JPH0587839A - Measurement of voltage distribution - Google Patents

Abstract

PURPOSE:To detect the voltage distribution on the surface of a measured article without requring probing, by irradiating the light beam on a film body in the state where an electrode body installed on the surface of a film body and a measured article are electrically connected. CONSTITUTION:An ITO electrode body 5 is formed on a high polymeric liquid crystal film 4 as measurement film, and the film 4 is superposed on the electrode films 2 and 3. An electric field is generated on the film 4 by earth-connecting 7 the earth potential of a TFT array driving circuit for a measured article which is constituted of a glass substrate 1, the films 2 and 3, etc., and the electrode body 5. The high polymeric liquid crystal 6 in the state free from the action of the electric field is set ordinarily at an attitude in the random direction for the film surface, and when light beams 8' irradiates, the outgoing light is scattered. When the electric field acts, the liquid crystal 6' changes its attitude in the electric field direction according to the balance between the force due to the electric inductive particle electric field of the liquid crystal and the force for regulating the liquid crystal 6. When the light beam 8 transmits, the outgoing light which has the relatively less scattering is obtained, and the light quantity increases, and observation is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring method for detecting voltage information distributed on a surface, and is particularly useful for inspecting a TFT array substrate in a liquid crystal display device or a photosensitive drum in an electrophotographic device. It is a thing.

[0002]

2. Description of the Related Art Recently, two-dimensional information display and printing technologies have been rapidly changing due to advances in electronics, and among them, liquid crystal display devices and electrophotographic devices have been particularly remarkable.

Common to these devices is the process of converting a one-dimensional signal into a two-dimensional signal, which provides a voltage distribution on the plane with a pitch spacing of about 10 to 100 microns.

The signal conversion process requires high fidelity, but in the case of a TFT array substrate in a liquid crystal display device or a photosensitive drum in an electrophotographic device, the fidelity at hundreds of thousands or millions of points in a plane. Will be required. Defects at these points can be intuitively determined by the two-dimensional information identification ability of the human eye when the final device is used.
In order to determine the state of the FT array substrate or the photosensitive drum, a method of performing probing at each point had to be used.

FIG. 6 shows a part of a TFT array substrate for a liquid crystal display device and shows measurement by probing. Each of the electrode films 28 formed on the glass substrate 27 is an area where one pixel is to be formed, and the source electrode line 2 to which a voltage ES is applied is applied to the electrode film 28.
A voltage is applied from 9 through the amorphous silicon transistor portion 30 and the drain electrode 31. The amorphous silicon transistor section 30 has a gate electrode 32.
Since the resistance value changes depending on the magnitude of the voltage EG applied to the electrode, the voltage applied to the electrode film 28 acts as a switch, and an electrical contact can be easily obtained by bringing the plug 33 into contact with the electrode film 28. In addition, the voltage V can be measured with an ordinary voltage measuring device.

[0006]

As described above, although the method of applying a probe to each electrode is certain, it has the following drawbacks.

As the display density increases, it becomes difficult to align the probing. As the display density increases and the area increases, the number of measurement points increases and the measurement time is increased.

Probing may damage a portion having a display function of the object to be measured. Moreover, there is a possibility that the probe may become contaminated due to contamination.

[0009]

According to the present invention, a measuring film comprising a film body containing a liquid crystal and an electrode body provided on the surface of the film body is provided between the surface of the object to be measured and the electrode body. Contact so that the film body including
At least one of the electrode body and the object to be measured is substantially transparent, the object to be measured and the electrode body are electrically connected to each other, and a light beam is incident on the film body containing the liquid crystal and emitted light. It detects a beam.

[0010]

By electrically connecting the DUT and the electrode body, the potential difference between the surface potential of the DUT and the electrode body,
An electric field is generated according to the distance between the object to be measured and the electrode body. Since there is a film body containing liquid crystal between the object to be measured and the electrode body, the posture of the liquid crystal changes depending on the direction and strength of the electric field. Since at least one of the DUT and the electrode body is a substantially transparent body, it is possible to make a light beam enter the film body, and at least the reflected light,
If both are transparent, the transmitted light is emitted through the film body. The light beam emitted at this time appears as a change in the amount of scattered light, a difference in the amount of transmitted polarized light, a change in the amount of birefringence, etc., depending on the attitude of the liquid crystal, so these physical quantities are detected. As a result, the voltage distribution on the surface of the measured object can be detected.

[0011]

EXAMPLES The present invention will be described below based on examples.

FIG. 1 shows a partial cross-sectional view of an object to be measured and a measuring film. The object to be measured is a TFT array for a liquid crystal display device as in the conventional example, and only the glass substrate 1 and the electrode films 2 and 3 are shown for convenience. The voltage VO is applied to the electrode film 2.
Is applied, and no voltage is applied to the electrode film 3. On the other hand, the measuring film is the polymer liquid crystal film 4 in which the ITO electrode body 5 is formed on the polymer liquid crystal film 4.
Are placed in contact with the electrode films 2 and 3, and the TFT of the DUT is measured.
An electric field acts on the polymer liquid crystal film 4 by connecting the ground 7 so that the ground potential of the array drive circuit (not shown) and the potential of the ITO electrode body 5 are the same. The polymer liquid crystal 6 in a state where no electric field is applied usually takes a posture in a random direction on the film surface. When the light ray 8'is incident on this, scattering occurs and the emitted light becomes scattered light. By the action of the electric field, the balance between the dielectric polarization of the polymer liquid crystal × the electric field force and the force that regulates the polymer liquid crystal,
The polymer liquid crystal 6'in the film changes its posture in the direction of the electric field. When the light ray 8 is transmitted therethrough, emitted light with relatively little scattering is obtained, and the amount of light is increased and observed.

