JP2015226296A - Display divice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display divice which allows both sides of a transparent screen to be used.SOLUTION: A timing controller 31 of a display divice 1 controls a screen 21 so that the screen 21 comes into a scattered state with timing of projecting an image projected on the back side of the screen 21 from a projector 11a and displayed on the front side and an image projected to the front side of the screen 21 from a projector 11b and displayed on the back side.

Description

  The present invention relates to a display device that displays an image.

  2. Description of the Related Art Conventionally, display devices that display a video by projecting a video projected from a light source such as a projector onto a screen are known.

  In such a display device, for example, Patent Document 1 discloses a one-frame period using a screen (transmission type screen) that can change a light transmission state and a light scattering state by controlling the transmittance. It is described that a high contrast image is displayed while maintaining a light transmission state by performing PWM driving so as to be in a scattering state only during a predetermined period.

  When such a transmissive screen is used for a shop show window or the like, the image is projected from the inside of the show window so that an observer etc. outside the show window can see the image and display it in the show window. It is possible to observe the actual object at the same time.

JP 2012-220540 A

  In the transmission type screen described in Patent Document 1, the forward scattering of incident light is strong and the reflection scattering is weak. Therefore, the projected image can be clearly seen from the opposite side of the screen where the projector or the like is disposed, but the projected image is hardly visible from the side where the projector or the like is disposed. Therefore, although an image can be displayed on one side of the screen, it has not been used for displaying an image on the other side which is the back side.

  In view of the above-described problems, an object of the present invention is to provide a display device that can use, for example, both sides of a transmissive screen.

  In order to solve the above-mentioned problem, the invention described in claim 1 is capable of switching between a transmission state and a scattering state with respect to visible light, and is provided on one side on which an image can be projected and the back side of the one side. A screen having the other surface on which the image can be projected, an image projected on the one surface of the screen, an image projected on the other surface of the screen, and the scattering state of the screen And a control unit that controls to synchronize with each other.

  The invention described in claim 7 is capable of switching between a transmissive state and a scattering state with respect to visible light, and has one surface on which an image can be projected and the other side on which the image can be projected on the back side of the one surface. A display device that projects and displays an image on a screen having an image on the screen, the image projected on the one surface of the screen and the image projected on the other surface of the screen; It is a control method of the display apparatus characterized by including the control process controlled so that the said scattering state of the said screen may synchronize.

  The invention described in claim 8 is a display control program characterized by causing a computer to execute the control method for a display device according to claim 7.

  The invention described in claim 9 is a computer-readable recording medium in which the display control program according to claim 8 is stored.

1 is a schematic configuration diagram of a display device according to a first embodiment of the present invention. It is typical sectional drawing of the screen shown by FIG. 3 is a timing chart of the display device shown in FIG. 1. It is explanatory drawing of the brightness adjustment operation | movement of the display apparatus shown by FIG. 2 is a flowchart showing a brightness adjustment operation of the timing control device shown in FIG. 1. 2 is a display example of the display device shown in FIG. 1. 2 is a display example of the display device shown in FIG. 1. 2 is a display example of the display device shown in FIG. 1. 2 is a display example of the display device shown in FIG. 1. It is explanatory drawing of the brightness adjustment operation | movement of the display apparatus concerning the 2nd Example of this invention. It is a schematic block diagram of the display apparatus concerning the 3rd Example of this invention. It is the schematic block diagram which showed the other example of arrangement | positioning of a projector. It is explanatory drawing of the synchronous control of the scanning of another structure of a screen, and a drive. FIG. 14 is a schematic timing chart of scanning and driving of the screen shown in FIG. 13.

  Hereinafter, a display device according to an embodiment of the present invention will be described. In the display device according to the embodiment of the present invention, the control unit can switch between a transmission state and a scattering state with respect to visible light, and can be projected on one side and the back side of the one side. The screen is controlled so that the image projected on one surface of the screen having the other surface on which the image can be projected and the image projected on the other surface of the screen are synchronized with the scattering state of the screen. ing. In this way, when the image is projected, the screen can be in a scattering state, or when the screen is in a scattering state, the image can be projected from both sides of the screen, so the forward scattering is strongly reflected In the case of a screen with low scattering, an image projected from the other surface is displayed on one surface, and an image projected from one surface is projected onto the other surface. Therefore, both sides of the transmissive screen can be used.

  In addition, the image projected on one surface is an image observed from one viewpoint, and the image projected on the other surface is an image observed from a viewpoint opposite to one viewpoint toward one viewpoint. It may be. In this way, for example, an image from the front of the person can be displayed on one side of the screen, and an image from the back of the same person can be displayed on the other side of the screen. Or not only images seen from two opposite points of view, such as a person, but also images seen from two opposite points (left bank seen from the right bank of the river, right bank seen from the left bank, Hokkaido seen from Honshu) And Honshu seen from Hokkaido).

