JP2009069286A - Projection type image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of image quality due to color breakup in a two-plate projection type image display device using two image display elements. <P>SOLUTION: A light source driving part 9 selects two of light sources 1A to 1C and makes them emit light, and switches combination of two light sources which emit light simultaneously by frequency three times as high as frame frequency in an image signal. An image display element driving part 11 supplies the image signal corresponding to color of light made incident on a first reflection type image display element 7A and a second reflection type image display element 7B in accordance with switching of combination of the two light sources which emit light simultaneously, so as to drive the first reflection type image display element 7A and the second reflection type image display element 7B. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a two-plate projection type image display apparatus that projects a color image onto a screen using two image display elements.

  Conventionally, as a two-plate projection type image display device that projects a color image using two image display elements, there is one disclosed in Patent Document 1.

  FIG. 4 is a schematic configuration diagram of a projection-type image display device disclosed in Patent Document 1. In the projection type image display apparatus shown in FIG. 4, red light (R light), green light (G light), and blue light (B light) included in the light emitted from the light source 101 and collected by the elliptical mirror 102. The three primary color lights are divided into two color light groups by the rotating color filter 103 and sequentially derived in a time division manner.

  The light that has passed through the rotating color filter 103 is made uniform in illuminance distribution by the glass rod 104, then becomes substantially parallel light by the illumination lens 105 and the field lens 106, and its polarization direction is aligned by the polarizing plate 107, The light enters the polarization control element 108.

  In the polarization control element 108, the polarization direction can be changed between two colors of light of R light, G light, and B light and the light of the other color, and the polarization beam splitter 109 responds to the polarization direction. It is separated into light, and the separated light is modulated by the image signal in the reflection type image display elements 110A and 110B.

After the light modulated by the reflective image display elements 110A and 110B is combined by the polarization beam splitter 109, the polarization control element 111 aligns the polarization directions of the R light, G light, and B light. The light leakage light that is originally cut is cut by the polarizing plate 112. Then, light incident on the projection lens 113 from the polarizing plate 112 is projected onto the screen.
JP 2000-347323 A

  In Patent Document 1, light of the three primary colors R light, G light, and B light from the light source 101 is divided into two color light groups by the rotating color filter 103 and sequentially derived and displayed in time division. When the frequency is low, a phenomenon in which each color can be recognized (hereinafter referred to as color breakup) occurs, and a high-quality image cannot be displayed.

  On the other hand, when trying to increase the time division frequency, the response speed of the liquid crystal in the reflective image display elements 110A and 110B, which are liquid crystal image elements, is slow, so the time division frequency cannot be increased to some extent. A high-quality image could not be displayed.

  The present invention has been made in view of the above, and an object of the present invention is to suppress deterioration in image quality due to color breakup in a two-plate projection type image display apparatus using two image display elements.

  In order to achieve the above object, the present invention provides a projection type image display apparatus having the following configuration.

  (A) The first to third light sources (1A to 1C) that emit the first to third colored lights and the first to third colored lights are incident from three different incident surfaces, respectively, A dichroic prism (4) for emitting third color light from a single emission surface; light source driving means (9) for emitting two color lights from any two of the first to third light sources; and the light source. Two reflective image display elements (7A, 7B) for modulating and reflecting the two color lights corresponding to the image signals of any two color lights emitted from the first to third light sources by the driving means; The light source driving means causes any two color lights emitted from the first to third light sources to be incident, separates the two color lights, and enters the two reflective image display elements. Modulated by two reflective image display elements In a projection type image display device comprising a polarization beam splitter (6) that synthesizes and emits two colored lights, the first to third light sources are arranged between the first to third light sources and the dichroic prism, and The first to third polarization rotation elements (3A to 3C) that emit the polarized light of the color light having a predetermined polarization plane, and the light source driving means emits the light from any one of the first to third light sources. Polarization rotation element driving means (10) for controlling the first to third polarization rotation elements so that the polarization planes of the colored lights are orthogonal to each other, and the first to third light beams controlled by the polarization rotation element driving means. An image display element driving means (11) for controlling to supply image signals corresponding to two color lights whose polarization planes emitted from the polarization rotation element are orthogonal to each other to the first and second reflective image display elements; , The image signal In synchronization with a period three times the frame period, the light source driving means selects any two of the first to third light sources, and the polarization rotation element driving means from the first to third light sources. The polarization planes of any two color lights to be emitted are orthogonal to each other, and the image display element driving means outputs image signals of any two color lights to be emitted from the first to third light sources to the two reflection types. A projection type image display device comprising control means (12) for supplying the image display element.

