JP2015169718A - display control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display control device that enables a user to safely use a screen even when the screen and an image projection device such as a projector are not synchronized to each other.SOLUTION: A synchronization signal acquisition unit 311 acquires a synchronization signal Ssync, and a synchronization signal determination unit 312 determines whether or not the synchronization signal Ssync and a common control signal Scom are synchronized to each other. When the synchronization signal determination unit 312 has determined that the synchronization signal Ssync and the common control signal Scom are not synchronized to each other, a shutter 51 is closed.

Description

  The present invention relates to a display control device that controls display of a screen or the like that displays an image.

  For example, Patent Document 1 discloses a display device that displays an image projected from a projector or the like using a transparent body such as glass as a screen.

  Patent Document 1 includes a screen in which a liquid crystal layer capable of taking a light transmitting state and a light scattering state is sandwiched between a pair of transparent substrates with electrodes, and an image projecting device that projects an image onto the screen. In the provided image display device, it is described that a frame composed of a minimum unit of repetition of a set of a light transmission state and a light scattering state satisfies a predetermined relationship.

JP 2004-184979 A

  The display device described in Patent Document 1 needs to synchronize the timing when the screen is in a scattering state and the timing when an image is projected from the image projection device (projector). If the synchronization is lost, not only the image is not correctly displayed, but also depending on the arrangement of the projector, there is a possibility that the observer looks directly at the projection light of the projector.

  In addition, since the projector and the screen are often configured separately from each other, they are naturally not synchronized when activated individually.

  However, although Cited Document 1 describes that the timing when the screen is in the scattering state and the timing when the image is projected from the image projection apparatus (projector) is synchronized, the case where the synchronization is lost or when the screen is activated There is no mention of screen behavior from sync to sync.

  Therefore, in view of the above-described problems, an object of the present invention is to provide a display control device that can safely use a screen even when the screen and an image projection device such as a projector are not synchronized. .

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a predetermined period is used to switch between the transmission state and the scattering state of the screen that can switch between the transmission state and the scattering state with respect to light. A waveform application unit that applies a voltage waveform generated based on a control signal, an image cycle signal acquisition unit that acquires an image cycle signal that is a signal related to a projection cycle of an image projected on the screen, and the image cycle signal When the synchronization determination unit determines that the image period signal and the control signal are not synchronized, the image is displayed on the screen. And a projection restricting unit that prevents the light from reaching.

  The invention according to claim 9 is based on a control signal having a predetermined period in order to switch between the transmission state and the scattering state of the screen capable of switching between the transmission state and the scattering state with respect to light. A waveform applying step for applying the generated voltage waveform, an image periodic signal acquiring step for acquiring an image periodic signal that is a signal related to a projection cycle of an image projected on the screen, and the image periodic signal and the control signal. When the synchronization determination step for determining whether or not the image is synchronized and the synchronization determination step determines that the image cycle signal and the control signal are not synchronized, the image is prevented from reaching the screen. A projection limiting step.

  The invention described in claim 10 is characterized in that the display control device control method described in claim 9 is executed by a computer.

  The invention described in claim 11 is characterized in that the control program for the display control device described in claim 10 is stored.

It is a schematic block diagram of the display apparatus provided with the display control apparatus concerning 1st Example of this invention. It is typical sectional drawing of the screen shown by FIG. It is explanatory drawing of the projector which projects in synchronization with the optical characteristic of the screen shown by FIG. It is explanatory drawing of the display state with which the image | video by the image light and the background of a screen overlap in the display apparatus shown by FIG. It is a functional block diagram of the synchronous control part shown by FIG. FIG. 7 is a functional configuration diagram of a synchronization signal determination unit, a common control signal acquisition unit, and a drive control signal generation unit shown in FIG. 6. It is a flowchart of operation | movement of the synchronous control part shown by FIG. 2 is a timing chart showing an example of a relationship between a signal waveform in the synchronization control unit shown in FIG. 1, a drive voltage waveform to be applied, and an optical state. 6 is a timing chart showing another example of the relationship between the signal waveform in the synchronization control unit shown in FIG. 1, the drive voltage waveform to be applied, and the optical state. 5 is a timing chart showing an operation of matching (synchronizing) the period and phase of a synchronization signal and a common control signal. 5 is a timing chart showing an operation of matching (synchronizing) the period and phase of a synchronization signal and a common control signal. 5 is a timing chart showing an operation of matching (synchronizing) the period and phase of a synchronization signal and a common control signal. 5 is a timing chart showing an operation of matching (synchronizing) the period and phase of a synchronization signal and a common control signal. It is a schematic block diagram of the display control apparatus concerning the other structural example. It is a schematic block diagram of the display control apparatus concerning the other structural example. It is a schematic block diagram of the display apparatus provided with the display control apparatus concerning the 2nd Example of this invention. It is a block diagram of the projector shown by FIG. It is typical sectional drawing of the screen which the synchronous control part concerning the 3rd Example of this invention controls. FIG. 19 is a schematic front view of a screen showing an arrangement of a plurality of control electrodes shown in FIG. 18. It is explanatory drawing of the synchronous control of the scanning of a screen shown by FIG. 18, and a drive. It is explanatory drawing of the projector which scans the screen shown by FIG. FIG. 19 is a schematic timing chart of scanning and driving of the screen shown in FIG. 18. It is a timing chart showing an example of driving by a common DC system.

  Hereinafter, a display device according to an embodiment of the present invention will be described. In the display control device according to the embodiment of the present invention, the image periodic signal acquisition unit acquires an image periodic signal that is a signal related to the projection period of the image projected on the screen, and the synchronization determination unit includes the image periodic signal and the control signal. It is determined whether or not they are synchronized. Then, when the projection limiting unit determines that the synchronization determination unit determines that the image cycle signal and the control signal are not synchronized, the image projected on the screen is prevented from reaching. In this way, when the image periodic signal output from the projector or the like and the control signal for controlling the scattering state of the screen are not synchronized, the image is not projected onto the screen. You can safely use the screen even if and are not synchronized.

  In addition, the projection limiting unit may include a shutter that transmits or blocks an image projected on the screen. By doing so, it is possible to prevent an image from reaching the screen by, for example, a mechanical shutter or a liquid crystal shutter. Further, by attaching such a shutter to a projection device such as a projector, a well-known projection device can be used.

  In addition, the projection limiting unit may control the projector so that the image is not projected from the projector that projects the image so that the image does not reach the screen. By doing so, it is possible to prevent the image from reaching the screen, for example, by directly controlling the light source or by inserting a black image so that the light source does not shine without using a shutter or the like. it can.

  The projection limiting unit may prevent the image from reaching the screen during a period from when the screen is activated until the synchronization determination unit determines that the image cycle signal and the control signal are synchronized. By doing so, the screen can be safely activated and used even when the screen is not synchronized with the projector or the like.

