JP2019194645A - Display unit and display method - Google Patents

Abstract

To provide a display unit that can simplify control of voltage in changing an optical state of an image display body in which its optical state changes between the transparent state and non-transparent state, and can reduce power consumption when it displays an image.SOLUTION: A display unit comprises: an image display body 100 having a display function layer in which its light scattering property is increased upon reception of ultraviolet light and its light scattering property is decreased upon reception of first visible light or application of voltage, and a transparent conductive layer for applying voltage to the display function layer; a first projector 200 that projects ultraviolet light on the image display body 100; a second projector 300 that projects first visible light on the image display body 100; a third projector 400 that projects second visible light on the image display body 100 to display an image 700 on the image display body 100; and a control unit 600 that, when displaying the image 700 on the image display body 100, operates the first projector 200 and third projector 400, and when not displaying the image 700 on the image display body 100, operates the second projector 300 and applies voltage to the transparent conductive layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a display device and a display method for displaying an image.

  In recent years, a technique for displaying an image on a transparent glass such as an automobile windshield or a window glass of a building has been developed.

  In relation to this, the following Patent Document 1 has a screen in which an optical state changes between a transmission state and a scattering state by application of a voltage, and a projector that projects an image light on the screen to display an image. Display devices have been proposed. According to the display device of Patent Document 1, it is possible to display an image on the screen by temporarily making the normally transparent screen temporarily opaque.

Japanese Patent No. 5856284

  However, in the display device of Patent Document 1, when displaying an image on the screen, it is necessary to continue to control the voltage applied to the control electrode arranged inside the screen. For this reason, the display device of Patent Document 1 has a problem in that control of a voltage applied to the screen is complicated when displaying an image on the screen, and power consumption is large.

  The present invention solves the above-described problems. Therefore, the object of the present invention is to simplify the control of the voltage when changing the optical state of the image display body in which the optical state changes between the transparent state and the non-transparent state, and when the image is displayed. It is an object of the present invention to provide a display device that can reduce power consumption.

  The above object of the present invention is achieved by the following means.

  The display device of the present invention has a display function layer that increases light scattering by receiving ultraviolet light and receives first visible light or decreases light scattering by applying voltage, and a voltage applied to the display function layer. An image display body having a transparent conductive layer for applying a light, an ultraviolet light projector that projects ultraviolet light onto the image display body, and a first visible light that projects first visible light onto the image display body A light projecting unit, a second visible light projecting unit that projects the second visible light on the image display body to display an image on the image display body, and an ultraviolet light projecting unit for displaying the image on the image display body And a control unit that operates the first visible light projecting unit and applies a voltage to the transparent conductive layer when the second visible light projecting unit is operated and no image is displayed on the image display body.

  The display method of the present invention projects ultraviolet light onto an image display body whose light scattering property increases by receiving ultraviolet light and receives first visible light or whose light scattering property decreases by applying a voltage. A first step, a second step of projecting the second visible light onto an image display body having increased light scattering and making it non-transparent, and displaying an image on the image display body, and displaying an image on the image display body And a fourth stage in which the first visible light is projected onto the image display body and a voltage is applied to lower the light scattering property of the image display body to make it transparent.

  According to the present invention, the voltage control for changing the optical state of the image display body in which the optical state changes between the transparent state and the non-transparent state is simplified, and the power consumption when displaying the image is simplified. Can be reduced.

