JP2014081580A - Image display method - Google Patents

Abstract

An image display method that enables transparent display with a large screen and high definition and high color reproducibility is provided.
An image in which an image is drawn by scanning a visible light beam from a light source onto the display screen on a display screen having a liquid crystal light control layer capable of switching between a light transmission state and a light scattering state by electric drive. In the display method, the light scattering state of the display screen is switched so as to form a band-like region, the main scanning direction in the scanning coincides with the length direction of the band-like region, and the sub-scanning direction in the scanning is the band-like region An image that matches the width direction of the region, scans the light beam in the belt-like region, changes the position of the belt-like region periodically in synchronization with the sub-scan of the scan, and displays the observer in the display region And an image display method characterized in that the background of the display area can be viewed at the same time.
[Selection] Figure 1

Description

  The present invention relates to an image display method using an image display device including a screen and an image projector. More specifically, the display screen includes a liquid crystal light control layer that can be switched between a light transmission state and a light scattering state by electric drive, and an image displayed on the display region by an observer, The present invention relates to an image display method characterized in that a background can be viewed simultaneously.

  In recent years, development of a transparent display in which an image is displayed on a transparent body such as a window glass or a film and the background of a non-display portion can be seen at the same time has been developed. As a conventional technique, a display that performs transparent display by transparentizing a conventional FPD member, such as a transparent LCD, a transparent OLED, and a transparent PDP, is known. However, these displays have a problem that the background cannot be seen in a dark place because the non-display portion has a high light transmittance of about 50%.

  On the other hand, a transparent display method is known in which a screen that can be switched between a light transmission state and a light scattering state is used as a transparent body, and an image projected by a projector is imaged and visible when the screen is in a light scattering state. ing. By using this display method, the light transmittance of the non-display portion can be made greater than 50%, and an unprecedented transparent image can be provided in which the background can be visually recognized even in a dark place. it can.

Patent Document 1 discloses a system that performs transparent display by setting a region in which light emitted from a projector is projected on a screen to a scattering state and the remaining region to a light transmitting state.
Patent Document 2 discloses a display system that periodically changes a light transmission state and a light scattering state of a screen to synchronize image projection by a projector with screen modulation. With the display method of Patent Document 2, it is not necessary to divide the screen display into segments, and a transparent display can be obtained with an inexpensive device. Furthermore, it is not necessary to precisely align the projector and the screen, and there is an advantage that the degree of freedom of the installation position of the projector is increased.

  In recent years, the development of laser modules and optical engines has been remarkable as projectors, and laser scanning projectors with high brightness and high light conversion efficiency have become available as consumer products so that images with high color reproducibility can be used. became. By combining a large-area screen and a laser scanning projector, you can create a vivid and powerful display.

JP 2010-197486 A JP 2004-184979 A

In the display method of Patent Document 1, when displaying an arbitrary image, it is necessary to make the screen a dot matrix display. Therefore, in order to obtain a large-area and high-resolution image, a large number of pixels are required, resulting in an expensive apparatus. In addition, the projector and the screen must be precisely aligned, and if the positions of both are slightly shifted, the image will be interrupted, a light scattering area will occur in a place where there is no image, and the appearance will deteriorate. Therefore, there is a problem that the installation position of the projector is greatly restricted.

  On the other hand, Patent Document 2 does not describe the idea of dividing the screen display into segments, and switches the entire screen at the same time. In this display method, when a high-definition image is displayed on a large-area screen using a scanning projector, the number of scanning lines greatly increases, so the scanning time increases and the screen display flickers. There is a problem. There is also a problem that the transparency of the background cannot be obtained sufficiently for the same reason.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image display method that enables transparent display with high resolution and high color reproducibility on a large screen.

  As a result of intensive studies to solve the above problems, the present inventors have performed screen modulation in a screen that can be switched between a light transmission state and a light scattering state by electric drive, and an image display method that scans and draws light on the screen. The inventors have found that a transparent display image with a large area can be displayed with a simple device by scanning the light beam in a band shape and synchronizing with the screen modulation, and have reached the present invention.

That is, the gist of the present invention is as follows.
(1) An image display that draws an image by scanning a visible light beam from a light source onto the display screen provided with a liquid crystal light control layer capable of switching between a light transmission state and a light scattering state by electric drive. A method,
The light scattering state of the display screen is switched to form a band-like region,
The main scanning direction in the scanning coincides with the length direction of the band-shaped region, and the sub-scanning direction in the scanning coincides with the width direction of the band-shaped region,
Scanning the beam with the beam, and periodically changing the position of the band in synchronization with the sub-scan of the scan,
An image display method characterized in that an observer can simultaneously view an image displayed in the display area and a background of the display area.
(2) The image display method according to (1), wherein an average value of the area of the belt-like region is 1% or more and 20% or less with respect to the area of the display region of the display screen.
(3) The image display method according to (1) or (2), wherein the refresh frequency is 40 Hz to 70 Hz.
(4) The image display method according to any one of (1) to (3), wherein a parallel light transmittance in the belt-like region is 30% or less.
(5) The image display method according to any one of (1) to (4), wherein a parallel light transmittance on the display screen in a light transmitting state is 80% or more.
(6) The liquid crystal light control layer has a pair of transparent substrates with electrodes arranged to face each other, and includes a composite containing a liquid crystal and a polymer resin between the substrates,
The image display method according to any one of (1) to (5), wherein the liquid crystal is a chiral nematic liquid crystal having positive dielectric anisotropy.
(7) The composite is obtained by curing a mixture including a chiral nematic liquid crystal having a positive dielectric anisotropy and a polymer precursor represented by the following general formula (1). The image display method according to (6).

[In General Formula (1), A ¹ and A ² each independently represent a hydrogen atom or a methyl group,
Ar ¹ , Ar ² and Ar ³ each independently represent a divalent aromatic hydrocarbon ring group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent. ,
X ¹ and X ² are each independently a direct bond, a carbon double bond, a carbon triple bond, an ether bond, an ester bond, a linear alkylene group having 1 to 6 carbon atoms which may have a substituent, and a substituent. Represents a linear oxyalkylene group having 1 to 6 carbon atoms which may have a group;
R ¹ and R ² are each independently a linear alkylene group having 1 to 6 carbon atoms that may have a substituent, or a linear chain having 1 to 6 carbon atoms that may have a substituent. Represents an oxyalkylene group or a linear alkyl ester group having 2 to 6 carbon atoms,
m, n, p and q each independently represents 0 or 1.
However, at least one of Ar ¹ , Ar ^2, and Ar ³ is a divalent aromatic hydrocarbon condensed ring group which may have a substituent or a divalent which may have a substituent. Represents an aromatic heterocyclic group. ]
(8) The image display method according to (7), wherein the polymer precursor represented by the general formula (1) is represented by the following general formula (2).

[In General Formula (2), A ¹ and A ² each independently represent a hydrogen atom or a methyl group,
Ar ⁴ represents a divalent aromatic hydrocarbon condensed ring group which may have a substituent or a divalent aromatic heterofused ring group which may have a substituent,
R ¹ and R ² are each independently a linear alkylene group having 1 to 6 carbon atoms that may have a substituent, or a linear chain having 1 to 6 carbon atoms that may have a substituent. Represents an oxyalkylene group or a linear alkyl ester group having 2 to 6 carbon atoms,
p and q each independently represents 0 or 1. ]

  The image display device of the present invention can be used for a notice board, a computer terminal, a projection, and the like.

