JPH04234730A - Display assembly - Google Patents

Abstract

PURPOSE: To reduce the thickness of a liquid crystal display as much as possible including its back light without deteriorating the entire strength of the display. CONSTITUTION: A display assembly consists of a back light 1 and a dichromatic liquid crystal display 2. The back light 1 consists of a matrix array including two glass plates 10 and 11 set parallel to each other and a trapezoidal pyramid- shaped support 12 and also the electrodes 13 and 14 which cause the discharge in a gas discharge space 5 to attain the coating of a fluorescent substance. The plate 10 of the display 2 is shared with the back light 1 out of both glass plates 10 and 25 which support two electrodes 21 and 26 respectively. In such a constitution, the thickness of the display assembly can be reduced together with reduction of its light radiation loss and increase of its structural strength.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a display assembly comprising a liquid crystal display having two glass plates separated by a liquid crystal material.
ly), each glass plate supports each electrode layer, and a flat fluorescent lamp is connected to a gas-discha space.
It is made up of two glass plates separated by a rge volume.

0002

[Background Art] This type of normal flat panel display
A nel display generally has a flat liquid crystal display behind which is placed a backlight, such as formed by a number of tubular fluorescent lamps, reflectors and diffusers. Recently, it has been proposed to use flat discharge lamps for backlighting. Examples of such lamps are WO 90/09676, Japanese Patent Application No. 58-4656.
8, European Patent Application No. 0283014, British Patent Application No. 2217905, WO 87/04562,
Patent Application No. 57-180067, Patent Application No. 59-12
No. 7357, British Patent No. 9115185 and British Patent No. 9105626. These flat lamps provide more uniform illumination than tubular lamps and have the advantage of being rugged and compact.

In many applications, the overall thickness of the display (
It is desirable to make the display (including its backlight) as small as possible without reducing the robustness of the display. However, the amount by which the thickness of the display can be reduced is limited by the thickness of the two glass plates forming the backlight and the two glass plates forming the display. Front panel of backlight (f
ront plate) and the back plate (back p
The gap between the
y) and multiple reflections that reduce the level of illumination. Even if the front side of the backlight is glued to the back side of the display, it does not completely avoid these problems since it is very difficult to completely remove all air bubbles between the two sides. A mismatch in the refractive index of the glass plate or adhesive material will also cause reflections at the interface. Adhesives also have a site for weakness.
) can be given. Furthermore, since the glass plates forming the display and the backlight must each be strong enough to prevent damage during assembly, the total thickness of the two plates when glued together is greater than necessary.

0004

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display assembly that can be used to avoid these disadvantages.

According to the invention, there is provided a display assembly of the type defined above, in which the liquid crystal display is formed integrally with the lamp and the lamp is arranged such that energization of the lamp causes illumination of the liquid crystal display. It is characterized in that one glass plate is provided with a liquid crystal display.

Fluorescent lamps are cold cathode lamps (cold cathode lamps).
It is preferable that the liquid crystal display is a dichroic display. This lamp has an array of pillars between the two plates of the lamp that support the plates. The glass plate may be soda glass. The assembly may include a filter layer of regions of distinct color transmission properties, the filter layer being supported by another plate of the display, and the regions of the filter layer being aligned with individual electrodes of one electrode layer. Another glass plate of the lamp may support the reflector on its external surface, and another glass plate may support the polarizer between the other plate and the reflector.

The assembly includes a second liquid crystal display having two glass plates separated by a liquid crystal material, each glass plate of the second liquid crystal display supporting a respective electrode layer, and the second liquid crystal display supporting a lamp. Another plate of the lamp may be integrally formed with the glass plate of the second liquid crystal display, such that activation of the lamp causes illumination of both liquid crystal displays.

The assembly may include a sensor responsive to inversion of the assembly to cause a change in the information provided by the display assembly.

