JP4329424B2 - Manufacturing method of liquid crystal display device, lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display device, for example, a method for manufacturing a liquid crystal display device in which a reflective display and a transmissive display are used in combination.
[0002]
[Prior art]
A liquid crystal display device is used as a display device for a wide range of electronic devices by taking advantage of its thinness and low power consumption. For example, there are electronic devices using liquid crystal display devices such as a notebook personal computer, a display device for car navigation, a personal digital assistant (PDA), a mobile phone, a digital camera, and a video camera.
[0003]
Such a liquid crystal display device is roughly divided into a transmissive liquid crystal display device that performs display by controlling transmission and blocking of light from an internal light source called a backlight with a liquid crystal panel, and external light such as sunlight. There is a reflection type in which display is performed by reflecting the light with a reflecting plate or the like, and controlling transmission and blocking of the reflected light with a liquid crystal panel.
[0004]
By the way, in recent years, as a liquid crystal display device that can solve both the transmissive type and the reflective type display device and can be displayed both indoors and outdoors, both the transmissive display and the reflective display are provided as a single liquid crystal panel. A liquid crystal display device of a reflection / transmission combined type realized by the above has been proposed (see Patent Document 1). In this combined type liquid crystal display device, display is performed by reflection of ambient light when the surroundings are bright, and display is performed by backlight light when the surroundings are dark.
[0005]
On the other hand, in transmission type, reflection type, and combination type liquid crystal display devices, studies are being made to provide photo spacers instead of spacer dispersion methods as a measure against uniformity due to cell gap variations.
[0006]
[Patent Document 1]
Japanese Patent No. 2955277 gazette [0007]
[Problems to be solved by the invention]
However, the alignment process in the manufacturing process of the combined type liquid crystal display device is still carried out by a rubbing method in which the drum around which the cloth is wound is rotated and the substrate surface is mechanically rubbed. Due to the difference in level between the two, the fibers could not enter the recess and the orientation was deteriorated.
[0008]
In particular, in a combination type liquid crystal display device, since the variation in the cell gap becomes noticeable, a method of providing a photo spacer instead of the spacer spraying method is being studied in order to improve the gap accuracy.
[0009]
However, when a photospacer is used, the conventional rubbing method is likely to cause the photospacer to fall, and the alignment region is disturbed in a minute region around the photospacer, causing defects due to microdomains in the display element. The display quality was degraded.
[0010]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a liquid crystal display device capable of improving the orientation of liquid crystals in the reflective region and the transmissive region and improving the display quality. It is in.
Another object of the present invention is to improve the alignment of the liquid crystal without affecting the spacer even when the spacer is processed on the substrate, thereby improving the uniformity of the substrate interval and the display quality. Another object of the present invention is to provide a method for manufacturing a liquid crystal display device.
[0011]
[Means for Solving the Problems]
In the method for manufacturing a liquid crystal display device of the present invention, a liquid crystal layer in which liquid crystal molecules are aligned by an alignment film subjected to an alignment treatment is sandwiched between a pair of substrates , and a reflective region and a transmissive region are arranged in parallel in a pixel. A step of manufacturing the liquid crystal display device disposed on the substrate, and the step of manufacturing the liquid crystal display device includes the step of forming the alignment film on at least one of the pair of substrates with an ultraviolet reactive resin ; bonding a step of performing an alignment treatment for the alignment film by irradiating ultraviolet light to the alignment film, after the implementation of the alignment process, the step of bonding the pair of substrates with a predetermined distance between the substrates, said pair of substrates after combined, liquid crystal is injected between the pair of substrates, and forming the liquid crystal layer by aligning liquid crystal molecules by the alignment control force of the alignment-treated alignment film Yes The step of performing the alignment treatment includes a step of emitting ultraviolet light from a light source so as to include an S-polarized component and a P-polarized component, and the ultraviolet light emitted from the light source as a reflected light composed of an S-polarized component. A step of reflecting by the star mirror, a first irradiation region for irradiating the alignment film with the reflected light reflected by the Brewster mirror, and ultraviolet light emitted from the light source without being reflected by the Brewster mirror. Reflecting the reflected light reflected by the Brewster mirror and a part of the ultraviolet light emitted from the light source without being reflected by the Brewster mirror so as to define a second irradiation region for irradiating the alignment film The alignment film is formed in a direction in which the first irradiation region and the second irradiation region are aligned. The alignment substrate is irradiated with reflected light reflected by the Brewster mirror by the transported substrate, and is emitted from the light source without being reflected by the Brewster mirror. The alignment treatment is performed by irradiating the alignment film with ultraviolet light in the second irradiation region .