It is a figure which shows the structure of the image display apparatus of 1st Embodiment. It is a figure which shows the display screen of 1st Embodiment. FIG. 3 is a view showing a glass substrate that sandwiches a liquid crystal-polymer composite in a liquid crystal light control layer provided in the display screen 1. It is the figure which made the display screen 1 the whole surface scattering state, and displayed the display image 5B. It is a figure which shows the switching method of the strip | belt-shaped area | region in the display screen 1, and the scanning method of a laser beam in 1st Embodiment. FIG. 3 is a diagram showing a glass substrate that sandwiches a liquid crystal-polymer composite in a liquid crystal light control layer provided in the display screen 1. It is a figure which shows a response | compatibility with a strip | belt-shaped area | region and display image at the time of using n glass substrates 6C with a striped transparent electrode in 1st Embodiment. It is a figure which shows the switching method of the strip | belt-shaped area | region in the display screen 1, and the timing of a laser beam projection in 2nd Embodiment. In 3rd Embodiment, it is a figure which shows the switching method of the strip | belt-shaped area | region in the display screen 1 using a dot matrix panel, and the scanning method of a laser beam. It is a figure which shows the display screen which combined the transparent display and the non-transparent display in 3rd Embodiment. A combination display method using transparent display and non-transparent display using a matrix panel will be described.

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents.
The image display method of the present invention is characterized in that an observer can simultaneously view an image displayed in the display area and a background of the display area. Hereinafter, such display is expressed as transparent display.

  An image display device used in the image display method of the present invention includes a display screen having a liquid crystal light control layer capable of switching between a light transmission state and a light scattering state in a display region, and a light source for drawing an image on the display screen. The display screen is arranged with respect to the light source. In this specification, unless otherwise specified, light means visible light (wavelength 380 to 800 nm).

The light transmission state of the present invention refers to a state in which a landscape facing the screen can be visually recognized, and a higher parallel light transmittance is preferable because the visibility is increased.
The light scattering state of the present invention refers to a state in which the screen is cloudy and it is difficult to visually recognize the landscape facing the screen. The lower the parallel light transmittance, the better the visibility of the image displayed in the display area. Therefore, it is preferable. Here, the parallel light transmittance is measured by the method of JIS K7136 (2000). Note that when switching between the light transmission state and the light scattering state, an intermediate transient state is usually used, so that an intermediate state between the light transmission state and the light scattering state may be taken during the switching.

  In the present invention, the display screen is periodically switched between a light transmission state and a light scattering state, and light is emitted from a light source and drawn during a period in which the screen is in a light scattering state, whereby an image is displayed on the screen. An image can be formed. Note that the term “periodic” generally means exactly the same every period, but may include a partly different period as long as it does not depart from the spirit of the present invention.

In the present invention, one cycle means the time from scanning of a light source from a light source to be described later until the entire display area of the display screen is scanned from the scanning start position and returned to the scanning start position.
Under the above conditions, let d be the ratio of the time during which the minimum unit area in which the screen is switched between the light transmission state and the light scattering state in one cycle is in the light scattering state. By setting d below a certain level, transparent display is possible. The smaller d is, the better the transparency of the background of the display area is. On the other hand, the brightness of the image is lowered, so the visibility is lowered. In order to ensure both image visibility and background transparency, d is preferably set to 0.01 or more and 0.20 or less.

  Also, if the frequency of switching between the light transmission state and the light scattering state of the screen is F, the screen appears to flicker when F is small, but by setting the frequency large, the flickering of the display image is not felt. Can be. However, if it is too large, it is generally impossible to follow the switching of the screen, and the transparency of the background is lowered. In order to ensure the transparency of the background without feeling flicker, it is preferable to set F to 40 Hz or more and 70 Hz or less.

Here, when the screen scattering time in one period is T _D , T _D = d / F.
In general, the following is a problem of large area display when drawing is performed by scanning a light beam without dividing the screen display as in Patent Document 2. The resolution of the image is determined by the scanning angle of the main scanning in the main scanning direction and the number of scanning lines in the sub-scanning direction. In the sub-scanning direction, assuming that the number of scanning lines is N and the main scanning frequency is F _H , the time required to scan the entire display area is approximately N / F _H. That is, T _D = N / F _H.

Here, assuming that 0.01 ≦ d ≦ 0.20 and 40 Hz ≦ F ≦ 70 Hz,
ms ≦ T _D ≦ 5.0 ms. However, F _H is limited to about 30 kHz due to limitations of current optical engine technology. Accordingly, 4 ≦ N ≦ 150. In other words, only a very small area can be transparently displayed by the scanning projector.
According to the image display method of the present invention, during scanning, the area near the light beam is switched to the light scattering state, and the area in the light scattering state is divided into strips that are easy to scan. This makes it possible to obtain a high-definition transparent display on a large screen even when the scanning projector provided is used.

  In the image display method of the present invention, the light scattering state of the display screen is switched so as to form a band-like region, the main scanning direction in the scanning coincides with the length direction of the band-like region, and the sub-scanning direction in the scanning is It coincides with the width direction of the belt-like region, the light beam is scanned in the belt-like region, and the position of the belt-like region is periodically changed in synchronization with the sub-scan of the scanning. The light beam is scanned in the belt-like region, and the position of the belt-like region is periodically changed in synchronization with the sub-scan of the scanning. That is, the background transparency can be effectively increased by switching to the light scattering state only in the vicinity of the area where the light beam is hit during scanning. Further, the number of scanning lines that can be transparently displayed can be increased by dividing the light scattering state into strips that are easy to scan.

<Display screen>
The display screen used in the present invention includes a liquid crystal light control layer that can switch between a light transmission state and a light scattering state by electric drive in a display region. As the liquid crystal light control layer, for example, a transmission-scattering type liquid crystal-polymer composite capable of switching between a light transmission state and a light scattering state by electric drive can be used.

Usually, the liquid crystal light control layer is sandwiched between a pair of substrates with electrodes arranged opposite to each other, and a DC voltage, an AC voltage, a pulse voltage or a combination thereof having an effective value equal to or greater than a threshold value is applied to the substrate. By doing so, it is possible to switch between a light transmission state and a light scattering state. The liquid crystal light control layer includes a normal mode in which light is transmitted in a light scattering state when no voltage is applied, and a light transmission state in a light transmission state when no voltage is applied. Any one that drives in a memory mode in which a voltage is applied only when switching between the light scattering state and the light scattering state may be used. Among them, the reverse mode and the memory mode are transparent at normal times (no voltage applied) in applications such as windows and showcases, and can display an image in a light scattering state when a voltage is applied. It is useful from.

<Light source>
The light source used in the present invention may be any general visible light source, and lasers, lamps, LEDs, OLEDs and the like can be used. Among these, a laser is preferable because of high color reproducibility of emitted light.
Light emitted from the light source is projected onto the screen as light rays. As a method of obtaining the light beam, a light source that emits a light beam such as a laser may be used, and light from a laser, a lamp, an LED, an OLED, or the like may be condensed using a collimator. Further, the beam diameter may be expanded by diffusing the light beam with a diffusion lens or the like.

As the color of light, a monochromatic light source may be used, or a multicolor light source such as white light may be used. Colors may be reproduced by combining single color light sources of red, green, and blue, or color adjustment may be performed by combining multicolor light and a color filter.
In order to scan the light beam on the screen, a known optical scanner can be used, such as an optical scanner using a movable mirror such as a MEMS scanner, a galvano scanner, or a polygon mirror, or in a solid such as an acoustooptic effect or an electrooptic effect. A refractive index modulation type optical scanner using a refractive index modulation effect may be mentioned. As a light scanner using a movable mirror, a small-sized and high-speed MEMS scanner is preferable, a method using a two-dimensional MEMS scanner, a method combining two one-dimensional MEMS scanners, and a one-dimensional MEMS scanner. And a combination of a light valve and a one-dimensional MEMS scanner. Examples of the MEMS scanner include known methods such as an electromagnetic method, an electrostatic method, and a piezoelectric method. Any commercially available scanning projector can be used as the device for scanning the light beam, and specific examples include SHOWWX LASER PICO PROJECTOR (Microvision).