  In addition, the image projected on one surface and the image projected on the other surface may be unrelated. By doing in this way, for example, a video for store outside can be displayed on one side, and a video for store inside can be displayed on the other side. Therefore, a plurality of information can be transmitted using both sides of the screen.

  In addition, an adjustment unit may be provided that adjusts a difference in brightness between an image projected on one surface and an image projected on the other surface within a predetermined range. When the image projected on the screen is bright, the amount of light reflected and scattered by the screen increases, and thus the image due to reflection and scattering may be noticeable. Therefore, when projecting images on both sides of the screen, if there is a large difference in brightness between the image projected on one surface and the image projected on the other surface, the image due to reflection scatter is noticeable due to transmission scatter that should be displayed originally. There is a risk of degrading the display quality of the video. Therefore, by adjusting the brightness difference between the image projected on one surface and the image projected on the other surface within a predetermined range, the image due to reflection scattering is made inconspicuous, and the display quality of the image is improved. The decrease can be suppressed.

  Further, the adjustment unit compares the value related to the light amount of the predetermined area of the image projected on one surface with the value related to the light amount of the area corresponding to the predetermined area of the image projected onto the other surface, Based on the comparison result, the value related to the light quantity in the predetermined area and the predetermined area so that the difference between the value related to the light quantity in the predetermined area and the value related to the light quantity in the area corresponding to the predetermined area is within the predetermined value. You may adjust at least any one among the values regarding the light quantity in the area | region to perform. By doing in this way, it can adjust so that the difference may become small about the part with a large brightness difference in an image | video.

  Further, the adjustment unit may adjust a value related to the amount of light in a region around the predetermined region. By doing in this way, the predetermined area adjusted to reduce the difference in brightness can be adapted to the area where adjustment is not performed, and the uncomfortable feeling of the entire image can be reduced.

  In the display device control method according to the embodiment of the present invention, the control process can switch between a transmission state and a scattering state with respect to visible light, and can project one image and one surface on which an image can be projected. The screen so that the image projected on one side of the screen having the other side on which the image can be projected and the image projected on the other side of the screen and the scattering state of the screen are synchronized. Is controlling. In this way, when the image is projected, the screen can be in a scattering state, or when the screen is in a scattering state, the image can be projected from both sides of the screen, so the forward scattering is strongly reflected In the case of a screen with low scattering, an image projected from the other surface is displayed on one surface, and an image projected from one surface is projected onto the other surface. Therefore, both sides of the transmissive screen can be used.

  In addition, a display control program that causes a computer to execute the above-described display device control method may be used. In this way, when the image is projected, the screen can be made to be in a scattering state, or when the screen is in the scattering state, the image can be projected from both sides of the screen. In the case of a screen with high scattering and low reflection scattering, an image projected from the other surface is displayed on one surface, and an image projected from the one surface is projected on the other surface. Therefore, both sides of the transmissive screen can be used.

  Further, the display control program described above may be stored in a computer-readable recording medium. In this way, the program can be distributed as a single unit in addition to being incorporated in the device, and version upgrades can be easily performed.

  A display device 1 according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the display device 1 includes a screen 21 and a timing control device 31. The display device 1, the projector 11a, and the projector 11b constitute a transmissive projection device that projects (projects) video light (projection light) emitted from the projector 11a and the projector 11b and transmits and scatters the light on the screen 21 (projection surface). To do.

  FIG. 2 is a schematic cross-sectional view of the screen 21 that can control the optical state. The screen 21 shown in FIG. 2 includes a light control unit 25 that is an optical layer in which a composite material containing liquid crystal is sandwiched between a pair of transparent glass substrates 23 and 24. A counter electrode 26 is formed on the entire surface of one glass substrate 24 on the light control unit 25 side. A control electrode 27 is formed on the entire surface of the other glass substrate 23 on the light control section 25 side. An intermediate layer made of an insulator may be formed between the electrodes 26 and 27 and the light control unit 25.

  The screen 21 includes a light control unit 25 made of an element or a material that can change an optical state by applying a voltage. The optical state of the light control unit 25 is a state in which the scattering state displays an image, and a transparent transmission state in which the scattering of incident light (visible light) is smaller and the linear transmittance of the light is higher than that does not display an image. It is a non-video display state. The light control unit 25 is disposed between the counter electrode 26 and the control electrode 27. That is, the light control unit 25 is sandwiched between two electrodes and can switch an optical state between a transmission state and a scattering state by a voltage applied between the two electrodes.

  As the light control unit 25, one capable of switching an optical state between a scattering state and a transparent state, for example, a so-called polymer dispersed liquid crystal (PDLC) in which nematic liquid crystal domains are distributed in a polymer can be used. In addition, a better optical state can be realized by using a composite material that is associated with the orientation of liquid crystal molecules in which a polymer network forms domains in a state where no voltage is applied.

