JP2000275595A - Method for inspection of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for the inspection of a liquid crystal display device with high inspection accuracy by which a reflection type liquid crystal display device can be inspected in a bright and uniform display state. SOLUTION: A light source 1 consisting of a point light source such as a xenon lamp or halogen lamp is disposed on an extended line of the diagonal line of a reflection type liquid crystal display device 2 equipped with a reflection layer such as a reflector and a reflection electrode having a reflecting function so as to irradiate the reflection type liquid crystal display device 2 with the light 3 from the light source 1. By this method, fluctuation in the reflection luminance can be decreased and generation of irregular reflection in stripes can be prevented. The light source 1 is disposed in such a manner that illuminance in the region 4 of the reflection liquid crystal display device 2 farthest from the light source 1 is highest, and that the illuminance decreases in steps in region 5, region 6 and region 7 nearer to the light source 1. Thus, the reflection characteristics of the reflection type liquid crystal display device are compensated to produce a homogeneous state of luminance of the display device 2, and thereby, the inspection accuracy for the display quality can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing a liquid crystal display device, and more particularly to a method for testing a reflection type liquid crystal display device having a reflective layer on one substrate.

[0002]

2. Description of the Related Art A reflection type liquid crystal display device which does not use a backlight as a lighting device has features that it consumes less power, can be made thinner and lighter, and is used as a display device of a portable terminal device. Attention is being paid to development and production.

In the reflection type liquid crystal display device, there has been a great demand for a small liquid crystal display device having a size of, for example, 5 inches or less, but recently, as a display device mounted on a notebook computer of a subnote class (B5 size). Needs are increasing.

[0004] Since the manufacturing process of such a liquid crystal display device is complicated, disconnection of a scanning line or a signal line, a linear defect due to a short circuit, a point defect such as a defective switching element, or a defect such as display unevenness occurs. As described above, since the production yield of the liquid crystal display device is not 100%, it is necessary to sufficiently inspect the display quality.

Here, a conventional display quality inspection method for a reflection type liquid crystal display device will be described with reference to FIG. FIG. 9 is an explanatory view showing a conventional reflection type liquid crystal display device inspection method.

As shown in FIG. 9, a reflection type liquid crystal display device 1
03 on the inspection table 102, and the reflection type liquid crystal display device 1
03 allows a drive signal for inspection to be input. Then, the inspection signal of the reflection type liquid crystal display device 103 generated by the drive signal generation device 104 is input to the reflection type liquid crystal display device 103 via the inspection table 102. Since the display of the reflective liquid crystal display device 103 cannot be confirmed unless light is irradiated from the front, the fluorescent lamp 101 is installed on the side to irradiate the reflective liquid crystal display device 103 with light. In this way, the inspector inspects the display state of the reflective liquid crystal display device 103.

[0007]

Here, the reflection characteristics of the reflection type liquid crystal display device will be described with reference to FIGS. 7 and 8. FIG. FIG. 7 is an explanatory diagram of specular reflection, and FIG. 8 shows the characteristics of the intensity (reflectance) of the reflected light when the direction of specular reflection of a general reflection type liquid crystal display device is set to 0 degree and the viewing angle is shifted to both sides. FIG.

As shown in FIG. 7, for example, when light from a light source 1 irradiates a reflective liquid crystal display device 2 through a condenser lens 9, the incident light 1 on the reflective liquid crystal display device 2 is
The light reflected at the same angle as the incident angle α of 7 is referred to as regular reflected light 18. The incident light 17 is generally reflected and scattered in all directions other than the specular reflection direction.

When inspecting a reflection type liquid crystal display device,
For example, it indicates that the inspector 21 is looking at the light 22 reflected from the specularly reflected light 18 in the direction of the angle β, and the inspector 19 is looking at the light 20 reflected from the specularly reflected light 18 in the direction of the angle −β. It is shown that.

As shown in FIG. 8, when the reflection type liquid crystal display device is viewed from the regular reflection direction, it looks bright. However, when the viewing angle deviates from the regular reflection direction, the reflectance greatly changes. And accurate inspection cannot be performed with a uniform display state.

When the reflection type liquid crystal display device is viewed from a direction deviated from the specular reflection direction by ± 30 to ± 50 degrees, a dark display state is obtained because the reflectance characteristic is comparatively gentle but the reflectance is low. Accurate inspection is not possible.

