JP2008032925A - Projection display system, projection display device, and screen - Google Patents

Abstract

An object of the present invention is to avoid black floating that occurs in an environment with high illuminance around a screen that projects an image from a projector with a simple configuration.
In a front projector system, a so-called electronic paper display (electronic ink) capable of monochrome display by an electrical signal is used for a screen 31 to be used. The electronic paper display displays the screen 31 with the black display image portion corresponding to the image 20 projected on the screen 31 being black and the image portion with high brightness and saturation being white. Then, an optical image (image 20) is projected from the projection display device 1 and displayed in an overlapping manner.
[Selection] Figure 1

Description

  The present invention relates to a projection display system, a projection display device, and a screen, and more particularly to a projection display system, a projection display device, and an image that are suitable for displaying an image on a screen in an environment with high ambient illuminance. Related to the screen.

  Conventionally, as a display device, a projector (projection display device) that projects and displays an image on a screen is known. A front projection type that projects an image from the front of the screen is also called a front projector (front projection type display device). FIG. 11 shows a configuration of a general front projector system.

  The projection display device 100 constituting the front projector system shown in FIG. 11 receives a video signal from the video input terminal 111 in the same manner as widely used. The video signal input to the projection display device 100 is subjected to predetermined signal processing by the video processing device 110 and becomes an image by the optical engine 112. Then, the projected image 114 is projected from the projection lens 113 toward the reflective screen 115, and the projected image 114 formed on the screen 115 is reflected and observed by the viewer.

  In the conventional projection display device 100, a white screen is used to project an image. However, when the projection display device 100 is used, if the illuminance around the screen to be projected is high, the image is originally displayed in black. The power black display portion is not displayed black because light from the surroundings hits the white screen.

  In other words, black or a video with low luminance and low saturation close to black cannot be expressed. This phenomenon is called “black floating” and is a problem to be solved by the front projector system. The black floating image will be described with reference to FIG. FIG. 12A shows a gabled lodge as an example of the original image of a video signal, and FIG. 12B shows an example of a black floating image in which a low-luminance portion is not reproduced. The image of the lodge shown in FIG. 12A appropriately reproduces low-luminance and low-saturation portions such as the back side 122 of the gable roof 121, the gable wall 123 under the eaves, and the casement window 124. On the other hand, in the image of FIG. 12B, the low-brightness and low-saturation portions such as the back side 122 of the gable roof 121, the gable wall 123, and the casement window 124 are not reproduced due to the black float, and thus are not sufficiently expressed. Each part is difficult to distinguish.

  In other words, the above-mentioned “black floating” problem cannot be said to be a sufficient contrast ratio with respect to the contrast of the video represented by the brightness ratio between the white video and the black video. Due to this black float, it is impossible to express gradations and differences in the video included in the dark part of the image. Especially in an environment with high ambient illuminance, the information that the video signal originally has cannot be expressed, and the entire video can be expressed. The quality of the product will be limited.

  Therefore, when a projector is used, it is necessary to sufficiently reduce the illuminance around the screen. On the contrary, it is possible to use a screen other than white because black appears on a white screen (no light is applied) in a bright environment, but in this case, the screen gain (reflection) The overall brightness of the image obtained by the projector is reduced, and on the contrary, a high-luminance portion close to white in the image (for example, the white wall 125 in FIGS. 12A and 12B) cannot be expressed. Absent. Also, the contrast itself is not improved.

  In order to solve these problems, a large number of microelements are arranged on a substrate, and each microelement has a high contrast screen whose surface changes to a low reflectance state or a high reflectance state by switching on / off. It has been proposed (see, for example, Patent Document 1). According to the technique described in Patent Document 1, it is possible to obtain a clear image with high contrast between the black portion and other portions of the image and a strong contrast.

JP 2002-365730 A

  By the way, in the thing of patent document 1, in order to control the reflectance of a screen, it is necessary to provide many fine elements on this screen. As microelements, a microbridge structure, an electrochromic structure, a structure in which an ITO transparent electrode covers the surface of a cell in which iron sand is placed, etc. are disclosed. When installed in a three-dimensional array, the screen has a complicated structure, so high manufacturing technology and cost are required.