1 is a perspective view illustrating a schematic configuration of a display device according to Embodiment 1. FIG. 2 is a cross-sectional view illustrating a schematic configuration of an image display body according to Embodiment 1. FIG. It is sectional drawing which shows schematic structure of the display function layer of a transparent state. It is sectional drawing which shows schematic structure of the display functional layer of a non-transparent state. It is a figure which shows the optical response characteristic of a display function layer when 1st visible light is projected in a non-transparent state. It is a figure which shows the optical response characteristic of a display function layer when a voltage is applied in a non-transparent state. It is a figure which shows operation | movement of the display apparatus when making an image display body non-transparent. It is a figure which shows operation | movement of the display apparatus in the case of displaying an image on an image display body. It is a figure which shows operation | movement of the display apparatus in case an image display body is made transparent. It is a figure which shows the state of the projection of the 1st visible light in the case of making an image display body transparent in the display apparatus which concerns on Embodiment 1, and the application of a voltage. It is a figure which shows the procedure of the display method which concerns on Embodiment 1. FIG. 5 is a cross-sectional view illustrating a schematic configuration of an image display body according to Embodiment 2. FIG. It is a figure which shows the state of the projection of the 1st visible light in the case of making an image display body transparent in the display apparatus which concerns on Embodiment 3, and the application of a voltage. It is a figure which shows the state of the projection of the 1st visible light in the case of making an image display body transparent in the display apparatus which concerns on Embodiment 4, and the application of a voltage. It is a figure which shows the state in the case of projecting 1st visible light from the edge part of an image display body in the display apparatus which concerns on Embodiment 5. FIG.

  Hereinafter, with reference to the drawings, embodiments of the present invention will be described by dividing them from [Embodiment 1] to [Embodiment 5]. In the drawings, the same reference numerals are used for the same members. In addition, the dimensional ratios in the drawings may be exaggerated for convenience of explanation and may be different from the actual ratios.

[Embodiment 1]
FIG. 1 is a perspective view illustrating a schematic configuration of a display device 10 according to the first embodiment. The display device 10 of this embodiment includes an image display body 100, a first projector 200, a second projector 300, a third projector 400, and a control unit 600.

  The image display body 100 is a thin plate-like member whose optical state changes between a transparent state and a non-transparent state. The front surface 100a faces the third projector 400 from the first projector 200 and the opposite side of the front surface 100a. And a back surface 100b. The image display body 100 changes from a transparent state to a non-transparent state by receiving ultraviolet light, and changes from a non-transparent state to a transparent state by receiving first visible light or by applying a voltage. . The image display body 100 is attached to a windshield of an automobile, for example. A detailed description of the image display body 100 will be described later.

  The first projector 200 is a projector that projects ultraviolet light, and is disposed to face the front surface 100 a of the image display body 100. For example, the first projector 200 projects ultraviolet light having an intermediate wavelength of around 365 nm as an ultraviolet light projector. The first projector 200 projects ultraviolet light onto the front surface 100a of the image display body 100, and changes the ultraviolet light projection area 100c on the image display body 100 from the transparent state to the non-transparent state.

  The second projector 300 is a projector that projects visible light having a specific wavelength, and is disposed to face the front surface 100 a of the image display body 100. For example, the second projector 300 emits first visible light having an intermediate wavelength of about 450 nm as the first visible light projecting unit. The second projector 300 projects the first visible light onto the front surface 100a of the image display body 100 in the non-transparent state, and changes the ultraviolet light projection region 100c on the image display body 100 from the non-transparent state to the transparent state. Change.

  The third projector 400 is a color projector and is disposed to face the front surface 100a of the image display body 100. The third projector 400 has, as the second visible light projector, any one of three colors of blue (intermediate wavelength is around 450 nm), green (intermediate wavelength is around 532 nm), and red (intermediate wavelength is around 640 nm). Or second visible light that is a combination of two or more colors of light. The third projector 400 projects the second visible light on the front surface 100 a of the non-transparent image display body 100 to display the image 700 on the image display body 100.

  The control unit 600 controls the operation of the first projector 200 to the third projector 400 and the on / off of the voltage applied to the image display body 100. The control unit 600 switches between light projection / non-light projection of the first projector 200 while communicating with a host control device (not shown). In addition, the control unit 600 performs switching between light projection / non-light projection of the second projector 300 and switching on / off of the voltage applied to the image display body 100 while communicating with a host control device. Furthermore, the control unit 600 sends image information to the third projector 400 while communicating with a higher-level control device.

