Display device

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2016-220794, filed Nov. 11, 2016, the entire contents of which are incorporated herein by reference.

Embodiments described herein relate generally to a display device.

An imaging device comprising, for example, a polarizing filter and a retroreflective element has been proposed. The imaging device forms aerial images at a position plane-symmetrical to an emission point of display light showing the images to be displayed with regard to the polarizing filter. Here, when an observer tries to touch an aerial image in simulation, it is difficult for the observer to acquire the feeling of “touching” the aerial image. Under these circumstances, there is a demand for establishing the technique which enables an observer to sense the feeling of touching aerial images.

FIG. 1 is a diagram showing a configuration example of a display device according to an embodiment.

FIG. 2 is a diagram showing an example of an appearance of the display device.

FIG. 3 is a diagram showing an optical path of display light.

FIG. 4 is a diagram showing position of an observer OB and an aerial image I 1 with relative to each other.

FIG. 5 is a diagram showing positions of a display surface IP 0 , an aerial display area ADA and an imaged plane IP 1 with relative to each other.

FIG. 6A is a diagram showing an example of arrangement of an air blower outlet.

FIG. 6B is a diagram schematically showing a state that an observer's finger is touching an air plate.

FIG. 7 is a diagram showing another example of arrangement of the air blower outlet.

FIG. 8 is a diagram showing another example of arrangement of the air blower outlet.

FIG. 9 is a diagram showing another example of arrangement of the air blower outlet.

FIG. 10 is a diagram showing another example of arrangement of the air blower outlet.

FIG. 11 is a diagram showing another example of arrangement of the air blower outlet.

FIG. 12 is a diagram showing another example of arrangement of the air blower outlet.

FIG. 13 is a diagram showing another example of arrangement of the air blower outlet.

FIG. 14 is a diagram schematically showing a blower mechanism.

FIG. 15 is a perspective view schematically showing a display device comprising the blower mechanism shown in FIG. 14 .

FIG. 16 is a diagram showing an example of an aerial image displayed on an aerial display area.

FIG. 17 is a diagram showing a configuration example of the display panel shown in FIG. 14 .

FIG. 18 is a cross section showing a configuration example of the display panel shown in FIG. 17 .

FIG. 19 is a plan view diagram showing a configuration example of the retroreflective element shown in FIG. 1 .

FIG. 20 is a perspective view showing a configuration example of a retroreflector shown in FIG. 19 .

FIG. 21 is a cross section showing a configuration example of a retroreflective element applicable to this embodiment.

In general, according to one embodiment, a display device comprises a display which emits display light, a retroreflective element which retroreflects incident light, an optical element comprising a lower surface opposing the display and the retroreflective element and an upper surface on an opposite side to the lower surface, which reflects part of the display light toward the retroreflective element and transmits reflection light retroreflected by the retroreflective element and a first blower mechanism which blows air to a side of the upper surface.

According to another embodiment, a display device comprises a display which emits display light, a retroreflective element which retroreflects incident light, an optical element comprising a lower surface opposing the display and the retroreflective element and an upper surface on an opposite side to the lower surface, which reflects part of the display light toward the retroreflective element and transmits reflection light retroreflected by the retroreflective element and an air plate located on an upper surface side and formed from airflow.

According to another embodiment, a display device comprises a display which emits display light, a retroreflective element which retroreflects incident light, an optical element comprising a lower surface opposing the display and the retroreflective element and an upper surface on an opposite side to the lower surface, which reflects part of the display light toward the retroreflective element and transmits reflection light retroreflected by the retroreflective element, a sensor which detects an object to be detected, located on the upper surface side and a blower mechanism comprising an air blower outlet between the sensor and the optical element.

Embodiments will be described hereinafter with reference to the accompanying drawings. Incidentally, the disclosure is merely an example, and proper changes within the spirit of the invention, which are easily conceivable by a skilled person, are included in the scope of the invention as a matter of course. In addition, in some cases, in order to make the description clearer, the widths, thicknesses, shapes, etc., of the respective parts are schematically illustrated in the drawings, compared to the actual modes. However, the schematic illustration is merely an example, and adds no restrictions to the interpretation of the invention. Besides, in the specification and drawings, the structural elements having functions, which are identical or similar to the functions of the structural elements described in connection with preceding drawings, are denoted by like reference numerals, and an overlapping detailed description is omitted unless otherwise necessary.

FIG. 1 is a diagram showing a configuration example of a display device 1 according to an embodiment.