  The projection limiting unit may prevent the image from reaching the screen when the image periodic signal acquisition unit cannot acquire the image periodic signal. By doing so, it is possible to prevent the image from reaching the screen when the image periodic signal output from the projector or the like cannot be periodically acquired.

  In addition, when the projection limiting unit acquires screen stop instruction information, the projection limiting unit may prevent the image from reaching the screen until the image periodic signal acquisition unit cannot acquire the image periodic signal. In this way, when the screen is stopped, it is possible to prevent the image from reaching the screen that is in a transmissive state until the projection of the projector or the like is completed. Therefore, the observer does not look directly at the light from the projector or the like before the projection of the projector or the like is finished.

  Moreover, you may have a synchronous control part which synchronizes an image period signal and a control signal in the period which the synchronization determination part determines with the image period signal and the control signal not synchronizing. By doing in this way, an image cycle signal and a control signal can be synchronized in the period when the image has not reached the screen.

  In addition, during the period in which the synchronization determination unit determines that the image periodic signal and the control signal are not synchronized and the projection limiting unit prevents the image from reaching the screen, the waveform application unit is set to transmit the screen. A voltage waveform may be applied to the. By doing so, the background can be observed through the screen during the period when the projection restricting unit prevents the image from reaching the screen.

  The display control apparatus control method according to an embodiment of the present invention acquires an image cycle signal that is a signal related to a projection cycle of an image projected on a screen in the image cycle signal acquisition step, and performs an image cycle in the synchronization determination step. It is determined whether the signal and the control signal are synchronized. When the synchronization determination step determines that the image period signal and the control signal are not synchronized in the projection limiting step, the image projected on the screen is prevented from reaching. In this way, when the image periodic signal output from the projector or the like and the control signal for controlling the scattering state of the screen are not synchronized, the image is not projected onto the screen. You can safely use the screen even if and are not synchronized.

  Moreover, it is good also as a control program of the display control apparatus which performs the control method of the display control apparatus mentioned above by computer. By doing so, the screen can be used safely even when the screen and the image projection apparatus such as a projector are not synchronized with each other using a computer.

  Further, the control program for the display control apparatus 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 including a display control device 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, a synchronization control unit 31, and a shutter 51, and a projector 11 is connected to the display device 1. The display device 1 is a transmissive projection device that transmits and scatters image light from the projector 11 through a screen 21.

  The projector 11 can use a transmission-type or reflection-type 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. The projector 11 may perform raster scanning in the video scanning cycle and project video light (image light) on the display surface of the screen 21 dot-sequentially. That is, video light is projected intermittently at a predetermined cycle. As the projector 11, for example, a laser projector or the like in which the irradiation direction of the intensity-modulated light beam is reflected by a movable mirror and shaken can be used. The projector 11 can be considered in the same manner as the image light irradiation position being sequentially scanned in one direction on the screen 21.

  The projector 11 may be any projector that can project video light modulated by video information (image information) onto the screen 21. Note that the video information is obtained from a video signal input to the projector 11. 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 projector 11 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 projector 11 may scan the screen 21 repeatedly with the same video light for displaying a still image.

  The screen 21 may be any screen that can change the optical state by applying a voltage. As for the optical state of the screen 21, a scattering state is an image state, and a transparent transmission state in which scattering of incident light is smaller and parallel light transmittance is higher than that is a non-image state. That is, it is possible to switch between a transmission state and a scattering state with respect to light.

  The screen 21 may be, for example, a light control screen that uses a liquid crystal material and changes a scattering state and a transparent transmission state in which scattering of incident light is small. The light control screen uses, for example, a liquid crystal element such as a polymer-dispersed liquid crystal, or an element that controls a transparent transmission state with small scattering of incident light by moving white powder in a transparent cell. There are things that use etc.

  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 has an optical layer 25 in which a composite material containing liquid crystal is sandwiched between a pair of transparent glass plates 23 and 24. A counter electrode 26 is formed on the entire surface of one glass plate 24 on the optical layer 25 side. A control electrode 27 is disposed on the entire surface of the other glass plate 23 on the optical layer 25 side. An intermediate layer made of an insulator may be formed between the electrodes 26 and 27 and the optical layer 25.

  The counter electrode 26 and the control electrode 27 are formed as transparent electrodes by using, for example, ITO (indium tin oxide). The optical layer 25 is disposed between the control electrode 27 and the counter electrode 26. Further, at least one of the counter electrode 26 and the control electrode 27 may be configured as an electrode that is a half mirror that transmits a part of incident light.

  A voltage is applied to the screen 21 so as to generate a potential difference between the counter electrode 26 as the first electrode and the control electrode 27 as the second electrode. The optical state in the optical layer 25 varies depending on the voltage applied to the counter electrode 26 and the control electrode 27.

  The screen 21 is classified into a reverse mode and a normal mode according to a state when a voltage is applied so as to generate a potential difference. The screen 21 operating in the reverse mode is in a transparent transmissive state in a normal state where no voltage is applied. When a voltage is applied, it becomes a scattering state with a scattering rate of parallel rays according to the applied voltage. In a screen operating in the normal mode, the screen is in a scattering state in a normal state where no voltage is applied. When a voltage is applied, a transparent transmission state with parallel light transmittance corresponding to the applied voltage is obtained. As for the optical state of the screen 21, a predetermined scattering state corresponds to an image state, and a transparent transmission state having a higher parallel light transmittance than that corresponds to a non-image state. In this embodiment, the reverse mode is described, but the normal mode is also applicable.

  The synchronization control unit 31 as the display control unit according to the first embodiment of the present invention controls the screen 21 on which the video (image) is projected as light so as to scatter the projected video light, and is projected. If not, control to transparent state. The synchronization control unit 31 is connected to the projector 11, the screen 21, and the shutter 51 as shown in FIG. The synchronization control unit 31 controls the optical state of the screen 21 and the operation of the shutter 51 in synchronization with the projection of the image light from the projector 11.

  Next, in the display device 1 according to the present embodiment, a projection method of the projector 11 that projects in synchronization with the optical characteristics of the screen 21 will be described with reference to FIG. FIG. 3 is an explanatory diagram of a method in which the projector 11 projects image light at intervals. In this case, as shown in FIG. 3B, image light is projected on the screen 21 in a short period of time during a part of the scanning cycle. As shown in FIG. 3C, the screen 21 may be in a scattering state during the partial period.

  When the optical state of the screen 21 is controlled so as to increase the parallel light transmittance of the screen 21 in a period other than the part, the see-through characteristic of the screen 21 is not caused in the scanning cycle without causing a decrease in the luminance of the image. Is obtained. In order to obtain the same luminance as compared with the case where image light is regularly projected, projection light whose intensity is approximately the reciprocal of the duty (duty: a) in the scattering state for one scanning period is required. It becomes. Therefore, in order to obtain a high see-through characteristic, a powerful pulsed projection light output is required.

  3B may be a light emission period of the light source of the projector 11 itself, or may be a period during which the shutter 51 transmits the image light.