  SUMMARY An advantage of some aspects of the invention is that it avoids black floating that occurs in an environment with high illuminance around a screen that projects an image from a projector with a simple configuration.

  In order to solve the above problems, the present invention is a projection display system that projects an image projected from a projection display device onto a screen, the projection display device including a projection image signal and a projection image signal. The video processing unit that generates the video signal for the screen compares the luminance threshold value set in advance with the luminance value of each pixel of the predetermined video signal, and the luminance value lower than the threshold value is compared with the video processing unit. A control unit that instructs to generate a video signal for a screen by setting a pixel having a black color and a pixel having a luminance value higher than the threshold value to be white, and converting the projection video signal into an optical image, and projecting the optical image on the screen An optical image generation unit. The screen also includes a display unit that displays black and white video based on the screen video signal supplied from the projection display device. An optical image based on the projection video signal is projected from the projection display device so as to be superimposed on the video displayed on the screen based on the screen video signal.

  According to the above-described configuration, a display function such as an electronic paper display is provided on the screen, and the display unit can display the screen in black for the black image portion of the projection video signal and in white for the high-luminance image portion. Therefore, for example, even when the screen periphery is bright, the occurrence of black float can be suppressed.

  According to the present invention, with a simple configuration, it is possible to avoid black floating that occurs in an environment where the illuminance around the screen that projects the image from the projector is high, and to improve the contrast.

  Hereinafter, an example of the best mode for carrying out the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a configuration example of a front projector system according to an embodiment of the present invention. The front projector system of the present embodiment uses a so-called electronic paper display (electronic ink) capable of displaying black and white by an electrical signal on the screen to be used, and supports images projected on the screen by the electronic paper display. The black display image portion is black, the image portion having high brightness and saturation is white, and the image is projected thereon.

  As shown in FIG. 1, the front projector system of this embodiment includes a projection display device 1 and a screen system 30 having a screen 31 and a screen drive circuit 39.

  The projection display device 1 receives a video signal from the video input terminal 11 and processes the video signal by the video processing device 10 and converts the video signal into an optical image (video) by the optical engine 12 in the same manner as widely used. To convert. Then, an optical image is projected from the projection lens 13 toward the screen 31, and the projected image 20 formed on the screen 31 is observed by the viewer. In FIG. 1, the optical engine 12 and the projection lens 13 described above are also provided integrally with the projection display device 1, but may be configured separately.

  Here, an example of the configuration of an optical engine that generates an optical image will be described. As shown in FIG. 2, a lamp 50 serving as a light source such as a discharge lamp such as an ultra high pressure mercury lamp (UHP lamp) or a metal halide lamp is disposed at a focal position of a reflector 51 (parabolic mirror). The light emitted from the lamp 50 is reflected by the reflector 51, collimated so as to be a parallel light beam substantially parallel to the optical axis, and emitted from the opening of the reflector 51.

  A light beam emitted from the opening of the reflector 51 is incident on fly-eye lenses (multi-lens arrays) 52 and 53. By passing through the fly-eye lenses 52 and 53, the luminous flux is efficiently and uniformly applied to the effective aperture of the spatial light modulator described later.

  The luminous fluxes that have passed through the fly-eye lenses 52 and 53 are separated by the PS conversion element 54 with high efficiency and polarized light is converted in a certain direction, so that an optimal amount of light is secured. Then, the light passes through the lens 55 and enters the color separation / synthesis optical system after the dichroic mirror 56. First, the dichroic mirror 56 reflects the blue light beam B and transmits the green light beam G and the red light beam R. The blue light beam B reflected by the dichroic mirror 56 is deflected by 90 ° in the optical path by the mirror 57 and guided to the condenser lens 71 in front of the blue spatial light modulator.

  On the other hand, the green and red light beams G and R transmitted through the dichroic mirror 56 are separated by the dichroic mirror 57. That is, in the dichroic mirror 57, the green light beam G is reflected and deflected in the traveling direction by 90 ° and guided to the condenser lens 75 in front of the green spatial light modulator.

