JPH10232113A - Method for measuring gap between electrodes of liquid crystal cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly measure the gap with the electrode plate opposite to the pixel electrode plate of a liquid crystal cell. SOLUTION: A luminous flux LT of a mercury lamp 611 is outputted for a proper amount of time by controlling a shutter 612, is focused to a spot Sp of excitation light (ultraviolet rays or near ultraviolet rays) by a pin hole p, a focusing lens 614, and an excitation filter 615, is projected to the surface of a first galss substrate 1a and is transmitted through each layer, excitation light reflected by the surface of each layer is eliminated, fluorescence R3' and R4' generated on the surface of both alignment layers 3a and 3b are transmitted and the images are formed at the element of a CCD sensor 623 by an image- focusing lens 622, a gap G' between the surfaces of both alignment layers 3a and 3b is calculated from the gap of both elements whose images are formed, and a thickness ΔG of the alignment layer 3b is added to it, thus obtaining the dimension of the a gap G between a picture element electrode plate 2a and the counter electrode plate 2b. As a result, by using fluorescence and a fluorescence transmission filter, unneeded reflection light of each layer is eliminated, thus positively and accurately measuring the gap G.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for measuring a gap size between electrodes of a liquid crystal cell.

[0002]

2. Description of the Related Art Recently, a color liquid crystal panel which is frequently used is manufactured by laminating a liquid crystal cell, a TFT substrate and the like. FIG.
Indicates a cross section of the liquid crystal cell. In the liquid crystal cell, a transparent pixel electrode plate 2a and an alignment film 3a are sequentially laminated on the back surface (lower side) of the first glass substrate 1a, and the color filter 4 is formed on the surface (upper side) of the second glass substrate 1b. And transparent electrode plate 2b
And an alignment film 3b are sequentially laminated, and the pixel electrode plate 2a and the counter electrode plate 2b are opposed to each other with a gap G of a predetermined size, and a liquid crystal (LCD) is provided in a gap G 'between the alignment films 3a and 3b. It is composed by injecting. Both glass substrates 1a,
The thickness of 1b varies depending on the size of the liquid crystal panel, but is 1m.
m, both electrode plates 2a and 2b are several μm or less, and both alignment films 3a and 3b have a very small thickness of about 500 nm. The pixel electrodes e for the respective color elements RGB of the color filter 4 are arranged on the pixel electrode plate 2a.

The liquid crystal in the liquid crystal cell changes its transmittance when the applied voltage changes, and transmits or blocks the illuminated light. The steeper the change characteristic of the transmittance with respect to the change of the applied voltage, the higher the voltage sensitivity. Good and desirable. The steepness of this change characteristic varies depending on the type of liquid crystal material, and the pixel electrode plate 2
a and the counter electrode plate 2b greatly varies depending on the size of the gap G. The optimum steepness is obtained when the gap G is, for example, about 10 μm. As described above, since the gap G affects the steepness, the gap G is measured to check whether the gap is appropriate. Hereinafter, a conventional gap measuring method will be described with reference to FIG.

In FIG. 2, if a liquid crystal cell is to be measured, the injected liquid crystal 5 has a bad influence on the measurement. Therefore, the liquid crystal cell is in an uninjected state, that is, an unfinished liquid crystal cell is to be measured. White light having an appropriate inclination angle θ _T , for example, 45 ° and a diameter φ of several μm is projected onto the surface of the first glass substrate 1a. The projected white light is applied to a glass substrate 1a, a pixel electrode plate 2a, both alignment films 3a and 3b, a counter electrode plate 2b,
The light sequentially passes through the color filters 4. During this time, the respective surfaces (upper surfaces) reflect the reflected lights R _{1 to} R ₆ (the respective optical axes are shown for convenience in the drawing) in the regular reflection direction, and these are incident on the CCD sensor to be applied to the corresponding elements. Each is received. Since the pixel electrode e of the pixel electrode plate 2a also interferes with the measurement, white light is projected so as to avoid this.
The measurement of the gap G, a lower surface of the pixel electrode plates 2a, i.e. the reflected light R ₃ of the surface of the alignment layer 3a in contact thereto, it is necessary and the reflected light R ₅ of the surface of the counter electrode plate 2b, other Since the reflected lights R ₁ , R ₂ , R ₄ , and R ₆ are useless, the element that has received the reflected lights R ₃ and R ₅ is identified based on the order of these positions, and the gap G is determined based on the distance between the two elements. Are calculated.