The display device 1 comprises a display DSP, an optical element 10 , a retroreflective element 20 , a sensor 30 , a loudspeaker 40 , a blower mechanism 50 , a controller 60 and the like.

The structure of the display DSP is not particularly limited as long as it is able to emit display light. An example of the display DSP is a liquid crystal display in which a liquid crystal layer is held between a pair of substrates. But, the display DSP may be a self-luminous display device such as an organic electroluminescent display device, an electronic paper display device comprising an electrophoretic element, and the like, a display device employing micro-electromechanical systems (MEMS), or a display device employing electrochromism. Specific examples of the display DSP will be described later.

The optical element 10 reflects at least part of incident light and transmits part the incident light. The optical elements 10 may be a half mirror having equal reflectivity and transmissivity to incident light, a polarization beam splitter, a reflective polarizer, a wire grid polarizer, or the like. The optical element 10 comprises a lower surface 10 B on a side opposing the display DSP and the retroreflective element 20 , and an upper surface 10 A on an opposite side to the lower surface 10 B.

The retroreflective element 20 retroreflects incident light. That is, the retroreflective element 20 reflects incident light made incident on a retroreflective surface 20 A to an opposite direction parallel to that of the incident light. The display DSP and the retroreflective element 20 are located on a side opposing the lower surface 10 B. The details of the retroreflective element 20 will be provided later.

In the display device 1 , display light emitted from the display DSP is imaged as an aerial image I 1 on an upper surface 10 A side as will be explained in detail with reference to FIG. 3 .

The sensor 30 is an infrared sensor, for example, and detects an object to be detected, such as a finger, in a detection range IRA indicated with a dotted line. The detection range IRA includes the region where the aerial image I 1 is imaged.

The loudspeaker 40 outputs sound. There may be a plurality of loudspeakers 40 .

The blower mechanism 50 comprises an air blower outlet 51 which blows air to the upper surface 10 A side. The blower mechanism 50 blows air in the direction parallel to the aerial image I 1 between, for example, the aerial image I 1 and the optical element 10 . The blower mechanism 50 may comprise a flow velocity adjustment mechanism which adjusts the flow velocity of the air blown, a temperature adjustment mechanism which adjusts temperature, a flow rate adjustment mechanism which adjusts the flow rate, and the like.

The controller 60 controls the display DSP, the loudspeaker 40 and the blower mechanism 50 . Further, the controller 60 can calculate out a relative position (coordinates) of an object to be detected with relative to the aerial image I 1 and also can detect movement of the object, from results detected with the sensor 30 . Based on the detection results of the sensor 30 , the controller 60 may control the display DSP, the loudspeaker 40 and the blower mechanism 50 . For example, when an object is detected at a predetermined position in the aerial image I 1 , the controller 60 may output sound from the loudspeaker 40 , or may change the display image of the display DSP, or may change the flow velocity, temperature, flow rate and the like of the air blown from the blower mechanism 50 .

FIG. 2 is a diagram showing an example of the appearance of the display device 1 . In the figure, a direction X, a direction Y and a direction Z are orthogonal to each other, but they may cross at an angle other than 90 degrees.

The display device 1 is configured by using a housing 70 . In the example illustrated, the housing 70 has substantially a rectangular parallelepiped shape, which comprises an upper surface 70 A parallel to an X-Y plane, etc. In the example illustrated, the upper surface 70 A has a rectangular shape which comprises an end 70 E extending along the direction X.

The optical element 10 is arranged so that the upper surface 10 A and the lower surface 10 B are parallel to the X-Y plane. In the example illustrated, the optical element 10 has a rectangular shape which comprises an end 10 E extending along the direction X. The optical element 10 and the upper surface 70 A are arranged along the direction Y and the end 10 E is brought into contact with the end 70 E. The display DSP and the retroreflective element 20 are accommodated in the housing 70 . The optical element 10 is located directly above the display DSP and the retroreflective element 20 along the direction Z.

The sensor 30 and the air blower outlet 51 are provided in the upper surface 70 A. In the example illustrated, the air blower outlet 51 is located between the sensor 30 and the optical element 10 and formed into a slit shape along the end 70 E. The air blower outlet 51 is located closer to the optical element 10 as compared to the sensor 30 . Along the direction X, a width W 51 having such a range that the air blower outlet 51 can be formed is greater than a width WDSP of the display DSP. The sensor 30 is located at substantially a center of the upper surface 70 A along the direction X.