  Further, the red light beam R passes through the dichroic mirror 57 and travels straight, and is guided to the condenser lens 79 in front of the red spatial light modulation element via the relay lens 59, the mirror 60, the relay lens 61, and the mirror 62. It is burned.

  In this way, the blue, green, and red light beams B, G, and R pass through the respective condenser lenses 71, 75, and 79 and are incident on the spatial light modulation elements for the respective colors.

  Each of the spatial light modulation elements of each color is composed of a liquid crystal panel and two polarizing plates. For example, the blue spatial light modulation element includes a liquid crystal panel 73 and an incident-side polarizing plate 72 for aligning the polarization direction of incident light in a predetermined direction before the liquid crystal panel 73. Further, a polarizing plate 74 that transmits only a light component having a predetermined polarization plane of the emitted light is disposed at the subsequent stage of the liquid crystal panel 73, and the light intensity is modulated according to the display image by the voltage of the circuit that drives the liquid crystal. It is made to do. Similarly, the green spatial modulation element includes a liquid crystal panel 77 and polarizing plates 76 and 78, and the red spatial modulation element includes a liquid crystal panel 81 and polarizing plates 80 and 82.

  The light beams of the respective colors light-modulated by the spatial light modulation element are incident on the light combining element (dichroic prism) 83 from three directions. The light combining element 83 is configured by combining a cubic prism divided into four and a reflection film formed on the divided surface.

  The blue light beam B in the light combining element 83 is reflected by the reflection film, and the red light beam R is reflected by the reflection film and emitted toward the projection lens 13. The green light beam G travels straight through the light combining element and is emitted toward the projection lens 13. Thus, the light beams B, G, and R are emitted toward the projection lens 13 in a state where they are combined into one light beam.

  The projection lens 113 converts the light beam incident from the light combining element 153 side into projection light, and projects it onto the front surface of the reflective screen 31 described above. In general, in a front projection display device that uses a liquid crystal panel as a light modulation element, the liquid crystal panel uses a polarization state, and therefore projects projection light in a predetermined polarization state.

  As the type of the optical engine 12, in addition to the transmissive liquid crystal panel shown in FIG. 2, a CRT (Cathode Ray Tube), a transmissive liquid crystal panel, a reflective liquid crystal panel, a micro device, etc. There are various types.

  The screen 31 on which the image projected from the optical engine 12 is projected normally has a high reflectance and uniform reflected light in order to efficiently use the light flux of the projected image 20 projected from the projection display device 1. It is required to be white. The present invention is characterized in that an electronic paper display (electronic ink) is used for the screen 31 and the display state of the screen 31 is partially changed in synchronization with the projected image 20.

  Here, the electronic paper display will be briefly described. There are various display methods, but typical ones include a microcapsule electrophoresis method called an electrophoresis method of E Ink of the United States, and a gyricon bead method of Gilicon Media of the United States. These are used as display media in which hemispheres of rotating particles are divided into different colors and charging characteristics, and are currently used in electronic books and the like.

  FIG. 3 shows an example of the structure of an electronic paper display. As shown in FIG. 3, in the electronic paper display, an ink layer (display layer) 33 such as a microcapsule or a gyricon bead and a driver layer 34 for controlling the ink layer are sandwiched between two plastic films (transparent sheets) 32 and 35. It has a structured. The ink layer and the device layer constitute a display unit. The driver layer 34 is made of a TFT (Thin Film Transistor) or an organic transistor, as in the active matrix type liquid crystal display, thereby enabling a self-printing function of electronic paper. Since these electronic paper displays are not self-luminous elements like paper, it is desirable to read or view them in a bright environment.

  A projection display device 1 shown in FIG. 1 includes a video processing device 10 that processes a video signal input from a video input terminal 11, an optical engine 12 that converts the video signal into an optical image, and a projection lens 13. The video processing apparatus 10 includes a video signal processing circuit 21, an SDRAM 23, a flash ROM 24, a control unit 25, and an internal bus 22 that connects the units.