  Note that the first projector 200 and the third projector 400 are included so that the image 700 displayed on the image display body 100 by the second visible light is included inside the ultraviolet light projection region 100c on the image display body 100. Projects ultraviolet light and second visible light. In addition, the second projector 300 projects the first visible light so that the ultraviolet light projection region 100 c is included in the first visible light projection region on the image display body 100.

  Next, the image display body 100 of the display device 10 will be described in detail with reference to FIG.

  FIG. 2 is a cross-sectional view illustrating a schematic configuration of the image display body 100 according to the first embodiment. The image display body 100 of the present embodiment includes a display function layer 120 and transparent conductive layers 130a and 130b. The image display body 100 is disposed such that the transparent conductive layers 130 a and 130 b sandwich the display function layer 120. The transparent conductive layer 130a is disposed on the front surface 100a side of the image display body 100, and the transparent conductive layer 130b is disposed on the back surface 100b side of the image display body 100.

  The display function layer 120 is a film member whose optical state changes between a transparent state and a non-transparent state. The display function layer 120 receives light of ultraviolet light, increases light scattering and becomes clouded, receives first visible light, or decreases the light scattering by applying voltage and returns to a transparent state. Has characteristics. The display function layer 120 of this embodiment is a liquid crystal film including host liquid crystal molecules 121 and azobenzene molecules 122. Note that the voltage applied to the display function layer 120 in the present embodiment is, for example, an AC voltage having a frequency of 50 Hz and a voltage value of 50V.

  The transparent conductive layers 130a and 130b are obtained by laminating a transparent conductive film that is transparent in the visible light region and has conductivity on a transparent base material such as glass or transparent resin. For the transparent conductive film, for example, an oxide semiconductor such as indium oxide, tin oxide, or zinc oxide is used.

  Next, the display functional layer 120 of the image display body 100 will be described in detail with reference to FIGS. 3A and 3B. 3A is a cross-sectional view showing a schematic configuration of the display functional layer 120 in a transparent state, and FIG. 3B is a cross-sectional view showing a schematic configuration of the display functional layer 120 in a non-transparent state.

  As described above, the display function layer 120 of the present embodiment is a liquid crystal film including host liquid crystal molecules (hereinafter, liquid crystal molecules 121) and azobenzene molecules 122. The structure of the azobenzene molecule 122 changes from the trans form to the cis form when receiving ultraviolet light, and the structure changes from the cis form to the trans form when receiving the first visible light. When the azobenzene molecule 122 changes to a cis form, it bends and disturbs the alignment of the liquid crystal molecules 121. Accordingly, ultraviolet light is projected onto the display function layer 120 in a state where the liquid crystal molecules 121 are aligned substantially perpendicular to the thickness direction of the display function layer (see FIG. 3A) and the liquid crystal phase is a nematic phase. For example, the liquid crystal molecules 121 change to the focal conic state, and the alignment is disturbed to change to the scattering state (see FIG. 3B), thereby increasing the light scattering property. On the other hand, when the first visible light is projected onto the display function layer 120 in the focal conic state when the liquid crystal molecules 121 are in a scattering state (see FIG. 3B), the liquid crystal molecules 121 are substantially perpendicular to the thickness direction of the display function layer. It changes to the arrangement | sequence state (refer FIG. 3A) arranged in (4), and light-scattering property falls. Hereinafter, the alignment state (state shown in FIG. 3A) in which the liquid crystal molecules 121 are aligned substantially perpendicular to the thickness direction of the display function layer is simply referred to as an alignment state, and the alignment of the liquid crystal molecules 121 is disordered. The scattered state (state shown in FIG. 3B) is referred to as a scattering state.

  As shown in FIG. 3A, the display function layer 120 in which the liquid crystal molecules 121 are in an aligned state is in a transparent state due to reduced light scattering properties. Therefore, when the second visible light VL is projected onto the display function layer 120, the second visible light VL passes through the display function layer 120. On the other hand, as shown in FIG. 3B, the display functional layer 120 in which the liquid crystal molecules 121 are in a scattering state has a light scattering property and is in a non-transparent state. For this reason, when the second visible light VL is projected onto the display function layer 120, the second visible light VL is irregularly reflected on the display function layer 120.

