JP2013011648A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device capable of uniformly illuminating an image display element by using a surface emission light source and without using an optical integrator being a complicated optical system.SOLUTION: An image display device includes: light quantity detection means that detects light quantity of a light beam modulated and emitted by an image display element on which an image of a surface emission light source is formed; and control means that detects light quantities of light beams emitted from a first region and a second region of the image display element, and when the light quantities of the light beams emitted from the first region and the second regions are different, controls a modulation amount of the image display element or a light emission amount of the surface emission light source.

Description

  The present invention relates to an image display device, and more particularly to an image display device that can be used for a projector that enlarges and projects an image on a projection surface.

  Conventionally, there are liquid crystal panels and micromirror array devices as image display elements used in projectors. These control the transmission and blocking of the light beam, or control the deflection to form a desired image. In a projector, the image is projected on a screen using a projection lens.

  Here, in order to reduce illuminance unevenness on a screen, it is known to use an optical integrator having two two-dimensionally arranged lens arrays as Koehler illumination. That is, the light flux from the light source is divided into a plurality of light fluxes by the first lens array, and the plurality of the divided light fluxes are superimposed on the display area of the image display element by the second lens array. In this method, since a plurality of divided light beams are superposed, a highly uniform irradiation light beam is obtained, and the illuminance unevenness on the screen is greatly improved.

  As Koehler illumination, there is a method of making a light source image uniform by passing a light beam from a light source through a kaleidoscope which is a rod-type optical integrator. That is, this is a method of illuminating the image display element by using the light flux on the end face on the light emission side of the uniformed kaleidoscope. This method is generally used to illuminate a digital mirror device type image display element called DMD.

  A projection type liquid crystal display device for critical illumination in which a rectangular light emitting region of an LED and an image display element are optically conjugate with respect to an illumination optical system is known (Patent Document 1). However, no mention is made regarding the illumination uniformity of a liquid crystal panel as an image display element.

JP 2006-350171 A

  As described above, a so-called fly-eye lens that is a two-dimensionally arranged lens array and a kaleidoscope that is a rod-type integrator are used as an optical integrator. Such an optical integrator is generally a complicated optical system. . This is because a high-pressure mercury lamp, a xenon lamp, or a metal halide lamp having high luminous efficiency has been used as a light source for a projector without a surface light source that emits bright luminance.

  Accordingly, an object of the present invention is to provide an image display device that can use a surface-emitting light source and uniformize the illuminance emitted from each partial area of the image display element without using an optical integrator that is a complex optical system. It is in.

  In order to achieve the above object, a typical configuration of an image display device according to the present invention is provided on a surface emitting light source, an imaging optical system that forms an image of the surface emitting light source on a predetermined surface, and the predetermined surface. An image display element and a light amount detecting means for detecting the light amount of the light beam modulated and emitted by the image display element, wherein the light amount of the light beam emitted from the first area and the second area of the image display element is When the light amount detecting means to detect and the light amount of the light beam emitted from the first region and the light amount of the light beam emitted from the second region are different, the light amount of the light beam emitted from the first region and the second region Control means for controlling the modulation amount of the image display element or the light emission amount of the surface-emitting light source so that the amount of light approaches.

  ADVANTAGE OF THE INVENTION According to this invention, the image display apparatus which can make uniform the illumination intensity emitted from each partial area of an image display element, without using the optical integrator which is a complicated optical system can be provided.

1 is a configuration perspective view of a projection type image display apparatus according to an embodiment of the present invention. (A), (B) is a schematic block diagram of the liquid crystal modulation panel used for embodiment of this invention. (A), (B) is a schematic block diagram of the LED light source used for embodiment of this invention. It is a block block diagram of the control driver used for embodiment of this invention. It is a figure explaining a field sequential display. It is a schematic block diagram of the projection type image display apparatus which has arrange | positioned the sensor for uniformity control in embodiment of this invention. It is a display area explanatory drawing of the liquid crystal modulation panel for demonstrating the method of uniformity control. It is explanatory drawing for demonstrating the control process of uniformity control.

  Hereinafter, as a preferred embodiment of the present invention, an image display device that is small and can be reduced in price will be described in detail with reference to the drawings.