  The control unit 25 controls the video processing apparatus 10 and includes a CPU (Central Processing Unit) and the like. Software (program) necessary for control is stored in the flash ROM 24. The SDRAM (Synchronous DRAM) functions as a memory for developing programs and data for the control unit 25 to execute software.

  A video signal supplied from the outside to the projection display device 1 is input from the video input terminal 11 to the video signal processing circuit 21 of the video processing device 10. As an external video signal, for example, a digital signal such as YUV defined in ITU-R BT.601 or ITU-R BT.709 is assumed. Alternatively, an analog signal or another type of signal is converted into a YUV digital signal at the input stage of the video signal processing circuit 21.

  The video signal processing circuit 21 is controlled by the control unit 25 and outputs two video signals according to the input video signal.

  One is a projector video signal (projection video signal), which is output to the optical engine 12. In a normal projector, only the video signal for this projector exists. Even in the system of this embodiment, if there is no corresponding screen system 30, it is possible to output the video signal only to the optical engine 12 manually or automatically. And

  The other is a screen video signal that is output from a screen output terminal (output unit) 14 of the video signal processing circuit 21 to a screen drive circuit 39 of the screen system 30 described later.

  Next, a screen system using an electronic paper display used in the present invention will be described.

  FIG. 4 is a diagram illustrating a configuration example of the screen system. As shown in FIG. 1, the screen system of this embodiment includes a screen 31 and a screen drive circuit 39. The screen 31 is an electronic paper that displays two colors, white and black, with the maximum contrast. Use the display. In order to drive the electronic paper display, a circuit for selecting a signal line (line) is required, and the drive is controlled for each line.

  The electronic paper display used in the present embodiment is composed of, for example, a small section 40 such as a capsule that constitutes a pixel capable of displaying the different colors (white and black), and the display color of each pixel is the same for each pixel 43. Is determined by a TFT 44 (thin film transistor) that determines the display color. The operation of the TFT 44 is executed by using an active matrix driving method similar to the display operation in a liquid crystal panel, for example.

  An example of an active matrix drive equivalent circuit is shown in FIG. In the equivalent circuit shown in FIG. 5, one small section includes a TFT functioning as a switch, a liquid crystal capacitor element CLC that controls liquid crystal, and a storage capacitor element Cstg. The gate terminal G of the TFT is connected to the scanning (gate) line N1, and the source terminal S is connected to the signal (data) line D1. The drain terminal of the TFT is connected to a common line through a parallel circuit of the liquid crystal capacitor element CLC and the storage capacitor element Cstg. The pixel electrode 45 of the liquid crystal capacitance element CLC is connected to the drain terminal of the TFT, and the counter electrode 46 is connected to the common line.

  The screen drive circuit 39 is provided with an input unit 38 to which a screen video signal to be displayed on the screen 30 is input from the projection display device 1 by wire or wirelessly. The screen image signal is transmitted to perform predetermined driving such as active matrix driving.

  The screen drive circuit 39 is provided with a timing controller 37 composed of LSI (Large Scale Integration), and the screen drive circuit 39 generates a timing signal based on the screen video signal to generate an electronic paper display (screen 31). ) Is controlled. In addition, the screen drive circuit 39 is provided with a power source (not shown) separately, but the description is omitted here. The screen driving circuit 39 may be provided integrally with the screen 31 or may be provided separately.

  Here, the active matrix driving method will be described. In the following description, the case where the screen 31 is formed with vertical 1080 pixels and horizontal 1920 pixels will be described as an example. In the active matrix driving method, an electrical signal is sent from the timing controller 37 to the driver layer of the electronic paper display in synchronization with the screen video signal input to the screen driving circuit 39. In the electronic paper display, line 1 to line 1080 are selected by the gate driver (H scan circuit) 41, and white or black is sequentially displayed on the horizontal 1920 pixels of each line by the source driver (V scan circuit) 42. Such an instruction is given to each TFT 44. Thereby, each pixel 43 on the screen 31 using the electronic paper display displays white or black (or an intermediate value described later) according to the instruction.