A display assembly according to the invention will now be described by way of example with reference to the accompanying drawings.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, a display assembly includes a backlight formed by a flat plate, a cold cathode fluorescent lamp 1, and a dichroic liquid crystal display (LCD) 2 above the lamp.

[0011] The lamp 1 is of the type described in WO 90/09676, but it may also be another flat fluorescent lamp. The lamp 1 comprises two parallel flat plates 10 and 11 of soda-lime glass, each such that the flat tops of the corresponding pyramids on each plate touch each other and support the column against inward deformation. , completed by a matrix array of rows and columns of support columns in the form of frusto-pyramids 12 on opposite sides. Other forms of support between the two plates can also be used. The two plates are sealed around their peripheries and the volume 5 between them is filled with a gas discharge mixture at low pressure and a phosphor coating 6 is deposited on the inner surfaces of the two plates. There is.

The two electrodes 13 and 14 extend oppositely into the gas discharge space 5 inside the lamp so that when the electrodes are energized a discharge occurs and light is generated from the phosphor coating 6. ing. A polarizer 15 is glued to the outer surface of the lower plate 11, and the polarizer is an optical path difference film (retardation film).
n film). An aluminum layer is deposited on the underside of the polarizer 15 to act as a reflector 16. The reflective layer may be flat or may have a profile that enhances the characteristics of light transmitted through the pillars 12.

In addition to forming the upper front plate of the lamp 1, the plate 10 also comprises the lower rear plate of the LCD 2 and is thus the intermediate plate of the assembly. Activation of lamp 1 causes illumination of LCD 2.

A matrix array of thin film transistors or diode switches 20 is deposited directly on the upper surface of plate 10, which is provided with a layer of individual electrodes 21 on its upper surface. Multiple wires 22 extend through the rows and columns of switches 20 so that individual electrodes of electrodes 21 can be addressed in a conventional manner.

The upper surface of the electrode 21 is made of a polar organic material (po
lower aligning layer of lar organic substance
) 23, the purpose of which is to impart a twist to the molecules of the normal liquid crystal material 24 that are drawn into the narrow space between the middle plate 10 and the top plate 25 of the LCD 2. A thin translucent layer 26 of indium tin oxide providing the upper common electrode of the LCD 2 is deposited directly on the underside of the top plate 25. External electrical connections to electrode layer 26 are made by wires 27 . A filter layer 28 is screen printed on the lower surface of the electrode layer 26. The filter layer 28 is a transparent polyamide or similar material and comprises a matrix array of red, green and blue regions of the same size and aligned with the individual electrodes 21 of the transistors of the array on the plate 10. There is. In reality, the dimensions of filter area 28 and individual electrodes 21 will be much smaller than illustrated. Details of the manufacture of suitable filter layers can be found in Kama Mori.
mori) et al., “Multicolo graphic LCD with three color layers formed by electrodeposition”
r Graphic LCD with Tricol
or Layers Formed by Elect
SID 84 Digest, pp. 215, 216. Where a monochromatic display is desired, filter layer 28 may be omitted. On the underside of the filter layer 28 there is an upper alignment layer 17 that is identical to the lower alignment layer 23 .

After the introduction of the liquid crystal material 24, the top plate 25 is sealed around its periphery to the intermediate plate 10 by a glass seal 29.

On top of the upper plate 25 is a stretched polycarbonate material with strong birefringence.
nate ) optical path difference film 30 is present. This film 30 is optional and, where used, serves to provide a phase difference in the radiation passing through the film. Radiation incident on film 30 that is elliptically polarized will become more linearly polarized after passing through the film. A polarizer 31 is located on the optical path difference film 30.