In the display function layer 120, when ultraviolet rays are projected and when the first visible light is projected, the structure of the azobenzene molecules 122 changes and the arrangement of the liquid crystal molecules 121 changes. For this reason, even if the projection of the ultraviolet rays and the first visible light is stopped, the alignment of the liquid crystal molecules 121 after the change is maintained. Therefore, the display function layer 120 maintains a non-transparent state after the ultraviolet light is projected, and maintains a transparent state after the first visible light is projected. , 130b, a liquid crystal molecule 121 scattered and existing as shown in FIG. 3B is forced along the direction of the generated electric field, even if the azobenzene molecule 122 remains in the cis form. Are regularly arranged in an array state. When the voltage is no longer applied, if the azobenzene molecules 122 are in the cis form, the regularly arranged liquid crystal molecules 121 return to the scattering state in which they are scattered as shown in FIG. 3B.

  Since the display functional layer 120 is in an arrangement state in which the liquid crystal molecules 121 are regularly arranged when a voltage is applied, the display function layer 120 is in a transparent state. Since the molecule 121 returns to the scattering state in which it is scattered, it becomes non-transparent. Therefore, the display function layer 120 becomes transparent only when a voltage is applied.

  Next, with reference to FIG. 4A and FIG. 4B, an optical response characteristic when the display functional layer 120 of the image display body 100 changes from a non-transparent state to a transparent state will be described. FIG. 4A is a diagram illustrating an optical response characteristic of the display function layer 120 when the first visible light is projected in a non-transparent state. FIG. 4B is a diagram illustrating optical response characteristics of the display functional layer 120 when a voltage is applied in a non-transparent state.

  When the first visible light is projected for 2 seconds onto the display function layer 120 of the image display body 100 in which the ultraviolet light is projected to become cloudy and non-transparent, as shown in FIG. 4A, the display function layer 120 is displayed. Gradually becomes transparent after the first visible light projection is started (on), and becomes transparent (transmittance of 80% or more) in about 7 seconds. The display function layer 120 has an optical characteristic that if the first visible light is projected for 2 seconds or longer, the transparent state is maintained even when the first visible light projection is finished (off). As described above, when the display functional layer 120 is made transparent only with the first visible light, it takes a long time of about 7 seconds until it becomes transparent, but has an optical response characteristic that the transparent state can be maintained.

  On the other hand, when a voltage is applied to the display function layer 120 of the non-transparent image display body 100, as shown in FIG. It becomes transparent (transmittance of 80% or more) in about 3 seconds, and the transparent state is maintained while a voltage is applied. The display function layer 120 becomes non-transparent after 0.3 seconds from the end of voltage application (off). As described above, when the display function layer 120 is made transparent only by voltage, it can be made transparent in a short time of 0.3 seconds, but when the application of voltage is finished (off), the transparent state cannot be maintained. Response characteristics.

  The display device 10 according to this embodiment uses the above-described optical response characteristics of the display function layer 120 of the image display body 100 to effectively use the voltage when changing the optical state of the display function layer 120. And the power consumption when the image 700 is displayed is reduced. In addition, the response speed when the display functional layer 120 is made transparent is also improved.

  Next, with reference to FIGS. 5 to 8, an operation of the display device 10 that displays the image 700 on the image display body 100 will be described.

  FIG. 5 is a diagram illustrating the operation of the display device 10 when the image display body 100 is not transparent, and FIG. 6 illustrates the operation of the display device 10 when the image 700 is displayed on the image display body 100. FIG. 7 is a diagram illustrating the operation of the display device 10 when the image display body 100 is transparent, and FIG. 8 is a diagram when the image display body 100 is transparent in the display device 10 according to the first embodiment. It is a figure which shows the state of the 1st visible light projection and the application of a voltage.