[0012]
The illumination device of the present invention irradiates ultraviolet light emitted from a light source onto an alignment film of an ultraviolet-reactive resin formed on a substrate from an optical system, thereby controlling the control force in the alignment direction of the liquid crystal and the pretilt of the liquid crystal. An illumination unit that performs an alignment process so as to give a control force to a corner to the alignment film, and the light source emits the ultraviolet light so as to include an S-polarized component and a P-polarized component, The optical system includes: a Brewster mirror that reflects ultraviolet light emitted from the light source as reflected light composed of an S-polarized component; reflected light that is reflected by the Brewster mirror; and the light that is not reflected by the Brewster mirror. A first irradiation region that irradiates the alignment film with the reflected light reflected by the Brewster mirror by shielding a part of the ultraviolet light emitted from the light source, and And a shielding plate for defining a second irradiation region that irradiates the alignment film with ultraviolet light emitted from the light source without being reflected by the Brewster mirror, and the first irradiation region and the second irradiation region. By transporting the substrate in a direction aligned with the irradiation region, the reflected light reflected by the Brewster mirror is irradiated on the alignment film in the first irradiation region and is not reflected by the Brewster mirror. The alignment process is performed by irradiating the alignment film with ultraviolet light emitted from the light source in the second irradiation region.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a method for manufacturing a liquid crystal display device of the present invention will be described below with reference to the drawings.
[0016]
In this embodiment, in the manufacture of a liquid crystal display device using a combination type liquid crystal display device having a transmissive region and a reflective region in a pixel or a photospacer, the alignment treatment for the alignment film that regulates the alignment of the liquid crystal is performed with ultraviolet light. Is performed. Before proceeding to the description of the manufacturing process of the liquid crystal display device, first, an example of the method and apparatus for photo-alignment treatment used in the present embodiment will be described in detail.
[0017]
FIG. 1A is a schematic configuration diagram of an example of an irradiation unit that realizes a photo-alignment process applied to the manufacture of the liquid crystal display device according to this embodiment, and FIG. 1B is a diagram illustrating FIG. It is the block diagram seen from the side. FIG. 2 is a diagram for explaining the light emission principle and process of the light source of the irradiation unit.
[0018]
The irradiation unit 1 shown in FIG. 1 roughly includes a light source 2 and an optical system 3.
The light source 2 includes, for example, a magnetron 4 that generates microwaves, a cylindrical bulb 5 that is filled with a light-emitting component such as mercury that is excited by microwaves, and a half that surrounds the bulb 5 on the side opposite to the light emission side. And a cylindrical reflecting mirror 6. As shown in FIG. 2, an igniter 7 is installed.
[0019]
The bulb 5 is filled with mercury and other light-emitting components, and the light-emitting components are adjusted so as to emit light in a wavelength band that matches the absorption characteristics of the material of the alignment film, as will be described later.
[0020]
The magnetron 4 generates a microwave that excites a light emitting component such as mercury filled in the bulb 5. The frequency of the microwave generated by the magnetron 4 is, for example, 2.45 MHz.
[0021]
The reflecting mirror 6 reflects the light emitted from the bulb 5 to make the irradiated light uniform and parallel. The igniter 7 is installed for start-up, and accelerates the rise of ultraviolet light by irradiating the light emitting component in the bulb 5 with photons.
[0022]
As shown in FIG. 2, as a light emission process of the light source 2, first, for example, a microwave of 2.45 MHz is generated from the magnetron 4, and photons are irradiated from the igniter 7. The generated microwave MW reaches the reflecting mirror 6 and is absorbed by a light-emitting component such as mercury filled in the bulb 5, and the light-emitting component such as mercury is excited to emit ultraviolet light. At this time, the photons irradiated from the igniter 7 are also absorbed by the light emitting component and promote the rising of the ultraviolet light, whereby uniform ultraviolet light is emitted.
[0023]
The light source is an electrodeless discharge lamp that does not use electrodes. The irradiation unit 1 provided with this light source has a high power of, for example, about 6 kW, and has an advantage that it has a very long life of 3000 hours or more because no electrode is used. Furthermore, the intensity of light emitted until the end of its life is not attenuated, and the irradiation uniformity is good. Further, as will be described later, the size can be increased by connection.
[0024]
FIG. 3 is a schematic configuration diagram of the optical system 3 of the irradiation unit 1.
As shown in FIG. 3, the optical system 3 cuts the aperture 12 for shaping light (polarized light) emitted from the bulb 5 and reflected by the reflecting mirror 6 into a predetermined beam shape, and light in a wavelength region of 270 nm or less. It has a cut filter 13, a Brewster mirror 14 that reflects only the S-polarized light of the ultraviolet light L, and shielding plates 15 and 16 that shield the light and define the irradiation area.
[0025]
The cut filter 13 blocks light in the wavelength region of 270 nm or less as described above. This is because organic polymer compounds such as UV-reactive polyimide, which will be described later, used for UV alignment treatment cause reactions other than those necessary to give alignment control power when irradiated with light in the short wavelength region. This is because by-products are increased and reliability and optical characteristics may be affected. If the optical characteristics are affected, the transmittance and chromaticity of the display panel will be affected.
[0026]
The Brewster mirror 14 is installed so as to be inclined by the Brewster angle (polarization angle) with respect to the incident light from the light source 2, reflects the incident light L from the light source 2, and emits reflected light composed of S-polarized light.
[0027]
The shielding plate 15 defines a second irradiation area LA2 of the incident light L from the light source 2 that is irradiated toward the substrate 10 without being reflected by the Brewster mirror 14. The ultraviolet light in the second irradiation region LA2 is the same as the light from the light source 2, that is, light having an S-polarized component and a P-polarized component.
[0028]
The shielding plate 16 defines a first irradiation area LA1 to which the S-polarized light reflected by the Brewster mirror 14 is irradiated, and the second irradiation is irradiated toward the substrate 10 without being reflected by the Brewster mirror 14. Region LA2 is defined.