FIG. 3 is a diagram showing an optical path of display light. FIG. 3 shows a plane parallel to a Y-Z plane.

The display DSP comprises a display surface IP 0 which displays images. Display light emitted from the display surface IP 0 is reflected by the optical element 10 toward the retroreflective element 20 as indicated by a solid line in the figure. The reflected light from the optical element 10 enters onto the retroreflective element 20 . As indicated by a dotted line in the figure, the reflected light from the optical element 10 is retroreflected by the retroreflective surface 20 A towards the optical element 10 . The light retroreflected by the retroreflective surface 20 A is allowed to pass through the optical element 10 and then imaged as the aerial image I 1 which exhibits the display image. The aerial image I 1 is located plane-symmetrical to the display surface IP 0 with regard to the optical element 10 .

Note that the display light may be circularly or linearly polarized light or the like. In this case, the optical element 10 may include a polarization element or a retardation film. When the display light is circularly polarized light, the display device 1 may further include a retardation film.

FIG. 4 is a diagram showing the positions of the observer OB and the aerial image I 1 with relative to each other.

The aerial image I 1 is located between the observer OB and the retroreflective element 20 . The observer OB is able to observe the aerial image I 1 in an observation range (indicated by the dotted line in the figure) including the retroreflective element 20 in a field of view of the observer OB. When the observation range does not overlap the aerial image I 1 , the aerial image I 1 cannot be observed. For this reason, the observer OB can observe the entire aerial image I 1 when viewing in a position where the entire aerial image I 1 overlaps the observation range. Note that it is desirable that the display DSP should not be located in the observation range.

FIG. 5 shows the positions of the display surface IP 0 , the aerial display area ADA, and an imaging plane IP 1 with relative to each other.

In the example illustrated, the display surface IP 0 has a rectangular shape. The display surface IP 0 displays the display image I 0 . The aerial display area ADA is defined as a region plane-symmetrical to the display surface IP 0 with regard to the optical element 10 , as indicated by a dashed line. The aerial image I 1 is displayed within the aerial display area ADA. Further, the imaging plane IP 1 is defined as a plane including the aerial display area ADA, as indicated by an alternate long and short dash line. Therefore, the imaging plane IP 1 is plane-symmetrical to the display surface IP 0 with respect to the optical element 10 .

In this embodiment, the imaging plane IP 1 is a plane defined along a direction D 1 and a direction D 2 . The direction D 1 corresponds to the direction X. The direction D 2 crosses the direction Y at an acute angle θ. That is, the imaging plane IP 1 is a plane crossing the X-Y plane or crossing the optical element 10 at the acute angle θ. Further, in this embodiment, the display surface IP 0 is a plane defined along the direction D 1 and a direction D 3 . The direction D 3 is symmetrical to the direction D 2 with regard to the direction Y and crosses the direction Y at the acute angle θ. The display surface IP 0 crosses the X-Y plane at an acute angle θ and is plane-symmetrical to the imaging plane IP 1 with regard to the optical element 10 . In terms of the relationship between the display image I 0 and the aerial image I 1 , the aerial image I 1 is inverted upside down with respect to the display image I 0 along the direction Z, and is laterally identical to the display image I 0 along the direction X.

FIG. 6A shows an arrangement example of the air blower outlet 51 .

The air blower outlet 51 is located between the sensor 30 and the aerial display area ADA. That is, the sensor 30 , the air blower outlet 51 and the aerial display area ADA are arranged along the direction D 2 in this order. The air blower outlet 51 has a slit shape formed along the direction D 1 . The blower mechanism 50 blows air from the air blower outlet 51 to the region which overlaps the aerial display area ADA. In the example illustrated, the blower mechanism 50 blows air in the direction D 2 on an upper surface 10 A side of the optical element 10 . Here, the air sent from the air blower outlet 51 is substantially parallel to the imaging plane IP 1 . In other words, the flow of the air blown from the air blower outlet 51 creates an air plate AP of planer air blow on the upper surface 10 A side. The air plate AP is formed along the imaging plane IP 1 . Further, the air plate AP entirely overlaps the aerial display area ADA. Note that the air plate AP should desirably be located within the imaging plane IP 1 or on an optical element 10 side with respect to the imaging plane IP 1 .