<< First Embodiment >>
(Illumination optics)
First, the illumination optical system used in this embodiment will be described with reference to FIG. FIG. 1 is a perspective view of main components constituting a projection type image display apparatus. The LED used as the light source uses three RGB color LEDs corresponding to the three primary colors of red, green and blue. 1R is an LED light source for R color (red color), and 1G is an LED light source for G color (green color). Reference numeral 1B denotes a B (blue) LED light source. The radiated light beams from the LEDs of each of the RGB colors are converted into substantially parallel light beams by the R color collimator lens 2R, the G color collimator lens 2G, and the B color collimator lens 2B, and the cross dichroic is a dichroic filter. Incident on the prism 3.

  The cross dichroic prism 3 as a color synthesis optical system has a characteristic of transmitting a G color light beam, and has a characteristic of reflecting an R color and a B color by a dichroic film arranged in a cross shape. Yes. It arrange | positions so that each RGB light beam may be guided to the right back side in the figure. The cross dichroic prism 3 is arranged so that the three colors of RGB pass through the same optical path. Next, the light beam emitted from the cross dichroic prism 3 passes only the polarization component in the vertical direction in the figure by the polarizing plate 4.

  Here, the light flux that has passed through the polarizing plate 4 is projected on the effective display area of the liquid crystal modulation panel 8 by the relay lens 5 as an image of the light emission area of each LED light source (near field pattern of the light emission light flux of the LED). That is, the combined optical system of the collimator lens 2 and the relay lens 5 forms an image of the LED light source on a predetermined surface on which the liquid crystal modulation panel is provided, and the LED light source and the liquid crystal modulation panel are optically conjugate.

  In the optical path of this substantially image projection, the polarization beam splitter 6 reflects the polarization component in the vertical direction in the figure, and guides the light beam in the direction in which the liquid crystal modulation panel 8 is disposed. Further, by passing through the wave plate 7, the polarization direction of the light beam is finely adjusted so as to match the black display retardation of the liquid crystal modulation panel 8. The light beam reaching the liquid crystal modulation panel 8 is reflected with a phase difference in each pixel area according to the modulation state of a plurality of pixels arranged in the display area of the liquid crystal modulation panel.

  Here, regarding the image information displayed on the liquid crystal and the control of the RGB display frame, the control driver 200 selects the RGB light emission color of the LED light source, determines the display image of the liquid crystal modulation panel according to the light emission color, and time-series. Is controlling. Further, the control driver 200 controls the uniform light illuminance to the liquid crystal modulation panel. The uniform light intensity control will be described later in detail.

  The light beam that has undergone the phase difference modulation of the image by the liquid crystal modulation panel 8 is reflected, passes through the wave plate 7 that corrects the retardation of the liquid crystal again, and enters the polarization beam splitter 6. The light beam incident on the polarization beam splitter 6 is reflected in the vertical polarization component in the figure and returned to the light source side, and the polarization component in the horizontal direction in the figure passes through the polarization separation film and is guided to the projection lens 9 side. That is, the state in which the phase difference modulation is applied to each pixel by the liquid crystal modulation panel 8 is converted into an optical image, and the portion to which the phase difference is applied is transferred to the projection lens 9 as an optical image.

  The projection lens 9 that is a projection optical system performs an enlarged conjugate projection on the screen 10 that is the projection surface of the image display area surface of the liquid crystal modulation panel 8, and an optical image is projected onto the screen 10. The screen 10 is composed of a light diffusing surface. By diffusing and reflecting the irradiated light, an image can be visually recognized by looking at the screen.

   Here, with respect to the imaging state of the LED light source for R color, G color, and B color on the liquid crystal modulation panel, the focus that eliminates the difference in the imaging state by individually adjusting the collimator lens for each color Adjustments can be made.

  If the collimator lens is adjusted, the difference in the imaging state of the R, G, and B light fluxes through the cross dichroic prism 3, the relay lens 5, the polarizing beam splitter 6 and the like, which are optical components after the collimator lens, can be obtained. Can absorb.

  The projection type image display apparatus described in the present embodiment is described in a system in which one liquid crystal modulation panel 8 is arranged. However, the liquid crystal display panels are for R color, G color, and B color. It can also be used in a system of three commonly called three-plate color liquid crystal projectors using three.