[0029]
On the substrate 10 on which the ultraviolet alignment process is performed by the irradiation unit 1, an ultraviolet reaction type alignment film 11 described later is applied. The substrate 10 coated with the alignment film 11 is mounted on a stage 8 that moves at a predetermined speed in the direction of the arrow in the figure, and passes through the first irradiation area LA1 and the second irradiation area LA2 formed by the irradiation unit 1. It will be. The surface of the stage 8 is preferably subjected to antireflection processing.
[0030]
When the substrate 10 coated with the alignment film 11 is exposed to the first irradiation region LA1 made of only the S-polarized component, for example, the alignment control force is such that the alignment direction of the liquid crystal is perpendicular to the polarization direction. 11 is given.
[0031]
Next, the substrate 10 coated with the alignment film 11 is exposed to the second irradiation region LA2 having the S-polarized component and the P-polarized component, whereby liquid crystal molecules along the incident direction of the light to the alignment film 11 are obtained. The pretilt angle is given to the alignment film 11.
[0032]
As described above, in the above-described photo-alignment processing, the substrate is transported in a certain direction without rotating the substrate or the like, and the liquid crystal is simply passed through the first irradiation area LA1 and the second irradiation area LA2. The orientation can be controlled including the sequence of and the expression of the pretilt angle.
[0033]
The irradiation unit applied to the manufacture of the liquid crystal display device according to the present embodiment can be applied without limitation from a small liquid crystal panel to a large liquid crystal panel. 4 and 5 are diagrams for explaining these.
[0034]
FIG. 4A shows a state in which a photo-alignment process is performed on the substrate 10 having a size that falls within the irradiation area LA of one irradiation unit 1 having the light source 2 and the optical system 3. In this case, it is possible to perform photo-alignment processing on the entire region of the substrate 10 by one irradiation unit 1.
[0035]
FIG. 4B shows a state in which the medium-sized to large-sized substrate 10 that exceeds the irradiation area LA of one irradiation unit 1 is irradiated. In this case, a plurality of irradiation units 1 are connected in multiples. Specifically, the irradiation units 1 are arranged so as to correspond to the length of one side of the substrate 10. As a result, the stage on which the large substrate 10 is mounted is moved at a predetermined speed (in the direction of the arrow in FIG. 4), and the large substrate 10 is scanned, so that the optical alignment process can be performed on the entire region of the large substrate 10. it can.
[0036]
Further, in the irradiation unit applied to the manufacture of the liquid crystal display device according to the present embodiment, it is possible to improve the process throughput. FIG. 5A and FIG. 5B are diagrams for explaining these.
[0037]
As shown in FIG. 5A, a state is assumed in which five irradiation units 1 are connected along one side of the substrate 10 such that one side of the substrate 10 enters the irradiation region LA. In this case, it is necessary to move the substrate 10 at a predetermined speed U1 in the direction of the arrow in the drawing according to the energy (integrated light amount) necessary for sufficiently reacting the alignment film.
[0038]
On the other hand, as shown in FIG. 5 (b), by arranging three connected irradiation units 1 in three stages in the traveling direction of the substrate 10, the substrate 10 is irradiated three times. The feed speed U2 of 10 can be made three times the speed U1, and the throughput of the photo-alignment process on the substrate 10 can be improved. FIG. 5B shows an example of three stages, but any number of stages can be arranged.
[0039]
An example of the structure of the alignment film subjected to the photoalignment treatment by the irradiation unit 1 is shown in FIG. 6A, and the UV absorption spectrum of the alignment film shown in FIG. 6A is shown in FIG.
[0040]
The alignment film shown in FIG. 6A is an ultraviolet reaction (decomposition) type polyimide, and is a semi-aromatic polyimide including an alicyclic part and an aromatic part. As shown in FIG. 6B, it can be seen that this ultraviolet-reactive polyimide has a high light absorbance in a wavelength region of 300 nm or less. That is, in order to sufficiently react this alignment film, it is advantageous to use a light source having high light intensity in a wavelength region of 300 nm or less.
[0041]
FIG. 7 is a spectral distribution of light irradiated by the electrodeless discharge type irradiation unit applied in the manufacture of the liquid crystal display device according to the present embodiment. FIG. 7 shows a spectral distribution SP2 (indicated by a broken line in the figure) of a mercury lamp as a comparative example, in addition to the light spectral distribution SP1 (indicated by a solid line in the figure) used in the present embodiment.
[0042]
As shown in FIG. 7, in the light used for the photo-alignment process in the manufacture of the liquid crystal display device according to the present embodiment, 250 to 260 nm, 260 to 270 nm, 280 to 290 nm, 290 to 300 nm, 300 to 305 nm, and 310 to 315 nm. , Has a characteristic peak at 360 to 370 nm. The total emission power in the wavelength region of 250 nm or more and 300 nm or less (the integrated value of the spectrum in FIG. 7) was 1.6 relative to the total emission power in the wavelength region of 300 nm or more and 350 nm or less.
[0043]
On the other hand, in the mercury lamp of the comparative example, the total emission output in the wavelength region of 250 nm to 300 nm was 0.6 relative to the total emission output in the wavelength region of 300 nm to 350 nm. That is, in the light for photo-alignment used in the present embodiment, the total emission output in the wavelength region of 250 nm to 300 nm exceeds the total emission output in the wavelength region of 300 nm to 350 nm.