FIG. 6B schematically shows a situation where the observer is touching the air plate AP shown in FIG. 6A with his/her finger. When the observer attempts to touch the aerial image I 1 in simulation, the observer touches the air plate AP with his/her finger. The observer can obtain the feeling of touching the aerial image I 1 by sensing the flow of the air formed in the region where the aerial image I 1 is formed as a tactile sensation.

Next, another configuration example of this embodiment will be described with reference to FIGS. 7 to 13 .

The configuration example shown in FIG. 7 is different from that of FIG. 6 in that an air blower outlet 51 is located on an opposite side to the sensor 30 over the aerial display area ADA. The blower mechanism 50 blows air from the air blower outlet 51 in a direction opposite to the direction D 2 , i.e., a direction towards a sensor 30 side.

The configuration example shown in FIG. 8 is different from that of FIG. 6 in further comprising an inlet mechanism 80 . An inlet 81 of the inlet mechanism 80 is provided along the direction D 1 , and opposes the air blower outlet 51 over the aerial display area ADA. With this configuration, between the air blower outlet 51 and the inlet 81 , an air flow along the direction D 2 is formed.

The configuration example shown in FIG. 9 is different from that of FIG. 6 in comprising an air blower outlet 52 in addition to the air blower outlet 51 . The air blower outlet 52 opposes the air blower outlet 51 over the aerial display area ADA. The air blown from the air blower outlet 51 is sent in the direction D 2 , and the air blown from the air blower outlet 52 is blown in a direction opposite to the direction D 2 . In other words, the air blower outlet 52 opposes the air blower outlet 51 along the blowing direction (the direction D 2 ) of the air blower outlet 51 . In the example illustrated, the air blower outlet 51 is provided in a blower mechanism 501 and the air blower outlet 52 is provided in a blower mechanism 502 . With this configuration, the flow velocities, temperatures and flow rates of the airs blown from these blower outlets 51 and 52 can be respectively varied from each other. Note that the blower outlets 51 and 52 may be provided in a common blower mechanism 50 .

The configuration example shown in FIG. 10 is different from that of FIG. 6 in that an air blower outlet 51 is provided along the direction D 2 and a blower mechanism 501 blows air in the direction D 1 .

The configuration example shown in FIG. 11 is different from that of FIG. 10 that an air blower outlet 52 is provided to oppose an air blower outlet 51 . The air blower outlet 52 is provided along the direction D 2 , and opposes the air blower outlet 51 over the aerial display area ADA. The air blown from the air blower outlet 51 is sent in the direction D 1 and the air blown from the air blower outlet 52 is sent in a direction opposite to the direction D 1 .

The configuration example shown in FIG. 12 is different from that of FIG. 6 in that a plurality of air blower outlets, i.e., an air blower outlet 51 and an air blower outlet 52 are arranged in line. In the example illustrated, the air blower outlets 51 and 52 are arranged along the direction D 1 , but they may be arranged along the direction D 2 . Further, along the direction D 1 , a width W 51 of the air blower outlet 51 and a width W 52 of the air blower outlet 52 are equal to each other, but they may differ. Naturally, three or more air blower outlets may be arranged along one direction. In the example illustrated, the air blower outlet 51 is provided in a blower mechanism 501 , and the air blower outlet 52 is provided in a blower mechanism 502 . The air blower outlets 51 and 52 may differ from each other in the flow rate, flow velocity and temperature of the airs blown therefrom.

The configuration example shown in FIG. 13 is different from that of FIG. 6 in that a plurality of air blower outlets 51 a and 52 a are provided around the aerial display area ADA.

In the example illustrated, air blower outlets 51 a 1 , 51 a 2 , 51 a 3 , 51 a 4 , 51 a 5 and 51 a 6 are arranged along the direction D 1 , and the air blower outlets 51 a 1 , 51 a 2 and 51 a 3 and the air blower outlet 51 a 4 , 51 a 5 and 51 a 6 respectively oppose along the direction D 2 . The air blower outlets 51 a 1 , 51 a 2 and 51 a 3 are provided in a blower mechanism 501 A, and the air blower outlet 51 a 4 , 51 a 5 and 51 a 6 are provided in a blower mechanism 501 B.

The air blower outlets 52 a 1 , 52 a 2 , 52 a 3 , 52 a 4 , 52 a 5 and 52 a 6 are arranged along the direction D 2 , and the air blower outlets 52 a 1 , 52 a 2 and 52 a 3 and the air blower outlet 52 a 4 , 52 a 5 and 52 a 6 respectively oppose along the direction D 1 . The air blower outlets 52 a 1 , 52 a 2 and 52 a 3 are provided in a blower mechanism 502 A, and the air blower outlets 52 a 4 , 52 a 5 and 52 a 6 are provided in a blower mechanism 502 B.