  As shown in FIG. 5, when displaying an image 700 on the image display body 100, first, the first projector 200 projects ultraviolet light onto the front surface 100 a of the image display body 100. When the ultraviolet light is projected, the display function layer 120 becomes clouded, and the ultraviolet light projection region 100c on the image display body 100 changes from the transparent state to the non-transparent state.

  Next, as shown in FIG. 6, the third projector 400 projects second visible light onto the light projection region 100 c on the image display body 100 in the non-transparent state, and the image 700 is displayed on the image display body 100. Is displayed.

  In order to prevent the image display body 100 from returning from the non-transparent state to the transparent state by receiving the second visible light while the image 700 is displayed on the image display body 100, the first projector 200 is used. May project ultraviolet light onto the image display body 100. Specifically, the first projector 200 projects the ultraviolet light with an output such that the action of maintaining the white turbid state by the ultraviolet light is greater than the action of returning to the transparent state by the second visible light. To do.

  On the other hand, as shown in FIG. 7, when the image 700 is not displayed on the image display body 100 (when the image 700 is erased), first, the first projector 200 and the third projector 400 are subjected to ultraviolet light and second visible light. Each of the lights is stopped.

  Next, the second projector 300 projects the first visible light onto the front surface 100a of the image display body 100, and at the same time, the control unit 600 applies a voltage to the image display body 100, and the ultraviolet light on the image display body 100 is displayed. Is returned from the non-transparent state to the transparent state.

  Specifically, as illustrated in FIG. 8, the control unit 600 starts the first visible light projection (turns on the first visible light) in the second projector 300 and simultaneously applies a voltage to the image display body 100. Start (voltage on). Next, the controller 600 ends the application of the voltage when the voltage is applied for 0.5 seconds (the voltage is turned off), and ends the projection of the first visible light when the first visible light is projected for 0.5 seconds ( Turn off the first visible light.

  As described above, when the first visible light projection and the voltage application are started simultaneously, the image display body 100 is changed from non-transparent to transparent by both the first visible light and the voltage. 100 changes to a transparent state in 0.3 seconds after the start of the first visible light projection and voltage application. As described above, since it took 7 seconds for the image display body 100 to become transparent only by projecting the first visible light (see FIG. 4A), the first visible light was projected simultaneously with the application of the voltage. By shining, the response speed until the image display body 100 becomes transparent can be increased. Further, the image display body 100 could not maintain the transparent state unless the first visible light was projected for 2 seconds or longer (see FIG. 4A), but started the first visible light projection and the voltage application at the same time. Sometimes, the transparent state can be maintained only by projecting the first visible light for 0.5 seconds. Accordingly, by simultaneously projecting the first visible light and applying the voltage, it is possible to speed up the time until the image display body 100 is made transparent, and to maintain the image display body 100 in the transparent state. The first visible light projecting time required for the operation can be shortened.

  As described above, in the present embodiment, since the first visible light projection and the voltage application are started at the same time, the time until the image display body 100 is changed to transparent is reduced (from 7 seconds to 0.3 Second) and the first visible light projection time required to maintain transparency can be shortened (from 2 seconds to 0.5 seconds). Therefore, when the image 700 displayed by the second visible light disappears, the image display body 100 can be instantly made transparent, and when the display device 10 of the present embodiment is used for a windshield of an automobile, the front view is visible. The image 700 can be displayed on the windshield without disturbing the sex.

  Next, the display method of this embodiment will be described with reference to FIG. FIG. 9 is a diagram illustrating a procedure of the display method according to the present embodiment. This procedure coincides with the operation of the display device 10 described with reference to FIGS.

  First, the image display body 100 is made opaque by projecting ultraviolet light onto the image display body 100 (first stage). The display functional layer 120 of the image display body 100 has an optical characteristic that light scattering increases when receiving ultraviolet light.

  Next, the second visible light is projected onto the image display body 100 to display the image 700 on the image display body 100 (second stage). When the second visible light is projected onto the non-transparent image display body 100 having increased light scattering properties, the image 700 can be displayed on the image display body 100.