  As an example using PDLC, a suitable amount of photopolymerizable monomer, nematic liquid crystal, and polymerization initiating material are mixed and placed between the glass and resin substrates of about 5 to 50 micrometers constituting the light control member. The liquid crystal domains can be dispersed in the polymer by irradiating with ultraviolet rays under conditions such as the temperature at which the phase separates. In this case, the normal mode is designed so that the scattering due to the refractive index difference between the polymer and the liquid crystal is large when no voltage is applied, and the refractive index difference in the substrate normal direction is small when the liquid crystal is aligned by an electric field. Called. In addition, it is also possible to use a capsule containing a nematic liquid crystal mixed with a monomer and a polymerization initiator.

  As a composite material associated with the orientation of liquid crystal molecules in which a polymer network forms domains in a state where no voltage is applied, a photopolymerizable monomer has liquid crystal properties. The substrate is subjected to an alignment process such as rubbing, and the mixed material disposed between the substrates has an arrangement based on the alignment process. By irradiating ultraviolet rays in this state, the above initial arrangement is obtained when no voltage is applied, and scattering occurs due to the difference in refractive index between the liquid crystal domain and the polymer when the voltage is applied. In addition, when the unidirectional arrangement is used, it has optical characteristics depending on this orientation. However, it is also possible to use an optical characteristic that does not depend on the polarization of incident light by adding a chiral material and twisting the initial arrangement. . In this case, the scattering due to the difference in refractive index between the polymer and the liquid crystal is small when a normal voltage is not applied, and the refractive index difference is increased when the liquid crystal is aligned by an electric field, which is called a reverse mode.

  That is, in the normal mode, a transmission state is obtained when a predetermined voltage is applied between the electrodes, and a scattering state is obtained when no voltage is applied between the electrodes. In the reverse mode, a scattering state occurs when a predetermined voltage is applied between the electrodes, and a transmission state occurs when no voltage is applied between the electrodes. In this embodiment, the reverse mode is basically described, but the normal mode is also applicable.

  The counter electrode 26 and the control electrode 27 are formed as transparent electrodes using, for example, ITO (indium tin oxide).

  When the image light is projected, the screen 21 shown in FIG. 2 is mainly scattered forward (scattered forward) in the projection direction (incident direction) by the light control unit 25 controlled to be in a scattering state and visually recognized as an image. . Therefore, the light that is reflected and scattered (reflected and scattered) in the projection direction by the light control unit 25 is small. Therefore, the image projected from the projector 11a is visible from the viewer 51a side, but is hardly visible from the viewer 51b side.

  From the observer 51a located on one surface side of the screen 21, when the light control unit 25 of the screen 21 is in a scattering state, the screen 21 appears to be clouded, for example. On the other hand, when the light control unit 25 is in the transmissive state, the screen 21 is in the transmissive state, so that the background can be observed through the screen 21. Therefore, when the light control unit 25 is in the scattering state, an image projected from the projector 11a is displayed on the screen 21 so that the observer 51a can visually recognize it. In the transmission state, the screen 21 can recognize the background. It has transparency. In addition, from the observer 51b located on the other surface side of the screen 21, when the dimming unit 25 is in a scattering state, an image projected from the projector 11b is displayed on the screen 21 so that the observer 51b can visually recognize it. In the transmissive state, the screen 21 is transparent so that the background can be recognized.

  A voltage is applied to the screen 21 so as to generate a potential difference between the control electrode 27 and the counter electrode 26. As the drive waveform (drive voltage waveform), for example, one electrode may be in a DC state (reference voltage, for example, 0 volt), and an AC voltage may be applied to the other electrode. An inverted AC voltage may be applied to cause a potential difference. That is, when a voltage is applied so as to generate a potential difference between the control electrode 27 and the counter electrode 26, the screen 21 is in a transmission state when in the normal mode, and is in a scattering state when in the reverse mode.

  The timing control device 31 as a control unit controls the dimming unit 25 of the screen 21 on which the image light is projected, for example, based on a synchronization signal input to the projectors 11a and 11b. As the synchronization signal input from the projectors 11a and 11b to the timing control device 31, for example, a synchronization signal synchronized with the video frame period of the video signal input to the projectors 11a and 11b can be used. By this synchronization signal, the projectors 11a and 11b can project an image when the screen 21 is in a scattering state. The synchronization signal may be input from either one of the projectors 11a and 11b.

  The timing control device 31 may include a CPU (Central Processing Unit), a memory, and the like, and may be configured by a computer whose operation is controlled by a program recorded in a recording device such as a memory, or an ASIC (Application Specific Integrated). Circuit) or other dedicated hardware may be used.