Due to such characteristics, as shown in FIG. 9, when the reflection type liquid crystal display device 103 is irradiated with light by the fluorescent lamp 101, the reflection 105 of the fluorescent lamp 101 may occur, which adversely affects the inspection accuracy. Have given.

These problems have a relatively small effect when the reflection type liquid crystal display device is small, but have a large effect when the size of the reflection type liquid crystal display device is increased, thereby lowering the inspection accuracy. There is a point. In addition, in order to avoid these problems, the inspector performs the inspection while changing the angle of the fluorescent lamp or moving his / her own head to change the viewing angle, but this is not desirable for a long-time operation because of a lot of fatigue.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and provides a method of inspecting a liquid crystal display device with high inspection accuracy, which can inspect a reflective liquid crystal display device in a bright and uniform display state. It is intended to be.

[0015]

According to a first aspect of the present invention, there is provided a method for inspecting a liquid crystal display device, comprising irradiating a liquid crystal display device having a rectangular external shape with light from a light source. In an inspection method of a liquid crystal display device for inspecting display quality, the light source is disposed on an extension of a diagonal line of the liquid crystal display device, and light is emitted in a direction along a diagonal line of the liquid crystal display device.

According to a second aspect of the present invention, there is provided a method of inspecting a liquid crystal display device according to the first aspect.
The light source is a point light source.

According to a third aspect of the present invention, in the inspection method for a liquid crystal display device according to the first or second aspect, the liquid crystal display device is a reflection type liquid crystal display device having a reflective layer. The liquid crystal display device is characterized by irradiating the liquid crystal display device with light so as to have an inclined luminance distribution such that a region far from the light source of the liquid crystal display device is bright and a region near the light source is dark.

According to a fourth aspect of the present invention, there is provided a method of inspecting a liquid crystal display device according to any one of the first to third aspects, wherein the liquid crystal display device is a reflection type liquid crystal display device having a reflective layer. The liquid crystal display device is characterized in that two light sources are arranged so as not to face each other, and light is emitted in directions along two diagonals of the liquid crystal display device.

When light is irradiated from a direction parallel to a signal line or a black matrix arranged in a matrix substantially parallel to the outer shape of a rectangular liquid crystal display device, the arrangement is parallel to the light traveling direction. The reflection area on the matrix is larger than the reflection area on the matrix, which is not arranged parallel to the light traveling direction, so that the difference in the reflection luminance between the former region and the latter region becomes larger, and the stripe shape Uneven reflection occurs.

According to the liquid crystal display device inspection method of the present invention, a light source is arranged on a diagonal extension of the liquid crystal display device,
By irradiating light in a direction along a diagonal line of the liquid crystal display device, a region where a signal line arranged in a matrix substantially in parallel with the outer shape of the rectangular liquid crystal display device and a light traveling direction are in a parallel positional relationship. Because there is no difference, the difference in luminance depending on the location is small, and it is possible to prevent the occurrence of streak-like reflection unevenness,
Inspection accuracy of display quality can be improved.

Further, since the light source is a point light source, it is possible to easily emit light in a direction along a diagonal line of the liquid crystal display device.

Further, the liquid crystal display device is a reflection type liquid crystal display device provided with a reflection layer, and the liquid crystal display device has a tilted luminance distribution such that a region far from the light source of the liquid crystal display device is bright and a region near the light source is dark. By irradiating the display device with light, a region having a low reflectance (a region having a large angle from the regular reflection) is irradiated with bright light and a region having a high reflectance (a regular reflection) due to the reflection characteristics of the reflective liquid crystal display device. (A region with a small angle from the light source) is irradiated with dark light, and a uniform luminance distribution state is obtained when the liquid crystal display device is viewed from the front, so that the inspector does not need to move his head and has high accuracy. Inspection is possible.