  The projection type image display apparatus described in this embodiment uses a liquid crystal modulation panel for image modulation, but a plurality of micromirrors constituting pixels such as a digital mirror device are individually provided as image modulation devices. A device that performs deflection modulation may be used. In this case, the polarizing plate 4 and the wave plate 7 are unnecessary, and illumination light called a total reflection tilt prism is obliquely incident on the digital mirror device instead of the polarizing beam splitter, and the modulation reflection direction is on the display surface of the digital mirror device. The optical system may be replaced with an optical system configured to reflect vertically.

(LCD modulation panel)
Next, a liquid crystal modulation panel used in the configuration of the projection type image display apparatus will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the liquid crystal modulation panel, where (A) is a perspective view and (B) is a top view. An image display area of the liquid crystal display panel is an area indicated by reference numeral 804, and the liquid crystal is disposed in an area sandwiched between the liquid crystal circuit substrate 801 and the counter glass substrate 802. The liquid crystal layer maintains a thickness of about 3 μm and is maintained by sealing on the outer periphery of the image display region with a sealing material mixed with a gap maintaining material such as beads.

  The image display area 804 is composed of a plurality of pixels arranged in a matrix, and each pixel is electrically controlled by an image signal and a control signal input from the flexible terminal 803. A predetermined voltage corresponding to an image is applied to each electrically controlled pixel, an ITO full-surface electrode is disposed on the opposing glass substrate, and a predetermined constant voltage is applied to the ITO electrode. In this state, a voltage corresponding to image information is applied to the liquid crystal sandwiched between the liquid crystal circuit substrate 801 and the counter glass substrate 802 at the position of each pixel.

  By this voltage, the liquid crystal displaces the direction of the molecular arrangement, and the liquid crystal having birefringence changes the direction, thereby giving a phase difference to the passing light and displaying an image. Here, the image display area 804 has a rectangular shape in which a plurality of images are arranged.

(LED light source)
Next, an LED light source which is a one-chip surface emitting light source used in the configuration of the projection display device will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of the LED light source, where (A) is a perspective view and (B) is a top view. The configuration of the LED light source is the same for each of the R color, G color, and B color. The light emission region of the LED light source is a surface region of the LED element 101, and the LED element 101 has a light emitting layer inside, and the light emitting layer is an electrode that injects electrons into the light emitting layer and an electrode that injects holes into the light emitting layer. It is a structure sandwiched between.

  Wire bonding 104 is connected to an electrode for injecting holes from the upper surface in the drawing, and wiring patterned on the LED element substrate 102 is connected to an electrode for injecting electrons from the lower and rear surfaces of the LED element in the drawing. These two wirings are connected to the terminal pad 103, and by supplying power to the terminal pad 103, the LED element 101 forms an exciton combination of electrons and holes in the light emitting layer, and photons are generated and emitted to the outside. It has a structure. Here, the light emitting region which is the upper surface of the LED element 101 has a rectangular shape.

  In this embodiment, an LED element is used as a surface emitting light source. However, an organic EL (an element in which an organic material emits photons by exciton coupling) or FED (an electron field) is used as long as it has surface emitting characteristics. An element that emits a phosphor by emission) may be used.

  Both the image display area 804 of the liquid crystal modulation panel described so far and the light emitting area of the LED element 101 are rectangular. More preferably, the aspect ratio, which is the aspect ratio of the long side and the short side of the rectangle of the image display area 804 of the liquid crystal modulation panel, is the same as the aspect ratio of the rectangle of the light emitting area of the LED element 101 and corresponds to the similar shape. It is the most preferable one. Therefore, in the present embodiment, the optical system of the projection display apparatus projects the near-field pattern of the light emission of the LED element to the image display area 801 of the liquid crystal modulation panel so as to have the same aspect ratio.

  The substantially conjugate projection means that the LED light emitting near-field image is moderately blurred in order to avoid the image of the wire bonding 104 that supplies power to the LED element 101 being projected clearly on the image display area 804. It is what you are doing.