  The projector 11a is disposed on the viewer 51b side of the screen 21. The projector 11b is disposed on the viewer 51a side of the screen 21. The projectors 11a and 11b can use a transmissive or reflective liquid crystal light valve that sequentially shifts the black state (a state in which no projection light is emitted) on the screen 21 during the scanning cycle, but other elements may be used. Good. The projectors 11a and 11b may perform raster scanning in a video scanning cycle and project video light (image light) on the display surface of the screen 21 in a line sequential manner. That is, video light is projected intermittently at a predetermined cycle. As the projectors 11a and 11b, for example, a laser projector or the like that reflects and shakes the irradiation direction of the intensity-modulated light beam by a movable mirror can be used. The projectors 11 a and 11 b can be considered in the same manner as the image light irradiation positions sequentially scanned in one direction on the screen 21.

  The projectors 11a and 11b may be any projector that can project video light modulated by video information. Note that the video information is obtained from video signals input to the projectors 11a and 11b. Video signals include, for example, NTSC (National Television Standards Committee), analog video signals such as PAL (Phase Alternation by Line), MPEG-TS (Moving Picture Experts Group-Transport Stream) format, HDV (High -There are video signals in digital format such as Definition Video) format. The projectors 11a and 11b may receive not only a moving image video signal but also a still image video signal such as JPEG (Joint Photographic Experts Group). In this case, the projectors 11a and 11b may scan the screen 21 repeatedly with the same video light for displaying a still image.

  FIG. 3 is a timing chart showing the state of the screen 21 configured as described above, the regular transmittance of the light control unit 25, and the intensity (light intensity) of the image light projected from the projectors 11a and 11b.

  As shown in FIG. 3, the screen 21 changes between a scattering state and a transmission state once within one video period. That is, the transmission state and the scattering state are alternately switched at a predetermined cycle. One video cycle is one frame period of a video signal inputted to the projectors 11a and 11b, and is about 50 to 60 Hz in terms of frequency. Therefore, the screen 21 is switched between the scattering state and the transmission state in a period shorter than one video cycle.

  When the screen 21 (the light control unit 25) is in a scattering state, the linear transmittance of the light beam of the light control unit 25 is lowered. Since light incident on the screen during this period is scattered, an image can be displayed. During this period, the projectors 11a and 11b project the image light onto the screen 21, so that the image light intensity increases and an image is displayed. That is, the screen 21 is controlled so that an image projected on one surface of the screen 21 and an image projected on the other surface of the screen 21 are projected in a scattered state. That is, the operation as shown in FIG. 3 corresponds to the control process.

  When the screen 21 is in the transmission state, the linear transmittance of the light beam of the light control unit 25 increases. Light incident on the screen during this period is transmitted as it is. Accordingly, the projectors 11a and 11b stop projecting the image light onto the screen 21. Therefore, the background can be observed through the screen 21 (through the screen 21).

  On the screen 21, the image of the entire screen is repeatedly projected every one image period, and this repetition is not recognized as blinking by the human eye, but is projected onto the screen 21 by time averaging (integration). The image and background can be observed simultaneously without feeling flicker.

  In FIG. 3, the images are projected from the projectors 11 a and 11 b in all the periods of the scattering state. However, for example, the images are more than the period of the scattering state, such as providing a margin for switching from the scattering state to the transmission state. The projected period may be short. That is, an image may be projected in an arbitrary period within the scattering state period. Alternatively, images may be projected from the projectors 11a and 11b during the transient state. In this case, although image light that is transmitted without being scattered is generated, the influence is small because it is a short time.

  In FIG. 3, the projectors 11a and 11b project images during the same period, but they may not be the same period. For example, the scattering state may be set twice in one video period, and one may be a period during which the projector 11a is projected, and the other may be a period during which the projector 11b is projected, or one scattering period may be divided into two. Good. Moreover, you may make it a part of period which the projectors 11a and 11b project an image | video overlap.

  Further, in order to project as shown in FIG. 3, a light source that can be switched on and off at high speed, such as a laser light source or LED, may be used as the light source of the projectors 11a and 11b. A configuration may be employed in which a shutter or the like is installed at the emission port or the like. In this case, the projectors 11a and 11b and the shutter are controlled so that an image projected on one surface of the screen 21 and an image projected on the other surface of the screen 21 are projected in the scattering state of the screen. In short, it is only necessary that the light emitted from the projectors 11a and 11b can be emitted intermittently (in a pulse shape).

  As is clear from the above description, the fact that the image projected on one surface of the screen 21 and the image projected on the other surface of the screen 21 and the scattering state of the screen 21 are synchronized is projected periodically. This includes both adjusting the timing of the scattering state of the screen 21 to the image to be displayed and adjusting the timing of projection from the projectors 11a, 11b, etc., to the screen 21 that periodically enters the scattering state.