  Next, a screen video signal created by the video signal processing circuit 10 of the projection display device 1 will be described. FIG. 6 is a flowchart showing processing for generating a screen video signal for one screen. In the following description, it is assumed that a YUV signal defined in ITU-R BT.709 is handled, and each pixel 43 of the screen 31 can display only white or black binary values.

  In the digital signal of ITU-R BT.709, the luminance is treated as 16 for the black digital value with the lowest luminance and 235 for the white digital value with the highest luminance among the numbers 0-255 that can be represented by 8 bits. . Therefore, the Y value of the YUV signal corresponding to all pixels is a digital value that normally falls between 16-235. Note that the UV signal is a signal representing a color difference, but will not be described in detail.

  In this embodiment, since each pixel 43 of the screen 31 can display white or black binary values, a threshold (threshold) is set in advance for the luminance value of each pixel in the video signal based on the illuminance around the screen. Set it. The video signal processing circuit 21 creates a screen video signal from an externally input video signal based on a preset threshold value.

  First, a threshold value a for the luminance signal Y of the video signal, which is manually or automatically supplied by the user from an operation unit (not shown), is set and stored in the flash ROM or the like (step S1). Next, the control unit 25 determines, for each pixel (m, n; natural number) of the video signal, whether the luminance value of the pixel is larger than the threshold value. This comparison operation is performed from the first pixel (m = 1, n = 1) of the video signal (step S2, step S3).

  If the luminance value of the target pixel (m, n) of the video signal exceeds the threshold value as a result of the comparison, the corresponding pixel (m, n) of the screen video signal is set to white (step S4). On the other hand, if the luminance value of the target pixel (m, n) of the video signal does not exceed the threshold value, the corresponding pixel (m, n) of the screen video signal is set to black (step S5).

  When the processes of step S4 and step S5 are completed, the controller 15 increments the variable m by setting m = m + 1 (step S6). That is, the comparison target pixel is moved in the horizontal direction of the image formed from the input video signal. And the control part 25 determines whether the pixel m of the horizontal direction exceeded 1920 (step S7), and when not exceeded, it returns to the comparison process of step S3. When the pixel m exceeds 1920 and the comparison of one line in the horizontal direction is completed, the variable n is incremented with n = n + 1 and the comparison target is moved to the lower pixel (step S8). Then, the control unit 25 determines whether or not the vertical pixel n exceeds 1080 (step S9). If not, the horizontal pixel m is set to 1 (reset), and the comparison process in step S3 is performed. Return. Further, when the pixel n exceeds 1080 and the comparison in the vertical direction is finished, since the comparison with the threshold value is finished for all the pixels, the screen video signal generation processing for one screen is finished.

  That is, assuming that the threshold value is 40, the control unit 25 determines that black is output when the luminance value of each pixel 43 is 16-39, and white is output when the luminance value is 40-235. A comparison is made between 1080 pixels and 1920 pixels in the horizontal direction, and the result is a screen video signal consisting of 1080 pixels in the vertical direction and 1920 pixels in the horizontal direction. Although the control related to the screen video signal generation processing has been described as being performed by the control unit 25, it may be performed within the video signal processing circuit 21.

  When the video signal to be displayed on the screen is a moving image, the projection display apparatus 1 performs the screen video signal generation processing shown in FIG. 6 for each frame, and the screen video signal generated is screen-driven by the screen system 30 as needed. Output to the circuit 39.

  On the other hand, as for the projector video signal supplied from the video signal processing circuit 21 to the optical engine 12, the same signal as the video signal from the outside is output as it is. It may be converted.

  The above-described projection video 20 of the projector video signal projected on the screen 31 and the video of the screen video signal displayed on the screen 31 by the electronic paper display are assumed to be aligned. The alignment can be performed by the following method, for example.

  The first method is a mechanical alignment method. The position of the projection display device 1 or the image to be projected is adjusted according to the size of the screen 31, and the position of the projection image 20 is adjusted to the predetermined area 31a of the screen 31 shown in FIG.