The air blown from the air blower outlets 51 a 1 , 51 a 2 and 51 a 3 is sent in the direction D 2 , and the air blown from the air blower outlets 51 a 4 , 51 a 5 and 51 a 6 is sent in a direction opposite to the direction D 2 .

The air blown from the air blower outlets 52 a 1 , 52 a 2 and 52 a 3 is sent in the direction D 1 , and the air blown from the air blower outlet 52 a 4 , 52 a 5 and 52 a 6 is sent in a direction opposite to the direction D 1 .

In the configuration example shown in FIG. 13 , the flow rate, flow velocity, temperature, etc., of the airs blown from the air blower outlets 51 a and 52 a can be varied as needed.

FIG. 14 schematically shows the blower mechanism 50 .

The blower mechanism 50 is provided near the display DSP. The blower mechanism 50 comprises an air blower outlet 51 , a fan 53 and a duct 54 . In the example illustrated, the display DSP is a liquid crystal display, and comprises a liquid crystal display panel PNL and a light source (backlight) LS. In this embodiment, the fan 53 is used for cooling the light source LS. That is, the fan 53 blows air towards the light source LS. The wind sent by the fan 53 is blown out from the air blower outlet 51 through the duct 54 while cooling down the light source LS. In the example illustrated, the duct 54 and the air blower outlet 51 are formed as one integral unit, but they may be prepared individually and the put together.

FIG. 15 is a perspective view schematically showing a display device 1 comprising blower mechanisms. FIG. 15 shows only the main portion. In the example illustrated, the display device 1 comprises blower mechanisms 501 and 502 . The blower mechanisms 501 and 502 can blow airs respectively which differ in the flow rate, flow velocity, temperature, etc. Note that the display device 1 may comprise one blower mechanism or three or more. The blower mechanisms 501 and 502 each comprise a fan 53 , a duct 54 and an air blower outlet 51 , but they may comprise a plurality of fans 53 , ducts 54 and air blower outlets 51 . The outlets of the blower mechanism 501 and 502 can be formed to correspond to the air blower outlets 51 and 52 shown in, for example, FIGS. 9, 11, 12 , etc. With this configuration, the blower mechanisms 501 and 502 for cooling display DSP can also function to form an air plate AP, and thus the device can be downsized and the cost can be reduced as compared to the case where a separate blower mechanism is provided.

FIG. 16 shows an example of the aerial image I 1 displayed on the aerial display area ADA.

In the example illustrated, a button A, a button B and a button C are displayed as the aerial image I 1 . Let us suppose now that a finger of the observer OB as an object to be detected approaches the button A. The sensor 30 detects the location and movement of the object. The controller 60 judges whether the object is located in the region where the button A is displayed in the aerial display area ADA, further whether the object makes the movement of pushing the button A and the like, based on the detection result of the sensor 30 . When judged that the object has made the movement of touching or pushing the button A, the controller 60 controls the display DSP to change the display image of the aerial image I 1 . For example, the aerial image I 1 is changed to such display image showing the button A is pushed into the back side of the aerial display area ADA as viewed from the observer OB. Further, the controller 60 controls the loudspeaker 40 in synchronous with the change of the aerial image I 1 , and instructs to output a sound effect for pushing the button A. At this time, as described above, air flow is produced in the area of the aerial image I 1 , which includes the region where the button A is displayed. Thus, if a finger is placed on the region where the button A is displayed, the observer can perceive the operation by the airflow on the finger as a tactile sensation and also visually by the change of the display image. Further, he or she can auditorily perceive it by the output of sound. In this manner, the feeling of “having touched the button A” can be reinforced for the observer.

FIG. 17 is a diagram showing a configuration example of the display panel PNL shown in FIG. 14 . Here, an active matrix-driving transmissive type liquid crystal display panel will be described as an example of the display panel PNL. More specifically, the display panel PNL comprises a first substrate SUB 1 , a second substrate SUB 2 opposing the first substrate SUB 1 and a liquid crystal layer LQ held between the first substrate SUB 1 and the second substrate SUB 2 . The first substrate SUB 1 and second substrate SUB 2 are attached together while a predetermined cell gap is formed therebetween. The display panel PNL comprises a display area DA which displays images. The display area DA comprises a plurality of subpixels PX arranged in a matrix.