  In addition, the term “periodic” means that the scattering state or the image is projected in a predetermined period of one video cycle, and the scattering state period or the period during which the image is projected is generated every certain period. Not exclusively. For example, a case where a period of 10% to 20% and a period of 80% to 90% from the beginning of one video period are in a scattering state are included periodically if they occur without changing in each video period. That is, it is only necessary to repeat a specific timing within one video cycle every video cycle.

  Here, when the image projected on the screen 21 is bright, the amount of light reflected and scattered by the screen 21 increases, and thus an image due to reflection and scattering that should be essentially invisible may be seen. Therefore, when images are projected on both surfaces of the screen 21, the image projected on one surface of the screen 21 (hereinafter referred to as the front surface for convenience) and the other surface behind the one surface (hereinafter referred to as the rear surface for convenience) are projected. If the difference in brightness from the image to be displayed is large, the image due to reflection / scattering may appear to overlap with the image due to transmission / scattering that should be displayed, thereby degrading the display quality of the image.

  Therefore, in this embodiment, the difference in brightness between the image projected on the front surface of the screen 21 and the image projected on the back surface is adjusted within a predetermined range. Specifically, as shown in FIG. 4, the screen 21 is divided into areas having a certain area such as 64 divisions in the horizontal direction, 40 divisions in the vertical direction, and 2560 divisions on the entire screen 21. Then, the timing control device 31 determines the brightness of the image projected for each area on both sides of the screen 21, and the amount of light projected on the area G on one side corresponds to the area G on the other side. The video signal levels (for example, luminance signal levels) of the projectors 11a and 11b are adjusted so that the amount of light projected to the area is three times or less. The area corresponding to the area G on the other side is an area projected on the screen 21 at the same position as the area G (front and back same positions). Moreover, 3 times is an example and may be changed as appropriate.

  That is, a value (luminance signal level) relating to the light amount of a predetermined area (area) of the image projected on one surface, a value relating to the light amount of an area corresponding to the predetermined region of the image projected on the other surface, Based on the comparison result, the value related to the light quantity in the predetermined area and the predetermined value so that the difference between the value related to the light quantity in the predetermined area and the value related to the light quantity in the area corresponding to the predetermined area is within a predetermined value. At least one of the values relating to the light amount in the region corresponding to the region is adjusted.

  This may be adjusted to make the darker projector 11a or projector 11b brighter, or may be adjusted to make the brighter projector 11a or projector 11b darker. Alternatively, both may be adjusted.

  Further, the brightness itself of the light source of the projector 11a or the projector 11b may be adjusted as a value relating to the light amount, instead of the video signal level. In addition, the adjustment may be made in consideration of the color signal instead of adjusting only the luminance signal.

  In addition, if the video signal level of only the operated area G is changed, it will be visually recognized as block noise in the projected video. Therefore, the luminance signal etc. are continuously adjusted including the area G. It is better to go. That is, the value related to the light amount in the area around the predetermined area may be adjusted.

  The brightness adjustment operation described above is summarized in the flowchart of FIG. The timing control device 31 executes the flowchart of FIG. First, in step S1, the luminance signal level of the image projected on the front side is acquired, and the process proceeds to step S2. In step S2, the luminance signal level of the image projected on the back side is acquired, and the process proceeds to step S3. In these steps, one frame is acquired and stored in storage means such as a frame memory.

  Next, in step S3, the front side activation signal level acquired in step S1 is compared with the back side luminance signal level acquired in step S2, and the process proceeds to step S4. For this comparison, for example, the average of the luminance signal levels of the pixels in the area G on the front side and the pixels in the area corresponding to the area G on the back side may be calculated and compared.

  Next, in step S4, as a result of the comparison in step S3, it is determined whether or not there is an area where the difference in luminance signal level is three times or more. If there is an area, the process proceeds to step S5.

  Next, in step S5, the luminance signal level is adjusted for an area where the difference in luminance signal level is three times or more, and the process returns to step S1. For example, the luminance signal of the darker image is changed to be bright so that it is less than three times. Note that the video signal whose luminance signal level has been adjusted is output to the projector 11 a or the projector 11 b and projected onto the screen 21.

  Note that the luminance signal level is not limited to the comparison after acquiring one frame, but the comparison operation may be performed when lines for the vertical direction of the area are stored in the frame memory or the like.

  As a display using the display apparatus 1 demonstrated above, what is shown to FIGS. 6-9 is mentioned, for example. The following example shows an example of an image, but may be character information.