The positional relationship between the screen and the light source in the present invention may be a rear projection method in which the observer and the light source face each other with the screen interposed therebetween, or a front projection method in which the observer and the light source are on the same side with respect to the screen. In the light scattering liquid crystal light control layer, the former may be used when backscattering is strong, and the latter may be used when forward scattering is strong.
Further, it may be installed such that the light exit of the light source is perpendicular to the screen, or may be installed at an angle. It is also possible to install the light source at an angle such that the light source cannot be seen with respect to the screen so as not to obstruct the observer's view. In this case, it is preferable to correct the shape of the projected image according to the display portion of the screen.

Further, it is preferable to correct the display area so that the luminance of the image is uniform. Light can be reflected by a plane mirror to make the light source invisible, and an image can be enlarged or reduced by a curved mirror.
In the image display method of the present invention, one light source may be arranged on one screen, or two or more light sources may be arranged on one screen. When two or more light sources are arranged on one screen, an image may be drawn at the same place on the screen, or an image may be drawn at different places. When two or more light sources are arranged on one screen, the light beams may be projected simultaneously from the respective light sources or may be projected at different timings. For example, when the light source is composed of three colors of red, green, and blue, the colors may be reproduced by simultaneously projecting the respective colors, or a field sequential color system that reproduces the colors by displaying red, green, and blue in a time division manner may be used. Two or more screens may be arranged for one light source. When two or more screens are arranged for one light source, the screens can be arranged in a plane or in the depth direction. When the screens are arranged in a plane, independent display can be performed on each screen, or multi-display can be performed in which the display of each screen is combined into one display as a whole.

<Display screen switching method>
In the image display method of the present invention, the light scattering state of the display screen is switched so as to form a band-like region. The band-like region is a generally rectangular region, and the length direction coincides with the long side direction, and the width direction coincides with the short side direction. However, within the scope not departing from the spirit of the present invention, polygons such as pentagons and octagons with rectangular corners cut off, parallelograms with acute angles of 60 degrees or more, trapezoids with acute angles of 60 degrees or more, rectangular shapes Any shape close to a rectangle, such as one to four rounded corners, can be used. In any case, the length direction is the direction of the longest side of the belt-like region (the direction in which the straight line portion of the circumference is the longest when the corner is round), and the width direction is the direction perpendicular to the length direction. It is.

  The display area of the display screen has a minimum unit having a different position. The minimum unit may be a band-like area or a unit obtained by further dividing the band-like area. Switching the minimum unit from the light scattering state to the light transmitting state and switching another minimum unit from the light transmitting state to the light scattering state changes the position of the minimum unit that performs the light scattering state from the light transmitting state. The light scattering state is switched.

The minimum units are preferably adjacent to each other in the width direction, and a gap may be left between adjacent minimum units. However, it is preferable that the gap is small, and it is more preferable that there is no gap at all. Further, the minimum unit may be adjacent in the length direction. By switching adjacent minimum units at the same timing, they can be handled as one band-like region.
The method of switching the light scattering state to a band shape can be set by the configuration of the electrodes provided on the display screen. For example, it is possible to divide the display screen electrode into segments and apply a voltage to a desired region. As a method of dividing into segments, the electrodes on one side can be formed in a stripe shape in which bands are arranged, and the other side can be formed in a solid shape, or both sides can be formed in a stripe shape. In the case of double-sided stripes, the bands of the opposing substrates can be arranged in parallel, or the dot matrix can be formed by arranging them orthogonally. Moreover, it is good also as an active matrix using TFT. When the electrodes form a dot matrix, the minimum unit of the belt-like region can be formed by simultaneously switching one row composed of an arbitrary number of dots.

The minimum units of the display screen may be different shapes, but preferably have the same width, and more preferably all have the same shape. In addition, when the screen is switched so that all the minimum units appear at the same time, it is preferable that the region in the light scattering state matches the display region of the screen.
The order of switching the band-like areas in one cycle can be switched in order from the band-like area at the end of the display area, or the order may be arbitrarily changed. For example, starting from the strip-shaped area at the first end of the display area, the odd-numbered strip-shaped areas are sequentially switched, and then starting from the strip-shaped area second from the end of the display area, the even-numbered strip-shaped areas are sequentially switched. For example, it can support an interlace method.

<Light beam scanning method>
A light beam scanning method used in the present invention will be described. Drawing with light rays is performed by drawing scanning lines over the entire display area by combining main scanning and sub-scanning. The main scan is a scan that draws one scan line by linearly moving the projection point of the light beam on the display screen. As the main scanning, the scanning line may be drawn by emitting light only in one way, or the scanning line may be drawn by emitting light in a reciprocating manner. The sub-scan is a scan that changes the position and repeats the main scan in parallel. Although the main scanning direction and the sub-scanning direction are usually vertical, an acute angle may be formed or an obtuse angle may be formed within a range that does not depart from the spirit of the present invention. Two-dimensional scanning is preferable because it is efficient.

A raster scan can be used as the scanning method. In the case of raster scanning, either a progressive method or an interlace method may be used, and a raster scan may be set for an arbitrary band-like area according to the switching position to the band-like area on the display screen.
All of the scanning lines are set so that at least a part or the whole of any one of the belt-like regions is included. In that case, since all the projection points are set so as to fall within the region that is in any one of the light scattering states, light leakage from the screen can be prevented, which is preferable in terms of safety. In addition, it is preferable to align the light beam scanning area and the display area of the display screen so that an image can be displayed on the entire display area.

<Synchronization of display screen switching and beam scanning>
In the image display method of the present invention, the light beam is scanned in the belt-like region, and the position of the belt-like region is periodically changed in synchronization with the sub-scan of the scanning. That is, the refresh frequency for periodically changing the position of the band-like area of the screen and the refresh frequency for the sub-scanning of the light beam are made to coincide with each other. Hereinafter, it is not distinguished in the present specification which refresh frequency.
One period may include a time during which the screen is switched so that two or more band-shaped regions are formed, and the light beam scans any one of the regions. One period may include a time during which the screen is switched so that one or two or more belt-like regions are formed and the light source does not emit light. Further, one period may include a time when the display screen has no band-like region and the light source does not emit light. For example, one period includes the time until the light source finishes sub-scanning and resets the light emission position. In the meantime, the light source does not emit light, and all the display areas on the display screen can be set to be in a light transmission state. In particular, it is preferable to set so that the ratio of the time during which the entire display area is in the light transmission state during one cycle can be regarded as almost zero, because the display looks smooth.

  In the present invention, it is preferable to draw 5 or more and 140 or less scanning lines per minimum unit of the display area of the display screen. A larger main scanning frequency is preferable because more scanning lines can be drawn within a unit time. The width of the minimum unit may be determined according to the number of scanning lines to be drawn. Usually, if a large number of scanning lines are drawn with respect to the length of the width, a high-definition and high-luminance image can be obtained.

For each belt-like region, d is preferably 0.01 or more, and more preferably 0.05. Further, it is preferably 0.20 or less, and more preferably 0.15 or less. By being in this range, the visibility of the image and the transparency of the background tend to be compatible.
Further, F is preferably 40 Hz or more, and more preferably 45 Hz or more. By satisfying ≦ F ≦ 70 Hz, the visibility of the image can be secured while suppressing flickering, which is preferable. More preferably, 45 Hz ≦ F ≦ 60 Hz.

When the average value of the area of the belt-like region in one cycle is 1% or more and 20% or less of the area of the display region of the display screen with respect to the periodic change in the position of the belt-like region, the visibility of the image is improved. This is preferable because the transparency of the background is compatible. More preferably, it is 5% or more and 15% or less.
If the refresh frequency is 40 Hz or more and 70 Hz or less, it is preferable because visibility of an image can be secured while suppressing flicker. More preferably, it is 45 Hz or more and 60 Hz or less.