  (B) The first to third light sources (1A to 1C) that emit the first to third color lights and the first to third color lights are incident from three different incident surfaces, respectively. A dichroic prism (4) for emitting third color light from a single emission surface; light source driving means (9) for emitting two color lights from any two of the first to third light sources; and the light source. Two reflective image display elements (7A, 7B) for modulating and reflecting the two color lights corresponding to the image signals of any two color lights emitted from the first to third light sources by the driving means; The light source driving means causes any two color lights emitted from the first to third light sources to be incident, separates the two color lights, and enters the two reflective image display elements. Modulated by two reflective image display elements In a projection type image display device comprising a polarization beam splitter (6) that synthesizes and emits two colored lights, the first to third light sources are arranged between the first to third light sources and the dichroic prism, and The first to third polarization rotation elements (3A to 3C) that emit the polarized light of the color light having a predetermined polarization plane, and the light source driving means emits the light from any one of the first to third light sources. Polarization rotation element driving means (10) for controlling the first to third polarization rotation elements so that the polarization planes of the colored lights are orthogonal to each other, and the first to third light beams controlled by the polarization rotation element driving means. An image display element driving means (11) for controlling to supply image signals corresponding to two color lights whose polarization planes emitted from the polarization rotation element are orthogonal to each other to the first and second reflective image display elements; , The image signal In synchronism with a period that is six times the frame period, the light source driving means selects any two of the first to third light sources, and the polarization rotation element driving means from the first to third light sources. The polarization planes of any two color lights to be emitted are orthogonal to each other, and the image display element driving means outputs image signals of any two color lights to be emitted from the first to third light sources to the two reflection types. A projection type image display device comprising control means (12) for supplying the image display element.

  According to the present invention, in a two-plate projection type image display apparatus using two image display elements, it is possible to suppress deterioration in image quality due to color breakup.

  The best mode for carrying out the projection type image display device of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a projection type image display apparatus according to an embodiment of the present invention. As shown in FIG. 1, the projection type image display apparatus according to the present embodiment includes light sources 1A to 1C, light pipes 2A to 2C, polarization rotation elements 3A to 3C, a cross dichroic prism 4, and a field lens 5A. , 5B, the polarization beam splitter 6, the first reflective image display element 7A, the second reflective image display element 7B, the projection lenses 8A and 8B, the light source drive unit 9, and the polarization rotation element drive unit. 10, an image display element driving unit 11, and a control unit 12.

  The light sources 1A to 1C include LEDs (Light Emitting Diodes), laser light sources, and the like. The light source 1A emits red light (R light), the light source 1B emits green light (G light), and the light source 1C emits blue light (B light). To do.

  The light pipes 2A to 2C average the intensity distribution of the light emitted from the light sources 1A to 1C, respectively.

  The polarization rotation elements 3 </ b> A to 3 </ b> C change the polarization direction of the light emitted from the light pipes 2 </ b> A to 2 </ b> C by the voltage applied from the polarization rotation element driving unit 10.

  The cross dichroic prism 4 has an R light reflecting dichroic film 4a and a B light reflecting dichroic film 4b arranged in an X shape therein. The cross dichroic prism 4 reflects the R light incident from the polarization rotating element 3A by the R light reflecting dichroic film 4a, reflects the B light incident from the polarization rotating element 3C by the B light reflecting dichroic film 4b, and also reflects the polarization rotating element. The G light incident from 3B is transmitted to synthesize each color light, and the synthesized light is emitted.