Further, the liquid crystal display device is a reflection type liquid crystal display device provided with a reflection layer, and two light sources are arranged so as not to face each other, and light is emitted in directions along two diagonal lines of the liquid crystal display device. Accordingly, due to the reflection characteristics of the reflection type liquid crystal display device, bright light is irradiated to a region having a low reflectance (a region having a large angle from regular reflection), and a region having a high reflectance (a region having a small angle from regular reflection) is irradiated. When the liquid crystal display device is viewed from the front, it has a uniform brightness distribution, which eliminates the need for the inspector to move his head. it can.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a reflective liquid crystal display device irradiated with light when viewed from the front of a display surface;
FIG. 2 shows points A and B in the reflection type liquid crystal display of FIG.
FIG. 3 is a diagram illustrating an illuminance distribution on a diagonal line including a point C, and FIG. 3 is a diagram illustrating a relationship between a regular reflection direction and a viewing angle direction.

The method of irradiating light in the inspection of the reflection type liquid crystal display device will be mainly described. As shown in FIG. 1, a light source 1 composed of a point light source such as a xenon lamp or a halogen lamp is provided on a reflective liquid crystal display device 2 with respect to a reflective liquid crystal display device 2 provided with a reflective layer such as a reflective plate or a reflective electrode having a reflective function. The light 3 from the light source 1 is disposed on a diagonal extension of the device 2.
In the direction along the diagonal line of the reflective liquid crystal display device 2.

In this manner, a region in which the signal lines or the black matrix arranged in a matrix substantially parallel to the outer shape of the rectangular reflective liquid crystal display device 2 and the traveling direction of the light 3 are in a parallel relationship. Therefore, the variation in the reflected luminance is reduced, the occurrence of streak-like reflection unevenness can be prevented, and the inspection accuracy of display quality can be improved.

Further, as shown by the density of the inside of the reflection type liquid crystal display device 2, the area 4 farthest from the light source 1 has the brightest illuminance, and the areas 5, 6 and 7 and the nearer to the light source 1 The light source 1 is arranged so that the illuminance becomes darker.

FIG. 2 shows a diagonal illuminance distribution including points A, B, and C in the reflection type liquid crystal display device 2 at this time. Point A is the corner closest to the light source 1, point B is the center, and point C is the corner farthest from the light source 1.

As shown in FIG. 2, the light from the light source 1 is adjusted by the condenser lens 9 so that the illuminance at the point C becomes the brightest, and the light 3 is irradiated to the reflection type liquid crystal display device 2. By doing so, the illuminance distribution 8 is inclined such that the illuminance at the point C farthest from the light source 1 is the brightest and the illuminance becomes darker toward the point A.

Further, at this time, the reflection type liquid crystal display device 2
The relationship between the incident angle of the light 3 to the lens, the specular reflection direction, and the viewing angle direction will be described with reference to FIG.

As shown in FIG. 3, the reflection type liquid crystal display device 2
Is irradiated with light from the light source 1 through the condenser lens 9. An inspector 16 inspects the display quality of the reflective liquid crystal display device 2 with the head fixed. The specularly reflected light of the light incident on the point A is indicated by the reference numeral 10, the specularly reflected light of the point B is indicated by the numeral 11, and the specularly reflected light of the point C is indicated by the arrow 12. Inspector 16 is at point A, point B,
Reference numeral 13 and reference numeral 1 denote the viewing angle directions when viewing point C, respectively.
4, indicated by an arrow 15. The angles formed by the specular reflection at the points A, B, and C and the viewing angle direction are denoted by reference numerals a, b, and c.

As can be seen, the angle a is the smallest, and the angle between the specular reflection and the viewing angle increases in the order of the angles b and c. In other words, it can be seen that the angle between the specular reflection direction and the viewing angle direction is small in a region near the light source 1 and large in a region far from the light source 1.

When this is compared with the above-described reflection characteristic of FIG. 8, at point A where the angle between the specular reflection direction and the viewing angle direction is small, it appears that the reflectivity is high and very bright, and at point C where this angle is large. In this case, the reflectance is low and it looks dark. In order to offset this, by irradiating brighter light to the point C than to the point A, the luminance of the reflected light as viewed from the inspector 16, that is, the luminance of the reflective liquid crystal display device 2 becomes uniform, and the display The quality inspection accuracy can be improved.

In the present embodiment, the light source is arranged in the upper left direction of the liquid crystal display device in FIG. 1, but the present invention is not limited to this, and the light source is arranged on a diagonal extension of the liquid crystal display device. The same effect can be obtained by irradiating light from any direction. Also, for the lamp used for the light source,
The light source is not limited to this as long as the light source can control the light irradiation angle.