  The second method is to provide a sensor on the screen side and perform alignment based on a light reception signal detected from a pattern test image projected from the projection display device 1 onto the screen 31. For example, as shown in FIG. 7, sensors, here, illuminance sensors 91 to 94 are installed at four locations on the screen 31. The sensor can detect the light emission pattern of the projected pattern test video, and the number of sensors installed is not limited to this example. The positions (coordinates) where the illuminance sensors 91 to 94 are installed are (m1, n1), (m2, n2), (m3, n3), and (m4, n4). Based on the received light signal of the pattern test image detected by each of the illuminance sensors 91 to 94, inverse calculation is performed to correct distortion and the like so that the projected image 20 is displayed in a predetermined area of the screen 31. In addition, alignment can be performed using a known technique.

  With reference to FIGS. 8A and 8B, an image of an image displayed on the screen 31 by the screen image signal and its effect will be described.

  FIG. 8A is a display example of the original image signal supplied from the outside to the projection display device 1, which is the same image as FIG. 12A. In the lodge image shown in FIG. 8A, low luminance and low saturation portions such as the back side 122 of the gable roof 121, the gable wall 123 under the eaves, and the casement window 124 are appropriately reproduced, and the contrast is also appropriate. Projection onto a white screen by a normal front projector or projection display device 1 in a dark environment where there is no surrounding light is almost similar to this image.

  On the other hand, FIG. 8B shows a projected image formed on the screen in a state where the illuminance around the screen is bright. The image of FIG. 8B is the same image as FIG. 12B, and low luminance and low saturation portions such as the back side 122 of the gable roof 121, the gable wall 123, and the casement window 124 are not reproduced. This is because the light from the surroundings causes black floating symptoms.

  Further, the display of the screen 31 by the screen video signal created as described above is as shown in FIG. 8C. The image shown in FIG. 8C is a binary image, and the back side 122 and the gable wall 123 of the gable roof 121 are black, and the casement window 124 is displayed in white like the white wall 125 near the first floor entrance.

  When the corresponding pixel (m, n) of the projected image 20 is projected with the pixel (m, n) of the image displayed on the screen 31, an image as shown in FIG. Observed. As can be seen in comparison with the image of FIG. 8B, the image of FIG. 8D is displayed in black where the back side 122 of the gable roof 121 or the gable wall 123 should be displayed in black or low brightness, and in white or high brightness. The displayed area (for example, the white wall 125) is displayed in white, and as a whole, an image with high contrast is obtained, and a high-quality image is obtained even in a bright place. This is because the pixel corresponding to the projected image of the binary image displayed on the screen 31 is displayed in black with respect to the portion where the luminance of the pixel corresponding to the image projected from the projection display device 1 is low. This is because black float does not occur due to the low reflectance of the screen.

  According to this method, there is a concern that the luminance change of the video observed by the viewer becomes large at the threshold value portion where the screen video signal is displayed in black. Therefore, for the projector video signal, if the pixel corresponding to the pixel of the projected video has a luminance equal to or lower than the set pixel threshold value, the video signal processing circuit 21 appropriately increases the luminance to smoothly May be appropriately converted so as to be connected.

  Further, regarding the display of each pixel on the screen 31 using the electronic paper display, the signal processing for performing black display of each part by adjusting the display to a desired display manually by the user or by the illuminance around the screen 31 is performed. It is desirable to change the threshold value, that is, the screen video signal generated by the video signal processing circuit 21. As means for knowing the ambient illuminance, it is desirable that a brightness sensor (illuminance sensor) is provided and integrated into the screen system 30, the projection display device 1, or the video processing device 10.

  Next, a method for adjusting the threshold value according to the ambient illuminance will be described. For example, when the surroundings have sufficiently low illuminance, the threshold luminance value in black display on the screen 31 is lowered. When the surroundings have sufficiently low illuminance, black floating is unlikely to occur. Therefore, the display state of the portion where the projected image 20 is projected is set to black for a portion where the partial luminance level of the image is low (for example, 25 or less of 0-255). FIG. 9A shows a display image on the screen 31 when the illuminance around the screen is low. The binary image shown in FIG. 9A has a white portion on the back side 122 of the gable roof 121, the gable wall 123, the casement window 124, and the like as compared with the binary image shown in FIG.