  Stop displaying the image 700 on the image display body 100 (third stage). When the second visible light projection is stopped, the image 700 disappears from the image display body 100.

  First visible light is projected onto the image display body 100 and a voltage is applied to make the image display body 100 transparent (fourth stage). When the first visible light projection and the voltage application are started simultaneously, the image display body 100 can be changed from the non-transparent state to the transparent state by both the first visible light and the voltage.

  As described above, according to the display device 10 and the display method of the present embodiment, the image 700 can be displayed on the image display body 100 by normally making the image display body 100 in a transparent state temporarily opaque.

  As described above, the described embodiment has the following effects.

  (A) The image display body 100 can be made non-transparent by projecting ultraviolet light, and the image display body 100 can be instantaneously turned off by simultaneously starting the first visible light projection and voltage application. It can be changed from a transparent state to a transparent state. Accordingly, the first visible light is not reflected on the image display body 100, and the front visibility seen through the image display body 100 is improved.

  (B) Since the image 700 displayed on the image display body 100 by the second visible light is projected with ultraviolet light so that it is included in the ultraviolet light projection region 100c on the image display body 100, the image display body An image 700 is displayed in 100 non-transparent areas. Therefore, the image 700 is not displayed in the transparent area of the image display body 100, and the visibility of the image 700 is improved.

[Embodiment 2]
The second embodiment will be described with reference to FIG. The second embodiment is an embodiment in which the light control layer 140 is provided on the image display body 100 of the first embodiment.

  FIG. 10 is a cross-sectional view illustrating a schematic configuration of the image display body 100 according to the second embodiment. The image display body 100 of this embodiment includes a transparent conductive layer 130a, a display function layer 120, a light control layer 140, and a transparent conductive layer 130b.

  The transparent conductive layer 130a is disposed on the front surface 100a side of the image display body 100, and the transparent conductive layer 130b is disposed on the back surface 100b side of the image display body 100. The display function layer 120 and the light control layer 140 are disposed between the transparent conductive layer 130a and the transparent conductive layer 130b.

  The light control layer 140 is disposed on the surface of the display function layer 120 opposite to the surface on which the ultraviolet light is projected, that is, on the back surface 100b side of the display function layer 120. The light control layer 140 has an optical characteristic that light absorption increases by receiving ultraviolet light, while light absorption decreases by receiving first visible light or applying a voltage.

  The light control layer 140 is a transparent film member containing a photochromic material or an electrochromic material, for example. For example, fulgide or diarylethene is used for the photochromic material. For the electrochromic material, tungsten oxide or the like is used. The light control layer 140 has an optical characteristic in which light absorption is increased by receiving ultraviolet light, the color is changed from colorless to gray (or black), and external light is attenuated. The light control layer 140 has an optical characteristic that does not receive ultraviolet light, receives first visible light, or applies a voltage so that the discoloration disappears.

  The light control layer 140 may be included in the display function layer 120.

  As described above, the described embodiment has the following effects in addition to the effects of the first embodiment.

  (C) Since the light control layer 140 is provided on the back surface 100b side of the display function layer 120, a function of absorbing light only in a portion that receives ultraviolet light is exhibited. For this reason, the sunlight and the light of a headlight which enter from the back surface 100b of the display function layer 120 can be absorbed. That is, the contrast is maintained even in a bright environment, and the visibility of the image 700 is improved.

  (D) Since the function of absorbing light of the light control layer 140 can be controlled by voltage, the time until discoloration of the light control layer 140 disappears (transparency) can be shortened.

[Embodiment 3]
A third embodiment will be described with reference to FIG. The third embodiment is an embodiment in which the first visible light projection and the voltage application timing of the first embodiment are shifted.

  FIG. 11 is a diagram showing a state of first visible light projection and voltage application when the image display body 100 is made transparent in the display device 10 according to the third embodiment.