(Embodiment 2) A second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a diagram showing a reflective liquid crystal display device irradiated with light from two light sources when viewed from the front of the display surface, and FIG. 5 includes points A, B and C in the reflective liquid crystal display device of FIG. FIG. 6 shows a diagonal illuminance distribution. FIG. 6 shows points D and B in the reflection type liquid crystal display device of FIG.
It is a figure which shows the illumination distribution on a diagonal line containing a point and point E.

The method of irradiating light in the inspection of the reflection type liquid crystal display device will be mainly described. As shown in FIG. 4, a light source 1 composed of a point light source such as a xenon lamp or a halogen lamp is connected to a reflection type liquid crystal display in a reflection type liquid crystal display device 2 provided with a reflection layer such as a reflection plate or a reflection electrode having a reflection function. The light 3 from the light source 1 is disposed on a diagonal extension of the device 2.
In the direction along the diagonal line of the reflective liquid crystal display device 2.

Further, a second light source 23 composed of a point light source such as a xenon lamp or a halogen lamp is arranged on a diagonal extension line of the reflection type liquid crystal display device 2 which does not face the light source 1, and light 24 from the light source 23 is disposed. In the direction along the diagonal line of the reflective liquid crystal display device 2.

In this way, the signal lines or the black matrix arranged in a matrix substantially parallel to the outer shape of the rectangular reflective liquid crystal display device 2 and the traveling direction of the light 3 or 24 are in a parallel relationship. Since there is no area, the variation in the reflected luminance is reduced, the occurrence of streak-like reflection unevenness can be prevented, and the inspection accuracy of display quality can be improved.

Further, as shown by shading in the reflection type liquid crystal display device 2, the illuminance in the region farthest from the light source 1 or 23 is the brightest, and the illuminance gradually decreases as it approaches the light source 1 or 23. Light sources 1 and 23 are arranged as described above.

FIG. 5 shows a diagonal illuminance distribution including points A, B and C in the reflection type liquid crystal display device 2 at this time.
FIG. 6 shows an illuminance distribution on a diagonal line including the points D, B, and E. Point A is the corner closest to the light source 1, point B is the center, point C is the corner farthest from the light source 1, point D is the corner closest to the light source 23, and point E is the corner farthest from the light source 23. is there.

As shown in FIG. 5, the light from the light source 1 is adjusted by the condenser lens 9 so that the illuminance at the point C becomes the brightest, and the light 3 is irradiated to the reflection type liquid crystal display device 2. By doing so, the illuminance distribution 25 is inclined such that the illuminance at the point C farthest from the light source 1 is the brightest and the illuminance becomes darker toward the point A.

Further, as shown in FIG. 6, the light from the light source 23 is adjusted by the condenser lens 9 so that the illuminance at the point E becomes the brightest, and the light 24 is irradiated to the reflection type liquid crystal display device 2. By doing so, the illuminance distribution 26 is inclined such that the illuminance at the point E farthest from the light source 23 is the brightest and the illuminance becomes darker toward the point D.

In this way, as described above, the reflection characteristics of the reflection type liquid crystal display device can be offset, and a uniform reflection luminance distribution can be obtained from the viewing angle direction of the inspector, and the brightness can be improved. Therefore, the inspection accuracy of the liquid crystal display device can be improved.

In this embodiment, the light sources are arranged in the upper left and upper right directions of the liquid crystal display device in FIG. 4, but the present invention is not limited to this, and the diagonal line of the liquid crystal display device is extended. If the two light sources do not face each other on the line, the same effect can be obtained by irradiating light from any direction. Further, the lamp used for the light source is not limited to this as long as the light source can control the irradiation angle of light.

[0046]

As described above, according to the inspection method of the liquid crystal display device of the present invention, by irradiating light in the direction along the diagonal line of the liquid crystal display device, it is possible to reduce the variation in the reflected luminance and to reduce the streak. It is possible to prevent the occurrence of uneven reflection in the shape of a circle, and to improve the inspection accuracy of display quality.

Further, since the light source is a point light source, it is possible to easily emit light in a direction along a diagonal line of the liquid crystal display device.