  Further, when light is shielded and the surroundings are dark, only white display may be performed as in the case of a conventional projector screen. The reason for this is that due to the low ambient illuminance, black floating due to the white screen is less likely to occur in areas where the brightness is not so low, and black floating occurs only in areas where the luminance is almost black. Because. Since the screen is white, there is an effect that color development is improved even in a portion where the luminance level is low.

  When the ambient illuminance is high or the ambient is sufficiently high, the threshold luminance value of black display on the screen 31 is increased. For example, in the case of a living room in the daytime, black float tends to occur. Therefore, the display state of the screen 31 is set to black with respect to a portion where the projected image 20 is projected and the partial luminance level of the image is not so low (for example, 0 to 255 or less). The threshold value of the luminance level may be adjusted to 50 or 60 according to the brightness. FIG. 9B shows a display image on the screen 31 when the illuminance around the screen is high. Compared with the image of FIG. 9A, the back side 122 of the gable roof 121, the gable wall 123, the casement window 124, and the like have many black portions, and the display is generally dark. As a result, black floating does not occur even in a portion close to black with low brightness, and as a result, the black image of the projected image 20 is expressed as black, thereby obtaining a sense of contrast and realizing an excellent image quality even in bright ambient conditions. There is.

  In the description so far, the display of the screen 31 using the electronic paper display has been described with binary values of white and black. However, as a modification example in the actual display, an intermediate gradation of the electronic paper display is used. You may make it display using. FIG. 10A shows a display state when four values are displayed synchronously in accordance with the luminance of the projected image 20. Compared with the image of FIG. 8C, a projector image with a fine gradation expression can be obtained.

  Furthermore, if a finer gradation can be expressed on the screen 31 using an electronic paper display, the display state on the screen 31 can be changed continuously and smoothly. FIG. 10B shows a display state in a case where display is performed with 16 gradations or more on the electronic paper display. Compared with the image of FIG. 10A, the back side 122 of the gable roof 121, the gable wall 123, the casement window 124, and the like, which are low-luminance parts, are also displayed in multiple gradations, and a projector image such as a more delicate monochrome image can be obtained. Therefore, the image projected on the screen 31 can be displayed with high contrast. In this case, by controlling the γ values of the screen 31 and the projected image 20 in synchronization or independently, a projected image with a high contrast feeling can be obtained at any luminance.

  Further, the resolution of the screen 31 using the electronic paper display may not be the same as that of the projected video 20 projected from the projection display device 1, and for example, one half of the resolution may be considered both vertically and horizontally. . In this case, when the projected image 20 is formed with vertical 1080 pixels and horizontal 1920 pixels, the resolution of the screen 31 is vertical 540 and horizontal 960 pixels. As a result, the circuit scale for driving the screen is reduced, and the cost can be reduced accordingly. Further, since the projected video 20 itself has a high resolution, a high resolution is obtained in a high-luminance video portion with high sensitivity, and a sense of resolution of the video that is synthesized and enters the eyes of the observer is obtained.

  Further, the ratio between the resolution of the screen 31 and the resolution of the projected video 20 does not have to be an integer ratio correctly. In this case, a scaling process is performed so that the corresponding video pixel portion is projected. .

  Further, there is no problem as long as the size of the screen 31 is larger than the projected image 20 projected from the projection display device 1, and it is conceivable to project the projected image 20 onto a part of the screen 31. In this case, for example, black and white binary characters and graphics may be displayed as a function of the original electronic paper display at a place other than where the projected video 20 is projected on a part of the screen 31. By doing so, an electronic paper display that is not a display that emits light naturally needs ambient brightness, but even in this state, a good electronic paper display and the projection display device 1 (front projector) are used. It is possible to achieve both high contrast and high quality images.

  According to the configuration described above, in the front projector display of the present invention, even when the brightness around the screen on which the image is projected by the projector is bright, only the luminance portion close to black in the image is blackened. The problem of black floating can be avoided. As a result, the contrast of the image projected by the projection display device can be improved, and the gradation and the difference in the image included in the dark image can be expressed. The quality of the entire image is limited even in an environment with high ambient illuminance. Display without any problems.