[0044]
That is, as in the present embodiment, if the total emission output in the wavelength region of 250 nm to 300 nm exceeds the total emission output in the wavelength region of 300 nm to 350 nm, the reaction of the alignment film such as the ultraviolet-reactive polyimide or the like. The energy in the wavelength region that contributes to increases, and the overall irradiation energy can be reduced. Since the irradiation energy depends on time, reducing the irradiation energy leads to an improvement in throughput.
[0045]
The manufacturing method of the liquid crystal display device according to the present embodiment using the above-described photo-alignment treatment can be applied to a combined type liquid crystal display device having a transmission region and a reflection region in a pixel. In addition, any liquid crystal display device that employs a photo spacer can be applied to the production of a reflective or transmissive liquid crystal display device, or a combined (semi-transmissive) liquid crystal display device having both a reflective type and a transmissive type. It is.
[0046]
FIG. 8 is a schematic configuration diagram of a combined liquid crystal display device by a spacer spraying method manufactured by the method of manufacturing a liquid crystal display device according to the present embodiment.
The liquid crystal display device shown in FIG. 8 has a reflective area Ar1 for displaying with ambient light taken from outside and a transmissive area Ar2 for displaying with light from an internal light source.
[0047]
As shown in FIG. 8, a gate electrode 42 to be a scanning signal line is formed on a transparent insulating substrate 41 made of glass or the like, and a semiconductor layer 43 made of low-temperature polysilicon is formed through a gate insulating film covering the gate electrode 42. Is formed. An interlayer insulating film 44 made of silicon oxide or the like is formed so as to cover the semiconductor layer 43, and source / drain electrodes 45 that are buried in the interlayer insulating film 44 and connected to the semiconductor layer 43 are formed. As described above, the bottom gate type thin film transistor (TFT) Tr having the gate electrode 45 below the semiconductor layer 43 is formed on the transparent insulating substrate 41.
[0048]
In the reflective region Ar1, a scattering layer 46 and a planarizing layer 47 having an uneven shape are sequentially formed so as to cover the thin film transistor Tr. In the transmissive region Ar2, the layer constituting the thin film transistor on the transparent insulating substrate 41, the scattering layer 46, and the planarizing layer 47 are removed, and a large step is formed between the reflective region Ar1.
[0049]
A transparent electrode 48 made of ITO or the like is formed on the planarizing layer 47 in the reflective region Ar1 and on the transparent insulating substrate 41 in the transmissive region Ar2. The transparent electrode 48 is connected to one source / drain electrode 45 of the thin film transistor Tr through a contact hole formed in the scattering layer 46 and the planarization layer 47.
[0050]
On the transparent electrode 48 in the reflective region Ar1, a reflective electrode 49 having a surface shape reflecting the uneven shape of the scattering layer 46 is formed. The reflective electrode 49 is made of a highly reflective material such as silver. By forming irregularities on the surface of the reflective electrode 49, it is configured to diffuse and reflect external light. As a result, the directivity of the reflected light can be relaxed and the screen can be observed in a wide angle range. In the transmission region Ar2, the reflective electrode 49 is removed, and the transparent electrode 48 is observed.
[0051]
Liquid crystal is filled and the liquid crystal layer 20 is held between the first substrate 10A on which the thin film transistor Tr, the transparent electrode 48, and the reflective electrode 49 are formed and the second substrate 10B on which the color filter is formed. . The first substrate 10A is a so-called TFT substrate, and the second substrate 10B is a color filter substrate.
[0052]
A spherical spacer 21 is interposed between the substrates 10A and 10B in order to control the cell gap (substrate interval) to be constant. The cell gap is an important factor that determines retardation, which is an optical numerical value of the liquid crystal, and affects the display characteristics such as light transmittance, contrast ratio, response speed, and the like, and the role of the spacer 21 is important. The spacer 21 is made of, for example, silica or polystyrene.
[0053]
Although not shown, the second substrate 10B is formed on a transparent insulating substrate made of glass or the like, a color filter that is a resin layer colored in each color formed on the transparent insulating substrate, and a color filter. And a counter electrode made of a transparent electrode such as ITO. If necessary, the material of the resin layer constituting the color filter may be changed between the reflective region Ar1 and the transmissive region Ar2.
[0054]
Between the first substrate 10A and the liquid crystal layer 20 and between the second substrate 10B and the liquid crystal layer 20, an alignment film 11 that regulates the alignment and pretilt angle of the liquid crystal is interposed. The first substrate 10A and the second substrate 10B on which the alignment film 11 is formed correspond to the substrate 10 that has been subjected to the photo-alignment process described with reference to FIGS.
[0055]
In the combined liquid crystal display device, quarter-wave plates 34 and 35 are provided outside the pair of substrates 10A and 10B sandwiching the liquid crystal layer 20, and polarizing plates 31 and 32 are provided further outside. . A backlight 33 is provided outside the polarizing plate 31 on the first substrate 10 </ b> A side where the TFT is formed.
[0056]
Next, a manufacturing method of the liquid crystal display device having the above configuration will be described.
First, as shown in FIG. 9A, the first substrate 10A on which the thin film transistor Tr, the transparent electrode 48, the reflective electrode 49, and the second substrate 10B on which the color filter is formed are illustrated in FIG. An alignment film 11 made of an ultraviolet reaction type polyimide shown in FIG.