The display area DA comprises, as subpixels PX, for example, a red pixel PXR which displays red, a green pixel PXG which displays green and a blue pixel PXB which displays blue. Note that the display area DA may further comprise a subpixel of a color different from red, green or blue (that is, for example, a white pixel which displays white). The pixels which realize color presentation comprises subpixels PX of these plurality of different colors. That is, a pixel discussed here is the minimum unit which forms a color image. In the example illustrated, the pixels each comprise a red pixel PXR, a green pixel PXG and a blue pixel PXB.

The red pixel PXR comprises a red color filter and is formed to be trasnmissive mainly to red light of the white light from the respective light source. The green pixel PXG comprises a green color filter and is formed to be trasnmissive mainly to green light of the white light from the respective light source. The blue pixel PXB comprises a blue color filter and is formed to be trasnmissive mainly to blue light of the white light from the respective light source among the white light from light source. Although will not be explained in full detail, the color filters may be provided on the first substrate SUB 1 or on the second substrate SUB 2 .

The first substrate SUB 1 comprises a plurality of gate lines G extending along a first direction D 11 and a plurality of source lines S extending along a second direction D 22 while crossing the gate lines G. The gate lines G are each drawn to an outer side of the display area DA and connected to the gate driver GD. The source lines S are each drawn to an outer side of the display area DA and connected to the source driver SD. The gate drivers GD and the source drivers SD are connected to the controller CNT. The controller CNT generates control signals based on the video signals, and controls the gate driver GD and the source driver SD.

The subpixels PX each comprise a switching element SW, a pixel electrode PE, a common electrode CE and the like. The switching element SW is electrically connected to a gate line G and a source line S. The switching element SW is formed from a thin film transistor, for example. The pixel electrode PE is electrically connected to the switching element SW. The common electrode CE opposes a plurality of pixel electrodes PE.

Although a detailed explanation of the structure of the display panel PNL is omitted here, in a display mode using a vertical electric field along the normal of the main surface of the substrate or using an inclined electric field at an oblique direction to the normal of the substrate main surface, the pixel electrodes PE are provided on the first substrate SUB 1 , whereas the common electrode CE is provided on the second substrate SUB 2 . In a display mode using a lateral electric field along the substrate main surface, both of the pixel electrodes PE and the common electrode CE are provided on the first substrate SUB 1 . Further, the display panel PNL may have such a structure as to be able to correspond to a display mode using an appropriate combination of the vertical, lateral and inclined electric fields, described above. Note that the main surface of the substrate is equivalent to a plane defined by the first direction D 11 and the second direction D 22 .

FIG. 18 is a cross section showing a configuration example of the display panel PNL shown in FIG. 17 . Here, a cross-sectional structure of the display panel PNL to which an fringe field switching (FFS) mode is applied, which is one of the display modes using the lateral electric field, will be briefly described.

The first substrate SUB 1 comprises a first insulating substrate 100 , a first insulating film 110 , a common electrode CE, a second insulating film 120 , pixel electrodes PE 1 to PE 3 , a first alignment film AL 1 and the like. The common electrode CE extends over the red pixel PXR, the green pixel PXG and the blue pixel PXB. A pixel electrode PE 1 of the red pixel PXR, a pixel electrode PE 2 of the green pixel PXG and a pixel electrode PE 3 of the blue pixel PXB each oppose the common electrode CE, and each comprise slits SLA. In the example illustrated, the common electrode CE is located between the first insulating film 110 and the second insulating film 120 , and the pixel electrodes PE 1 to PE 3 are located between the second insulating film 120 and the first alignment film AL 1 . Note that the pixel electrodes PE 1 to PE 3 may be located between the first insulating film 110 and the second insulating film 120 and the common electrode CE may be located between the second insulating film 120 and first alignment film AL 1 . In this case, the slits SLA are formed in the common electrode CE.

The second substrate SUB 2 comprises a second insulating substrate 200 , a light-shielding layer BM, color filters CFR, CFG and CFB, an overcoat layer OC, a second alignment film AL 2 and the like. The color filters CFR, CFG and CFB oppose the pixel electrodes PE 1 , PE 2 and PE 3 , respectively, while interposing the liquid crystal layer LQ between each pair. The color filter CFR is a red filter, the color filter CFG is a green filter and the color filter CFB is a blue filter. In the example illustrated, the color filter CFR, CFG and CFB are provided in the second substrate SUB 2 , but they may be provided in the first substrate SUB 1 .

