JPH06347764A - Display device - Google Patents

Abstract

PURPOSE:To improve the intensity of backward scattering of a display device of a scattering type using a liquid crystal with a low electric power consumption and small size. CONSTITUTION:This display device is constituted by positioning a lenticular plate 25 of a lenticular structure having a refractive surface 25a formed into a projecting body group shape and a counter surface 25b on the opposite side between a liquid crystal panel 24 formed by inserting the liquid crystal layer 23 between two sheets of glass substrates 22a and 22b and a light absorptive layer 26 arranged behind this panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scattering type display device using liquid crystal.

In recent years, with the progress of display technology, a display device with low power consumption has been desired. Therefore, it is necessary to perform highly accurate display without using a backlight.

[0003]

2. Description of the Related Art Conventionally, among display devices, there is a liquid crystal display device using a liquid crystal panel that does not use a polarizing plate, and high brightness is obtained because light is not absorbed by the polarizing plate.

Therefore, FIG. 9 shows a configuration diagram of a main part of a conventional display device. In the display device 11 in FIG. 9, an absorber 13 such as a color reflector, a black absorber or a dark box is arranged behind the liquid crystal panel 12.

The liquid crystal panel 12 includes two glass plates 14a and 14b on which ITO (conductive transparent electrode) is formed,
A scattering type liquid crystal layer 15 is sandwiched. Liquid crystal layer 1
For example, polymer dispersed liquid crystal, DSM (dynamic scattering mode) liquid crystal, cholesteric nematic phase transition liquid crystal, or the like is used for 5. Of these, the polymer-dispersed liquid crystal exhibits strong scattering.

In the display device 11 shown in FIG. 9, when polymer-dispersed liquid crystal is used for the liquid crystal layer 12, the light 1 incident from the normal direction to the liquid crystal layer 12 in a scattering state when a voltage is applied.
6a is scattered in the liquid crystal layer 12, totally reflected by the glass plate 14b by probability, and is observed again in a state of being scattered in the liquid crystal layer 12.

Further, since the light 16b incident from an oblique direction is not sufficiently bent in the traveling direction, the glass plate 14
It is not observed because it passes through b and is absorbed by the absorber 13. Further, even light 16c incident at a shallow angle is transmitted through the glass plate 14b, absorbed by the absorber 13 and not observed.

[0008]

However, even when a polymer-dispersed liquid crystal capable of obtaining strong scattering is used, the method of displaying the backscattering as white does not have sufficient backscattering, so that the driving voltage is high. Must. As a result, there is a problem that the power consumption increases and the cost of the drive circuit increases.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a display device capable of improving the intensity of backscattering with low power consumption and low cost.

[0010]

FIG. 1 is a block diagram showing the principle of the present invention. FIG. 1 is a configuration diagram of a main part of a display device 21 of the present invention, in which glass substrates 22a and 22b (22b may be plastic substrates) which are two transparent substrates on which ITO (conductive transparent electrode) is formed. A liquid crystal panel 24, which is a display unit in which a predetermined liquid crystal layer 23 is sandwiched, a refraction surface 25a for refracting light incident at a predetermined angle, and a reflection surface 25b for reflecting light incident from the refraction surface to the refraction surface. It is composed of a lenticular plate 25 which is a refraction and reflection means to be formed, and a light absorption layer 26.

[0011]

As shown in FIG. 1, when the liquid crystal panel 24 is in the scattering state, of the light incident from the glass substrate 22a,
Not only the light 27a having a deep incident angle, but also the light 27b, 2 having a shallow incident angle which is conventionally absorbed by the light absorption layer 26 (FIG. 9).
7c is refracted by the refracting surface 25a of the lenticular plate 25, then totally reflected by the reflecting surface, and again emitted from the refracting surface 25a through the liquid crystal panel 24 (27b ₁ , 27c ₁ ).

When the liquid crystal panel 24 is transmitting, the incident light 27b is absorbed by the light absorbing layer 26 (27).
b ₂ ), the light 27 c having a shallower incident angle is totally reflected and emitted (27 c ₂ ) at an angle shallower than the reflecting surface 25 a of the lenticular plate 25 and is not observed.

As described above, even the light having a small incident angle is totally reflected by the lenticular plate 25, so that the backscattering intensity can be improved with low power consumption and low cost.

[0014]

1 is a block diagram of the first embodiment of the present invention. 2 (A) and 2 (B) are schematic diagrams showing the main part of the display device 21 of the present invention.

The liquid crystal panel 24, which is the display portion of the display device 21 in FIG. 2A, has a glass substrate 22a, which is a transparent substrate on which ITO is formed, and a plastic film substrate 2
2b sandwiches the liquid crystal layer 23 with the ITO (21a ₁ , 21b ₁ ) facing each other.