  The field lenses 5A and 5B use light emitted from the cross dichroic prism 4 as light that is condensed on the first reflective image display element 7A and the second reflective image display element 7B.

  The polarization beam splitter 6 has a polarization film 6a disposed so as to be incident at approximately 45 degrees with respect to the optical axis of the light from the cross dichroic prism 4 incident through the field lenses 5A and 5B. The light incident on the film 6a is split in two directions according to the polarization direction. Then, one of the lights dispersed in two directions is incident on the first reflective image display element 7A, and the other is incident on the second reflective image display element 7B.

  Further, the polarization beam splitter 6 reflects the light that has been polarized and modulated by the first reflective image display element 7A, reflected by the polarizing film 6a, and then radiates the optical axis by about 90 ° and emits the light. The polarization beam splitter 6 transmits the light that has been polarized and modulated by the second reflective image display element 7B, and combines and emits the light from the first reflective image display element 7A.

  The first reflection-type image display element 7A reflects the light that has been transmitted through the polarizing film 6a of the polarizing beam splitter 6 and polarized and modulated by an image signal corresponding to the color of the light, and has been polarization-modulated. Is incident on the polarization beam splitter 6.

  The second reflective image display element 7B reflects and reflects the light that has been reflected and incident on the polarizing film 6a of the polarizing beam splitter 6 with the image signal corresponding to the color of the light. Is incident on the polarization beam splitter 6.

  The projection lenses 8A and 8B project the light emitted from the polarization beam splitter 6 onto the screen 13.

  The light source drive unit 9 drives the light sources 1A to 1C under the control of the control unit 12, and the polarization rotation element drive unit 10 drives the polarization rotation elements 3A to 3C under the control of the control unit 12. The image display element driving unit 11 drives the first reflective image display element 7A and the second reflective image display element 7B under the control of the control unit 12. The control unit 12 controls the entire apparatus including the light source driving unit 9, the polarization rotation element driving unit 10, and the image display element driving unit 11.

  Next, the operation of the projection type image display apparatus according to this embodiment will be described.

  In the projection type image display apparatus according to the present embodiment, as shown in FIG. 2, the first reflection type image display element 7A and the second reflection type image display element 7B are R light, G light, B light. Are driven by an image signal always corresponding to a combination of two different colors. The combination of the two colors is sequentially switched at a frequency three times the frame frequency in the image signal. That is, as shown in FIG. 2, when the frame display interval is t, the combination of two colors is switched every t / 3. Therefore, one frame is displayed in three subframes (SF).

  Corresponding to this, the light sources 1A to 1C and the polarization rotation elements 3A to 3C are driven at the timing shown in FIG.

  As shown in FIG. 2, the light source driving unit 9 selects two light sources among the light sources 1 </ b> A to 1 </ b> C to emit light under the control of the control unit 12, and determines a combination of the two light sources that emit light simultaneously in the image signal. Switching is performed sequentially at a frequency three times the frame frequency.

  Then, in synchronization with the drive timing of the light sources 1A to 1C, the polarization rotation element driving unit 10 rotates the polarization so as to change the polarization direction of each color light emitted from the light sources 1A to 1C under the control of the control unit 12. The elements 3A to 3C are driven.

  For example, in the first sub-frame display period of the first frame, the control unit 12 controls the light source driving unit 9 so as to emit light from the light sources 1A and 1B, and the polarization rotating element 3A converts the R light into the polarization beam splitter 6. The polarization rotation element driving unit 10 is controlled so that the polarization light is P-polarized with respect to the polarization film 6a and the G rotation light is S-polarization with respect to the polarization film 6a by the polarization rotation element 3B.

  The R light converted to P-polarized light with respect to the polarizing film 6 a is reflected by the R light reflecting dichroic film 4 a of the cross dichroic prism 4, and its optical axis is bent by approximately 90 °, and the polarized light of the field lenses 5 A and 5 B and the polarizing beam splitter 6. The light passes through the film 6a and enters the first reflective image display element 7A.