  By controlling the projector 11, the screen 21, and the shutter 51 in this way, the screen 21 has transparency that can recognize the object on the back surface, and has the same brightness as that in the case where the screen 21 is always in a scattering state. Can scatter and transmit light. That is, it is possible to achieve both a see-through property capable of recognizing a background object and a high image visibility.

  The switching timing information for synchronizing control among the projector 11, the screen 21, and the shutter 51 is transmitted from the synchronization control unit 31 to the screen 21 and the shutter 51 based on an image periodic signal such as a vertical synchronizing signal output from the projector 11. Sent out. The projector 11, the screen 21, the shutter 51, and the synchronization control unit 31 may be capable of wireless communication using electromagnetic waves such as microwaves and infrared rays, and information for obtaining these synchronizations may be exchanged by radio signals.

  In the display device 1, for example, in the installation environment of FIG. 1, an image can be visually recognized as shown in FIG. FIG. 4 is an explanatory diagram of a display state in which the image by the image light and the background of the screen 21 overlap. In FIG. 4, an image of a person 41 by video light is shown on the right side of the screen 21, and a tree 42 as a background on the other side of the screen 21 can be seen on the left side.

  Next, FIG. 5 shows a functional configuration of the synchronization control unit 31. The synchronization control unit 31 includes a synchronization signal acquisition unit 311, a synchronization signal determination unit 312, a common control signal acquisition unit 313, and a screen control signal generation unit 314.

  A synchronization signal acquisition unit 311 as an image periodic signal acquisition unit acquires an image periodic signal output from the projector 11. In the present embodiment, a vertical synchronization signal of a video projected by the projector 11 will be described as an image periodic signal (in the following description, it is simply referred to as a synchronization signal). That is, the vertical synchronization signal corresponds to a signal related to the projection cycle of the image projected on the screen 21. Then, the synchronization signal acquisition unit 311 calculates a synchronization signal period Tsync that is a value of one period from the synchronization signal (vertical synchronization signal) Ssync. Then, as illustrated in FIG. 6, the synchronization signal acquisition unit 311 outputs the synchronization signal (vertical synchronization signal) Ssync and the synchronization signal cycle Tsync acquired by itself to the synchronization signal determination unit 312.

  The synchronization signal determination unit 312 as the synchronization determination unit is configured as shown in FIG. The synchronization signal determination unit 312 includes a synchronization signal detection unit 312a, a period information setting unit 312b, a period deviation detection and adjustment unit 312c, a delay information setting unit 312d, a phase deviation detection and adjustment unit 312e, and a synchronization determination unit 312f. And.

  The synchronization signal detection unit 312a detects the synchronization signal Ssync based on the synchronization signal Ssync output from the synchronization signal acquisition unit 311 and the cycle Tcom of the common control signal Scom output from the common control signal acquisition unit 313. Is output to the synchronization signal determination unit. This detects whether or not the synchronization signal Ssync has a pulse waveform to be detected for each cycle (see FIG. 8 and the like for the waveform of the synchronization signal Ssync). For example, it is assumed that one period of Scom or an n period period synchronization signal Ssync is not detected when it is not detected.

  The cycle information setting unit 312b sets the synchronization signal cycle Tsync output by the synchronization signal acquisition unit 311.

  The period shift detection and adjustment unit 312c performs the synchronization signal Ssync and common control based on the synchronization signal period Tsync set in the period information setting unit 312b and the period Tcom of the common control signal Scom output from the common control signal acquisition unit 313. A shift amount of the period from the signal Scom is detected. Then, the value of the cycle Tcom is adjusted based on the deviation amount.

  The delay information setting unit 312d calculates a delay time (phase difference) between the synchronization signal Ssync and the common control signal Scom and sets it as the phase difference Dsync.

  The phase shift detection and adjustment unit 312e determines the phase of the common control signal Scom based on the phase difference Dsync set in the delay information setting unit 312d and the cycle Tcom of the common control signal Scom output from the common control signal acquisition unit 313. To detect. Then, the phase is adjusted based on the deviation amount.

  The synchronization determination unit 312f determines whether or not the synchronization signal Ssync and the common control signal Scom are synchronized based on the results of the period shift detection / adjustment unit 312c and the phase shift detection / adjustment unit 312e. Further, it is also determined whether or not the synchronization signal Ssync has been detected based on the detection result of the synchronization signal detection unit 312a. These determination results are output as determination signals. Further, a shutter control signal is output to the shutter 51 based on the determination result.

  The common control signal acquisition unit 313 includes a cycle information setting unit 313a and a common control signal generation unit 313b.

  In the cycle information setting unit 313a, an initial value of the cycle of the common control signal Scom is set. In addition, when the plurality of screens 21 are used at the same time and the cycle information setting unit 313a is set as the slave side, the cycle information setting unit 313a is the common information output from the synchronization control unit 31 that controls the other screens 21 on the master side. A control signal Scom is acquired. That is, the synchronization signal Scom may be generated and acquired internally, or may be acquired by being input from the outside.

  The common control signal generation unit 313b generates a common control signal Scom that is a signal that is a basis of a voltage waveform applied to the counter electrode 26 of the screen 21, for example. The common control signal Scom is a waveform whose initial value is the period set in the period information setting unit 313a, and the period and phase are adjusted based on the output of the synchronization signal determination unit 312. That is, the common control signal Scom corresponds to a control signal having a predetermined cycle.

  A screen control signal generation unit 314 as a screen control unit includes a see-through control determination unit 314a2, a delay information setting unit 314b, a startup signal generation unit 314c, a drive control signal generation unit 314d, drivers 314f and 314g, and a projection. A period information setting unit 314h.

  The see-through control determination unit 314a2 determines whether or not to cause the screen 21 to perform a see-through operation (alternate switching between the scattering state and the transmission state) based on the determination signal from the synchronization determination unit 312f. The see-through control determination unit 314a2 performs a see-through operation when the determination signal indicates that the determination signal is synchronized. If the determination signal indicates that the determination signal is not synchronized or the synchronization signal Ssync cannot be detected, the see-through control determination unit 314a2 The delay information setting unit 314b is instructed to fix the scattering state.

  The delay information setting unit 314b sets the delay time of the rise signal Sup generated by the rise signal generation unit 314c and the drive control signal Sdrv generated by the drive control signal generation unit 314d. The delay time αup of the start-up signal Sup varies depending on the characteristics of the material forming the optical layer 25 of the screen 21, the ambient temperature, the voltage applied to the electrodes, and the like. However, if the ambient temperature is constant and the voltage waveform applied to the electrode is determined in advance, the rising period αup can be calculated in advance. Further, by setting the rate of change of the rising period αup with respect to the temperature change in a table or the like, the rising period αup can be reflected in the delay information setting unit 314b corresponding to the temperature change.