  In addition, when the LED element 101 is used as a light source for controlling one color by arranging N LED elements in a state where N LED elements are close to each other, the light emitting surface of the LED element 101 in FIG. The near field pattern is a pattern of N times N light emitting areas. In this case, the optical system of the projection display apparatus appropriately blurs the image of the near-field pattern of the light emission of the LED element to the image display area 801 of the liquid crystal modulation panel. As a result, the image display area 804 of the liquid crystal modulation panel can be illuminated with light almost evenly.

(Operation process of image display device)
Next, an operation process in which the projection type image display apparatus according to this embodiment displays an image will be described with reference to FIGS. Details of the configuration of the control driver 200 shown in FIG. 1 are shown in FIG. The image signal to be displayed is stored in the frame memory 201 from the main body of the apparatus or an external PC apparatus or video player apparatus. The frame memory 201 can store image information of three frames for R, G, and B colors. On the other hand, the control driver 200 has a control clock 202 and operates by synchronizing the timing based on this clock signal. The timing control unit 203 receives a synchronous basic clock from the control clock 202.

  Regarding the drive of the liquid crystal modulation panel 8, the timing control unit 203 performs information transfer from the frame memory 201 and operation timing control of the image output control unit 204 for transferring image information to the liquid crystal modulation panel 8. On the other hand, for the LED light sources 1R, 1G, and 1B, the timing control unit 203 performs operation timing control of the switching control unit 205 that switches the operations of the R driver 206R, G driver 206G, and B driver 206B that drive light emission. . Further, a liquid crystal power source 207 that controls power supply to the liquid crystal modulation panel 8 and an LED power source 208 that controls power supply to the LED light sources 1R, 1G, and 1B are provided.

(Image display process)
An image display process using the above-described control driver will be described with reference to FIG. The image information displayed on the liquid crystal modulation panel 8 is cyclically repeated with one set for the R color, the G color, and the B color. In synchronism with the cyclically repeated liquid crystal display image, the R color LED light source 1R emits and lights and the G color image is displayed for the time during which the R color image is displayed. The LED light source 1G for G color emits light. The process in which the LED light source 1B for B color emits light is repeated during the time when the B color image is displayed. On the screen 10, the R color component, the G color component, and the B color component are displayed in time series for one image frame.

  This is generally called a field sequential display method. If the display time of an RGB color image of one image frame is short, a user observing the image recognizes a mixed color of RGB colors. A color image is observed. Generally, 60 Hz image signals are widely used as the image information data that is the source to be displayed at present. When the RGB color display is displayed at 180 Hz with respect to the 60 Hz image information, it is a color for normal viewing. It can recognize images.

(Light illumination uniformity control)
If the LED light source has light emission intensity unevenness in the light emitting surface due to individual differences of the LED light sources, the light emission unevenness of the light source is directly transferred to the illumination unevenness of the image display element when performing critical illumination. In addition, when the LED light source emits light for a long time, even when the state of uneven emission intensity changes due to a change in time, unevenness occurs in the amount of light projected on the screen, which is not preferable.
Even if the light emission intensity of the light emitting surface of the LED light source itself is uniform, the illuminance unevenness on the image display element also occurs when there is a wavelength dependency and an angle dependency of the imaging relationship between the light source and the image display element. .

  In the present invention, since the control means for equalizing the illuminance emitted from each part of the image display element is provided, the above problem can be solved.

  A control method for equalizing the illuminance emitted from each partial area of the image display element will be described with reference to FIGS. FIG. 6 shows a projection type image of a light quantity sensor 300 as a light quantity detecting means for detecting the quantity of light emitted from the first area and the second area of the liquid crystal modulation panel 8 as an image display element and entering the projection lens 9. The case where it inserts into a display apparatus is shown.

  Only when the light intensity sensor 300 performs control to equalize the light illuminance, the light receiving surface is directed to the light incident side position of the projection lens that is emitted from the liquid crystal modulation panel 8 and enters the projection lens 9, and the light receiving surface is directed to the polarization beam splitter 6 side. Inserted and fixed. Here, when performing control to make the light illuminance uniform, as shown in FIG. 7, the image display area 804 of the liquid crystal modulation panel 8 is an area divided into M times N and is white in time order (maximum reflectance). Will be displayed. Note that the area not displaying white displays black (reflectance minimum state).