When the parallel light transmittance in the band-like region that is in the light scattering state is 30% or less, the visibility of the display image becomes favorable, which is preferable. More preferably, it is 20% or less, and the lower the better, but the lower limit is 0%.
It is preferable that the parallel light transmittance in the display area of the display screen in the light transmission state is 80% or more because the background visibility of the display area is improved. More preferably, it is 90% or more, and the higher the better, but the upper limit is 100%.

<Liquid crystal light control layer>
As the liquid crystal light control layer, a known method such as a transmission-scattering type liquid crystal-polymer composite, a ferroelectric liquid crystal, a dynamic scattering liquid crystal, or the like can be used, and among them, a transmission-scattering type liquid crystal-polymer composite. However, it is preferable because the area can be easily increased. As the transmission-scattering type liquid crystal-polymer composite, known ones such as Polymer Dispersed Liquid Crystals (PDLC) and Polymer Network Liquid Crystals (PNLC) can be used. Among them, PNLC is a switching speed between a light transmission state and a light scattering state. Is fast and preferable. Among PNLCs, Polymer Stabilized Cholesteric Texture (PSCT) using chiral nematic liquid crystal having positive dielectric anisotropy as liquid crystal is preferable because it can achieve both high contrast and high-speed response.

  Normally, when a voltage is applied to the liquid crystal light control layer, it takes a finite time for the parallel light transmittance to be reduced when switching to the light scattering state, while the parallel light beam when switching to the light transmission state. It also takes a finite time for the transmittance to increase. Due to the presence of these transient states in which the parallel light transmittance fluctuates with time, the parallel light transmittance is the timing at which the parallel light transmittance is low or the light scattering state is originally desired at the timing at which the light transmittance is desired. Inconvenience that the image quality is high. As a result, the transparency of the background is lowered and the visibility of the display image is lowered.

The response time described in the present specification refers to T _max for the parallel light transmittance when the display screen is in the light transmitting state, T _{min for} the minimum parallel light transmittance when the display screen is in the light scattering state, and t ₁ , assuming that the application end time is t ₂ , the rising response time is τ ₁ , and the falling response time is τ _{2. In} the normal mode: τ ₁ has a parallel light transmittance T _{10 for the} first time from t _2. Τ ₂ is defined as the time until the parallel light transmittance reaches T ₉₀ for the first time from t ₁ .

In reverse mode and memory mode: τ ₁ has parallel light transmittance T for the first time from t ₁
A time to reach _10, tau ₂ is defined as first parallel light transmittance from t ₂ is the time to reach the T _90.
However, T ₁₀ and T ₉₀ are respectively expressed as follows.
T ₁₀ = 0.1 × (T _max −T _min )
T ₉₀ = 0.9 × (T _max −T _min )
When a burst voltage having a frequency of 40 Hz to 70 Hz and a duty ratio of 0.01 to 0.20 is applied to the display screen of the present invention, the display screen changes from a light transmission state to a light scattering state, and light is emitted. In the process of returning to the transmissive state, it is preferable that both the rising response time τ ₁ and the falling response time τ ₂ of the display screen are 3.0 ms or less. More preferably, both are 2.0 ms or less.

It is preferable that the screen of the present invention is in a light transmission state when no voltage is applied, enters a light scattering state when a voltage is applied, and the haze is switched to 85% or more by applying a DC voltage or a continuous wave of an AC voltage to the screen. 90% or more is preferable. The upper limit is 100%, and the higher the better. Within these ranges, the visibility of the displayed image tends to be good.
The upper limit of the operating temperature of the screen of the present invention is Tni of the chiral nematic liquid crystal phase. However, since the response time tends to be longer at low temperatures, the operating temperature range is preferably −10 ° C.
Above, more preferably 0 ° C. or higher. Moreover, it is preferably 60 ° C. or lower, and more preferably 40 ° C. or lower.

<LCD>
The liquid crystal used in the screen of the present invention is preferably a chiral nematic liquid crystal having a positive dielectric anisotropy. Since chiral nematic liquid crystal is used and the dielectric anisotropy is positive, both T _min can be reduced and τ ₁ and τ ₂ can be shortened.
The dielectric anisotropy value (Δε) of the chiral nematic liquid crystal is not particularly limited as long as it is positive, but is preferably 5 or more, and more preferably 8 or more for reducing the driving voltage of the screen. Moreover, when using a polymerization initiator, it is preferable from the point which shortens the hardening time of a polymerizable monomer that each molecule | numerator which comprises a chiral nematic liquid crystal does not have absorption of the wavelength which overlaps with the absorption wavelength of an initiator.

  As the chiral nematic liquid crystal, the liquid crystal itself may be an assembly of liquid crystalline compounds exhibiting a cholesteric phase, or a chiral nematic liquid crystal may be formed by adding a chiral agent to the nematic liquid crystal. From the viewpoint of designing the liquid crystal composition, it is preferable to add a chiral agent to the nematic liquid crystal according to the purpose and control the chiral pitch length (p) and the liquid crystal-isotropic phase transition temperature (Tni).

  The relationship g / p between the chiral pitch length p of the chiral nematic liquid crystal and the distance g between the substrates with electrodes is preferably 1 or more. More preferably, it is 2 or more, particularly preferably 4 or more. Moreover, it is preferable that it is 20 or less, and it is especially preferable that it is 12 or less. The larger the g / p, the greater the scattering during driving and the light-shielding characteristics, but the screen drive voltage also increases at the same time. Therefore, from the viewpoint of achieving both the light-shielding characteristics and energy saving and safety, the above range. It is preferable to fit within.

The p of the chiral nematic liquid crystal is preferably 0.3 μm or more, and more preferably 0.8 μm or more. On the other hand, it is preferably 3 μm or less, more preferably 2 μm or less.
If p is too small, the screen drive voltage tends to be high, and if it is too large, the contrast tends to be poor. In general, since p is inversely proportional to the concentration of the chiral agent, the concentration of the chiral agent may be determined by calculating backward from the necessary value of p. When p × n (n is the refractive index of the chiral nematic liquid crystal) is in the range of visible light wavelength (380 nm to 800 nm), the finally obtained screen is colored when no voltage is applied, and is out of the visible light range. In some cases, it becomes colorless and transparent when no voltage is applied, so p may be selected according to the purpose.

  The distance (g) between the substrates with electrodes of the display screen is usually preferably 3 μm or more, and more preferably 5 μm or more. Moreover, 100 micrometers or less are preferable and 20 micrometers or less are still more preferable. When using a chiral nematic liquid crystal, the distance (g) between the substrates with electrodes of the display screen is preferably not less than p of the chiral nematic liquid crystal to be used. The light transmittance of the screen when no voltage is applied decreases with increasing g, and the response time of the display may become longer. On the other hand, if g is too small, the light-shielding characteristic during driving is reduced, and in the case of a large-area screen, the screen may be short-circuited. By being in the above range, these requirements can be satisfied in a balanced manner.

Tni of the chiral nematic liquid crystal is preferably 50 ° C. or higher, and more preferably 70 ° C. or higher, because the upper temperature limit at which the screen can operate is determined by Tni of the chiral nematic liquid crystal. On the other hand, as Tni increases, the viscosity tends to increase, so that it is preferably 200 ° C. or lower, and more preferably 150 ° C. or lower.
The nematic liquid crystal may be any known one, and the molecular skeleton, substituent, and molecular weight of the constituent molecules are not particularly limited, and may be a synthetic product or a commercial product. The dielectric anisotropy of the nematic liquid crystal is preferably positive and large in order to make the dielectric anisotropy of the chiral nematic liquid crystal phase of the screen and the chiral nematic liquid crystal of the liquid crystal composition positive. In addition, when a polymerization initiator is used, it is preferable from the viewpoint of shortening the curing time of the polymerizable monomer that each molecule constituting the constituent molecule does not have absorption at a wavelength overlapping the absorption wavelength of the initiator.