The liquid crystal layer 23 is a polymer dispersion type liquid crystal, DS.
Either M (dynamic scattering mode) liquid crystal or cholesteric nematic phase transition liquid crystal (preferably polymer dispersion type liquid crystal) is used, and a predetermined number of spacers 28 are used.
Is mixed in.

It should be noted that one side is not the glass substrate but the plastic film substrate 22b. The plastic film substrate is more preferable in order to facilitate the connection with the lenticular plate described later.

Therefore, the plastic film substrate 22b
A lenticular plate 25, which is a refracting / reflecting means, is located on the back surface of the. The lenticular plate 25 is a prism sheet in which the refracting surface 25a is formed in the shape of a projecting group of parallel aggregates of triangular prisms (isosceles triangular prisms), and the reflecting surface 25b is formed in a smooth surface shape. It is attached to the back surface of the plastic film substrate 22b with an adhesive 29 of UV curable resin.

In this case, the refracting surface 2 of the lenticular plate 25
In order to prevent moire (striped pattern) due to a period shift from the pixel pitch of the liquid crystal panel 24, the pitch of the projecting group in 5a is an integer multiple of the corresponding pixel pitch or an integer part thereof. It is desirable to have one.

The reflecting surface 25 of the lenticular plate 25
b and the light absorption layer 26 also serving as a reinforcing plate
It is attached by the adhesive material 29 with the intervening. That is,
The spacer 30 allows the lenticular plate 25 and the light absorption layer 26 to be formed.
A gap layer 31 of a gas such as air having a low refractive index of about ten and several μm is formed between and, and the gap layer 31 is held by preventing bending when a pressing force is applied from above and below. The gap layer 31 increases the critical angle of complete reflection on the reflection surface 25b of the lenticular plate 25.

The gap layer 31 may be provided with a liquid or solid having a refractive index smaller than that of at least the lenticular plate 25.

Further, the display device 21 shown in FIG.
Reflective surface 25b of lenticular plate 25 ₁The fine unevenness
It is formed on a rough surface, and other configurations are the same as those in FIG.
is there.

The display device 21 shown in FIGS. 2A and 2B.
The light incident at a deep angle is reflected by the interface on the back surface of the plastic film substrate 22b as shown in FIG. 1, and passes twice through the liquid crystal layer 23 in the scattering state as in the conventional case.

Further, as shown in FIGS. 2 (A) and 2 (B),
The light 27d (or the light whose optical path is changed by the scattering layer) incident at a shallow angle is refracted by the refracting surface 25a of the lenticular plate 25, is totally reflected by the reflecting surfaces 25b, 25b ₁ that are smooth surfaces or rough surfaces, and is again reflected. Liquid crystal layer 2 in a scattering state through refraction surface 25a
Through 3. When the liquid crystal layer 23 is in the transmissive state,
It is absorbed by the light absorption layer 26 as described above.

Therefore, FIG. 3 shows a graph of the relationship between the reflectance and the prism angle in FIG. 2 (A). The prism angle is the angle θ (FIG. 2A) of the hypotenuse of each projecting body having a triangular cross section on the refracting surface 25a of the lenticular plate 25. Therefore, the graph of FIG. 3 shows how the reflectance on the reflecting surface 25b changes depending on the prism angle. In FIG. 3, A
Indicates a conventional case where no lenticular plate is provided, B indicates a case where the liquid crystal layer 23 is in a scattering state when the lenticular plate 25 is used, and C indicates a case where the liquid crystal layer 23 is in a transmitting state.

As shown in FIG. 3, when the liquid crystal layer 23 is in the scattering state, the reflectance of the reflecting surface 25b of the lenticular plate 25 depends on the prism angle to some extent (the shape of the reflecting surface 25b (FIG. 2B)). However, the reflectance increases as the angle increases and the state of each projection becomes sharper.

Here, FIG. 4 shows a diagram for explaining the occurrence of a ghost. In FIG. 4, when the transmissive region 32 exists in a part of the scattering region of the liquid crystal layer 23, the transmissive region 3
The light 27e that has passed through 2 is reflected by the reflection surface 2 of the lenticular plate 25.
The image 33 is totally reflected by 5b and is generated in the liquid crystal layer 23 to be displayed as a ghost image.

This is a liquid crystal layer 23 and a lenticular plate 25.
When there is a distance from the (reflecting surface 25b), the reflecting surface 2
5b caused by total internal reflection.

Therefore, in order to suppress the occurrence of this ghost, it is desirable that the distance from the scattering layer of the liquid crystal layer 23 to the reflecting surface 25b of the lenticular plate 25 is smaller than the size of the pixel. That is, one substrate 2 of the liquid crystal panel 24
By forming the film 2b into a film and attaching the lenticular plate 25 to the back surface of the plastic film substrate 22b, ghost generation is suppressed.