Further, the liquid crystal display device is a reflection type liquid crystal display device provided with a reflection layer, and the liquid crystal display device has an inclined luminance distribution such that a region far from the light source of the liquid crystal display device is bright and a region near the light source is dark. By irradiating the display device with light, a uniform luminance distribution state is obtained when the liquid crystal display device is viewed from the front due to the reflection characteristics of the reflective liquid crystal display device, so that the inspector does not need to move his head. High-precision inspection can be performed.

Further, the liquid crystal display device is a reflection type liquid crystal display device having a reflection layer, and two light sources are arranged so as not to face each other, and light is emitted in two diagonal directions of the liquid crystal display device. Due to the reflection characteristics of the reflection type liquid crystal display device, a uniform luminance distribution state is obtained when the liquid crystal display device is viewed from the front, so that the inspector does not need to move his head, and the accuracy is improved in a brighter display state. Good inspection can be done.

[Brief description of the drawings]

FIG. 1 is a diagram showing a case where a reflective liquid crystal display device irradiated with light is viewed from the front of a display surface.

FIG. 2 shows points A and B in the reflection type liquid crystal display device of FIG.
It is a figure which shows the illumination distribution on a diagonal line containing a point and a point C.

FIG. 3 is a diagram illustrating a relationship between a specular reflection direction and a viewing angle direction.

FIG. 4 is a diagram showing a reflective liquid crystal display device irradiated with light from two light sources when viewed from the front of the display surface.

5 shows points A and B in the reflection type liquid crystal display device shown in FIG. 4;
It is a figure which shows the illumination distribution on a diagonal line containing a point and a point C.

6 is a view showing points D and B in the reflection type liquid crystal display device shown in FIG. 4;
It is a figure which shows the illumination distribution on a diagonal line containing a point and point E.

FIG. 7 is an explanatory diagram of specular reflection.

FIG. 8 is a diagram showing characteristics of the intensity (reflectance) of reflected light when the direction of regular reflection of a general reflection type liquid crystal display device is set to 0 degree and the viewing angle is shifted to both sides thereof.

FIG. 9 is an explanatory view showing a conventional inspection method for a reflection type liquid crystal display device.

[Explanation of symbols]

Reference Signs List 1 light source 2 reflective liquid crystal display device 3 light 4 area farthest from light source 5 area 6 area 7 area closest to light source 8 diagonal illuminance distribution including points A, B, and C in FIG. 9 9 condenser lens 10 Specular reflected light of light incident on point A 11 Specular reflected light of light incident on point B 12 Specular reflected light of light incident on point C 13 Viewing angle direction when inspector looks at point A 14 Inspector B Viewing angle direction when looking at point 15 Viewing angle direction when inspector looks at point C 16 Inspector 17 Incident light 18 Regular reflection light 19 Inspector 20 Light reflected from specular reflection light in the direction of angle −β 21 Inspection Member 22 Light reflected from specularly reflected light in the direction of angle β 23 Second light source 24 Light from second light source 25 Illuminance distribution on diagonal line including points A, B and C in FIG. 4 26 Illuminance distribution 101 on a diagonal line including points D, B, and E 101 Fluorescent lamp 102 Inspection table 103 Reflective liquid crystal display device 104 Drive signal generator 105 Reflection of fluorescent lamp

Claims (4)

[Claims] 1. An inspection method for a liquid crystal display device in which a liquid crystal display device having a rectangular outer shape is irradiated with light from a light source to inspect display quality, wherein the light source is arranged on a diagonal line of the liquid crystal display device. And irradiating light in a direction along a diagonal line of the liquid crystal display device. 2. The method according to claim 1, wherein the light source is a point light source. 3. The liquid crystal display device is a reflection type liquid crystal display device having a reflective layer, and has a tilted luminance distribution such that a region far from the light source of the liquid crystal display device is bright and a region near the light source is dark. 3. The method for inspecting a liquid crystal display device according to claim 1, further comprising irradiating the liquid crystal display device with light. 4. The liquid crystal display device is a reflection type liquid crystal display device having a reflection layer, wherein two light sources are arranged so as not to face each other, and light is emitted in a direction along two diagonal lines of the liquid crystal display device. 4. The method for inspecting a liquid crystal display device according to claim 1, wherein the irradiation is performed.