  The delay time αdrv of the drive control signal Sdrv indicates a period during which the screen 21 is in a scattering state and is a variable value that can be appropriately changed although an initial value is set. When the see-through control determination unit 314a2 determines to perform the see-through operation of the screen 21, the delay time αdrv is set so that the transmittance set by the user or the like is set, so that the screen is alternately switched between the scattering state and the transmission state. To. When the see-through control determination unit 314a2 determines not to cause the screen 21 to perform the see-through operation, the screen 21 is fixed in a transmission state or a scattering state (in this embodiment, it is fixed in a transmission state). When the screen 21 is set to the transmissive state, the delay time αdrv is set to “0”. In the case of the scattering state, the delay time αdrv is such that the screen 21 calculated based on the half-cycle period Tcom of the common control signal Scom, the delay time αup, and the projection period αpj is always in the scattering state. Set to period.

  The rising signal generation unit 314c generates the rising signal Sup by delaying the common control signal Scom by the delay time αup.

  The drive control signal generation unit 314d delays the rising signal Sup by the projection period αpj + delay time αdrv to generate the drive control signal Sdrv. In the case of the always scattering state, the delay time αdrv may be a value of the half cycle period Tcom−delay time αup of the common control signal Scom.

  The drive voltage circuit 314e is a circuit that generates a drive voltage to be applied to the counter electrode 26 and the control electrode 27 from the drivers 314f and 314g.

  The driver 314f as a waveform applying unit is a driver circuit that is connected to the counter electrode 26 side and outputs a driving voltage supplied from the driving voltage circuit 314e. The driver 314f outputs a drive voltage based on the common control signal Scom. The driver 314g is a driver circuit that is connected to the control electrode 27 side and outputs a driving voltage supplied from the driving voltage circuit 314e. The driver 314g outputs a drive voltage based on the drive control signal Sdrv. That is, the drivers 314f and 314g apply a voltage waveform generated based on the common control signal Scom in order to switch between the transmission state and the scattering state of the screen 21.

  The projection period information setting unit 314h sets a projection period αpj that is a period during which the projector 11 projects image light based on the specifications of the projector 11 and the like.

  When the synchronization determination unit 312f determines that the synchronization signal Ssync and the common control signal Scom are not synchronized, the screen control signal generation unit 314 delays the see-through control determination unit 314a2 to fix the screen 21 in the transmissive state. An instruction is given to the information setting unit 314b. The driver 314g applies a voltage waveform such that the drive control signal generation unit 314d generates the drive control signal Sdrv based on the delay information set in the delay information setting unit 314b and sets the screen 21 in the transmission state. Even if the screen 21 is in the transmission state when it is determined that the synchronization signal Ssync and the common control signal Scom are not synchronized, the shutter 51 is closed as will be described later. Never reaches the screen 21.

  The shutter 51 as the projection limiting unit includes, for example, a mechanical shutter composed of a light chopper type that rotates a partially transparent black disk, a driving device that rotates the disk, and the like. The projector 11 is provided on the front surface of a lens or the like on which image light is projected. The shutter 51 is disposed between the projector 11 and the screen 21, and is controlled to open or close (transparent or black) by the synchronization control unit 31 to control transmission or blocking of the image light projected by the projector 11. The shutter 51 is not limited to the optical chopper type, but may be any device that can control the transmission or blocking of image light by being controlled to open and close, such as a method of opening and closing an optical path with one or a plurality of shutter blades. Other types of mechanical shutters may be used. Of course, the shutter 51 may be incorporated in the projector 11. In the following description, the shutter 51 is in an open state when image light is transmitted, and the shutter 51 is in a state in which image light is blocked.

  The shutter 51 is not limited to a mechanical shutter, and may be a known liquid crystal shutter. By using a liquid crystal shutter, a driving device such as a motor becomes unnecessary, and the installation space can be reduced and the durability and safety can be improved. The shutter 51 is not limited to be disposed near the projector 11, and the position of the shutter 51 is not limited as long as it is on the optical path of the image light projected from the projector 11 and can block the image light. Note that the blocking of the image light performed by the shutter 51 is not limited to completely blocking the image light, but includes a case where the light is reduced to such an extent that the observer does not feel dazzling.

  Next, an operation of synchronizing the synchronization signal Ssync and the common control signal Scom in the synchronization control unit 31 having the above-described configuration will be described with reference to the flowchart of FIG.

  First, in step S21, activation of the screen 21 is started. Next, in step S22, the presence / absence of the synchronization signal Ssync is determined. If the synchronization signal Ssync is not present (NO), the process proceeds to step S23 where the shutter 51 is closed to block the image light. That is, when the determination signal output from the synchronization determination unit 312f indicates that the synchronization signal Ssync is not present (cannot be detected), the shutter control indicating that the shutter 51 is closed (the image light is blocked). The signal is output from the synchronization determination unit 312f.

  On the other hand, if the synchronization signal Ssync is present (in the case of YES), the process proceeds to step S24 to determine the synchronization deviation (period or phase deviation) between the synchronization signal Ssync and the common control signal Scom. If YES, the process proceeds to step S23, and if there is no synchronization shift (NO), the process proceeds to step S25. That is, when the determination signal output from the synchronization determination unit 312f indicates that the synchronization is not synchronized, a shutter control signal indicating that the shutter 51 is in a closed state (transmits image light) is determined as the synchronization determination. Output from the unit 312f. If the determination signal indicates synchronization, the screen control signal generation unit 314 generates the drive control signal Sdrv based on the common control signal Scom output from the common control signal acquisition unit 313 in step S25. And the screen is controlled in a scattering state and a transmission state (see-through operation). In this case, the shutter 51 is controlled to the open state. The delay time αdrv during the see-through operation is a preset value.

  That is, step S22 functions as an image periodic signal acquisition process, steps S22 and S24 function as a synchronization determination process, and steps S23 and S25 function as a projection restriction process. Step S25 functions as a waveform applying step.

  Here, the synchronization signal Ssync, the projection signal Spj, the common control signal Scom, the drive control signal Sdrv, the common drive voltage output Vcom that is the drive voltage output from the driver 314f based on the common control signal Scom, and the drive control signal. A selection drive voltage output Vdrv which is a drive voltage output from the driver 314g based on Sdrv, a screen drive voltage indicating a voltage waveform applied to the optical layer 25, and a screen scattering transmission state indicating a scattering or transmission state of the screen Is described with reference to the timing chart shown in FIG. FIG. 8 shows a waveform when the synchronization signal Ssync and the common control signal Scom are synchronized.

  Further, in FIG. 8, the synchronization signal Ssync, the projection signal Spj, the common control signal Scom, and the drive control signal Sdrv are time on the horizontal axis and high level or low level on the vertical axis. The common drive voltage output Vcom, the selection drive voltage output Vdrv, and the screen drive voltage are time on the horizontal axis and voltage on the vertical axis. The screen 21 scattering transmission state is the optical state of the screen 21 (optical layer 25), the horizontal axis is time, and the vertical axis is scattering or transmission.