[0057]
Next, as shown in FIG. 9B, the first substrate 10A and the second substrate 10B are each irradiated with polarized ultraviolet rays at a predetermined incident angle from the normal direction. The emission spectrum distribution of the emitted light used in this photo-alignment process is as shown in the spectrum SP1 in FIG. In addition, it is preferable to shield and irradiate an emission spectrum of 270 nm or less with a cut filter.
[0058]
Next, as shown in FIG. 9 (c), a spacer having a dimension that can provide a predetermined cell gap without performing substrate cleaning is provided on at least one of the two substrates 10A and 10B subjected to the photo-alignment treatment. Scatter. As a method of applying the spacer, a spacer is mainly dispersed in a low boiling point organic solvent such as alcohol by ultrasonic waves, and the spacer dispersion is sprayed and then dried to fly the organic solvent, and by air current. There are dry methods for dispersion, but any of them can be adopted.
[0059]
Next, as shown in FIG. 9D, after the substrates 10A and 10B are bonded together with a cell gap determined by the size of the spacer 21, the alignment film 11 subjected to photo-alignment processing is sealed by enclosing liquid crystal. As a result, the liquid crystal molecules are aligned. In the subsequent steps, the liquid crystal display device shown in FIG. 8 is manufactured by bonding the quarter-wave plates 34 and 35 and the polarizing plates 31 and 32 together.
The manufacturing process after the photo-alignment process is the same as the conventional manufacturing method of the liquid crystal panel.
[0060]
FIG. 10 is a schematic configuration diagram of a combined liquid crystal display device that employs a photo spacer manufactured by the method of manufacturing a liquid crystal display device according to the present embodiment.
[0061]
As shown in FIG. 10, unlike the spacer 21 provided by the spacer spraying method shown in FIG. 8, the photo spacer 22 has a columnar structure. The photo spacer 22 is interposed between the substrates 10A and 10B in order to control the cell gap (substrate interval) to be constant. The photo spacer 22 is made of, for example, an acrylic resin, but is not limited to a material.
[0062]
In the spacer spraying method described with reference to FIGS. 8 and 9, the spacers 21 may not be uniformly sprayed on the substrate, which may cause the cell gap to be non-uniform. On the other hand, in the photospacer 22, since the photospacer 22 can be arranged at a desired position by patterning using a lithography technique as will be described later, the uniformity of the cell gap is improved.
[0063]
Next, a manufacturing method of the liquid crystal display device having the above configuration will be described.
First, as shown in FIG. 11A, for example, an acrylic resin is applied to the first substrate 10A on which the thin film transistor Tr, the transparent electrode 48, and the reflective electrode 49 of FIG. 10 are formed, thereby forming a photospacer layer 22a. To do.
[0064]
Next, by applying a resist on the photospacer layer 22a, patterning the resist by lithography, and etching the photospacer layer 22a using the resist as a mask, as shown in FIG. Photo spacers 22 arranged for each pixel are formed. Thereafter, the resist is removed.
[0065]
Next, as shown in FIG. 11C, the alignment film 11 made of, for example, an ultraviolet-reactive polyimide shown in FIG. 6 is applied to the first substrate 10A on which the photospacers 22 are formed. Subsequently, the first substrate 10A is irradiated with polarized ultraviolet rays at a predetermined incident angle from the normal direction. The emission spectrum distribution of the emitted light used in this photo-alignment process is as shown in the spectrum SP1 in FIG. In addition, it is preferable to shield and irradiate an emission spectrum of 270 nm or less with a cut filter.
Similarly, an ultraviolet-reactive alignment film is applied to the second substrate 10B on which the color filter is formed, and a photo-alignment process is performed by irradiating polarized ultraviolet rays.
[0066]
Next, as shown in FIG. 11D, after the substrates 10A and 10B are bonded together with a cell gap determined by the size of the photo spacer 22, the liquid crystal is sealed, whereby the liquid crystal molecules are aligned by the alignment film 11. Will be. As the subsequent steps, the liquid crystal display device shown in FIG. 10 is manufactured by bonding the quarter-wave plates 34 and 35 and the polarizing plates 31 and 32 that have been subjected to the photo-alignment treatment.
The manufacturing process after the photo-alignment process is the same as the conventional manufacturing method of the liquid crystal panel.
[0067]
Below, the effect in the case of manufacturing a combined low-temperature polysilicon liquid crystal panel with a spacer dispersion method or a photospacer using manufacturing conditions as an example will be described with reference to a comparative example.
[0068]
Example 1
In manufacturing a combined low-temperature polysilicon LCD having a structure shown in FIG. 8 and having a diagonal of 9.7 cm and 150,000 pixels, a 350 × 320 mm first substrate 10A and a 350 × 320 mm second substrate 10B After applying the alignment film 11 made of the ultraviolet-reactive polyimide shown in FIG. 6, it was temporarily dried at 80 ° C. for 30 minutes and then baked at 220 ° C. for 60 minutes. Subsequently, by the method shown in FIG. 1 to FIG. 3, 0.8 J / cm ² (first irradiation region LA1 and second irradiation) on the first substrate 10A and the second substrate 10B at an incident angle of 45 ° from the normal direction. Of the irradiation region LA2 including the irradiation flow region LA2). Although the orientation direction of each substrate is shown in FIG. 12, the incident angle is not limited to this.