  In the present embodiment, the control unit 600 applies a voltage to the image display body 100 and then operates the second projector 300 while the voltage is applied, so that the voltage display and the second projector 300 are applied by the image display body 100. After being in a transparent state (after 0.5 seconds or more have passed since the first visible light projection), they are simultaneously stopped.

  First, when the control unit 600 applies a voltage to the image display body 100, the image display body 100 attempts to change from a non-transparent state to a transparent state. Then, the control unit 600 operates the second projector 300 while attempting to change from the non-transparent state to the transparent state (within 0.3 seconds from the application of the voltage), and causes the image display body 100 to receive the first visible light. Light up.

  When the first visible light is projected after the voltage is applied, the first visible light is projected when the image display body 100 is about to be in a transparent state, so that the first visible light is reflected on the image display body 100. Therefore, the image display body 100 can be prevented from being colored for a moment.

  As described above, the described embodiment has the following effects in addition to the effects of the first embodiment.

  (E) Since the first visible light is projected onto the image display body 100 with increased transparency, it is possible to suppress the first visible light from being scattered by the image display body 100. For example, when the image display body 100 is attached to the windshield of an automobile, the first visible light can be suppressed from being reflected on the image display body 100, and the front visibility of the windshield is improved.

[Embodiment 4]
Embodiment 4 will be described with reference to FIG. The fourth embodiment is an embodiment in which the first visible light projection and the voltage application timing of the first embodiment are further shifted from those of the third embodiment.

  FIG. 12 is a diagram illustrating a state of first visible light projection and voltage application when the image display body 100 is transparent in the display device 10 according to the fourth embodiment.

  In the present embodiment, the control unit 600 activates the second projector 300 after the image display body 100 becomes transparent due to the application of a voltage to the image display body 100, and the voltage application and the second projector 300 are performed. After the image display body 100 becomes transparent (after 0.5 second or more has passed since the first visible light projection), the image display body 100 is stopped simultaneously.

  First, when the control unit 600 applies a voltage to the image display body 100, the image display body 100 changes from a non-transparent state to a transparent state. Then, the control unit 600 operates the second projector 300 after the image display body 100 changes to a transparent state (after 0.3 seconds or more have elapsed from the voltage application), and causes the image display body 100 to move to the first image display body 100. Projects visible light.

  When the first visible light is projected after the image display body 100 is in the transparent state, the first visible light is projected onto the transparent image display body 100, and thus the first visible light is projected onto the image display body. 100 can be prevented from being reflected.

  As described above, the described embodiment has the following effects in addition to the effects of the first embodiment.

  (F) Since the first visible light is projected onto the image display body 100 in the transparent state, unintentional coloring of the image display body 100 can be prevented. For example, when the image display body 100 is attached to the windshield of an automobile, the first visible light is not reflected on the image display body 100, and visibility in front of the windshield is improved.

[Embodiment 5]
The fifth embodiment will be described with reference to FIG. The fifth embodiment is an embodiment in which the first visible light of the first embodiment is projected from the end of the image display body 100.

  FIG. 13 is a diagram illustrating a state where first visible light is projected from the end of the image display body 100 in the display device 10 according to the fifth embodiment.

  The image display body 100 of the present embodiment is the same as the image display body 100 of the first embodiment. In the present embodiment, as shown in FIG. 13, the second projector 300 displays an image from a direction intersecting with the direction in which the third projector 400 (see FIG. 1) projects the second visible light (front side 100a side). First visible light is projected onto the end of the body 100.

  As described above, when the first visible light is projected from the end portion of the image display body 100, the first visible light is guided through the display function layer 120, and thus the first visible light leaks outside the display function layer 120. In other words, unintentional coloring of the image display body 100 can be prevented. Therefore, the transparency of the image display body 100 can be ensured.