  On the other hand, the S-polarized G light with respect to the polarizing film 6a passes through the cross dichroic prism 4 and the field lenses 5A and 5B, is reflected by the polarizing film 6a of the polarizing beam splitter 6, and has an optical axis of approximately 90 °. It is bent and enters the second reflective image display element 7B.

  The control unit 12 supplies an image signal corresponding to the R light to the first reflective image display element 7A, and supplies an image signal corresponding to the G light to the second reflective image display element 7B. The image display element driving unit 11 is controlled so as to drive the first reflective image display element 7A and the second reflective image display element 7B.

  The R light incident on the first reflective image display element 7A is polarized and modulated by an image signal corresponding to the R light, and is incident on the polarization beam splitter 6. Further, the G light that has entered the second reflective image display element 7B is polarized and modulated by an image signal corresponding to the G light, and is incident on the polarization beam splitter 6.

  The polarization direction of the R light that has been polarization-modulated by the first reflective image display element 7 </ b> A changes from P-polarized light to S-polarized light with respect to the polarizing film 6 a of the polarizing beam splitter 6. For this reason, the R light is reflected by the polarizing film 6 a, and its optical axis is bent by approximately 90 ° and emitted from the polarizing beam splitter 6.

  The polarization direction of the G light polarized and modulated by the second reflective image display element 7B is changed from S-polarized light to P-polarized light with respect to the polarizing film 6a of the polarizing beam splitter 6. For this reason, the G light passes through the polarizing film 6 a, is combined with the R light, and is emitted from the polarizing beam splitter 6.

  The light emitted from the polarizing beam splitter 6 is projected as a color image on the screen 13 by the projection lenses 8A and 8B.

  Then, at the display timing of the second sub-frame of the first frame, the control unit 12 controls the light source driving unit 9 so as to switch the light source that emits light from the light sources 1A and 1B to the light sources 1B and 1C.

  In synchronization with the switching timing of the light source that emits light, the control unit 12 continuously changes the polarization direction of the G light to the S-polarized light with respect to the polarization film 6a of the polarization beam splitter 6 by the polarization rotation element 3B, and B light by the polarization rotation element 3C. Is controlled to be P-polarized light with respect to the polarizing film 6a.

  Further, the control unit 12 supplies an image signal corresponding to the B light to the first reflective image display element 7A in synchronization with the switching timing of the light source that emits light, and continues to the image signal corresponding to the G light. The image display element driving unit 11 is controlled so as to drive the first reflection type image display element 7A and the second reflection type image display element 7B.

  In the same manner, as shown in FIG. 2, the combination of two light sources that simultaneously emit light among the light sources 1A to 1C is sequentially switched at a frequency three times the frame frequency, and in synchronization with the timing of switching the light sources, The polarization rotation elements 3A to 3C, the first reflection type image display element 7A, and the second reflection type image display element 7B are driven.

  As described above, according to the present embodiment, since the first reflective image display element 7A and the second reflective image display element 7B are used, images of two colors of the three primary colors are always displayed. Compared with a device that sequentially displays two of the three primary colors in a time-division manner as in Document 1, the occurrence of color breakup can be reduced and a higher quality image can be displayed.

  As shown in FIG. 3, a combination of two light sources that simultaneously emit light among the light sources 1A to 1C is sequentially switched at a frequency six times the frame frequency, and in synchronization with the switching timing of the light sources, the polarization rotation element You may make it drive 3A-3C, 7 A of 1st reflective image display elements, and the 2nd reflective image display element 7B. In this case, one frame is displayed with six subframes (SF).

  By doing so, compared to the case where each unit is driven at the timing of FIG. 2, the color changes at twice the frequency, and further, the phenomenon of color breakup can be prevented, resulting in a higher quality image. Can be displayed.