[0069]
In the photo-alignment treatment, as shown in FIG. 4B, three electrodeless irradiation units 1 are connected and used. The emission spectrum distribution of the emitted light at this time is as shown in the spectrum SP1 of FIG. The cut filter was used to shield and emit an emission spectrum of 270 nm or less. The energy of polarized ultraviolet rays irradiated to the alignment film coated substrate was 0.8 J / cm ² and the degree of polarization was about 3: 1. As a result of the measurement, the intensity of ultraviolet rays applied to the substrates 10A and 10B was 95 ± 10 mW / cm ² .
[0070]
Both substrates subjected to the photo-alignment treatment were manufactured by spraying spacers 21 so as to have a cell gap of 2.5 μm without performing substrate cleaning, encapsulating liquid crystal, and performing heat treatment.
The manufacturing process after the photo-alignment process is the same as the conventional manufacturing method of the liquid crystal panel.
[0071]
FIG. 13 shows the results of the alignment and contrast evaluation of the liquid crystal panels produced by the above-described examples and the comparative examples that follow the examples.
As shown in FIG. 13, it was confirmed that the liquid crystal panel produced according to Example 1 had good display quality without any alignment defects. Also, in the electro-optical characteristics, as shown in FIG. 13, the contrast ratio was good with the transmissive part 87 and the reflective part 21.
[0072]
(Example 2)
In manufacturing a combined low-temperature polysilicon LCD having the structure shown in FIG. 10 and having a photo spacer with a diagonal of 9.7 cm and 150,000 pixels, the first substrate 10A and the second substrate 10B are compared with the first embodiment. A liquid crystal panel was manufactured by performing photo-alignment treatment with the same alignment film 11 and polarized ultraviolet rays. However, the cell gap was 2.0 μm, and the orientation direction was as shown in FIG. The orientation orientation is not limited to this.
[0073]
As shown in FIG. 13, the alignment performance of the liquid crystal panel produced in this way was excellent in display performance without any defects such as microdomains, similar to the result shown in Example 1. Further, as a result of measuring the electro-optical characteristics, as shown in FIG. 13, good values were obtained for the contrast ratio of the transmissive portion 92 and the reflective portion 17.
[0074]
(Comparative Example 1)
Using the same substrate as in Example 1, the alignment film was subjected to alignment treatment by conventional mechanical rubbing to produce a liquid crystal panel. As shown in FIG. 13, the combined type liquid crystal panel produced in this way had a reduced degree of alignment order and a contrast ratio that caused a decrease in contrast with the transmissive portion 62 and the reflective portion 15. In addition, in the transmission region Ar2 corresponding to the concave portion of the pixel, fibers could not reach during rubbing, and microdomains were observed.
[0075]
(Comparative Example 2)
A photo spacer was applied to each pixel on the substrate shown in Example 2, and the alignment film was subjected to alignment treatment by a conventional rubbing method in the same manner as in Comparative Example 1 to produce a liquid crystal panel. Evaluation of the combined type liquid crystal panel produced in this manner revealed that display quality was significantly deteriorated due to partial gap unevenness due to spacer collapse and alignment failure around the photo spacer. Also, the electro-optic characteristics reflected the deterioration of the orientation, and as shown in FIG. 13, the contrast ratio showed a decrease in characteristics with the transmissive part 45 and the reflective part 12.
[0076]
As described above, according to the present embodiment, it is possible to perform a highly accurate alignment process for a fine region associated with the production of a fine high-definition liquid crystal panel, which is difficult to cope with a mechanical rubbing rubbing process. One of them is an alignment process in a combined liquid crystal display device as shown in FIG. In the combined type liquid crystal display device shown in FIG. 8, the reflective region Ar1 and the transmissive region Ar2 have irregularities on the substrate, and in the rubbing process, the alignment film 11 applied to the transmissive region Ar2 that becomes the concave portion is mechanically applied. It becomes difficult to rub. On the other hand, by realizing the photo-alignment process, it is possible to perform the alignment process by irradiating such fine recesses with ultraviolet rays. As a result, the alignment control power of the liquid crystal can be improved, and the display performance of the liquid crystal panel can be improved.
[0077]
Further, in the manufacture of a liquid crystal display device employing a photospacer, the rubbing method has a non-uniform cell gap due to the fall of the photospacer already formed, and the alignment due to the fact that the alignment film in the vicinity of the photospacer cannot be rubbed. A decrease occurs. On the other hand, by adopting a method of performing alignment by irradiating ultraviolet rays, it is possible to realize a high degree of cell gap uniformity and high alignment without problems such as collapse of the photo spacer and alignment failure. As a result, display quality can be improved.
[0078]
Further, in the photo-alignment treatment for the ultraviolet-reactive alignment film, light in a wavelength band that causes the alignment film to undergo a reaction that is absorbed by the alignment film and required to give alignment control power is irradiated. As an example, ultraviolet light having a total emission output in a wavelength region of 250 nm to 300 nm exceeding a total emission output in a wavelength region of 300 nm to 350 nm is used. Thereby, the energy in the wavelength region contributing to the reaction of the alignment film is increased, and the overall irradiation energy can be reduced. Since the irradiation energy depends on time, reducing the irradiation energy leads to an improvement in throughput.