The structure and operation of the LCD 2 are conventional, except that the lamp 1 is provided with an upper plate 10 in contrast to the lower plate of the LCD. Usually LCD
are made using aluminosilicate glass or aluminoborosilicate glass. This is because they have a very low alkaline content. It was thought that the alkali ions present in inexpensive soda-lime glass would induce instability in the material forming the thin film transistor layer and contaminate the liquid crystal material. However, it is currently believed that inexpensive soda-lime glass can be used in LCDs. Regarding this, please refer to Uchikoga (Uchikoga).
``SodaLime Glass as a Substrate for TFT-LCD'', et al.
a Substrate for TFT-LCD'
s)”, Japan Display 1989, p. 4
See 26-428. Another previously questioned problem with the suitability of soda-lime glass in LCDs is its large shrinkage during processes such as chemical vapor deposition (CVD). However, this problem occurs when the glass is
This can be avoided by pre-annealing to a degree C.

The assembly of the present invention has several advantages over previous ones where the LCD is a separate component from the backlight. First, by using only three glass plates instead of four, the assembly can be thinner and lighter than previous displays. This is particularly important for large area displays. This is because any increase in the weight of the display makes the assembly more susceptible to deformation, which has a negative effect on the performance of the LCD. Second, this structure requires two glass/air interfaces between the backlight and the LCD.
ace). This reduces radiation losses at the interface and avoids multiple reflections between surfaces. Third, the overall characteristics of the LCD and backlight are L
Provides a much more robust structure than previous assemblies where the CD was separated from the backlight. This makes the assembly of the invention less susceptible to damage by vibration and mechanical shock. Even if the LCD and backlight of the previous assembly were glued together, this results in the total thickness of the two glued glass plates being thicker than required by the present invention. Glued boundaries also provide points of mechanical weakness and radiation losses. Furthermore, the gluing process of the assembly adds numerous processing steps, thus increasing the cost of the assembly.

The fact that the LCD forms part of the backlight means that there is good heat transfer between the backlight and the LCD. This can be an advantage where the assembly is used in cold environments. I mean,
This is because it avoids the need to use a separate display heater. This is because the heat generated by the backlight is sufficient to keep the intermediate wall at about 45 degrees Celsius. Temperature fluctuations are also reduced, which would otherwise adversely affect the display.

[0021] Cold cathode fluorescent lamps of the type described above have a long life compared to heated electrode lamps. Therefore, the lamp life can be similar to the LCD life, which is 15
,000 to 20,000 hours.

The display assembly described above is of the dichroic type, even twisted nematec.
matic), supertwist display
display), ferroelectric display
ctric display), polymer dispersed TN display (polymer dispersed TN dis
This is true even though the use of various alternative liquid crystal displays, such as any of the following: These alternatives include the need for an additional polarizer to polarize the radiation from the backlight. This additional polarizer is for example backlight 1 and L
It can be located between the CD 2, for example between the common electrode 26 and the filter layer 28. Alternatively, the polarizer can be located on the underside of the backlight between the bottom plate 11 and the reflector 16. Thus, the polarizer polarizes the light reflected by the reflector 16, so that the light emitted from the intermediate plate 10 has a significant portion that is polarized. However, since the light has to pass through the polarizer in two directions, this reduces the overall level of radiation and the polarized portion.

The display assembly of the present invention can be used in many applications such as transportation equipment, large area flat television screens, and advertising equipment.

An alternative display assembly is shown in FIG. 2, which has a single backlight 1' identical to that of FIG. 1, except that it has a reflective layer on its bottom plate 11'. Not yet. Instead, the lower plate 11' forms one plate of the second LCD 2'' which is identical to the upper LCD 2'. In this way, the light from one backlight 1' is transmitted to the upper and lower displays. This type of double-sided display assembly can be used in a variety of applications. For example, as shown in Figure 3, it can be used in advertising displays 130, where it is mounted vertically. , and rotated about a vertical axis by motor 131. Displays on opposite sides of the assembly can be arranged for displaying the same or different messages.

Alternatively, the display assembly can be incorporated into a handheld display terminal 40, such as a calculator. Different information can be displayed on opposite sides 41 and 42 of the assembly. Terminal 40 may, for example, be a tilt switch upon inversion of the terminal causing a change in the displayed information.
It may also include a sensor 43 such as. In this way, the terminals can be arranged to simulate a book with different pages of information on each side that change each time the terminal is flipped. The sensor can also respond to flipping of the terminal in different orientations (right-to-left or left-to-right), so that the terminal produces either a subsequent page or a previous page of information to be displayed.