  In addition, it is possible to achieve both high-contrast and high-definition video display using an electronic paper display in a bright place and video using a projection display device.

It is a figure which shows the structure of the front projector system which concerns on one Embodiment of this invention. It is a figure which shows the example of an optical engine. It is a figure which shows the structure of the electronic paper display which concerns on one Embodiment of this invention. It is a figure which shows the structure of the screen system which concerns on one Embodiment of this invention. It is a figure which shows the equivalent circuit of an active matrix system. It is a flowchart which shows the video signal generation process for screens for one screen concerning one embodiment of the present invention. It is a figure where it uses for description of the video signal generation process for screens concerning one embodiment of the present invention. It is a figure which shows the image of the image | video displayed on a screen by the video signal for screens concerning one Embodiment of this invention. It is a figure which shows the display state of the screen by the screen surrounding illuminance which concerns on one Embodiment of this invention. It is a figure which shows the example of a display in the multi-value gray scale on the electronic paper display which concerns on one Embodiment of this invention. It is a figure which shows the structure of a general front projector system. It is a figure where it uses for description of a black float.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Projection type display apparatus, 10 ... Video processing apparatus, 11 ... Video input terminal, 12 ... Optical engine, 13 ... Projection lens, 14 ... Output terminal for screens, 20 ... Projection image, 21 ... Video signal processing circuit, 22 ... Internal bus, 23 ... SDRAM, 24 ... Flash ROM, 25 ... Control unit, 30 ... Screen system, 31 ... Screen, 31a ... Predetermined area, 32, 35 ... Plastic film, 33 ... Ink layer, 34 ... Driver layer, 37 ... Timing controller, 38 ... input unit, 39 ... screen drive circuit, 91, 92, 93, 94 ... illuminance sensor

Claims (7)

In a projection display system that projects an image projected from a projection display device on a screen,
The projection display device includes: a video processing unit that generates a projection video signal and a screen video signal from a predetermined video signal;
A predetermined luminance threshold value is compared with the luminance value of each pixel of the predetermined video signal, and as a result of comparison, the pixel having a luminance value lower than the threshold value is determined to be black and higher than the threshold value. A control unit for instructing to generate a video signal for the screen with white pixels having luminance values;
An optical image generation unit that converts the projection video signal into an optical image and projects the optical image onto the screen;
The screen includes a display unit that performs black and white video display based on a screen video signal supplied from the projection display device,
A projection display system, wherein an optical image based on the projection video signal is superimposed and projected from the projection display device onto an image displayed on the screen based on the screen video signal. The projection type display system according to claim 1, wherein a user can arbitrarily set the threshold value of the luminance. The projection display system according to claim 1, wherein the illuminance around the screen is measured, and the threshold value of the brightness is set according to the measured illuminance. The projection display system according to claim 1, wherein display based on the screen video signal on the screen is performed in a multi-value gray scale. The projection display system according to claim 1, wherein the screen is formed using an electronic paper display. In a projection display device that projects and displays an image on a screen,
A video processing unit that generates a projection video signal and a screen video signal from a predetermined video signal;
A predetermined luminance threshold value is compared with the luminance value of each pixel of the predetermined video signal, and as a result of comparison, the pixel having a luminance value lower than the threshold value is determined to be black and higher than the threshold value. A control unit for instructing to generate a video signal for the screen with white pixels having luminance values;
An optical image generation unit that converts the projection video signal into an optical image and projects the optical image onto the screen;
The screen video signal is output to the screen, and an optical image based on the projection video signal is projected on the video displayed on the screen based on the screen video signal. Projection display device. In the screen that projects the image projected from the projection display device,
A display unit that displays a black and white image of a screen video signal supplied from the projection display device, and a screen drive that outputs a drive signal to the display unit based on the screen video signal supplied from the projection display device Circuit part,
An optical image based on a projection video signal from the projection display device is projected onto the video displayed on the screen by the display unit based on the screen video signal.