[0079]
Organic polymer compounds such as UV-reactive polyimides may be damaged when irradiated with light in the short wavelength region, which may affect the optical characteristics, but block light in the wavelength region of 270 nm or less. By irradiating the alignment film, this can be prevented, and the transmittance and chromaticity as a display panel are not affected.
[0080]
The first irradiation area LA1 is composed of S-polarized light and includes a first irradiation region LA1 that gives the alignment film a control force in the alignment direction of the liquid crystal, and a first irradiation region LA that includes the S-polarization and P-polarized light. The alignment including the alignment of the liquid crystal and the pretilt angle expression level can be controlled only by passing the substrate 10 on which the alignment film 11 is formed through the irradiation region LA having two irradiation regions LA2. Therefore, the throughput of the photo-alignment process can be improved.
[0081]
Further, since the photo-alignment process without the rubbing process can be realized, the problem in the rubbing process is solved. For example, management such as cloth attachment in the rubbing method and replacement due to cloth damage is unnecessary. In addition, a cleaning process for removing fiber dust attached to the substrate surface after the rubbing process is not required. Furthermore, it is possible to prevent defects such as scratches on the alignment film surface caused by the rubbing method, film peeling, and electrostatic breakdown of the TFT element.
[0082]
The present invention is not limited to the description of the above embodiment.
In addition, the chemical structure of the ultraviolet-reactive polyimide described in this embodiment is an example, and if it has a high absorbance in the wavelength band of 350 nm or less, an ultraviolet-reactive resin having another chemical structure should be adopted as the alignment film. Is also possible.
Furthermore, as an example of an irradiation unit for irradiating light having a total emission output of 250 nm or more and 300 nm or less larger than a total emission output of 300 nm or more and 350 nm or less as the light used for the photo-alignment treatment, If it can irradiate, various changes are possible.
In addition, various modifications can be made without departing from the scope of the present invention.
[0083]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display device which improved the orientation of the liquid crystal in a reflective area | region and a transmissive area | region, and improved display quality can be manufactured.
In addition, even when manufacturing spacers on a substrate, the alignment of the liquid crystal can be improved without affecting the spacers, and a liquid crystal display device with improved uniformity of substrate spacing and display quality is manufactured. can do.
[Brief description of the drawings]
FIG. 1A is a schematic configuration diagram of an example of an irradiation unit that realizes a photo-alignment process in the manufacture of a liquid crystal display device according to the present embodiment, and FIG. It is the block diagram which looked at from the side.
FIG. 2 is a diagram for explaining a light emission principle of a light source of an irradiation unit.
FIG. 3 is a schematic configuration diagram of an optical system of an irradiation unit.
4A is a diagram for explaining a photo-alignment process of a substrate by one irradiation unit, and FIG. 4B is a diagram for explaining a photo-alignment process of a substrate by multiple irradiation units.
FIG. 5 is a diagram for explaining a photo-alignment process of a substrate by a multi-stage irradiation unit.
6A is an example of the chemical structure of the alignment film used for the photo-alignment treatment in the present embodiment, and FIG. 6B is a UV absorption spectrum of the alignment film shown in FIG. 6A. .
FIG. 7 is a spectral distribution of light irradiated by an electrodeless discharge type irradiation unit used in the present embodiment.
FIG. 8 is a schematic configuration diagram of a combined liquid crystal display device manufactured by the method for manufacturing a liquid crystal display device according to the present embodiment.
FIG. 9 is a process cross-sectional view in the manufacture of a combined liquid crystal display device.
FIG. 10 is a schematic configuration diagram of a combined liquid crystal display device including a photo spacer manufactured by the method of manufacturing a liquid crystal display device according to the present embodiment.
FIG. 11 is a process cross-sectional view in manufacturing a combined liquid crystal display device including a photo spacer.
FIG. 12 is a diagram showing an example of the orientation direction of the alignment film in the example.
FIG. 13 is a diagram showing the results of alignment and contrast evaluation of a liquid crystal panel manufactured according to an example and a liquid crystal panel manufactured according to a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Irradiation unit, 2 ... Light source, 3 ... Optical system, 4 ... Magnetron, 5 ... Bulb, 6 ... Reflector, 7 ... Igniter, 8 ... Stage, 10 ... Substrate, 10A ... First substrate, 10B ... Second substrate DESCRIPTION OF SYMBOLS 11 ... Alignment film | membrane, 12 ... Aperture, 13 ... Cut filter, 14 ... Brewster mirror, 15, 16 ... Shielding plate, 20 ... Liquid crystal layer, 21 ... Spacer, 22 ... Photo spacer, 31, 32 ... Polarizing plate, 33 ... Backlight, 34, 35 ... 1/4 wavelength plate, 41 ... Transparent insulating substrate, 42 ... Gate electrode, 43 ... Semiconductor layer, 44 ... Interlayer insulating film, 45 ... Source / drain electrode, 46 ... Scattering layer, 47 ... Flattening layer, 48 ... transparent electrode, 49 ... reflecting electrode, MW ... microwave, L ... light, LA ... irradiation region, LA1 ... first irradiation region, LA2 ... second irradiation region.