The display assembly has a touch sensitive membrane on top of the polarizer 31 for data entry or selection.
-sensitive membrane).

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one form of the present assembly.

FIG. 2 is a cross-sectional view of an alternative assembly.

FIG. 3 is a perspective view illustrating the form of the assembly.

FIG. 4 is a perspective view illustrating another form of the assembly.

[Explanation of symbols]

1 (Fluorescent) lamp or backlight 1' Single backlight 2 (Dichroic) Liquid crystal display (LCD) 2' Liquid crystal display (LCD) 2'' Second liquid crystal display (LCD) 5 Space 6 Phosphor coating 10 Flat plate or Upper plate or glass plate or intermediate plate 11 Flat plate or lower plate or glass plate 11'
Lower plate or glass plate 12 Trapezoidal pyramid or column 12' Pillar 13 Electrode 14 Electrode 15 Polarizer 16 Reflector 17 Upper alignment layer 20 Matrix array of thin film transistors or diode switches 21 Electrode 22 Multiple wires 23 Lower alignment layer 24 Liquid crystal material 24' Liquid crystal material 24'' Liquid crystal material 25 Top plate or glass plate 25' Glass plate 25'' Glass plate 26 Semi-transparent layer or (common) electrode 27 Wire 28 Filter layer or filter area 29 Glass seal 30 Optical path difference film 31 Polarizer 31' Polarized light Polarizer 40 Handheld display terminal 41 Side surface 42 Side surface 43 Sensor 130 Advertising display 131 Motor

Claims (10)

[Claims] 1. A display assembly comprising a liquid crystal display having two glass plates separated by a liquid crystal material, each glass plate supporting a respective electrode layer, and a flat fluorescent lamp separated by a gas discharge space. In a display assembly formed by two separated glass plates, the liquid crystal display is formed integrally with the lamp, and the lamp (1) is arranged such that energization of the lamp (1) causes illumination of the liquid crystal display (2). 1) One glass plate (
Display assembly characterized in that 10) comprises one glass plate of a liquid crystal display (2). 2. Display assembly according to claim 1, characterized in that the fluorescent lamp (1) is a cold cathode lamp. 3. The display assembly according to claim 1, wherein the liquid crystal display (2) is a dichroic display. [Claim 4] Two plates (10
, 11) between which the lamp (2) has an array of columns (12). 5. Display assembly according to claim 1, characterized in that the glass plates (10, 11) are soda glass plates. 6. The assembly comprises a filter layer (28) of areas of distinct color transmission properties, the filter layer (28) having a display (
2), and the area of the filter layer (28) is aligned with the individual electrodes of one electrode layer (21, 26). A display assembly according to any one of the above. [Claim 7] Another glass plate (11) of the lamp (1)
Display assembly according to any one of claims 1 to 6, characterized in that the reflector (16) supports a reflector (16) on its external surface. Claim 8: Another glass plate (11) is another glass plate (11).
Display assembly according to claim 7, characterized in that it supports a polarizer (15) between the reflector (16) and the reflector (16). 9. The assembly comprises a second liquid crystal display (2'') having two glass plates (11', 25'') separated by a liquid crystal material (24''), each of the second liquid crystal display Another plate (11') of the lamp is arranged such that a glass plate supports each electrode layer and a second liquid crystal display is formed integrally with the lamp, and energization of the lamp causes illumination of both liquid crystal displays. Display assembly according to any one of claims 1 to 6, characterized in that it comprises one glass plate of the second liquid crystal display (2''). 10. Any one of claims 1 to 9, characterized in that the assembly includes a sensor (43) responsive to inversion of the assembly to cause a change in the information provided by the display assembly. Display assembly as described in .