  When using a known liquid crystal substance, specifically, the Japan Society for the Promotion of Science 142nd edition; “Liquid Crystal Device Handbook”, Nihon Kogyo Shimbun (1989), pages 152 to 192 and the Liquid Crystal Handbook Editorial Committee Chapter: “Liquid Crystal Handbook” Maruzen Co., Ltd. (2000), using various low molecular compounds such as biphenyl, phenylcyclohexane, cyclohexylcyclohexane and mixtures as described in pages 260-330 can do. In addition, a high molecular weight compound or a mixture described in “Liquid Crystal Handbook” Maruzen Co., Ltd. (2000), pages 365 to 415, edited by the Liquid Crystal Handbook Editorial Committee, can also be used. As a compound constituting a nematic liquid crystal, for example,

Etc. As the cholesteric liquid crystal and nematic liquid crystal, those having a low viscosity and a high dielectric anisotropy are preferable in terms of high-speed response and manufacturability of the screen.
The chiral agent may be any chiral compound that is compatible with the host liquid crystal, may be a synthetic product or a commercial product, may exhibit liquid crystal properties, or may have a polymerizable functional group. good. Further, dextrorotatory or levorotatory may be used, and a dextrorotatory chiral agent and a levorotatory chiral agent may be used in combination. Moreover, as a chiral agent, its own dielectric anisotropy is positively large,
A low viscosity is preferable from the viewpoint of reducing the driving voltage of the screen and the response speed, and it is preferable that the helical twisting power, which is an index of the force with which the chiral agent twists the liquid crystal, is large. When a polymerization initiator is used, it is preferable that the polymerization initiator does not have absorption at a wavelength that overlaps the absorption wavelength of the initiator.

Examples of the chiral agent include CB15 (trade name, manufactured by Merck), C15 (trade name, manufactured by Merck), S-811 (trade name, manufactured by Merck), R-811 (trade name, manufactured by Merck), S-1011 ( Trade name Merck), R-1011 (trade name Merck) and the like.
<Polymer resin>
The polymer resin of the present invention is preferably one obtained by curing a specific polymer precursor.
The polymer resin of the present invention is preferably 10% by mass or less, and more preferably 7% by mass or less with respect to the chiral nematic liquid crystal. Moreover, it is preferable that it is 0.1 mass% or more, and it is preferable that it is 1 mass% or more. When the ratio of the polymer resin is too small, the polymer resin becomes mechanically fragile, and the repeated durability deteriorates. In addition, since the liquid crystal molecules cannot receive sufficient interface interaction, the screen contrast and response speed may deteriorate. On the other hand, when the ratio of the polymer resin is too large, the driving voltage may increase or the transparency of the screen may deteriorate.

The polymer resin used in the liquid crystal light control layer of the present invention is not particularly limited as long as the effects of the present invention are not impaired, but the composite of the present invention includes a chiral nematic liquid crystal having a positive dielectric anisotropy and the following: That the mixture containing the polymer precursor represented by the general formula (1) is cured reduces the minimum value T _min of the parallel light transmittance when a screen voltage is applied, and τ ₁ , τ _2. It is preferable because there is a tendency that both can be shortened.

[In Formula (1), A ¹ and A ² each independently represent a hydrogen atom or a methyl group,
Ar ¹ , Ar ² and Ar ³ each independently represent a divalent aromatic hydrocarbon ring group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent. ,
X ¹ and X ² are each independently a direct bond, a carbon double bond, a carbon triple bond, an ether bond, an ester bond, a linear alkylene group having 1 to 6 carbon atoms which may have a substituent, and a substituent. Represents a linear oxyalkylene group having 1 to 6 carbon atoms which may have a group;
R ¹ and R ² are each independently a linear alkylene group having 1 to 6 carbon atoms that may have a substituent, or a linear chain having 1 to 6 carbon atoms that may have a substituent. Represents an oxyalkylene group or a linear alkyl ester group having 2 to 6 carbon atoms,
m, n, p and q each independently represents 0 or 1.
However, at least one of Ar ¹ , Ar ² and Ar ³ is a divalent aromatic condensed ring group which may have a substituent or a divalent aromatic which may have a substituent. Represents a heterocyclic group. ]
The divalent aromatic hydrocarbon ring group which may have a substituent for Ar ¹ , Ar ² and Ar ³ is not particularly limited as long as it does not impair the effects of the present invention. The hydrocarbon ring group is a divalent group obtained by removing two hydrogen atoms from a single ring or a condensed ring formed by condensing 2 to 4 thereof. Specific examples include a benzene ring and a naphthalene ring. , Anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring and the like. Among these, the number of carbon atoms is preferably 6 or more, and on the other hand, it is preferably 30 or less, more preferably 26 or less, and particularly preferably 18 or less from the viewpoint of curability during polymerization. Specific examples include the following structures.

Among the divalent aromatic hydrocarbon ring groups that may have a substituent of Ar ¹ , Ar ^2, and Ar ³ , the following structure is particularly preferable among the above, and the curability of the polymer precursor is high. preferable.

Examples of the substituent that the divalent aromatic hydrocarbon ring group of Ar ¹ , Ar ² and Ar ³ may have include a fluorine atom, a chlorine atom, a hydroxyl group, a cyano group, a methyl group, an ethyl group, n- Propyl group, isopropyl group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butyl group, isobutyl group, t-butyl group and the like can be mentioned. From the viewpoint of curability of the polymer precursor, Are a fluorine atom, a hydroxyl group, a cyano group, a methyl group, and a methoxy group.

The divalent aromatic heterocyclic group which may have a substituent for Ar ¹ , Ar ² and Ar ³ is not particularly limited as long as it does not impair the effects of the present invention. It is a divalent group obtained by removing two hydrogen atoms from a condensed ring formed by condensing 2 to 4, and specific examples include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, and a pyrazole. Ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzo Isothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring , Triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring and the like. Among these, the number of carbon atoms is preferably 6 or more, and on the other hand, it is preferably 30 or less, more preferably 26 or less, and particularly preferably 18 or less from the viewpoint of curability during polymerization. Specific examples include the following structures.

As the divalent aromatic heterocyclic group which may have a substituent of Ar ¹ , Ar ² and Ar ³ , the following structure is particularly preferable among the above, since the curability of the polymer precursor is high. .

Examples of the substituent that the divalent aromatic heterocyclic group represented by Ar ¹ , Ar ² and Ar ³ may have include a fluorine atom, a chlorine atom, a hydroxyl group, a cyano group, a methyl group, an ethyl group, and n-propyl. Group, isopropyl group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butyl group, isobutyl group, t-butyl group and the like. From the viewpoint of curability of the polymer precursor, A fluorine atom, a hydroxyl group, a cyano group, a methyl group, and a methoxy group.

X ¹ and X ² are each independently a direct bond, a carbon double bond, a carbon triple bond, an ether bond, an ester bond, a linear alkylene group having 1 to 6 carbon atoms which may have a substituent, and a substituent. A straight-chain oxyalkylene group having 1 to 6 carbon atoms which may have a group is preferable, and a direct bond, an ether bond, an ester bond, or a methylene group is preferable. The substituents that may be included are fluorine atom, chlorine atom, hydroxyl group, cyano group, methyl group, ethyl group, n-propyl group, isopropyl group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group. Group, n-butyl group, isobutyl group, t-butyl group and the like, preferably fluorine atom, hydroxyl group, cyano group, methyl group and methoxy group.

R ¹ and R ² are each independently a linear alkylene group having 1 to 6 carbon atoms that may have a substituent, or a linear chain having 1 to 6 carbon atoms that may have a substituent. An oxyalkylene group or a linear alkyl ester group having 2 to 6 carbon atoms is represented. A C2-C6 linear alkylester group represents the following structures, for example.