  6A shows a front image of a person on the front surface of the screen 21 (projected from the projector 11 arranged on the back side of the screen 21), and FIG. 6B shows the same person on the back surface of the screen 21. Is displayed (projected from a projector disposed on the front side of the screen 21). That is, an image projected on one surface is an image observed from one viewpoint, and an image projected on the other surface is an image observed from a viewpoint opposite to one viewpoint toward one viewpoint. It has become. By doing in this way, the front and back of a person can be displayed using the front and back of one screen 21. Not only the front and back of a person, but also images projected on one side, such as the left bank seen from the right bank of the river and the right bank seen from the left bank, Hokkaido seen from Honshu and Honshu seen from Hokkaido, etc. Any other combination may be used as long as the image projected from the viewpoint is the one projected from the viewpoint opposite to the one viewpoint toward the one viewpoint.

  Alternatively, the image projected on one surface may be an image observed on one side from a position, and the image projected on the other surface may be an image observed on the side opposite to the one side from the position. For example, an image obtained by photographing the front of a traveling vehicle and a vehicle obtained by photographing the rear are included.

  7A is an example in which a front image of a person is displayed on the front surface of the screen 21, and an internal image (an organ, bone, blood vessel, etc.) of the same person is displayed on the back surface of the screen 21. FIG. is there. By doing in this way, a normal image and its X-ray photograph etc. can be displayed on the front and back of the screen 21. In FIG. 7, an internal image as a mirror image is displayed on the rear surface, but it may be a normal image. Of course, the internal image is not limited to X-ray photographs, but may be computer graphics or the like, and not only a person but also a front image and an internal image of other living things, and an external image of an artificial object such as a machine / equipment or a building. It may be a cross-sectional image or the like.

  FIG. 8A is an example in which a front image of a person is displayed on the front surface of the screen 21 and a front image of the same person is displayed on the back surface of the screen 21 (a mirror image of FIG. 8A). . By doing in this way, a normal image and a mirror image can be displayed on the front surface and the back surface of the screen 21. Note that the same image (normal image and normal image) may be used instead of the normal image and the mirror image.

  FIG. 9 shows an example in which (a) displays a front image of a person on the front surface of the screen 21 and (b) displays a front image of another person on the back surface of the screen 21. It should be noted that the video projected on one surface and the video projected on the other surface are not related to each other, such as a video displayed outside the store and a video displayed inside the store, for example. Good. By doing in this way, the same different image can be displayed on the front surface and the back surface of the screen 21.

  According to this embodiment, the timing control device 31 causes the screen 21 to be in a scattering state at the timing when the image projected on the front surface of the screen 21 and the image projected on the back surface of the screen 21 are projected. 21 is controlled. In this way, when the screen 21 is in a scattering state, images are projected from both sides of the screen 21, so that the image projected from the back is displayed on the front, and the image projected from the front is projected on the back. The Therefore, both sides of the transmissive screen can be used.

  In addition, the image projected on the front is an image observed from one viewpoint (for example, a front image of a person), and the image projected on the back is an image observed from a viewpoint opposite to one viewpoint (for example, the same person's front image). It may be a rear image). In this way, the image from the front of the person can be displayed on the front of the screen, and the image from the back of the same person can be displayed on the back of the screen. Can be observed in the same way.

  Further, the image projected on the front surface and the image projected on the back surface may be unrelated images. In this way, for example, a front image of a person on the front can be displayed and a front image of another person can be displayed on the back, and the front and back of the screen 21 can be displayed differently. can do. Therefore, a plurality of information can be transmitted using the front and back surfaces.

  Further, the timing control device 31 compares the luminance signal level of a predetermined area of the image projected on the front surface with the luminance signal level of the same area of the image projected on the rear surface, and there is a difference of three times or more. In this case, the luminance signal level of the darker side or the luminance signal level of the brighter side is adjusted so as to be within 3 times, so that the difference is reduced in the portion where the difference in brightness is large in the video. Can be adjusted.

  Further, the luminance signal level of the area around the predetermined area G may be adjusted. By doing so, the area G adjusted so as to reduce the difference in brightness can be adapted to the area that is not adjusted, and the uncomfortable feeling caused by adjusting the luminance signal level as a whole image can be reduced. .

  Next, a display device according to a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  The display device 1A of this embodiment has the same configuration as that of the first embodiment, but the brightness difference between the image projected on the front surface of the screen 21 and the image projected on the back surface is within a predetermined range. The adjustment method is different. That is, the operation of the timing control device 31 is different, and the timing control device 31A is provided.

  In the first embodiment, the screen 21 is divided into areas having a certain area, and the brightness is determined for each area. However, in this embodiment, as shown in FIG. Instead, the brightness is determined for each point of 1 to several adjacent pixels. Specific operations and the like are the same as those in the flowchart shown in FIG.