  In FIG. 8, a rectangular wave having a cycle Tsync is input to the synchronization signal Ssync. The projection signal Spj is a signal indicating a projection period αpj in which the projector 11 projects image light onto the screen 21, and is delayed from the synchronization signal Ssync by a delay time Di. The projection period αpj and the delay time Di of the projection signal Spj are values determined in advance according to the specifications, settings, and the like of the projector 11 (the projection period αpj is set in the projection period information setting unit 314h, the delay time Di is the specification, etc. Based on the rise period αup). The common control signal Scom is a rectangular wave with a cycle of 2Tcom. However, in FIG. 8, since the synchronization signal Ssync and the common control signal Scom are synchronized, Tsync = Tcom. Further, the screen 21 starts switching from the transmission state to the scattering state in synchronization with the rising of the common control signal Scom. That is, when the common control signal Scom rises, a potential difference is generated between the electrodes of the screen 21, and the optical layer 25 is switched to the scattering state.

  The drive control signal Sdrv is a rectangular wave having the same cycle as the common control signal Scom. The drive control signal Sdrv is a signal obtained by delaying (shifting the phase of) the common control signal Scom by a period obtained by adding the values of the rising period αup, the projector projection period αpj, and the screen scattering period αdrv. The added value is preferably equal to or shorter than a half-cycle period Tcom of the common control signal Scom.

  In this embodiment, the common drive voltage output Vcom has the same waveform as the common control signal Scom. The common drive signal output Vcom is the voltage V1 when the common control signal Scom is High, and is 0 volts during the Low period. In this embodiment, the selected drive voltage output Vdrv has the same waveform as that of the drive control signal Sdrv, and is the voltage V1 when the drive control signal Sdrv is High and 0 volt during the Low period.

  The screen driving voltage indicates a voltage waveform applied to the optical layer 25. That is, the common drive voltage output Vcom is applied as a positive voltage to the counter electrode 26 of the screen 21, and the selection drive voltage output Vdrv is applied as a negative voltage to the control electrode 27, that is, the common drive voltage output Vcom−the selection drive voltage output. Vdrv is shown. The screen drive voltage waveform shown in FIG. 8 is a frame inversion method in which two video cycles are one cycle. That is, AC voltage driving is performed in which a positive voltage and a negative voltage are alternately applied every 1 Tsync.

  The screen scattering state is a scattering state as a state in which a voltage is applied when the potential difference (the absolute value of the screen driving voltage) between the counter electrode 26 and the control electrode 27 is V1. When V1 is applied as a screen drive voltage, the screen 21 reaches a peak in the scattering state after the rising period αup, and enters the transmissive state after a predetermined period when V1 is not applied.

  When the see-through operation is performed, the scattering period of the screen 21 is equal to the period of αup + αpj + αdrv, as is apparent from FIG. That is, by setting the screen scattering period αdrv in addition to the rising period αup of the screen 21 and the projection period αpj that is the period in which the image light is projected onto the screen 21, the scattering period is changed by adjusting the screen scattering period αdrv. It is possible to make it. The screen scattering period αdrv is a value set in the synchronization control unit 31, and the set value is reflected in the screen control signal generation unit 314 shown in FIG.

  As described above, since the scattering state of the screen 21 peaks after the rising period αup has elapsed, it is desirable that the image light from the projector 11 be projected after the rising period αup has elapsed. Therefore, it is preferable that the synchronization signal Ssync has a phase relationship that rises after the rising period αup from the change point of the common control signal Scom (the projection period αpj is located).

  The projection signal Spj is output (generated) after the delay time Di has elapsed from the synchronization signal Ssync. That is, the projector 11 projects the image light during the projection period αpj after the delay time Di has elapsed from the synchronization signal Ssync. Therefore, the screen 21 needs to synchronize the projection signal Spj and the scattering state in order to scatter and display the image light. Therefore, the screen 21 is in the scattering state before the rising period αup before the rising (leading) of the projection signal Spj. The migration needs to start. Therefore, the common control signal Scom rises before the rising period αup before the rising of the projection signal Spj. Therefore, the phase difference Dsync between the common control signal Scom and the synchronization signal Ssync is αup−Di. The phase difference Dsync between the common control signal Scom and the synchronization signal Ssync is a phase difference between the change point of the common control signal Scom and the head of the synchronization signal Ssync.

  This rising period αup varies depending on the characteristics of the material forming the optical layer 25 of the screen, the ambient temperature, the voltage applied to the electrode, and the like. However, if the ambient temperature is constant and the voltage waveform applied to the electrode is determined in advance, the rising period αup can be calculated in advance. In addition, by setting the rate of change of the rising period αup with respect to the temperature change in a table or the like, the rising period αup can be reflected in the synchronization signal determination unit 312 corresponding to the temperature change.

  In the present embodiment, matching the phases does not match the timing of the start point of the synchronization signal Ssync and the change point of the common control signal Scom. For example, the synchronization signal Ssync rises after the rising period αup shown in FIG. It is to match a specific phase relationship such as a phase relationship (that is, image light is projected).

  FIG. 9 shows a waveform in the case of the rising period αup <delay time Di. In FIG. 9, since αup <Di, the common control signal Scom changes after detection of the synchronization signal Tsync. Accordingly, the phase difference Dsync in this case is Tcom + αup−Di. Even in such a phase relationship, this embodiment can be applied. That is, the phase may be adjusted in this way.

  Next, the operation of matching (synchronizing) the period and phase of the synchronization signal Ssync and the common control signal Scom in this embodiment will be described with reference to the timing charts shown in FIGS. FIGS. 10 to 13 are timing charts from immediately after power-on to synchronization, in which time elapses in the order of FIGS. 10, 11, 12, and 13.

  The period of the synchronization signal Ssync is Tsync in FIGS. 10 to 13 (the period Tsync is calculated by the synchronization signal acquisition unit 311 during the period of FIG. 10). In FIG. 10, the common control signal Scom has a half cycle period Tcom (0) that is different from the cycle Tsync of the synchronization signal Ssync (Tsync ≠ Tcom (0)). The shutter control signal Sshut is a signal that the synchronization determination unit 312f outputs to the shutter 51. As described above, since the synchronization determination unit 312f determines that the synchronization is not synchronized because it is immediately after the power is turned on and is different from the cycle Tsync of the synchronization signal Ssync, the shutter control signal Sshut should close the shutter 51. It becomes the Low level (see also the shutter waveform in FIG. 10). That is, the shutter 51 prevents the image light from reaching the screen 21 when the synchronization determination unit 312f determines that the synchronization signal Ssync and the common control signal Scom are not synchronized.

  In FIG. 10, since the shutter control signal Sshut is at the low level (the synchronization determination unit 312f determines that the synchronization is not synchronized), the startup signal Sup is commonly controlled without delaying by the delay time αup. A waveform in phase with the signal Scom is output. Since the see-through control determination signal Sshut is at the low level in FIG. 10, the drive control signal Sdrv has a waveform in phase with the common control signal Scom so that the delay time αdrv is set to “0” so that the transmission control signal Sdrv is always in the transmission state. Is output.