[0005]

The above reflected lights R _{1 to} R ₆ are not necessarily all clear, but may be indistinct with weak intensity or, conversely, reflected light on the back surface of each layer. sell. For this reason, the reflected light R
_In some cases, it is difficult to correctly discriminate between the two devices that have received R ₃ and R _{5. In} such a case, the gap G is not measured correctly or cannot be measured. Therefore, there is a demand for a means for removing unnecessary reflected light, receiving only necessary reflected light by a CCD sensor, and correctly measuring the gap G. The present invention has been made in view of the above, and it is an object of the present invention to remove unnecessary reflected light, receive only necessary reflected light by a CCD sensor, and measure a gap G correctly.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for measuring the gap between electrodes of a liquid crystal cell, wherein an incomplete liquid crystal cell in which liquid crystal has not been injected is measured. An optical axis forms an appropriate inclination angle with respect to the surface of the first glass substrate, and a light projecting system having a light source for generating excitation light and a focusing lens, and a direction in which the optical axis is symmetric with respect to the light projecting system. None, a fluorescence transmission filter and a light receiving system having an imaging lens and a CCD sensor are provided. The excitation light is focused to a spot by a focusing lens and projected on the surface of the first glass substrate, and the first glass substrate, the pixel electrode plate, the counter electrode plate,
The excitation light reflected from each surface of the color filter is removed, the fluorescence generated on the surfaces of both light distribution films by the excitation light is transmitted, and the image is formed on each element of the CCD sensor by the imaging lens. The gap size between the surfaces of both light distribution films is calculated from the distance between the two formed elements, and the thickness of the light distribution film is added to the gap size to obtain the gap size between the pixel electrode plate and the counter electrode plate. In the above, a mercury lamp is used as a light source of the light projecting system, and ultraviolet light or near ultraviolet light emitted from the mercury lamp is used as excitation light, and an excitation filter that selects and transmits excitation light from a luminous flux including various wavelengths of the mercury lamp, and an excitation filter. A shutter for controlling the light projection time is provided in the light projection system.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above-described gap measuring method, an alignment agent forming an alignment film is an organic substance such as an organic silane, and when irradiated with excitation light having an appropriate wavelength, fluorescence having a different wavelength is emitted. The glass substrate, the two electrode plates, and the color filters, which are frequently generated, reflect the excitation light as it is and do not generate the fluorescence, or focus on the extremely weakness even if the fluorescence is generated. The measurement target is an unfinished liquid crystal cell into which liquid crystal has not been injected as in the related art, and the excitation light generated by the light source of the light projecting system is focused to a spot by a focusing lens, and is focused on the surface of the first glass substrate. It is projected at an appropriate tilt angle. The projected excitation light spot is reflected in the regular reflection direction by the respective surfaces of the first glass substrate, the pixel electrode plate, the counter electrode plate, and the color filter.
Since these reflected lights remain the excitation light and are useless, they are removed by the fluorescence transmission filter of the light receiving system. On the other hand, on the surfaces of both light distribution films, fluorescent light is generated by the projected excitation light, passes through the fluorescent light transmitting filter, and is formed on the elements of the CCD sensor by the image forming lens. The gap size between the surfaces of both light distribution films is calculated from the distance between the two devices on which the fluorescent light is imaged, and the thickness of the light distribution film is added to this to obtain the correct gap size between the pixel electrode plate and the counter electrode plate. Can be As described above, according to the present invention, by using the fluorescence and the fluorescence transmission filter, the problem of the identification of the reflected light, which has been difficult in the past, is solved. Only the required fluorescence is reliably received by the CCD sensor, and the gap G is reduced. It can be measured correctly.