1 is a schematic configuration diagram of a projection type image display apparatus according to an embodiment of the present invention. It is a timing chart which shows an example of the drive timing of a light source, a polarization | polarized-light rotation element, and a reflection type image display element. It is a timing chart which shows another example of the drive timing of a light source, a polarization rotation element, and a reflection type image display element. It is a schematic block diagram of an example of the conventional projection type image display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A-1C Light source 2A-2C Light pipe 3A-3C Polarization rotation element 4 Cross dichroic prism 5A, 5B Field lens 6 Polarization beam splitter 7A 1st reflection type image display element 7B 2nd reflection type image display element 8A, 8B Projection Lens 9 Light source drive unit 10 Polarization rotation element drive unit 11 Image display element drive unit 12 Control unit

Claims (2)

The first to third light sources that emit the first to third color lights and the first to third color lights are incident from three different incident surfaces, and the first to third color lights are single Emission from the first to third light sources by the dichroic prism to be emitted from the emission surface, light source driving means for emitting two colored lights from any two of the first to third light sources, and the light source driving means. Any one of the two reflection-type image display elements that modulates and reflects the two color lights corresponding to the image signals of any two color lights, and any of the first to third light sources emitted by the light source driving means. The two color lights are incident, the two color lights are color-separated and incident on the two reflective image display elements, and the two color lights modulated by the two reflective image display elements are combined and emitted. Polarizing beam splitting In the projection type image display device provided with bets,
First to third polarization rotation elements that are arranged between the first to third light sources and the dichroic prism and emit the first to third color light with a polarization plane as a predetermined polarization plane;
A polarization rotation element driving means for controlling the first to third polarization rotation elements so that the polarization planes of the colored lights emitted from any two of the first to third light sources are orthogonal to each other by the light source driving means; ,
The first and second reflection-type image displays image signals corresponding to two color lights whose polarization planes emitted from the first to third polarization rotation elements are orthogonal to each other, controlled by the polarization rotation element driving means. Image display element driving means for controlling the supply to each element;
The light source driving means selects any one of the first to third light sources in synchronization with a period three times the frame period of the image signal, and the polarization rotation element driving means causes the first to first The polarization planes of any two color lights emitted from the three light sources are orthogonal to each other, and the image display element driving means outputs the image signals of any two color lights emitted from the first to third light sources. A projection-type image display device comprising: a control unit configured to supply the two reflection-type image display elements. The first to third light sources that emit the first to third color lights and the first to third color lights are incident from three different incident surfaces, and the first to third color lights are single Emission from the first to third light sources by the dichroic prism to be emitted from the emission surface, light source driving means for emitting two colored lights from any two of the first to third light sources, and the light source driving means. Any one of the two reflection-type image display elements that modulates and reflects the two color lights corresponding to the image signals of any two color lights, and any of the first to third light sources emitted by the light source driving means. The two color lights are incident, the two color lights are color-separated and incident on the two reflective image display elements, and the two color lights modulated by the two reflective image display elements are combined and emitted. Polarizing beam splitting In the projection type image display device provided with bets,
First to third polarization rotation elements that are arranged between the first to third light sources and the dichroic prism and emit the first to third color light with a polarization plane as a predetermined polarization plane;
A polarization rotation element driving means for controlling the first to third polarization rotation elements so that the polarization planes of the colored lights emitted from any two of the first to third light sources are orthogonal to each other by the light source driving means; ,
The first and second reflection-type image displays image signals corresponding to two color lights whose polarization planes emitted from the first to third polarization rotation elements are orthogonal to each other, controlled by the polarization rotation element driving means. Image display element driving means for controlling the supply to each element;
The light source driving unit selects any one of the first to third light sources in synchronization with a period that is six times the frame period of the image signal, and the polarization rotation element driving unit causes the first to first polarization units to select. The polarization planes of any two color lights emitted from the three light sources are orthogonal to each other, and the image display element driving means outputs the image signals of any two color lights emitted from the first to third light sources. A projection-type image display device comprising: a control unit configured to supply the two reflection-type image display elements.

Images