  In an ideal state where the illuminance emitted from each partial area of the image display element is uniform, the output of the light quantity sensor 300 that receives the light beams sequentially emitted from each partial area of the image display element has a constant value over time. When the output of the light quantity sensor 300 does not become a constant value in time, the output of the light quantity sensor 300 becomes a constant value in time by modulating each partial area of the image display element or the surface emitting light source.

  FIG. 8 illustrates a sequence for equalizing the illuminance emitted from each partial area of the image display element. First, the light quantity sensor 300 is inserted into the above-described position, and the liquid crystal modulation panel is displayed as a black state at the time of R color display. Next, the LED light source is turned on for the R color. The N-divided M divided area of the liquid crystal modulation panel is sequentially modulated into a white state by a loop j of i, and the output value of the light quantity sensor 300 is sequentially read in synchronization with the loop order, and the control driver 200 Set the data in the memory.

  The aforementioned R color display is repeated in the order of G color display and B color display. The light amount sensor output value data in the white state at the display positions of all RGB colors is read and set in the memory, and then the light amount sensor 300 is retracted from the optical path.

  Based on the white state display light quantity data of each color of RGB set in the memory, the control driver 200 controls the modulation amount of the image display element or the surface emitting light source so as to be in the initial manufacturing state (ideal state) of the apparatus. The amount of light emission is controlled for each partial area. When the image display element is modulated for each partial area, each partial area is an area of a pixel or a pixel group (a group of a plurality of adjacent pixels). When the surface emitting light source is modulated for each partial area, each partial area is an area of a unit light source constituting the surface emitting light source.

  Even when the emission intensity of the surface light source varies with time, the light quantity sensor 300 receives the light beams sequentially emitted from the partial areas emitted from the liquid crystal modulation panel 8, and the illuminance is the same as described above. Can be made uniform. That is, when the output of the light quantity sensor 300 does not become a constant value in time, the same correction can be performed by modulating each partial area of the liquid crystal modulation panel 8 as an image display element or the LED light source 1 as a surface light source. It becomes possible.

(Modification)
In the embodiment described above, the liquid crystal modulation panel is a reflection type, but may be a transmission type. Further, as the imaging optical system, any lens optical system other than the above-described embodiment or any mirror optical system can be used.

1 .... LED light source, 2 .... collimator lens, 3 .... cross dichroic prism, 4 .... polarizing plate, 5 .... relay lens, 6 .... polarizing beam splitter, 7 .... wavelength plate, 8 .... liquid crystal modulation panel 9, Projection lens, 10 ... Screen, 200 ... Control driver, 300 ... Light sensor

Claims (7)

A surface emitting light source;
An imaging optical system for imaging the surface-emitting light source on a predetermined surface;
An image display element provided on the predetermined surface;
Light amount detection means for detecting the light amount of the light beam modulated and emitted by the image display element, the light amount detection means for detecting the light amount of the light beam emitted from the first area and the second area of the image display element, respectively. When,
When the light amount of the light beam emitted from the first region is different from the light amount of the light beam emitted from the second region, the light amount of the light beam emitted from the first region and the second region is made closer to each other. Control means for controlling the modulation amount of the image display element or the light emission amount of the surface-emitting light source;
An image display device comprising:   The surface-emitting light sources are a plurality of light sources that respectively emit three primary colors of red, green, and blue. The image display device according to claim 1, wherein the image display element is illuminated by combining the two through a dichroic filter. A plurality of collimator lenses for converting light beams emitted from the respective surface-emitting light sources into parallel light beams;
The image display device according to claim 2, wherein the focus adjustment for forming each surface emitting light source on the image display element is performed by adjusting each collimator lens.   The image display apparatus according to claim 1, wherein the surface-emitting light source is an LED light source.   The image display apparatus according to claim 1, wherein the surface-emitting light source is a one-chip surface-emitting light source. The aspect ratio of the light emitting area of the surface-emitting light source is the same as the aspect ratio of the image display area of the image display element,
The long side and the short side of the light emitting region of the surface-emitting light source are projected in a variable magnification corresponding to the long side and the short side of the image display region of the image display element. The image display device according to any one of the above.   The image display apparatus according to claim 1, further comprising a projection optical system that projects a light beam emitted from the image display element onto a projection surface.