Examples of the substituent that R ¹ and R ² may have include a fluorine atom, chlorine atom, hydroxyl group, cyano group, methyl group, ethyl group, n-propyl group, isopropyl group, methoxy group, ethoxy group, n -Propoxy group, isopropoxy group, n-butyl group, isobutyl group, t-butyl group and the like can be mentioned, and preferred are fluorine atom, hydroxyl group, cyano group, methyl group and methoxy group.

At least one of Ar ¹ , Ar ² and Ar ³ is a divalent aromatic condensed ring group which may have a substituent or a divalent aromatic heterocyclic ring which may have a substituent. It is a group. By having a divalent aromatic condensed ring group that may have a substituent or a divalent aromatic heterocyclic group that may have a substituent in the molecule, the rigidity of the polymer resin phase after curing Tends to shorten τ ₁ and τ _2, which is preferable.

  More preferably, the polymer precursor represented by the general formula (1) is a polymer precursor represented by the following general formula (2).

[In Formula (2), A ¹ and A ² each independently represent a hydrogen atom or a methyl group,
Ar ⁴ represents a divalent aromatic hydrocarbon condensed ring group which may have a substituent or a divalent hetero condensed ring group which may have a substituent,
R ¹ and R ² each independently represents an alkylene group having 2 to 6 carbon atoms which may have a substituent,
p and q each independently represents 0 or 1. ]
Specific examples of the divalent aromatic hydrocarbon ring group that may have a substituent of Ar ^{4 and} the divalent heterocyclic group that may have a substituent include those listed for Ar ^1. It is synonymous and the substituent which may have is also synonymous. Among these, the structure represented below is preferable because the curability of the polymer precursor is increased.

  Specific examples of the polymer precursor represented by the general formula (1) are illustrated below. This invention is not limited to these unless it exceeds the gist.

As the polymer precursor used in the liquid crystal light control layer of the present invention, only one kind of polymer precursor represented by the above formula (1) may be used, or two or more kinds may be used in combination.
The ratio of the polymer precursor represented by the general formula (1) used for the screen of the present invention and the other polymer precursor is not particularly limited as long as the effects of the present invention are not impaired, but the general formula (1) ) Is preferably 30% by mass or more, more preferably 50% by mass or more, and most preferably 80% by mass or more.

If the proportion of the polymer precursor represented by the above formula (1) is too small, one of screen production in a short time, high contrast, short response time, or a plurality of the precursors may not be sufficient. The upper limit of the polymer precursor represented by the above formula (1) is 100% by mass.
Moreover, when the polymer resin which the polymer resin phase of this invention has is a copolymer, any of an alternating copolymer, a block copolymer, a random copolymer, and a graft copolymer may be sufficient.

<Others>
The chiral nematic liquid crystal of the screen of the present invention has a polymerization initiator, a light stabilizer, an antioxidant, a thickener, a polymerization inhibitor, a photosensitizer, an adhesive, an antifoaming agent, a surfactant and the like. It may be. Moreover, content of the said other component can be mix | blended in arbitrary ratios in the range which does not impair the performance of the screen of this invention.

The curing method of the polymer precursor may be either photocuring or heat curing, but photocuring is preferable, and among the photocuring, curing with ultraviolet rays or near ultraviolet rays is particularly preferable. The light source for photopolymerization may be any light source having a spectrum at the absorption wavelength of the radical photopolymerization initiator used, and typically any light source capable of irradiating light with a wavelength of 220 nm to 450 nm. . Examples include a high pressure mercury lamp, an ultra high pressure mercury lamp, a halogen lamp, a metal halide lamp, a UV-LED, a blue LED, a white LED, and the like. In addition, a heat ray cut filter, an ultraviolet ray cut filter, a visible light cut filter, or the like may be used in combination. Light may be applied to at least one surface from the transparent substrate of the screen, and if both surfaces of the substrate sandwiching the liquid crystal composition are transparent, both surfaces may be irradiated with light. Light irradiation may be performed at one time or may be performed by dividing into several times. So-called PSCOF (Phase Separated Composite Film) (V. Vorflusev and S. Kumar, Science 283, 1903), in which the irradiance of light is distributed in the thickness direction of the screen and the density of the polymer resin is continuously changed. (1999)).

In the case of photocuring, the irradiance of the light irradiated on the screen, typically 0.01 mW / cm ² or more, preferably 1 mW / cm ² or more, more preferably 10 mW / cm ² or more, particularly preferably 30 mW / cm ² That's it. If the irradiance is too small, the polymerization does not proceed sufficiently. Further, the photocurable liquid crystal composition, usually, 2J / cm ² or more, preferably may be given to 3J / cm ² or more integrated irradiation dose, irradiation time may be determined according to the radiation intensity of the light source However, from the viewpoint of increasing productivity, the light irradiation is usually completed within 200 seconds, preferably within 60 seconds, while it is preferable to perform light irradiation for 10 seconds or more. If the light irradiation time is too short, the repetition durability of the screen may be inferior. When manufacturing a sheet-like screen with a large area using a plastic film substrate, it is possible to irradiate light continuously while moving the light source or the sheet, and the moving speed can be adjusted according to the irradiance of the light source. That's fine.
In the liquid crystal light control layer obtained as described above, the chiral nematic liquid crystal is dispersed or formed into a continuous layer in a thin transparent polymer, but the continuous layer exhibits the best contrast. Is formed.

<Display screen configuration>
The display screen used in the present invention includes a liquid crystal light control layer that can switch between a light transmission state and a light scattering state by electric drive in a display region. The screen used in the present invention is not particularly limited as long as it is the above-mentioned screen, but a typical structure will be described below.
The liquid crystal light control layer is sandwiched between two opposing substrates, and at least one of the substrates is transparent, and preferably both are transparent. Examples of the material of the substrate include colorless transparent or colored transparent or opaque materials such as inorganic transparent materials such as glass and quartz, metals, metal oxides, semiconductors, ceramics, plastic plates, and plastic films. On the substrate, for example, a thin film of metal oxide, metal, semiconductor, organic conductive material or the like is formed on the entire surface of the substrate or partially by a known coating method, printing method, vapor deposition method such as sputtering, or the like. is there. Alternatively, a part etched after forming a conductive thin film or a part removed with a laser or the like may be used. In particular, in order to obtain a large-area screen, from an aspect of productivity and workability, an ITO (mixture of indium oxide and tin oxide) electrode is deposited on a transparent polymer film such as PET or PEN. It is desirable to use an electrode substrate formed by using, for example.

  A wiring for connecting the electrodes or connecting the electrodes and the outside may be provided on the substrate. For example, a segment driving electrode substrate, a matrix driving electrode substrate, an active matrix driving electrode substrate, or the like may be used. In the case of a segment drive electrode substrate, a strip-shaped electrode can be formed on one substrate in the direction of the short side of the strip, and a solid electrode can be used on the other to form a strip-shaped segment. A strip-shaped electrode can be used to form a matrix-like segment so that the strips face each other so as to be orthogonal. When the segment is formed on the electrode, the smaller the distance between the segments, the less light is not noticeable at the time of display, preferably 100 μm or less, and more preferably 30 μm or less. On the other hand, since a short circuit between segments is a concern, it is preferably 1 μm or more, and more preferably 5 μm or more.