  The common drive signal output Vcom has the same waveform as the common drive signal Scom as described with reference to FIG. The selection drive voltage waveform Vdrv is the same waveform as the drive control signal Sdrv as described with reference to FIG. As described with reference to FIG. 8, the screen drive voltage indicates the common drive voltage output Vcom−the selected drive voltage output Vdrv, which is constant at 0 volt in FIG. 10. Therefore, in the screen scattering transmission state, a potential difference is not always applied to the optical layer 25, and the transmission state is always constant.

  Next, in FIG. 11, the cycle Tcom (1) of the common control signal Scom is matched with the cycle Tsync of the synchronization signal Ssync calculated in the period of FIG. 10 (Tcom (1) = Tsync). Then, the shift amount (phase difference) Dsync between the synchronization signal Ssync and the common control signal Scom is confirmed (detected). Also in FIG. 11, since the synchronization signal Ssync and the common control signal Scom are not synchronized, the shutter control signal Sshut remains at the low level, and therefore the screen 21 is always in the transmissive state and the shutter 51 is in the closed state. It has become.

Next, in FIG. 12, in order to match the phases of the synchronization signal Ssync and the common control signal Scom, the half-cycle period Tcom (2) of the common control signal Scom is adjusted as a value calculated by the following equation (1). . The equation (1) is calculated by the period shift detection / adjustment unit 312c and the phase shift detection / adjustment unit 312e. During this period, the screen 21 is always in the transmissive state and the shutter 51 is in the closed state.
Tcom (2) = ((Dsync− (αup−Di)) / 2) + Tcom (1) (1)
In the above formula, “/” indicates division.

Here, the above equation (1) will be described. As apparent from FIGS. 11 to 13, in order for the phase difference Dsync from the synchronization signal Ssync to become the delay time αup at the stage of Tcom (3), Tcom (2) needs to be expressed by the following equation: .
Dsync (2) + 2Tsync− (αup−Di) = 2Tcom (2) (2)

Since Tsync in equation (2) is the same as Tcom (1),
(Dsync (2) − (αup−Di)) / 2 + Tcom (1) = Tcom (2) (3)

  In FIG. 13, the phase and period of the synchronization signal Ssync and the common control signal Scom are matched (synchronized) by the adjustment according to FIG. 12. Therefore, the shutter control signal Sshut is at a high level, the shutter 51 is in an open state, and the delay times αup and αdrv are originally set values. For this reason, the screen drive voltage is applied so that it is in the scattering state only during the period in which it should originally be in the scattering state, and the screen 21 matches the projection of the image light from the projector 11 as shown in the screen scattering transmission state. To change the scattering state and the transmission state alternately (see-through operation).

  As shown in FIGS. 10 to 12, the synchronization signal determination unit 312 closes the shutter 51 from when the screen 21 is activated until it is determined that the synchronization signal Ssync is synchronized with the common control signal. It is controlled so that.

  Further, as shown in FIGS. 10 to 13, in the period shift detection / adjustment unit 312 c and the phase shift detection / adjustment unit 312 e, the synchronization determination unit 312 f does not synchronize the synchronization signal Ssync and the common control signal Scom. Is functioning as a synchronization control unit that synchronizes the synchronization signal Ssync and the common control signal Scom.

  According to the present embodiment, the synchronization signal acquisition unit 311 acquires the synchronization signal Ssync, and the synchronization signal determination unit 312 determines whether the synchronization signal Ssync and the common control signal Scom are synchronized. When the synchronization signal determination unit 312 determines that the synchronization signal Ssync and the common control signal Scom are not synchronized, the shutter 51 is closed. By doing in this way, when the synchronizing signal Ssync output from the projector 11 and the common control signal Scom are not synchronized, the image light does not reach the screen 21, and thus the screen 21 and the projector 11 are not synchronized. Even in this case, the screen 21 can be used safely.

  In addition, since the image light does not reach by closing the shutter 51, a well-known projector 11 can be used by externally attaching the shutter 51 to the projector 11.

  The shutter 51 is in a closed state from the time when the screen 21 is activated until the synchronization signal determination unit 312 determines that the synchronization signal Ssync and the common control signal Scom are synchronized. Sometimes the screen 21 can be safely activated and used even when not synchronized with the projector 11.

  Further, the drive control signal generator synchronizes the synchronization signal Ssync and the common control signal Scom during a period when the synchronization signal determination unit 312 determines that the synchronization signal Ssync and the common control signal Scom are not synchronized. Thus, the synchronization signal Ssync and the common control signal are not synchronized, and the screen 21 can be synchronized during the scattering state. This is also because the projection period αpj and the period of the scattering state of the screen 21 are synchronized as shown in FIGS.

  In addition, the synchronization signal determination unit 312 determines that the synchronization signal Ssync and the common control signal Scom are not synchronized, and applies a voltage waveform so that the screen 21 is in a transmissive state while the shutter 51 is closed. Therefore, the background can be observed through the screen 21 during the synchronization period. Therefore, it is possible to prevent the observer from being aware of the screen 21.

  Further, the screen control signal generation unit 314 alternates the screen 21 between the transmission state and the scattering state during the period when the synchronization signal determination unit 312 determines that the synchronization signal Ssync and the common control signal Scom are synchronized. The drivers 314f and 314g may be controlled so as to be switched. By doing in this way, the image currently projected on the screen 21 and the background which can be observed through the screen 21 can be observed simultaneously.

  The synchronization determination unit 312f also closes the shutter 51 when the synchronization signal Ssync cannot be detected. That is, when the synchronization signal acquisition unit 311 cannot acquire the synchronization signal Ssync, the screen 21 is controlled to be in a scattering state. In this way, when the synchronization signal Ssync output from the projector 11 cannot be acquired periodically, light such as an image projected with the screen 21 in a scattering state is prevented from projecting the screen 21. Can do.

  The synchronization determination unit 312f can acquire the synchronization signal Ssync from the projector 11, for example, when the stop instruction information of the screen 21 such as operation of the power switch is acquired from the operation unit when the synchronization control unit 31 is not shown or the screen 21. The shutter 51 may be closed until it disappears. By doing so, when the screen 21 is stopped, it is possible to prevent the image light from reaching the screen 21 that has been in a transmissive state until the projection of the projector 11 is completed. Therefore, the observer does not look directly at the image light of the projector 11 before the projection of the projector 11 ends.

  Further, the arrangement of the projector 11 and the shutter 51 is not limited to that shown in FIG. 1, and for example, a mirror 52 may be used as shown in FIGS. The mirror 52 reflects the image light projected from the projector 11 toward the screen 21. FIG. 14 shows an example in which the shutter 51 and the mirror 52 are separately arranged, and FIG. 15 shows an example in which the shutter 51 and the mirror 52 are overlapped at the same position. In the example of FIGS. 14 and 15, the shutter 51 is provided so as to block the image light projected from the projector. However, the shutter 51 may be provided on the optical path after being reflected by the mirror 52.