  If the first visible light is projected not from the front surface 100a side of the image display body 100 but from the end of the image display body 100, the irradiation distance of the first visible light is extended. For this reason, there is a slight time lag for the first visible light to reach every corner of the image display body 100. However, since the image display body 100 becomes transparent by applying a voltage and the first visible light is projected thereafter, there is no loss due to scattering of the display function layer 120, and the first visible light is projected. 2 There is no need to increase the output of the projector 300.

  As described above, the described embodiment has the following effects in addition to the effects of the first embodiment.

  (G) Since 1st visible light is projected from the edge part of the image display body 100 used as the transparent state, the unintentional coloring of the image display body 100 can be prevented. For example, when the image display body 100 is attached to the windshield of an automobile, the first visible light is not reflected on the image display body 100, and visibility in front of the windshield is improved.

  (H) Since the second projector 300 that projects the first visible light does not need to be provided together with the first projector 200 and the third projector 400, installation space can be saved.

  As described above, the display device 10 of the present invention has been described in the first to fifth embodiments described above. However, the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of the technical idea.

  For example, the timing and time of the first visible light projection and voltage application are not limited to the timing and time illustrated in FIGS. 8, 11, and 12, and various patterns can be applied.

10 display device,
100 image display,
100a front side,
100b back,
100c Projection area,
120 display functional layer,
121 host liquid crystal molecules,
122 Azobenzene molecule,
130a, 130b transparent conductive layer,
140 light control layer,
200 First projector (ultraviolet light projector),
300 Second projector (first visible light projector),
400 third projector (second visible light projector),
600 control unit,
700 images,
VL Second visible light.

Claims (12)

A display function layer that increases light scattering by receiving ultraviolet light and receives first visible light or decreases light scattering by applying voltage; and for applying the voltage to the display function layer. An image display body having a transparent conductive layer;
An ultraviolet light projector for projecting the ultraviolet light on the image display body;
A first visible light projecting unit that projects the first visible light on the image display body;
A second visible light projector that projects second visible light on the image display and displays an image on the image display;
When displaying the image on the image display, the ultraviolet light projector and the second visible light projector are operated, and when not displaying the image on the image display, the first visible light projector. A control unit for operating the unit and applying the voltage to the transparent conductive layer;
A display device. The image display body is:
The display device according to claim 1, wherein the transparent conductive layer is disposed so as to sandwich the display functional layer. The image display body is:
On the surface side of the display function layer opposite to the surface on which the ultraviolet light is projected, light absorption is increased by receiving the ultraviolet light, while receiving the first visible light or The display device according to claim 1, further comprising a light control layer that reduces the light absorption by applying a voltage. The controller is
The display device according to claim 1, wherein after applying the voltage to the image display body, the first visible light projecting unit is operated while the voltage is applied. The controller is
The display device according to claim 4, wherein the first visible light projecting unit is operated after the image display body is made transparent by applying the voltage. The controller is
The display device according to claim 1, wherein the operation of the first visible light projecting unit and the application of the voltage are stopped after the image display body becomes transparent.   The first visible light projecting unit projects the first visible light onto an end portion of the image display body from a direction intersecting a direction in which the second visible light is projected. The display apparatus in any one of.   The display device according to claim 1, wherein the voltage applied to the display function layer is an alternating voltage. A first stage of projecting the ultraviolet light onto an image display body that increases light scattering by receiving ultraviolet light and receives first visible light or decreases light scattering by applying a voltage;
A second step of projecting a second visible light to the image display body that has been made light-scattering and non-transparent to display an image on the image display body;
A third stage for stopping the display of the image on the image display body;
A fourth step of projecting the first visible light onto the image display body and applying the voltage to lower the light scattering property of the image display body and make it transparent;
Including display method. In the fourth stage,
The display method according to claim 9, wherein the first visible light is projected onto the image display body while the voltage is applied after the voltage is applied to the image display body. In the fourth stage,
The display method according to claim 9, wherein the first visible light is projected onto the image display body while the voltage is applied after the image display body is made transparent by application of the voltage. In the fourth stage,
The display method according to claim 9, wherein the first visible light and the voltage are stopped after the image display body becomes transparent.