Since ghosts are unlikely to occur in the symmetry axis direction of the lenticular plate 25 (the direction of the apex side of the triangular prism projection and the direction perpendicular to the paper surface of FIG. 4), the direction of the incident light beam which is direct light The axis of symmetry is set to be parallel.

By stacking the two lenticular plates 25 so that the axes of symmetry are substantially orthogonal to each other, it is possible to totally reflect light from all directions and suppress ghosts.
The brightness can be improved.

Here, FIG. 5 shows a configuration diagram of a main part of a modification of the ghost suppression. FIG. 5A shows a lenticular plate 25A.
The projection group of the refracting surface 25a ₁ is formed as a parallel assembly of semi-cylindrical convex lenses. According to this, part of the light 27e transmitted through the transmissive region 32 of the liquid crystal layer 23 and incident on the refraction surface 25a ₁ of the lenticular plate 25A passes through the reflection surface 25b and is absorbed by the light absorption layer 26. In other words, the ghost 23 due to the reflection on the reflecting surface 25b can be blurred.

FIG. 5B shows the lenticular plate 25.
The shape of the projection group of the refracting surface 25a ₂ of B is formed in the closest packed state as a polygonal pyramid such as a triangular pyramid or a quadrangular pyramid. According to this, it is possible to make the ghost 33 blur in all directions transmitted through the transparent region 32.

Further, FIG. 5C shows the lenticular plate 2.
The shape of the projecting body of the refracting surface 25a ₃ of 5C is formed into a parallel aggregate of isosceles triangular prisms, and the angle formed by the isosceles is changed in a minute cycle. As a result, the ghost 3 due to the light 27e transmitted through the transmission region 32 is also generated.
3 can be blurred.

Next, FIG. 6 shows a block diagram of the essential parts of a second embodiment of the present invention. The display device 21 according to the second embodiment includes a liquid crystal panel 24A as a display unit, a glass substrate 34a on which an ITO film 34a ₁ is formed, and a triangular prism (isosceles triangular prism).
Jo convex lens is formed by sandwiched a liquid crystal layer 23a in the plastic film substrate 34b lenticular structure having a protruding member surface 34b ₁ of the protruding member group shape formed as a parallel assembly.

The liquid crystal layer 23a is made of soft liquid crystal mixed with the spacer 28, and the ITO film 23a ₁ is formed on the plastic film substrate 34 side. In this case, the liquid crystal layer 2 is on the side of the projecting surface 34b ₁ of the plastic film substrate 34b.
It is placed on the 3a side. Therefore, the projecting surface 34b ₁ of the plastic film substrate 34b becomes a refracting surface, and the opposite surface becomes a reflecting surface 34b ₂ . Incidentally, in the reverse surface opposite to the protruding member surface 34b _1, the projecting member surface 34b ₁ may be reflecting surfaces.

Further, in FIG. 6, a gap layer 31 is formed between the plastic film substrate 34b and the light absorption layer 26 with the spacer 30 interposed by the adhesive 29.

As a result, even if the light 27f having a shallow incident angle is incident, it is totally reflected by the plastic film substrate 34b constituting the liquid crystal panel 24A, and the backscattering intensity can be improved.

Next, FIG. 7 shows a block diagram of the essential parts of a third embodiment of the present invention. FIG. 7 shows a liquid crystal panel 24B which is a display unit.
In which a liquid crystal layer 23b is arranged between two glass substrates 35a and 35b, and a gap layer 37 is formed between the liquid crystal layer 23b and the glass substrate 35b by a spacer 36.
Is being formed. The liquid crystal layer 23 of the glass substrate 35
The ITO film 35a ₁ is formed on the b side.

The liquid crystal layer 23b is made of soft liquid crystal and
Parallel assembly of triangular prisms (isosceles triangular prisms) on the lath substrate 35b side
A projecting body surface 23b in the form of a projecting body formed as a body₁Have
Lenticular structure, and its projecting surface 23b₁Above
ITO film 23b with a fixed pattern ₂Is formed.

In such a liquid crystal panel 24B, when light 27g having a shallow incident angle is incident, the glass substrate 35 is used.
The light 27h having a shallow incident angle that is totally reflected on the upper surface of b and is incident from the opposite side reflects the ITO film 35 of the glass substrate 35a.
Total reflection is performed on the opposite surface on which a ₁ is formed. This allows
The intensity of backscattering can be improved.

It should be noted that it is desirable to form the prism angle θ of the projecting surface 23b ₁ of the liquid crystal layer 23b in the case of the incident light 27g up to 35 degrees. Further, when this is applied to a display device, a light absorption layer (not shown) is arranged on the side opposite to the incident light 27g, 27h side.