  In the first embodiment described above, the projector 11 projects the image light only during the projection period αpj. However, the projector 11 always projects the image light, and the shutter 51 is controlled to open and close the screen 21. Video light may be projected according to the period of the scattering state. The projection period αpj in this case may be set in the projection period setting unit 314h.

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

  In the display device 1 of this embodiment, the shutter 51 is deleted and the projector 11A is added as shown in FIG. Further, the shutter control signal output from the synchronization determination unit 312f of the synchronization control unit 31 to the shutter 51 is output to the projector 11 as a projector control signal.

  A functional configuration example of the projector 11A is shown in FIG. As shown in FIG. 17, the projector 11A includes a laser control circuit 11a, a red laser light source 11b, a blue laser light source 11c, a green laser light source 11d, collimating lenses 11e, 11f, 11g, a lens 11k, and a mirror. 11j, dichroic mirrors 11h and 11i, a MEMS mirror 11l, and a MEMS mirror control circuit 11m.

  The laser control circuit 11a outputs the video signals converted into the gradation data of the three colors red, blue, and green to the red laser light source 11b, the blue laser light source 11c, and the green laser light source 11d, respectively. The red laser light source 11b, the blue laser light source 11c, and the green laser light source 11d output laser light of each color according to the gradation data input from the laser control circuit 11a. Further, the laser control circuit 11a performs switching control of light emission or extinction of the red laser light source 11b, the blue laser light source 11c, and the green laser light source 11d based on the projector control signal input from the synchronization control unit 31 (synchronization determination unit 312f). Do.

  The laser light output from the red laser light source 11b is collimated by the collimating lens 11e, then passes through the dichroic mirror 11h and the lens 11k and enters the MEMS mirror 11l. The laser light output from the blue laser light source 11c is collimated by the collimator lens 11f, reflected by the dichroic mirror 11i toward the dichroic mirror 11h, reflected by the dichroic mirror 11h toward the lens 11k, and the lens 11k. Is incident on the MEMS mirror 11l. The laser light output from the green laser light source 11d is collimated by the collimating lens 11g, reflected by the mirror 11j toward the dichroic mirror 11i, then transmitted through the dichroic mirror 11i, and directed by the dichroic mirror 11h toward the lens 11k. Is reflected, passes through the lens 11k, and enters the MEMS mirror 11l.

  The MEMS mirror 11l is a mirror (scanning element, spatial modulator) configured by MEMS (Micro Electro Mechanical Systems) that scans incident laser light in the horizontal and vertical directions of the screen 21, and is formed integrally with the mirror. It is driven by an actuator (not shown). The operation of the MEMS mirror 11l is controlled by the MEMS mirror control circuit 11m. The laser light incident on the MEMS mirror 11 l is projected toward the screen 21.

  In this embodiment, instead of opening or closing the shutter 51, the light source (red laser light source 11b, blue laser light source 11c, green laser light source 11d) of the projector 11 emits or turns off the image light. Does not reach the screen 21. That is, the light source is turned off (light emission is stopped) during a period in which the synchronization signal Ssync and the common control signal Scom are not synchronized or a period in which the synchronization signal Ssync is not detected. That is, the laser control circuit 11a functions as a projection limiting unit.

  According to the present embodiment, since the laser control circuit 11a stops the light emission of the light sources (red laser light source 11b, blue laser light source 11c, green laser light source 11d) of the projector 11, the screen is used without using the shutter 51. It is possible to prevent the image light from reaching 21.

  In the second embodiment, the laser control circuit 11a stops the light emission of the light source of the projector 11 so that the image light does not reach the screen 21, but a black image is inserted into the image to be projected. You may do it. By doing so, since the period during which the black image is inserted is substantially equivalent to the case where the light source does not emit light, it is possible to prevent the image light from reaching the screen 21 without using the shutter 51. .

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

  In the display device 1 according to the present embodiment, as shown in FIGS. 18 and 19, the screen 21 is divided into a plurality of regions. FIG. 18 is a schematic cross-sectional view of a screen 21 that can control the optical state for each divided region, and FIG. 19 is a schematic screen diagram showing the arrangement of a plurality of control electrodes on the screen 21 shown in FIG. A typical front view is shown. The screen 21 shown in FIG. 18 has an optical layer 25 in which a composite material containing liquid crystal is sandwiched between a pair of transparent glass plates 23 and 24. A counter electrode 26 is formed on the entire surface of one glass plate 24 on the optical layer 25 side. A plurality of control electrodes 27 are arranged side by side on the optical layer 25 side of the other glass plate 23.

  The plurality of control electrodes 27 divide the area irradiated with the image light on the screen 21 into strips in one direction (for example, the scanning direction) (see FIG. 19). The plurality of control electrodes 27 are individually connected to the synchronization control unit 31 and can individually apply voltages. Adjacent control electrodes 27 are arranged apart from each other. In FIG. 19, strip-like regions are arranged vertically, but the regions may also be divided into a matrix by dividing the region in the horizontal direction.

  Further, the optical layer 25 of this embodiment can be adjusted for each divided region between a transparent transmission state in which the scattering of incident light is small and a scattering state in which the incident light is scattered.

  The width of the gap region in the optical layer 25 corresponding to the region where the control electrode 27 is not formed between the control electrodes 27 is about 5 to 100 micrometers, and is desirably as narrow as possible. The thickness of the optical layer 25 is several to several tens of micrometers, and is determined in consideration of optical characteristics and drive voltage.

  Next, the basic operation principle of the display device 1 of this embodiment will be described. FIG. 20 is an explanatory diagram of the synchronization control between scanning and driving of the screen 21. The projector 11 vertically scans the screen 21 from the top to the bottom with image light modulated by the image 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).

  20A to 20E show the scanning state at each time point in one scanning cycle in the scanning order. The screen 21 in FIG. 20 has five divided regions 22. The five divided regions 22 are arranged vertically along the scanning direction of the image light.

  The synchronization control unit 31 controls the optical states of the five divided regions 22 individually 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 irradiated 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 synchronization control unit 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 region 221 from the top of the screen 21 as shown in FIG. The synchronization control unit 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. Further, the synchronization control unit 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. After that, as shown in FIGS. 20C to 20E, the synchronization control unit 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. 21 illustrates the projection method of the projector 11 according to the present embodiment. FIG. 21 is an explanatory diagram of the projector 11 that scans the screen 21. FIG. 21A is an explanatory diagram of a projection method in which the projector 11 scans the screen 21. In this case, video light is always projected onto the screen 21 during the scanning cycle. However, paying attention to each part of the screen 21, the image light is projected in a part of the scanning cycle as shown in FIG. For this reason, as shown in FIG. 21C, each part of the screen only needs to be in a scattering state in the partial scanning period TP in which each part is scanned. Further, if each part of the screen 21 is controlled so as to increase the parallel light transmittance in a period other than the partial scanning period TP, the see-through characteristic of the screen 21 can be achieved without causing a decrease in the luminance of the image in the scanning period. can get.