FIG. 2 is a graph conceptually showing the relationship between the voltage applied to the electrode films 2 and 3 in FIG. 1 and the transmitted light 8 and 8 '. The change in the light amount appears from a certain voltage value (point A). ,
When it exceeds a higher voltage value, it does not change (point B). When the reference voltage applied to the electrode films 2 and 3 is set to VO, T
A defective voltage applied to the electrode films 2 and 3 due to disconnection, short circuit, deterioration of amorphous silicon characteristics, etc. on the FT array substrate can be grasped as a change in light amount.

FIG. 3 is a partial cross-sectional view of a measuring film in another embodiment, in which an ITO film 11 is formed on a film body containing liquid crystal droplets 10 and 10 'dispersed in a polymer film 9. In the film for use, the orientation of the liquid crystal molecules in the liquid crystal droplet 10 in which no electric field is applied has a different direction for each liquid crystal droplet, and the incident light 12 is emitted as scattered light. On the other hand, on the side of the liquid crystal droplet 10 'where an electric field is applied, the direction of the liquid crystal is aligned with the direction of the electric field, and by adjusting the refractive index of the liquid crystal molecules in this direction and the refractive index of the polymer film 9 in advance, incident light Since 13 is transparent as it is, the voltage O
N / OFF can be detected.

FIG. 4 is a partial sectional view of a measuring film showing still another embodiment. Stretched polyimide film 1
A spacer sphere 16 and liquid crystals 17 and 17 'are sandwiched between 4 and 15, and one of the polyimide films 14 is provided with an ITO electrode body 18, and a supporting glass substrate 19 is provided on the ITO electrode body 18, and two polyimide films 14 and 15 are provided. The liquid crystal 17 is oriented so that the stretching direction is orthogonal, and the liquid crystal is refined so that when the electric field acts on the liquid crystal 17 ', the liquid crystal is oriented in the direction perpendicular to the plane, and the amount of birefringence of the liquid crystal can be observed. Can be measured with high sensitivity, and the effect of flatness can be obtained for supporting the substrate.

FIG. 5 is a partial sectional view of an array substrate and a measuring film according to still another embodiment. A polarizing plate film 21 is provided on the back surface of the array substrate 20, and a liquid crystal polymer film is used as a measuring film. 22, an electrode body 23, a glass substrate 24, and a polarizing plate film 25 are sequentially stacked, and a small space 26 is formed in the array substrate 20.
The measurement film is superposed with the liquid crystal polymer film 22 facing each other with the film interposed therebetween. By refining in this way, when an electric signal is applied to the array substrate 20, a portion which does not have a regular voltage is easily grasped by human eyes as a difference in intensity of light transmitted through the polarizing plate. And the effect that the array substrate is not contaminated because it does not come into direct contact with the array.

As described above, while the conventional technique uses the electric conduction in the conductor by the electric field as the basic mechanism of the measurement, the present invention changes the posture of the liquid crystal substance by the electric field (specifically, the liquid crystal molecules are It can be understood that the voltage is measured by using the dielectric polarization and the displacement due to the electrical moment accompanying it as the basic measurement mechanism.

[0018]

As described above, the present invention has the following advantages.

Operation is fast because there is no need for probing. Positioning is not necessary, and because it is a method that detects light with a light that does not damage the object to be measured, it is possible to perform two-dimensional information processing, so processing is fast, and it is also sensible to the human eye. It is also possible to let them judge.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a measuring film and an object to be measured according to an embodiment of the present invention.

FIG. 2 is a graph showing the electro-optical operation of FIG.

FIG. 3 is a partial sectional view of a measuring film showing another embodiment.

FIG. 4 is a partial sectional view of a measuring film showing another embodiment.

FIG. 5 is a partial cross-sectional view of a measuring film and an object to be measured showing a measuring method according to another embodiment.

FIG. 6 Partial perspective view showing a conventional example

[Explanation of symbols]

 6, 6 ', 10, 10', 17, 17 'Liquid crystal 4, 9, 14, 15 Film 5, 11, 18 Electrode body 2, 3, 20 DUT

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 29/784

Claims (7)

[Claims] 1. A measuring film comprising a film body containing at least a liquid crystal and an electrode body provided on the surface of the film body, wherein the film body containing the liquid crystal is located between the surface of the object to be measured and the electrode body. So that at least one of the electrode body and the cost measurement object is substantially a transparent body, and the cost measurement object and the electrode element are electrically connected, a light beam is applied to the film body containing the liquid crystal. A voltage distribution measuring method for reading the surface potential of an object to be measured by detecting a light beam that is incident on and emitted. 2. The voltage distribution measuring method according to claim 1, wherein the film body containing liquid crystal is a high molecular weight liquid crystal polymer film. 3. The voltage distribution measuring method according to claim 1, wherein the film body containing liquid crystal is formed by dispersing liquid crystal molecules in a polymer film. 4. The liquid crystal-containing film body is a film body in which liquid crystal is enclosed between two polyimide stretched films and a distance between the two polyimide stretched films is kept constant by a spacer. The voltage distribution measuring method according to item 1. 5. The voltage distribution measuring method according to claim 1, wherein the film body containing liquid crystal and the electrode body are fixed on a solid plate so that the film body containing liquid crystal appears on the surface. 6. The voltage distribution measuring method according to claim 1, wherein a polarizing plate is placed on a film body containing at least an object to be measured and a liquid crystal, and the amount of light emitted from the polarizing plate is detected. 7. The voltage distribution measuring method according to claim 1, wherein a phase difference between an incident light beam and an emitted light beam is detected.