Next, FIG. 8 is a block diagram showing the essential parts of the fourth embodiment of the present invention. FIG. 8 shows a liquid crystal panel 24C which is a display unit sandwiched between a plastic film substrate 38a and a glass substrate 38b.
On the incident side of b, a projecting surface 38a ₁ having a lenticular structure in the form of a projecting group formed as a parallel assembly of triangular prisms (isosceles triangular prisms) is formed.

Then, similarly to the above, the gap layer 31 is formed between the light absorbing layer 26 and the spacer 30.

Therefore, for example, the light 27i having a shallow incident angle is
When incident from the projecting surface 38a ₁ of the plastic film substrate 38a of the liquid crystal panel 24c, it is totally reflected at the interface of the gap layer 31 of the glass substrate 38b, which also improves the strength of backscattering. .

As described above, as shown in the first to fourth embodiments, the light whose optical path is changed by the scattering layer of the liquid crystal panel or the light which is incident at a shallow angle is supplied to either the lenticular plate or the lenticular structure. Total reflection can be performed by the liquid crystal panel at the interface, and the intensity of backscattering can be improved. Moreover, it is not necessary to increase the drive voltage of the liquid crystal panel, and it is possible to achieve low voltage consumption and cost reduction.

[0047]

As described above, according to the present invention, a refracting / reflecting means having a refracting surface and a reflecting surface is provided between the display section and the light absorbing layer, or any interface of members constituting the display section. By forming the projecting surface of the projecting group shape with, low power consumption,
The strength of backscattering can be improved at low cost.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of a first embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the reflectance and the prism angle in FIG. 2 (A).

FIG. 4 is a diagram for explaining a ghost occurrence.

FIG. 5 is a main part configuration diagram of a modified example of ghost suppression.

FIG. 6 is a configuration diagram of a main part of a second embodiment of the present invention.

FIG. 7 is a main part configuration diagram of a third embodiment of the present invention.

FIG. 8 is a configuration diagram of a main part of a fourth embodiment of the present invention.

FIG. 9 is a main part configuration diagram of a conventional display device.

[Explanation of symbols]

21 Display Device 22a, 34a Glass Substrate 22b, 34b Plastic Film Substrate 23 Liquid Crystal Layer 24, 24A to 24C Liquid Crystal Panel 25a Refractive Surface 25b Reflective Surface 25 Lenticular Plate 26 Light Absorbing Layer 31, 37 Gap Layer 32 Transmissive Area 33 Image (Ghost) 34b ₁ projecting surface 34b ₂ reflecting surface

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideaki Tsuda 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (7)

[Claims] 1. A display section (24) in which a predetermined liquid crystal layer (23) is sandwiched between two transparent substrates (22a, 22b), and a light absorption layer provided on the display section (24) at a predetermined distance. (2
And a display device that performs display by transmitting or scattering light in the display unit (24), between the display unit (24) and the light absorption layer (26),
A refracting surface (25a) for refracting light incident at a predetermined angle,
And light incident from the refracting surface (25a)
5a) is provided with a refracting / reflecting means (25) having a reflecting surface (25b) for reflecting the display device. 2. A layer having a refractive index smaller than that of the refracting / reflecting means (25) at the interface between the refracting / reflecting means (25) and the display section (24) and the light absorbing layer (26). 31)
The display device according to claim 1, wherein the display device is interposed. 3. The refracting / reflecting means (25) according to claim 1, wherein the refracting surface (25a) is formed in a projection group shape, a smooth surface shape, or a rough surface shape. Display device. 4. The refracting / reflecting means (25) is characterized in that the reflecting surface (25b) is formed in a smooth surface shape, a rough surface shape, or a projection group shape. Display device described. 5. The display device according to claim 3, wherein the refracting / reflecting means (25) is formed by laminating a predetermined number of the refracting surface (25a) and the reflecting surface (25b). 6. Two transparent substrates (34a, 34b, 35)
a, 35b, 38a, 38b) has a predetermined liquid crystal layer (23a
〜23c) is sandwiched between the display portions (24A-24C),
The display section (24A to 24C) is provided with a light absorption layer (26) provided at a predetermined distance, and the display section (24A to 24C).
In the display device that performs display by transmitting or scattering light, the two transparent substrates (34a, 34b, 35a, 35b, 38a, 3) that constitute the display unit (24A to 24C).
8b), at least one of the liquid crystal layer (23a to 23c) are protruding member surface (34b _1, 23b formed in the protruding member group shape
₁ , 38a ₁ ). 7. The projection surfaces (34b ₁ , 23b ₁ , 38) with respect to the light incident on the display portions (24A-24C).
7. The display device according to claim 6, wherein a ₁ ) is an entrance surface or an exit surface.