  When the light is divided into strips in one direction like the screen 21 shown in FIG. 19, the projection light of the projector 11 is sequentially scanned in the division direction of the screen 21. Based on the synchronization signal from the projector 11, the synchronization control unit 31 sets the plurality of divided regions 22 so that the part irradiated with the projection light of the projector 11 is maintained in the video state (scattering state in this embodiment). In the scanning order, the transparent transmission state is controlled to the scattering state. By this synchronization control, each divided region 22 of the screen 21 is in a scattering state as a video state in a period Ton (see FIG. 22) including a video period in which projection light is irradiated on the region. Further, in the non-video period Toff (see FIG. 22) where the projection light is not irradiated, a transparent transmission state as a non-video state is obtained.

  Therefore, the screen 21 can scatter and transmit the image light with the same brightness as the case where the screen 21 is always in a scattering state while having transparency that can recognize the object on the back surface. That is, it is possible to achieve both a see-through property capable of recognizing a background object and a high image visibility.

  FIG. 22 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. 22, the image light scanning is indicated by three arrows, which indicate image light corresponding to 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.

  Even in such a configuration, the synchronization signal Ssync and the common control signal Scom can be synchronized by applying the configurations of the first and second embodiments. This is because the period of the scattering state of each divided region can be controlled by providing the drive control signal Sdrv for each divided region. Since the drive control signal Sdrv is a signal obtained by delaying the common control signal Scom, by synchronizing the common control signal Scom with the synchronization signal Ssync as shown in the first to second embodiments, the screen 21 or The screen 21 and the projector 11 can be synchronized without adversely affecting the synchronization control unit 31.

  Of course, when the synchronization signal Ssync and the common control signal Scom are not synchronized, the image light can be prevented from reaching the screen 21 by the control of the shutter 51 and the projector 11. Since the shutter control signal and the projector control signal are signals based on the determination result of the synchronization determination unit 312f, even if the screen 21 is divided, the image light is applied to the screen 21 by the same operation as in the first and second embodiments. It is possible to prevent it from reaching.

  In each of the above-described embodiments, the voltage output from the common drive voltage output Vcom and the selective drive voltage output Vdrv is set to be excessively higher than the threshold voltage in order to speed up the change (rise) to the scattering state. In some cases, a phenomenon may occur in which the degree of scattering decreases after the scattering characteristics of the screen 21 reach the peak of scattering. For this reason, a driving method (also referred to as overdrive) in which a first voltage is applied to speed up the start to the scattering state, and then a second voltage that can stably maintain the scattering state is applied. May be applied).

  Further, in each of the embodiments described above, the screen 21 is driven by the frame inversion method, but it may be driven by a common DC method as shown in FIG. The common DC system is a system that generates a potential difference in a scattering state by changing the potential of one electrode while keeping the potential of one electrode constant. In the example of FIG. 23, the common drive voltage output Vcom is 0 volt, and the selected drive voltage output Vdrv includes a period during which the common control signal Scom is “High” and the drive control signal Sdrv is “Low”, and the common control signal Scom is A rectangular wave that changes between V1 and −V1 during a period when the drive control signal Sdrv is “High” at “Low” is applied.

  Moreover, you may comprise the operation | movement in the synchronous control part 31 mentioned above as a computer program (control program) which operate | moves with CPU. In this way, a part of the synchronization control unit 31 can be caused to function in the computer.

  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 also included in the scope of the present invention as long as the configuration of the display control apparatus of the present invention is provided.

DESCRIPTION OF SYMBOLS 1 Display apparatus 11 Projector 21 Screen 31 Synchronization control part (display control apparatus)
51 Shutter (Projection restriction part)
311 Synchronization signal acquisition unit (image periodic signal acquisition unit)
312 Synchronization signal determination unit (synchronization determination unit, synchronization control unit)
314 Screen control signal generation unit (waveform application unit)
314f driver (waveform application unit)
314g driver (waveform application unit)
Scom common control signal (control signal)
Ssync image periodic signal (image periodic signal)

Claims (11)

A waveform application unit that applies a voltage waveform generated based on a control signal having a predetermined period in order to switch between the transmission state and the scattering state of a screen that can switch between a transmission state and a scattering state with respect to light. When,
An image periodic signal acquisition unit that acquires an image periodic signal that is a signal related to a projection period of an image projected on the screen;
A synchronization determination unit for determining whether or not the image periodic signal and the control signal are synchronized;
If the synchronization determination unit determines that the image periodic signal and the control signal are not synchronized, a projection limiting unit that prevents the image from reaching the screen;
A display control device comprising:   The display control apparatus according to claim 1, wherein the projection restriction unit includes a shutter that transmits or blocks the image projected on the screen.   The display control apparatus according to claim 1, wherein the projection restriction unit controls the projector to project the image so that the image is not projected so that the image does not reach the screen.   The projection limiting unit prevents the image from reaching the screen during a period from when the screen is activated until the synchronization determination unit determines that the image period signal and the control signal are synchronized. The display control apparatus according to claim 1, wherein the display control apparatus is a display control apparatus.   5. The projection restriction unit prevents the image from reaching the screen when the image periodic signal acquisition unit cannot acquire the image periodic signal. 6. The display control apparatus described.   The projection restriction unit, when acquiring the screen stop instruction information, prevents the image from reaching the screen until the image periodic signal acquisition unit cannot acquire the image periodic signal. Item 6. The display control device according to any one of Items 1 to 5.   A synchronization control unit that synchronizes the image cycle signal and the control signal during a period when the synchronization determination unit determines that the image cycle signal and the control signal are not synchronized with each other. Item 7. The display control device according to any one of Items 1 to 6.   During the period when the synchronization determination unit determines that the image period signal and the control signal are not synchronized and the projection limiting unit prevents the image from reaching the screen, the waveform application unit The display control apparatus according to claim 1, wherein the voltage waveform is applied so as to be in a transmissive state. A waveform applying step of applying a voltage waveform generated based on a control signal having a predetermined period in order to switch between the transmission state and the scattering state of the screen that can switch between a transmission state and a scattering state with respect to light. When,
An image periodic signal acquisition step of acquiring an image periodic signal that is a signal related to a projection period of an image projected on the screen;
A synchronization determination step for determining whether or not the image periodic signal and the control signal are synchronized;
If the synchronization determination step determines that the image periodic signal and the control signal are not synchronized, a projection limiting step for preventing the image from reaching the screen;
A control method for a display control device, comprising:   A control program for a display control apparatus, characterized by causing a computer to execute the display control apparatus control method according to claim 9.   A computer-readable recording medium storing the control program for the display control device according to claim 10.

Images