  According to this embodiment, the luminance signal level at a predetermined point of the image projected on the front surface is compared with the luminance signal level at the same point of the image projected on the rear surface, and there is a difference of three times or more. Since the luminance signal level of the darker side or the luminance signal level of the brighter side is adjusted to be within 3 times, the luminance signal level can be adjusted in units finer than the area. Therefore, finer adjustment can be made.

  It should be noted that the value relating to the light quantity such as the luminance signal level may be adjusted in advance between both the source projected from the projector 11a and the source projected from the projector 11b. However, the above-described adjustment method is effective for a source that is difficult to adjust in advance (for example, a video shot in real time by a TV broadcast, a TV camera, or the like).

  Next, a display device according to a third embodiment of the present invention is described with reference to FIG. The same parts as those in the first and second embodiments described above are denoted by the same reference numerals and description thereof is omitted.

  In the first and second embodiments, the timing control device 31 adjusts the video signal level (luminance signal level). However, in this embodiment, as shown in FIG. 11, the video signal level detection / control is performed. This is done with the device 61. The video signal level detection / control device 61 includes a first video transmission device 62a that transmits video for output to the projector 11a and a second video transmission device 62b that transmits video for output to the projector 11b. It is connected.

  The video signal level detection / control device 61 adjusts the luminance signal level for each area or point by comparing the video sent from the first video sending device 62a and the video sent from the second video sending device 62b, The adjusted video signal is output to the projector 11a and the projector 11b. The first video transmission device and the second video transmission device are, for example, a recording medium playback device such as a TV tuner, an HDD (Hard Disk Drive) recorder, a BD (Blu-ray Disc) player, or a TV camera.

  According to the present embodiment, since the timing control device 31 does not adjust the luminance signal level, the configuration of the timing control device 31 can be simplified. In addition, since the function of adjusting the luminance signal level is separated from the timing control device 31, the video signal level detection / control is performed in accordance with the installation positions of the first video transmission device 62a and the second video transmission device 62b transmitted to the projectors 11a and 11b. A device 61 can be installed. Therefore, for example, a tuner, a video reproduction device, and the like, and the video signal level detection / control device 61 can be integrally configured.

  The arrangement positions of the projectors 11a and 11b are not limited to those shown in FIG. 1 and the like, and may be as shown in FIG. Or you may make it project by reflecting with a mirror etc. instead of direct projection. In short, it is only necessary to project images from the respective projectors 11 on the front surface and the back surface of the screen 21.

  Further, the projection method for the screen 21 is not limited to the method shown in FIG. For example, the screen 21 may be divided into a plurality of regions, and each divided region may be sequentially in a scattering state, and an image may be projected onto the divided regions that are in a scattering state. The basic operation principle will be described with reference to FIG. The projector 11 (11a and 11b) vertically scans the screen 21 from top to bottom with video light modulated by video information. The projector 11 scans the screen 21 vertically from top to bottom for each scanning repetition period (hereinafter also referred to as a scanning cycle).

  FIGS. 13A to 13E show the scanning state at each time point in one scanning cycle in the scanning order. The screen 21 in FIG. 13 has five divided regions 22. The five divided regions 22 are arranged vertically along the scanning direction of the image light.

  The timing control device 31 individually controls the optical states of the five divided regions 22 in synchronization with the one-dimensional vertical scanning of the screen 21 by the projector 11. When the image light is not projected, each divided region 22 is controlled to a non-image state, that is, a transparent transmissive state with small scattering of incident light.

  When the scanning of the image light is started, the scanning light of the projector 11 is first applied to the uppermost divided area 22 of the screen 21 as shown in FIG. Hereinafter, in this description, reference numeral 221 is used to distinguish the divided region 22 irradiated with the scanning light from other divided regions 22 that are not scanned. The timing control device 31 specifies a period during which the uppermost divided area 221 is scanned in the scanning cycle based on the synchronization signal from the projector, and controls the uppermost divided area 221 to the video state. The image light that scans the uppermost divided area 221 is scattered by the divided area 221 in the scattering state and passes through the screen 21.

  Next, the scanning of the image light moves to the second divided area 221 from the top of the screen 21 as shown in FIG. The timing control device 31 specifies a period during which the second divided region 221 from the top in the scanning cycle is scanned, and controls the second divided region 221 from the top to the video state. The image light that scans the second divided region 221 from the top is scattered by the divided region 221 in the scattering state and passes through the screen 21. The timing control device 31 controls the second divided area 221 from the top to the video state, and then controls the uppermost divided area 22 to the non-video state. Thereafter, as shown in FIGS. 13C to 13E, the timing control device 31 controls the divided area 221 scanned by the scanning light to the video state, and sets the other divided areas 22 to the non-video state. Control.