Next, it is generally considered that light having a relatively short wavelength such as ultraviolet light or near ultraviolet light is suitable as excitation light for generating fluorescence. Since the mercury lamp used as the light source of the light-emitting system generates luminous flux of various wavelengths including ultraviolet light and near-ultraviolet light, this is used as a light source, and either ultraviolet light or near-ultraviolet light is provided in the light-emitting system. The excitation light is selected by the excitation filter. In addition, ultraviolet rays and near ultraviolet rays have a heating effect and chemical action stronger than visible light, and if the projection time is long, both electrode plates, both light distribution films, color filters, etc. may be damaged. These damages are prevented by controlling the projection time to an appropriate short time by the shutter.

[0009]

FIG. 1 shows an embodiment of a gap measuring apparatus 10 for carrying out the present invention. The gap measuring device 10 shown in FIG. 1 includes a measuring optical system 6 including a light projecting system 61 and a light receiving system 62,
The control / calculation unit 7 includes a shutter control circuit 71 and a gap calculation circuit 72. The light projecting system 61 includes a mercury lamp 611, a shutter 612, a pinhole plate 613 having a pinhole p, a focusing lens 614, and an excitation filter 615 that transmits ultraviolet light or near ultraviolet light.
On the surface of the first glass substrate 1a, as in the related art,
It is set in the direction of the inclination angle theta _T to avoid the pixel electrode e. The light receiving system 62 includes a fluorescence transmission filter 621, an imaging lens 622, and a CCD sensor 623, and its optical axis is set in a direction symmetric to the light projecting system 61.

In the gap measurement, a mercury lamp 611 is used.
With respect to the light beam L _T include more various wavelengths, the shutter 61
2 is controlled by the shutter control circuit 71 opens the appropriate time, the light beam L _T pinhole p output during this time, the focusing lens 614, the excitation filter 615, together with the ultraviolet or near-ultraviolet light is selected, a small is focused to the excitation light spot S _P output diameter, it is projected onto the surface of the first glass substrate 1a. Note that the opening time of the shutter 612 is determined by an experiment or the like. Projected spot _SP
Are sequentially transmitted through each layer of the liquid crystal cell, and are reflected by the respective surfaces of the first glass substrate 1a, the pixel electrode plate 2a, the counter electrode plate 2b, and the color filter 4 as R ₁ , R ₂ , R ₅ , R ₆
(The figures show the respective optical axes) are reflected.

Since these reflected lights R ₁ , R ₂ , R ₅ , R ₆ are the excitation lights as they are, they are removed by the fluorescence transmission filter 621 of the light receiving system 62 as unnecessary. On the other hand, both light distribution films 3
a, the surface of the 3b is excited by the projected spots S _P fluorescent R ₃ ', R _4' generates respectively, these are transmitted through the fluorescence transmission filter 621, by the imaging lens 622 C
An image is formed on the corresponding element of the CD sensor 623. The output signals of the two devices on which the fluorescences R ₃ ′ and R ₄ ′ are formed are input to the gap calculation circuit 72, and the light distribution films 3a, 3a,
The dimension of the gap G ′ (shown in the enlarged view) between the surfaces of the pixel electrode plate 2b is correctly calculated, and the thickness ΔG of the light distribution film 3b is added thereto. The dimensions of the gap G are obtained, and the measurement data of the gap G output from the gap G is compared with a reference value or an allowable value to check the quality. It should be noted that the gap G needs to be uniform and of a predetermined size over the entire surface of the liquid crystal cell. For this reason, the gap G should be formed at a plurality of appropriate locations corresponding to the size of the area of the liquid crystal cell. Measure the dimensions,
The dimensions and uniformity of each part are inspected.