The liquid crystal layer LQ is enclosed between the first alignment film AL 1 and the second alignment film AL 2 .

The light source LS opposes the first substrate SUB 1 . The light source LS may take various implementable applications, but a detailed explanation of the structure is omitted.

A first optical element OD 1 including a first polarizer PL 1 is disposed on an external surface of the first insulating substrate 100 . A second optical element OD 2 including a second polarizer PL 2 is disposed on an external surface of the second insulating substrate 200 . For example, a first absorption axis of the first polarizer PL 1 and a second absorption axis of the second polarizer PL 2 are orthogonal to each other.

The pixels each containing a red pixel PXR, a green pixel PXG and a blue pixel PXB are arranged at a pitch P 1 .

FIG. 19 is a plan view showing a configuration example of the retroreflective element 20 shown in FIG. 1 . Here, the illustration is shown along a plane defined by a third direction D 33 and a fourth direction D 44 orthogonal to each other.

The retroreflective element 20 comprises a plurality of retroreflectors 23 . In the illustrated plan view, the retroreflectors 23 each has an outline of an equilateral triangle. Further, in each of the retroreflectors 23 , a center O is depressed toward the back of the page to form a concavity CC in the retroreflective surface 20 A shown in FIG. 1 . Moreover, the boundary between each adjacent pair of retroreflectors 23 is indicated by a dotted line in FIG. 19 , and is equivalent to a convexity CV of the retroreflective surface 20 A. The retroreflectors 23 are arranged along the third direction D 33 . Further, the retroreflectors 23 are arranged at a pitch P 2 along the fourth direction D 44 . The retroreflectors 23 adjacent to each other along the third direction D 33 and the fourth direction D 44 are inversed with respect each other at 180 degrees.

A retroreflector 231 in the figure comprises three reflective surfaces A 1 , B 1 and C 1 orthogonal to each other. The retroreflector 231 comprise a concavity CC 1 surrounded by the reflective surfaces A 1 , B 1 and C 1 . The retroreflector 231 and a retroreflector 232 are arranged along the fourth direction D 44 . The retroreflector 232 comprises three reflective surfaces A 2 , B 2 and C 2 orthogonal to each other. The retroreflector 232 comprises a concavity CC 2 surrounded by the reflective surface A 2 , B 2 and C 2 . An intersection between the reflective surface A 1 of the retroreflector 231 and the reflective surface A 2 of the retroreflector 232 forms a convexity CVA of the retroreflective surface. The convexity CVA extends along a direction parallel to the third direction D 33 . The retroreflector 231 and the retroreflector 232 are line-symmetrial to each other with respect to the convexity CVA. Similarly, the boundary between each adjacent pair of retroreflectors 23 corresponds to a convexity. That is, the outline (triangle) of each of the retroreflectors 23 is defined by the convexity. The outline of the retroreflector 231 is defined by convexities CVA, CVB and CVC. The convexitys CVB and CVC each extend along a direction crossing the third direction D 33 and the fourth direction D 44 . For example, the extending direction of the convexity CVB makes an angle with the third direction D 33 at θB3 of 60 degrees, and an angle with the fourth direction D 44 at θB4 of 30 degrees. The extending direction of the convexity CVC makes an angle with the third direction D 33 at θC3 of 60 degrees, and an angle with the fourth direction D 44 at θC4 of 30 degrees.

The resolution of the aerial image I 1 is dependent on the pitch P 2 of the retroreflectors 23 . In order to suppress degradation of resolution, the pitch P 2 should desirably be less than the pitch P 1 of the pixels in the display panel PNL shown in FIG. 3 .

FIG. 20 is a perspective view showing a configuration example of a retroreflector 23 shown in FIG. 19 . Here, an xyz coordinate system is applied, in which the axes are orthogonal to each other, to illustrate the form of the retroreflector 23 .

More specifically, the retroreflector 23 comprises three reflective surfaces 23 A, 23 B and 23 C in the xyz coordinate system. The reflective surfaces 23 A to 23 C are all identical in shape and are right-angled isosceles triangles. Further, the reflective surfaces 23 A to 23 C are arranged to be orthogonal to each other. The retroreflector 23 comprising the reflective surfaces 23 A to 23 C of such a form is called a corner cube or a corner reflector.