  Through the above-described synchronization control, the portion of the screen 21 irradiated with the scanning light is maintained in the video state. Thereby, the image light that scans the screen 21 is scattered by the screen 21 in the scattering state. Further, the portion of the screen 21 that is not irradiated with the scanning light is controlled to a non-image state. Each divided region 22 is controlled to a transparent transmission state in a non-video state during most of the period that is not scanned by the scanning light. During the image light projection period, the see-through characteristic of the screen 21 is obtained while maintaining the image visibility.

  FIG. 14 is a schematic timing chart of scanning and driving of the screen 21. The horizontal axis is time. The vertical axis indicates the position in the vertical direction of the screen, and corresponds to a plurality of divided regions 22 on the screen 21.

  Each divided region 22 of the screen 21 is controlled from a transparent transmission state to a scattering state before the timing at which the image light starts to scan each region. Further, the divided region 22 in the scattering state is controlled from the scattering state to the transparent transmission state after the scanning of the region is completed.

  The plurality of divided regions 22 are controlled in the image state (scattering state) in synchronization with the partial scanning period TP in which the image light is irradiated to each region, thereby sequentially shifting the time in the scanning order. Switch to video state. The image light that scans the screen 21 is efficiently scattered by the portion maintained in the image state, and it is possible to obtain bright and high visibility. In FIG. 14, the image light scanning is indicated by three arrows, and this indicates image light corresponding to each of the three primary colors of red, green and blue light.

  By the above synchronization control, the screen 21 can display an image because the portion irradiated with the image light is maintained in the scattering state in the period Ton including the timing when the image light is irradiated.

  Moreover, since the screen 21 is controlled to be in a transparent transmissive state at times other than the period Ton during the projection period of the image light, the screen 21 can be seen through. Since the light transmitted through the screen 21 appears to be averaged (integrated) to the human eye, a see-through characteristic without flicker is obtained in a sufficiently short scanning period.

  In the above-described embodiment, the brightness adjustment is performed for each area (area, point). However, the brightness of the entire screen may be adjusted.

  In the above-described embodiment, the screen 21 is described as having strong forward scattering and weak reflection scattering. However, the present invention can also be applied to a screen having strong reflection scattering and weak forward scattering. In this case, an image displayed on one surface of the screen is projected from a projector disposed on one surface side, and an image displayed on the other surface of the screen is projected from a projector disposed on the other surface side. That is, the present invention can be applied to a case where an image is displayed using both sides of a screen where either forward scattering or reflection scattering is strong and the other is weak.

  Further, the present invention is not limited to the above embodiment. That is, those skilled in the art can implement various modifications in accordance with conventionally known knowledge without departing from the scope of the present invention. Of course, such modifications are included in the scope of the present invention as long as the configuration of the display device of the present invention is provided.

1, 1A, 1B Display device 11a, 11b Projector 21 Screen 31, 31A Timing control device (control unit, adjustment unit)
51a, 51b Observer 61 Video signal level detection / control device (adjustment unit)
62a First video transmission device 62b Second video transmission device

Claims (9)

A screen that can switch between a transmission state and a scattering state with respect to visible light, and has one surface on which an image can be projected and the other surface on the back side of the one surface on which an image can be projected;
A controller that controls the image projected onto the one surface of the screen and the image projected onto the other surface of the screen to be synchronized with the scattering state of the screen;
A display device comprising:   The image projected on the one surface is an image observed from one viewpoint, and the image projected on the other surface is observed from a viewpoint opposite to the one viewpoint toward the one viewpoint. The display device according to claim 1, wherein the display device is an image.   The display device according to claim 1, wherein an image projected on the one surface and an image projected on the other surface are not related to each other.   4. The apparatus according to claim 1, further comprising an adjustment unit that adjusts a difference in brightness between an image projected on the one surface and an image projected on the other surface within a predetermined range. A display device according to claim 1.   The adjustment unit includes a value related to a light amount of a predetermined region of the image projected on the one surface and a value related to the light amount of a region corresponding to the predetermined region of the image projected onto the other surface. And comparing the value in the predetermined area so that a difference between the value relating to the light quantity in the predetermined area and the value relating to the light quantity in the area corresponding to the predetermined area is within a predetermined value based on the comparison result 5. The display device according to claim 4, wherein at least one of a value relating to a light amount and a value relating to the light amount in an area corresponding to the predetermined area are adjusted.   The display device according to claim 5, wherein the adjustment unit adjusts a value related to the light amount in a region around the predetermined region. Projection of an image onto a screen that can be switched between a transmission state and a scattering state for visible light, and has one surface on which an image can be projected and the other surface on the back side of the one surface on which the image can be projected. Control method of a display device to be displayed,
Including a control step of controlling the image projected on the one surface of the screen and the image projected on the other surface of the screen and the scattering state of the screen to be synchronized. Display device control method.   A display control program for causing a computer to execute the control method for a display device according to claim 7.   A computer-readable recording medium storing the display control program according to claim 8.