Furthermore, the electrode surface provided on the substrate is a protective film made of an organic compound such as polyimide, polyamide, polyvinyl alcohol, silicon, and cyanide, an inorganic compound such as SiO ₂ , TiO ₂ , and ZrO ₂ , or a mixture thereof. Alternatively, the entire surface or a part thereof may be covered with an alignment film. The substrate may be aligned so that the liquid crystal is aligned with respect to the surface of the substrate. When the alignment process is performed, any alignment process may be used as long as the chiral nematic liquid crystal that is in contact has a planar structure. It doesn't matter. For example, the two substrates may be in a homogeneous orientation, or may be a so-called hybrid in which one is homogeneous orientation and the other is homeotropic orientation. For these alignment treatments, the electrode surface may be directly rubbed, or a normal alignment film such as polyimide used for TN liquid crystal, STN liquid crystal or the like may be used. In addition, as a method for producing the alignment film, a so-called photo-alignment method may be used in which the organic thin film on the substrate is irradiated with light having anisotropy such as linearly polarized light to give the film anisotropy.

  The opposing substrate may have an adhesive layer containing a resin body for adhering and supporting the substrate as appropriate at the peripheral part. Note that the end face of the screen or the liquid crystal injection port used in the present invention is provided with an adhesive tape, a thermocompression bonding tape, a heat Tapes such as curable tapes, and / or thermosetting resins, photocurable resins, moisture curable resins, room temperature curable adhesives, anaerobic adhesives, epoxy adhesives, silicone adhesives, By sealing with a curable resin such as a fluorine resin adhesive, a polyester adhesive, or a vinyl chloride adhesive, or a thermoplastic resin, it is possible to prevent the internal liquid crystal from leaking out. This sealing may also work to prevent deterioration of the screen at the same time. In this case, the end face may be protected by covering the entire end face, or by pouring curable resins or thermoplastic resins into the screen from the end face and solidifying it. It may be covered with a kind.

  Spacers such as spherical or cylindrical glass, plastic, ceramic, or plastic film may be present between the substrates arranged to face each other. The spacer may be dispersed in the liquid crystal composition, or may be fixed in the liquid crystal light control layer between the substrates. The spacer may be dispersed on the substrate during screen assembly or mixed with an adhesive to bond the adhesive layer. It may be present in

  The liquid crystal light control layer included in the light control screen used in the present invention is, for example, a sealing cell formed by forming an adhesive layer with a photo-curing adhesive or the like on the periphery of a pair of substrates with electrodes arranged opposite to each other via a spacer. Or by immersing and injecting the liquid crystal composition in a notch of one or more adhesive layers provided in advance under normal pressure or vacuum, or applying the liquid crystal composition on one substrate using a coater, After being sandwiched by a known method such as stacking the other substrate on top, it is formed by polymerization and curing by radiation such as ultraviolet light, visible light, or electron beam. In the case of a plastic film substrate, a substrate with electrodes supplied continuously can be sandwiched between two rolls and the like, and a liquid crystal composition containing and dispersed a spacer can be fed between them, and then it can be photocured continuously. So productivity is high.

At least one surface or both surfaces of the screen may be covered with an antireflection film, an antiglare film, an ultraviolet blocking film, or an antifouling film. For example, covering the front and back of the screen with an antireflection film may prevent external light reflection on the substrate surface and improve the appearance of the screen.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The technical scope of the present invention is not limited to the following embodiments. Various modifications are possible without departing from the spirit of the present invention.

(First embodiment)
The configuration of the first embodiment of the present invention will be described. The image display method of the present invention will be described with an example applied to a show window.
FIG. 1 shows a configuration of a show window to which the image display method of the present invention is applied. Reference numeral 1 denotes a display screen, which is a rear projection system in which the laser projector 2 and the observer O face each other. The observer O can see the background B (product) through the display screen 1. The laser projector 2 is a projector that uses red, green, and blue lasers as light sources and uses a MEMS mirror as a scanner. The laser projector 2 can scan the laser beam at the main scanning frequency F _H = 18 kHz. The control screen 3 controls the display screen 1 for the position and timing of switching the band-like region, and the laser projector 2 controls the scanning position and timing.

FIG. 2 shows the display area 4 of the display screen 1 viewed from the observer O, and shows a state in which the background B can be seen simultaneously with the image 5A.
A display screen 1 shown in FIG. 1 has a pair of transparent electrode substrates in which a reverse mode transmission-scattering type liquid crystal-polymer composite is sandwiched between display areas 4 shown in FIG. The configuration of the transparent electrode substrate will be described with reference to FIG. As the transparent electrode substrate, ITO sputtered on glass is used, one of which is a glass substrate 6A with a striped transparent electrode and the other is a glass substrate 6B with a solid transparent electrode. The interval between the strips of the glass substrate 6A with the striped transparent electrodes is 20 μm, and the peripheral electrodes coincide with the end of the display region. The glass substrate 6B with a solid transparent electrode has ITO sputtered over the entire display area. Therefore, the display screen 1 includes five independent band-like segments. Further, the transmission-scattering type liquid crystal-polymer composite is driven in the reverse mode, and the display region 4 is in a light transmission state without applying a voltage. By using a glass substrate 6B with a solid transparent electrode as a common electrode and applying a voltage to each electrode of the glass substrate 6A with a striped transparent electrode, a band-like region can be formed at any one of the five locations.

When the display screen 1 shown in FIG. 1 is made to scatter all over and the display image 5B is displayed, it is as shown in FIG. In order to facilitate the following description, the display image is changed from 5A to 5B in FIG. The light emitted from the laser projector 2 scans the entire display area 4, and the position is adjusted so that the scanning does not exit the display area 4. The main scanning direction and the sub-scanning direction are orthogonal.
Next, a method for switching the band-like area on the display screen 1 in one cycle and a method for scanning with laser light will be described with reference to FIG. First, the display screen 1 is switched so that a strip-like area 7a is formed at the uppermost stage, the approximate area is scanned with light rays, and a display image 5a is drawn. Next, the uppermost band-like region is switched to the light transmission state. At the same time, the screen is switched so that the band-like region 7b is formed in the second row from the top, the approximate region is scanned with light rays, and the display image 5b is drawn. Similarly to this procedure,
The display images 5c to 5e are drawn in the belt-like regions 7c to 7e repeatedly for all the belt-like regions. When the scanning of the lowermost belt-like region 7e is completed, the lowermost belt-like region 7e is switched to the light transmission state. At the same time, the laser beam is stopped and the scanning position is reset to the initial position, which is a blank time. This completes one cycle, and the next cycle starts.

  In the first embodiment, the laser beam is projected only during a period in which the screen changes to the light scattering state and is in a steady state. Since switching between the light transmission state and the light scattering state takes a certain time, switching is started before the laser light is projected. The switching timing from the light scattering state to the light transmission state is adjusted so as to match the moment when the next band-like region becomes a steady state.

When the refresh frequency F is set to 56.81 Hz and the blank time is set to 0.1 ms, the scanning time becomes 3.5 ms per one band-like region, and 64 scanning lines can be drawn. In this case, the average value of the ratio of the area of the band-like region in one cycle is 20% with respect to the area of the display region, and the total number of scanning lines in one cycle is 320.
Instead of the five glass substrates 6A with striped transparent electrodes that sandwich the liquid crystal light control layer, the glass substrate 6C with n striped transparent electrodes shown in FIG. 6 is used. In this case, as shown in FIG. 7, the belt-like regions 7 _{1 to} 7 _n can be switched. Display image 5B obtained by dividing display image 5B into n ₁
˜5 _n are sequentially drawn in the band-like regions 7 _{1 to} 7 _n . Assuming that the refresh frequency is F and the main scanning frequency of the projector 2 is F _H , the average value of the area of the band-like area in one cycle is calculated as 1 / n with respect to the area of the display area. Further, the total number of scanning lines in one cycle is calculated by F _H / F. However, the blank time is short enough to be effectively ignored with respect to 1 period 1 / F. Therefore, in the first embodiment, the glass substrate 6C with striped transparent electrodes is used.
If the number of stripes is increased, the transparency of the background in the display area 4 is improved. In order to suppress display flicker, F may be increased. However, in order to obtain a high-definition image, it is desirable that F _H is sufficiently large.