Claims (9)

A process of manufacturing a liquid crystal display device in which a liquid crystal layer in which liquid crystal molecules are aligned by an alignment film subjected to alignment treatment is sandwiched between a pair of substrates , and a reflective region and a transmissive region are arranged in parallel in a pixel
It has
The step of manufacturing the liquid crystal display device includes:
Forming the alignment film on at least one of the pair of substrates by using an ultraviolet reactive resin ;
A step of performing an alignment treatment for the alignment film by irradiating ultraviolet light to the alignment film,
After the alignment treatment, the step of bonding the pair of substrates with a predetermined substrate interval;
After bonding the pair of substrates, liquid crystal is injected between the pair of substrates, and forming the liquid crystal layer by aligning liquid crystal molecules by the alignment control force of the alignment-treated alignment film Yes, and
The step of performing the alignment treatment includes
Emitting ultraviolet light from a light source so as to include an S-polarized component and a P-polarized component;
Reflecting the ultraviolet light emitted from the light source by a Brewster mirror as reflected light comprising an S-polarized component;
A first irradiation region for irradiating the alignment film with the reflected light reflected by the Brewster mirror, and a second for irradiating the alignment film with ultraviolet light emitted from the light source without being reflected by the Brewster mirror. Shielding the reflected light reflected by the Brewster mirror and a part of the ultraviolet light emitted from the light source without being reflected by the Brewster mirror with a shielding plate so as to define an irradiation area;
Including
By transporting the substrate on which the alignment film is formed in the direction in which the first irradiation region and the second irradiation region are aligned, the reflected light reflected by the Brewster mirror is transmitted in the first irradiation region. Irradiating the alignment film, and irradiating the alignment film with ultraviolet light emitted from the light source without being reflected by the Brewster mirror in the second irradiation region, and performing the alignment process,
A method for manufacturing a liquid crystal display device. Before the step of bonding the pair of substrates with a predetermined substrate interval,
Forming a spacer layer for defining the substrate interval on either of the pair of substrates;
And forming a spacer by processing the layer the spacer, further comprising,
The manufacturing method of the liquid crystal display device of Claim 1. Before the step of bonding the pair of substrates with a predetermined substrate interval,
A step of spraying spacers defining the substrate interval on at least one of the pair of substrates.
Further having
The method according to claim 1. The step of performing the orientation treatment includes
In the ultraviolet light emitted from the light source , including a step of cutting by a cut filter a wavelength band that promotes the growth of by-products due to the reaction of the alignment film,
The manufacturing method of the liquid crystal display device in any one of Claim 1 to 3 .   The light source is
  A magnetron that generates microwaves;
  An igniter that emits photons,
  A bulb that emits ultraviolet light as a light-emitting component by the microwave generated by the magnetron and the photon irradiated by the igniter;
  A reflecting mirror that emits the ultraviolet light by reflecting the ultraviolet light emitted by the light-emitting component of the bulb;
  Have
  The valve has a cylindrical shape,
  The reflecting mirror has a semi-cylindrical shape and is arranged so as to surround the bulb on the side opposite to the side from which the ultraviolet light is emitted.
  The manufacturing method of the liquid crystal display device in any one of Claim 1 to 4.   By irradiating the alignment film of the UV-reactive resin formed on the substrate with the ultraviolet light emitted from the light source from the optical system, the control force to the alignment direction of the liquid crystal and the control force to the pretilt angle of the liquid crystal are obtained. An illumination unit for performing an alignment process so as to give to the alignment film
  Comprising
  The light source emits the ultraviolet light so as to include an S-polarized component and a P-polarized component;
  The optical system is
  A Brewster mirror that reflects the ultraviolet light emitted from the light source as reflected light comprising an S-polarized component;
  The reflected light reflected by the Brewster mirror and the reflected light reflected by the Brewster mirror by shielding a part of the ultraviolet light emitted by the light source without being reflected by the Brewster mirror. A first irradiation region for irradiating the alignment film; and a shielding plate for defining a second irradiation region for irradiating the alignment film with ultraviolet light emitted from the light source without being reflected by the Brewster mirror.
  Have
  By illuminating the alignment film in the first irradiation area with the reflected light reflected by the Brewster mirror by transporting the substrate in a direction in which the first irradiation area and the second irradiation area are aligned, Irradiating the alignment film with ultraviolet light emitted from the light source without being reflected by the Brewster mirror in the second irradiation region, and performing the alignment treatment;
  Lighting device.   The optical system is
  Cut filter that cuts the wavelength band that promotes the growth of by-products due to the reaction of the alignment film in the ultraviolet light emitted from the light source
  Having
  The lighting device according to claim 6.   The light source is
  A magnetron that generates microwaves;
  An igniter that emits photons,
  A bulb that emits ultraviolet light as a light-emitting component by the microwave generated by the magnetron and the photon irradiated by the igniter;
  A reflecting mirror that emits the ultraviolet light by reflecting the ultraviolet light emitted by the light-emitting component of the bulb;
  Have
  The valve has a cylindrical shape,
  The reflecting mirror has a semi-cylindrical shape and is arranged so as to surround the bulb on the side opposite to the side from which the ultraviolet light is emitted.
  The lighting device according to claim 6 or 7.   A plurality of the lighting units are arranged along the surface of the substrate,
  The lighting device according to claim 6.

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