[0012]

As described above, the gap measuring method of the present invention focuses on the generation of fluorescence from the alignment film, and uses, for example, ultraviolet light or near ultraviolet light emitted from a mercury lamp light source as excitation light. Then, the spot is projected on a liquid crystal cell before liquid crystal is injected, and unnecessary reflected light as excitation light from the first glass substrate or the like is removed by a fluorescence transmission filter, and the surfaces of both alignment films are generated. The size of the gap between the lower surface of the pixel electrode plate and the upper surface of the opposing electrode plate is accurately measured by transmitting the emitted fluorescent light to the CCD sensor element without fail, so that each layer of the liquid crystal cell is not damaged. Consideration is given to limiting the projection time of the excitation light, and there is a great effect that contributes to reliable and accurate measurement of the gap between the electrodes of the liquid crystal cell.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a gap measuring device that executes the present invention.

FIG. 2 is an explanatory view of a cross section of a liquid crystal cell and a conventional gap measuring method.

[Explanation of symbols]

1a: first glass substrate, 1b: second glass substrate, 2
a: pixel electrode plate, 2b: counter electrode plate, 3a, 3b: alignment film, 4: color filter, 5: liquid crystal (LCD), 6: measuring optical system of the present invention, 61: light projecting system, 611: mercury lamp ,
612: shutter 613: pinhole plate, 614: focusing lens, 615: excitation filter, 62: light receiving system, 621: fluorescence transmission filter, 622:
Imaging lens, 623: CCD sensor, 7: control / calculation unit,
71: shutter control circuit, 72: gap calculation circuit, 10 ...
Gap measuring apparatus for executing the present invention, R ₁ to R ₆ ... reflected _{light, R 3 ', R 4'} ... fluorescent, e ... pixel electrode, p ... pinhole, L _T ... light beams, the S _P ... pumping light spot G: a gap between the lower surface of the pixel electrode plate 2a and the upper surface of the counter electrode plate 2b;
G ': gap between the surfaces of both alignment films 3a and 3b.

Claims (2)

[Claims] 1. A first glass substrate on which a pixel electrode plate and an alignment film are sequentially laminated on a back surface side, and a second glass substrate on which a color filter, a counter electrode plate and an alignment film are sequentially laminated on a front surface side In a liquid crystal cell formed by facing the pixel electrode plate and the counter electrode plate with a gap of a predetermined size and injecting liquid crystal into the gap between the alignment films, the liquid crystal is not injected. The unfinished liquid crystal cell in the state of
A light projecting system having an optical axis forming an appropriate inclination angle with respect to the surface of the first glass substrate and having a light source for generating excitation light and a focusing lens; and an optical axis being symmetrical with respect to the light projecting system. A light-transmitting filter, an imaging lens, and a light-receiving system having a CCD sensor are provided. The excitation light is focused on the spot by the focusing lens and projected on the surface of the first glass substrate. By the transmission filter, the first glass substrate, the pixel electrode plate, the counter electrode plate, the color filter,
The excitation light reflected from each surface is removed, the fluorescence generated on the surfaces of both light distribution films is transmitted by the excitation light, and the image is formed on the elements of the CCD sensor by the imaging lens. Calculate the gap size between the surfaces of both light distribution films from the distance between the two elements on which the images are formed, add the thickness of the light distribution film to the calculated size, and calculate the gap between the pixel electrode and the counter electrode. A method for measuring a gap between electrodes of a liquid crystal cell, the method comprising measuring dimensions. 2. A mercury lamp is used as a light source of the light projecting system, and ultraviolet light or near ultraviolet light emitted by the mercury lamp is used as the excitation light, and the excitation light is converted from a luminous flux including various wavelengths of the mercury lamp. 2. The method for measuring a gap between electrodes of a liquid crystal cell according to claim 1, wherein an excitation filter that selectively transmits light and a shutter that controls a projection time of the excitation light are provided in the light projection system.