(Second Embodiment)
In the second embodiment, the timing of screen switching and laser light projection is changed from the timing in the first embodiment. The image display apparatus has the same apparatus configuration as that of the first embodiment. In the second embodiment, the laser beam is projected in a part of the period in which the screen is changed to the light scattering state and is in the steady state.

The timing of screen switching and laser light projection in the second embodiment will be described with reference to FIG. In FIG. 8, the ratio of the time during which one segment is switched to the light transmission state and the time during which the laser light is projected onto the belt-like region is set to 2: 1 during one period. For example, during the period in which the belt-like region 7a is scanned with laser light, that is, during the period in which the belt-like region 7a is in the light scattering state, while the display image 5a ¹ is drawn, the belt-like regions 7a and 7e are in the light scattering state while rendering a display image 5a ² as strip-like regions 7a and 7b is a light scattering state, and switches the screen. When the laser beam scanning to the belt-like region 7a is completed, the laser beam scanning to the belt-like region 7b is started. Period for scanning the laser beam in the band region 7b, the band-like region 7a and 7b while drawing the display image 5b ^1, but also while drawing the display image 5b ² are strip-shaped regions 7b and 7c are, respectively light scattering state Switch the screen so that Hereinafter similarly to switch, band-like region 7c, 7d, respectively display image 5c ¹ to 7e 5
c ² , display images 5d ¹ and 5d ² , and display images 5e ¹ and 5e ² are drawn. By setting in this way, even if the timing of laser projection is slightly shifted back and forth, the display is not affected, and a precise control device is not required. The ratio of the time during which one segment is switched to the light transmission state during one period and the time during which the laser beam is projected onto the band-like region is preferably 1.1: 1 to 3: 1. The larger the ratio of time for switching to the state, the longer the laser projection timing margin and the easier the control, but the background transparency in the display area 4 tends to decrease.

(Third embodiment)
In the third embodiment, image display when a dot matrix panel is used as the display screen 1 will be described. Other configurations of the apparatus are the same as those of the first embodiment. In the dot matrix panel, for example, the substrate sandwiching the liquid crystal light control layer provided in the display screen 1 is the glass substrate 6C with n striped transparent electrodes shown in FIG. Can be obtained as a passive matrix panel.

  FIG. 9 shows a method for switching a band-like region on the display screen 1 using a matrix panel and a laser beam scanning method in the third embodiment. In the case of a matrix panel, a minimum unit of an arbitrary band-like region can be set by switching a plurality of adjacent pixels as a group and switching at the same timing. In FIG. 9, a belt-like region having the same position and shape as in FIG. 5 in the first embodiment is set as a minimum unit. In this case, the completely same display method as in the first embodiment can be taken.

The matrix panel that can be used in the present invention can have a high resolution like a general dot matrix panel, but even a simple matrix panel having several pixels to several tens of pixels can display a large area with transparent display. Can be realized.
In the third embodiment, a transparent display and a display in which a normal background cannot be seen (represented as a non-transparent display) can be combined and displayed. FIG. 11 shows an example of a display screen that combines transparent display and non-transparent display. In the transparent display area 10, both the display image 5A and the background B can be seen. In addition, the non-transparent display area 11 can be displayed without showing the background. By displaying in this way, the product in the background is emphasized, and the video becomes more dramatic. In such a display, the same display method as in the first embodiment is performed in the area where the transparent display is performed, and all the pixels may be kept in the scattering state in the area where the non-transparent display is performed. In the case of the display of FIG. 10, a matrix panel as shown in FIG. 11 is used, and within the transparent display region 10, the strip-like regions 711 to 714 (the strip-like region 711 indicates the shaded portion in FIG. 11) What is necessary is just to set as an area | region which collected several such pixels. Non-transparent area 1
1, all the elements of the non-transparent region 11 such as the pixel 9b may be kept in the light scattering state. One light source may be used to scan the entire display region, or separate light sources may be used for the transparent display region 10 and the non-transparent region 11.

1: Display screen 2: Laser projector 3: Control device 4: Display area 5A: Display image 5B: Display image 5 _{1 to} 5n: Display image 5a to 5e: Display image 5a ¹ , 5a ² to 5e ¹ , 5e ² : Display image 6A: Glass substrate with striped transparent electrode 6B: Glass substrate with solid transparent electrode 6C: Glass substrate with striped transparent electrode 7 _{1 to} 7n: Strip regions 7a to 7e: Strip region 8: Dot matrix 9: Pixel 9a, 9b: Pixel 10: Transparent display area 11: Non-transparent display area 711 to 714: Band-shaped area
B: Background
O: Observer
L: Ray

Claims (8)

This is an image display method for drawing an image by scanning a visible light beam from a light source onto the display screen provided with a liquid crystal light control layer capable of switching between a light transmission state and a light scattering state by electric drive. And
The light scattering state of the display screen is switched to form a band-like region,
The main scanning direction in the scanning coincides with the length direction of the band-shaped region, and the sub-scanning direction in the scanning coincides with the width direction of the band-shaped region,
Scanning the beam with the beam, and periodically changing the position of the band in synchronization with the sub-scan of the scan,
An image display method characterized in that an observer can simultaneously view an image displayed in the display area and a background of the display area. 2. The image display method according to claim 1, wherein an average value of the area of the belt-like region is 1% or more and 20% or less with respect to the area of the display region of the display screen. The image display method according to claim 1, wherein the refresh frequency is 40 Hz to 70 Hz. The image display method according to any one of claims 1 to 3, wherein a parallel light transmittance in the belt-like region is 30% or less. The image display method according to any one of claims 1 to 4, wherein a parallel light transmittance of the display screen in a light transmission state is 80% or more. The liquid crystal light control layer has a pair of transparent substrates with electrodes arranged to face each other, and includes a composite containing a liquid crystal and a polymer resin between the substrates,
The image display method according to claim 1, wherein the liquid crystal is a chiral nematic liquid crystal having positive dielectric anisotropy. The composite is obtained by curing a mixture including a chiral nematic liquid crystal having a positive dielectric anisotropy and a polymer precursor represented by the following general formula (1). The image display method described in 1.

[In General Formula (1), A ¹ and A ² each independently represent a hydrogen atom or a methyl group,
Ar ¹ , Ar ² and Ar ³ each independently represent a divalent aromatic hydrocarbon ring group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent. ,
X ¹ and X ² are each independently a direct bond, a carbon double bond, a carbon triple bond, an ether bond, an ester bond, a linear alkylene group having 1 to 6 carbon atoms which may have a substituent, and a substituent. Represents a linear oxyalkylene group having 1 to 6 carbon atoms which may have a group;
R ¹ and R ² are each independently a linear alkylene group having 1 to 6 carbon atoms that may have a substituent, or a linear chain having 1 to 6 carbon atoms that may have a substituent. Represents an oxyalkylene group or a linear alkyl ester group having 2 to 6 carbon atoms,
m, n, p and q each independently represents 0 or 1.
However, at least one of Ar ¹ , Ar ^2, and Ar ³ is a divalent aromatic hydrocarbon condensed ring group which may have a substituent or a divalent which may have a substituent. Represents an aromatic heterocyclic group. ] The image display method according to claim 7, wherein the polymer precursor represented by the general formula (1) is represented by the following general formula (2).

[In General Formula (2), A ¹ and A ² each independently represent a hydrogen atom or a methyl group,
Ar ⁴ represents a divalent aromatic hydrocarbon condensed ring group which may have a substituent or a divalent aromatic heterofused ring group which may have a substituent,
R ¹ and R ² are each independently a linear alkylene group having 1 to 6 carbon atoms that may have a substituent, or a linear chain having 1 to 6 carbon atoms that may have a substituent. Represents an oxyalkylene group or a linear alkyl ester group having 2 to 6 carbon atoms,
p and q each independently represents 0 or 1. ]

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