panel 10. In the second embodiment, an organic EL element may be used as the light emitting elements 32, 34, and 36 in order to write image data on the light emitting unit 2 side. The light emitting elements 32, 34, and 36 in the pixels formed in the light emitting unit 2 are connected in the column direction by data lines for each color.

  The light emission control unit 60 of the second embodiment includes a data line driving circuit 62 and receives image data and a synchronization signal. The light emission control unit 60 processes the input image data, and supplies the R, G, and B image data from the data line driving circuit 62 to the corresponding color data lines. The data line driving circuit 62 sequentially switches from one color data line to another color data line in accordance with the synchronization signal in order to turn on the light emitting unit 2 in a circulating manner. At this time, if the image data is a digital value, the luminance of each color is adjusted by PWM control.

  The liquid crystal panel 10 of the second embodiment has no data lines and is provided with a plurality of scanning lines at predetermined intervals in the row direction. Unlike the first embodiment, the panel control unit 50 of the second embodiment has a configuration in which the data line driving circuit 52 is removed. A synchronization signal is input to the panel control unit 50. The scanning line driving circuit 54 controls the light from the light emitting unit 2 to be transmitted from the pixels of the specific scanning line in accordance with the synchronization signal. For example, when the data line driving circuit 62 switches the data line that supplies the image data within 1/60 [s], the scanning line is switched at the same timing to transmit the light from the light emitting device 2. . Other configurations are the same as those of the first configuration example.

  As described above, according to the second embodiment, similarly to the first embodiment, an image with high color purity can be obtained by switching the monochromatic display of R, G, and B at such a high speed that humans cannot recognize. . In addition, since the data lines for writing and displaying the image data and the scanning lines are arranged separately in the light emitting unit 2 and the liquid crystal panel 10, wiring can be simplified.

  Note that the light emission control unit 60 may insert a turn-off period when switching from one color data line to another color data line. Further, when the scanning line driving circuit 54 selects one scanning line, a light shielding period may be inserted each time R, G, and B colors are displayed. According to these, there is an effect equivalent to inserting a black display, and the contrast ratio can be improved.

  Note that the present embodiment is not limited to the light emitting unit 2 in which a plurality of light emitting elements 32, 34, and 36 are embedded in a recess, and a plurality of light emitting elements 32, 34, and 36 are provided corresponding to pixels. It may be a thing. For example, a plurality of light emitting elements 32, 34, and 36 may be arranged corresponding to each pixel on a flat substrate.

  FIG. 6 shows a block diagram of the display device 1 in the third embodiment of the present invention. Unlike the display device 1 in the second embodiment, the display device 1 in the third embodiment is an example in which not only writing of image data but also scanning is performed by the light emitting unit 2. The light emission control unit 60 of the third embodiment includes a data line driving circuit 62 and a scanning line driving circuit 64. The light emission control unit 60 processes the input image data, and supplies the R, G, and B image data from the data line driving circuit 62 to the corresponding color data lines. The data line driving circuit 62 sequentially switches from one color data line to another color data line in accordance with the synchronization signal in order to turn on the light emitting unit 2 in a circulating manner.

  The scanning line driving circuit 64 controls the image data given to the data line to be output from the pixels of the specific scanning line in accordance with the synchronization signal. For example, when the data line driving circuit 62 switches the data line that supplies the image data within 1/60 [s], the scanning line is switched at the same timing. The third embodiment is basically an organic EL display that switches between three primary colors and can reproduce and display image data without the liquid crystal panel 10.

  In order to improve the contrast ratio, the panel control unit 50 can control the liquid crystal panel 10 to shield the image displayed by the light emitting unit 2 at predetermined time intervals. For example, a light shielding period may be inserted each time R, G, and B colors are displayed. This has the same effect as inserting a black display. The panel control unit 50 receives the synchronization signal from the synchronization generation unit 70 and can synchronize with the display timings of R, G, and B.

  As described above, according to the third embodiment, similarly to the first and second embodiments, an image with high color purity can be obtained by switching the monochromatic display of R, G, and B at such a high speed that humans cannot recognize. Can do. In addition, since each pixel is partitioned by the light shielding film 20, light mixing between pixels can be prevented.

  FIG. 7 is a diagram showing an example in which the display device 1 of the present invention is applied to a projector 100. The light from the light emitting unit 2 passes through the liquid crystal panel 10 and enters the projection lens 80. The projection lens 80 enlarges the incident light and projects it onto the screen 90.

  Thus, according to the projector 100, an image with high color purity can be obtained by switching the monochromatic display of R, G, and B at such a high speed that humans cannot recognize. Unlike conventional projectors, there is no need to provide three liquid crystal panels and optical systems corresponding to R, G, and B, respectively. Moreover, since it is not necessary to generate light of each color from a light source such as a high-pressure mercury lamp using a color filter, the light efficiency does not decrease.

  The present invention has been described above based on the embodiments. The present invention is not limited to these embodiments, and various modifications thereof are also effective as aspects of the present invention. The display device of the present invention can also be used as a display for a mobile phone, a notebook PC, a PDA (Personal Digital Assistants) or the like.

It is sectional drawing of the side surface of the image display apparatus which concerns on this invention. It is sectional drawing of the front of a light emission part. It is sectional drawing of the side surface of the image display apparatus using organic EL which concerns on this invention. 1 is a block diagram of a display device according to a first embodiment of the present invention. It is a block diagram of the display apparatus in 2nd Embodiment of this invention. It is a block diagram of the display apparatus in 3rd Embodiment of this invention. It is a figure which shows the example which applied the display apparatus of this invention to the projector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image display apparatus, 2 Light emission part, 10 Liquid crystal panel, 20 Light shielding film, 32, 34, 36 Light emitting element, 40 Insulating film, 50 Panel control part, 60 Panel control part, 60 Light emission control part, 70 Synchronous generation circuit

Claims (5)

A light emitting unit provided with a plurality of light emitting elements for each pixel;
A light emission control unit for circulating and lighting the plurality of light emitting elements,
The display device according to claim 1, wherein the light emission control unit controls, for each color, brightness of light of a plurality of colors emitted sequentially from the plurality of light emitting elements according to brightness to be realized in each pixel. A liquid crystal panel for controlling the light transmittance from the light emitting part by changing the orientation of liquid crystal molecules;
The display device according to claim 1, further comprising a panel control unit that controls the transmittance for each of the pixels. A light emitting unit in which a plurality of light emitting elements are embedded in a recess corresponding to a pixel;
A light emission control unit for circulating and lighting a plurality of light emitting elements in each recess;
A liquid crystal panel that changes the orientation of liquid crystal molecules to control the transmittance of light from the light emitting portion;
A panel control unit for controlling the transmittance for each pixel;
The display device according to claim 1, wherein the panel control unit controls, for each color, the transmittance of light of a plurality of colors emitted from each of the plurality of light emitting elements in accordance with the brightness to be realized in each pixel.   The display device according to claim 3, wherein the concave portion is formed of a conductive light shielding film.   The display device according to claim 1, wherein the light emission control unit provides a light extinction period between the cyclic lighting of the light emitting elements.

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