When a point A on an x-axis is represented by (α, 0, 0), a point B on a y-axis by (0, α, 0) and a point C on a z axis by (0, 0, α), the reflective surface 23 A is formed on an x-y plane and is defined by an origin point O, the point A and the point B. The reflective surface 23 B is formed on a y-z plane and is defined by the origin point O, the point B and the point C. The reflective surface 23 C is formed on an x-z plane and is defined by the origin point O, the point A and the point C. A line segment AB which connects the point A and the point B, a line segment BC which connects the point B and the point C and a line segment AC which connects the point A and the point C correspond to the convexity described above.

The retroreflector 23 does not comprise a surface defined by the three points A, B and C. That is, the inner side surrounded by the three reflective surfaces 23 A to 23 C is equivalent to the concavity described above and is an air layer. The retroreflector 23 can realize retroreflection, in which incident light rays are reflected by the three reflective surfaces 23 A to 23 C, respectively, to reflect back in substantially the same optical paths as those of the incident light rays. But, the vicinities of the three points A, B and C may be non-retroreflective portions (where the light is not reflected by the three reflective surfaces).

Note that the form of the retroreflectors 23 is not limited to that of the example illustrated here, but may be such a form similar to that of the retroreflector but the non-retroreflective portions thereof are cut off.

FIG. 21 is a cross section showing configuration examples of a retroreflective element 20 applicable to this embodiment.

The retroreflective element 20 comprises a base 21 and a metal thin film 22 . The base 21 is formed from, for example, a resin material. The metal thin film 22 is formed from, for example, a material which exhibits light reflexivity, such as silver (Ag), aluminum (Al), or an aluminum alloy. Note that the metal thin film 22 may be subjected to a surface treatment to prevent corrosion or coated with an inorganic material such as silicon nitride (SiN).

A configuration example shown in FIG. 21 , part (a) comprises a retroreflective surface 20 A on a front surface 21 A side of the base 21 . The metal thin film 22 covers the surface 21 A of the base 21 and forms a retroreflective surface 20 A. A rear surface 21 B of the base 21 is flat. As indicated an arrow in the figure, incident light entering the retroreflective element 20 is reflected by the retroreflective surface 20 A without passing through the base 21 .

A configuration example shown in FIG. 21 , part (b) comprises a retroreflective surface 20 A on a rear surface 21 B side of the base 21 . The metal thin film 22 covers the rear surface 21 B of the base 21 , and forms a retroreflective surface 20 A. A front surface 21 A of the base 21 is flat. As indicated an arrow in the figure, incident light entering the retroreflective element 20 passes through the base 21 , and thereafter, is reflected by the retroreflective surface 20 A.

A configuration example shown in FIG. 21 , part (c) comprises a retroreflective surface 20 A on an interface between a base 21 and a cover member 24 . The base 21 and the cover member 24 are formed respectively from materials having refractive indexes different from each other, and at least the cover member 24 has a light transmissivity. The retroreflective surface 20 A is formed of a metal thin film 22 provided between the base 21 and the cover member 24 . As indicated an arrow in the figure, incident light entering the retroreflective element 20 passes through the cover member 24 , and thereafter, is reflected by the retroreflective surface 20 A.

When the base 21 is formed from a material exhibiting light reflectivity, the metal thin film 22 may be omitted, and the front surface 21 A or rear surface 21 B of the base 21 may form the retroreflective surface 20 A. The transmissivity in the retroreflective surface 20 A is substantially zero, and most of the incident light entering the retroreflective surface 20 A does not reach the rear surface 20 B of the retroreflective element 20 . That is, most incident light entering the retroreflective element 20 is retroreflected by the retroreflective surface 20 A without passing through the base 21 .

In each of the above-described embodiments, the blower mechanisms 50 , 501 and 501 A correspond to the first blower mechanism. The blower mechanisms 502 and 502 A correspond to the second blower mechanism. The air blower outlet 51 corresponds to the first air blower outlet. The air blower outlet 52 corresponds to the second air blower outlet. Further, the air blower outlet 51 a corresponds to the third air blower outlet, and the air blower outlet 51 b corresponds to the fourth air blower outlet. The air blower outlet 52 a corresponds to the fifth air blower outlet, and the air blower outlet 52 b corresponds to the sixth air blower outlet. The direction D 1 correspond to the first direction and the direction D 2 corresponds to the second direction. Further, the direction D 2 corresponds to the air blowing direction.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.