JP2012208180A - Contrast inspection method and contrast inspection device - Google Patents

Abstract

An object of the present invention is to reduce the inspection time of contrast of a liquid crystal panel 10 used in a light valve of a projector.
Before inspection, a mirror is held instead of the liquid crystal panel 10 and a quarter-wave plate is held instead of the phase difference compensation plate 60 so that the illuminance information of the light receiving unit 80 becomes the maximum value. In addition, the rotation angle θ of the first polarizer 40, the rotation angle θ of the polarization beam splitter 50, and the rotation angle θ of the second polarizer 70 are respectively adjusted. When inspecting the liquid crystal panel 10, the mirror is replaced with the liquid crystal panel 10, and the quarter-wave plate is replaced with the phase difference compensation plate 60. Then, the rotation angle x and rotation angle y of the liquid crystal panel 10 and the rotation angle θ of the phase difference compensation plate 60 are adjusted so that the illuminance information of the light receiving unit 80 becomes the maximum value.
[Selection] Figure 2

Description

  The present invention relates to a contrast inspection method and a contrast inspection apparatus.

  The liquid crystal panel is used as a light valve of a projector in addition to a display device of an electronic device. In the projector, a modulated image of about 1 inch diagonally is generated by the liquid crystal panel, and this image is enlarged and projected onto the screen. When such a liquid crystal panel is inspected, if it is a transmissive type, a technique has been proposed in which the transmitted light of each dot is imaged by a CCD camera and a defect in the inspection target dot is detected from the inspected image (for example, Patent Document 1).

JP 2005-338261 A

In recent years, reflective liquid crystal panels have appeared in addition to transmissive types. In the reflection type, the aperture ratio is increased and light leakage is suppressed, so that a high contrast image display is possible as compared with the transmission type. For this reason, in the inspection process, it is important to determine the level of contrast of the liquid crystal panel separately from the pixel defect. When the contrast is inspected with a conventional inspection apparatus, there is a problem that a large number of panels cannot be inspected because the inspection takes time.
Accordingly, the present invention has been made in view of the above-described circumstances, and one of its purposes is to provide a technique capable of shortening the time required for, for example, contrast inspection of a liquid crystal panel.

  In order to achieve the above object, in the contrast inspection method according to the present invention, a light source that irradiates light to an inspection object, a light receiving unit that receives reflected light from the inspection object, and from the light source to the inspection object And an optical member disposed on an optical axis from the inspection target to the light receiving unit, and a holding unit that holds each position of the optical member and the inspection target to be adjustable with respect to the optical axis. The optical member includes a first polarizer, a polarization beam splitter, a phase difference compensation plate, and a second polarizing plate, and transmits light from the light source to the first polarizer, the polarization beam splitter, Irradiating the inspection object via a phase difference compensation plate, and receiving the reflected light from the inspection object by the light receiving unit via the phase difference compensation plate, the polarization beam splitter, and the second polarizer, Inspection target An inspection method for inspecting contrast based on reflected light received by the light receiving unit, wherein a mirror is held instead of the panel before inspecting the panel to be inspected, and the phase difference compensation plate Instead, the quarter wavelength plate is held to adjust each position of the optical member, and when inspecting the panel to be inspected, the panel is held instead of the mirror, and the 1 The phase difference compensation plate is held in place of the / 4 wavelength plate to adjust the position of the panel, and the phase difference compensation amount is adjusted according to the position of the phase difference compensation plate. According to the present invention, each position of the optical member is adjusted by holding the mirror. Therefore, when inspecting the panel, the position where the panel is held and the phase difference compensation amount by the phase difference compensation plate are adjusted. The contrast of the panel can be inspected. For this reason, the time required for the inspection can be shortened.

In this invention, it has an adjustment part which adjusts each position of the said 1st polarizing plate by the said holding | maintenance part, the said polarizing beam splitter, the said phase difference compensation plate, the said test object, and the said 2nd polarizing plate, When the panel is inspected, it is preferable that the adjustment unit prohibits adjustment of each position of the first polarizing plate, the polarizing beam splitter, and the second polarizing plate. According to this aspect, since each position of the optical member is adjusted without manual intervention, the time required for the adjustment is shortened and adjusted accurately. In this aspect, it is preferable that the adjusting unit adjusts to a point where the brightness of the light received by the light receiving unit is minimized.
The present invention can be conceptualized as a contrast inspection apparatus in addition to a contrast inspection method.

It is a perspective view which shows the structure of the liquid crystal panel used as a test object. It is a figure which shows the optical structure of the contrast inspection apparatus which concerns on embodiment. It is a figure which shows the rotating shaft of the phase difference compensating plate of a contrast inspection apparatus. It is a block diagram which shows the structure of a contrast inspection apparatus. It is a flowchart which shows operation | movement of a contrast inspection apparatus. It is a figure which shows the optical structure after adjustment with the mirror of a contrast inspection apparatus. It is a figure which shows the rotating shaft of the phase difference compensating plate in an application form. It is a figure which shows the contrast fall by the adjustment defect of a panel.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a configuration of a liquid crystal panel 10 to be inspected in the contrast inspection apparatus according to the embodiment. The liquid crystal panel 10 is a reflection type used as a light valve of a projector, and the display unit body 12 generates a modulated image in the display area when incident light from the upper side is reflected upward in the drawing. The display area is rectangular in plan view. The display unit body 12 is casing in a frame 14 having an open display area.

The display unit main body 12 is configured such that an electrode substrate is opposed to each other with a constant gap between an element substrate having individual pixel electrodes for each of a plurality of pixels and a counter substrate having a common electrode common to the plurality of pixels. And the liquid crystal is sandwiched between the gaps.
One end of an FPC (Flexible Printed Circuits) substrate 20 is connected to the display unit main body 12. A bare chip driver IC 22 is mounted on the FPC board 20 by COF (Chip On Film) technology, and a plurality of terminals 26 are provided in a terminal portion 24 opposite to one end connected to the display unit main body 12. Yes. When the terminal unit 24 is connected to the connector of the adjusting unit described later and various control signals and video signals are supplied from the adjusting unit via the terminal 26, the driver IC 22 drives the display unit body 12, Thus, the display unit body 12 is configured to generate a modulated image corresponding to the video signal.

FIG. 2 is a schematic diagram illustrating an optical system of the contrast inspection apparatus 1 according to the embodiment.
The contrast inspection apparatus 1 includes a light source 110, an optical member, and a light receiving unit 120. The optical member includes a first polarizer 40, a polarization beam splitter 50, a phase difference compensation plate 60, and a second polarizer 70. It has become.
Among these, the light source 110 is LED (Light Emitting Diode), for example, and irradiates light. The light source 110 is configured to emit light upward along the optical axis a in the drawing.

On the other hand, in the contrast inspection apparatus 1, the liquid crystal panel 10 to be inspected is set on an inspection jig (not shown). The inspection jig holds the liquid crystal panel 10 so as to be rotatable about the X axis 202, the Y axis 204, and the Z axis in FIG. Here, the X-axis 202 is an axis that passes through the diagonal center of the display area and extends along the length of the display area. The Y axis 204 is an axis that passes through the diagonal center of the display area and extends along the short side of the display area. The Z axis 206 is an axis that passes through the diagonal center of the display area and is normal to the display area.
Note that the actuator 32 shown in FIG. 2 rotates the liquid crystal panel 10 with respect to the X axis 202 in the inspection jig. Similarly, the actuators 34 and 36 rotate with respect to the Y axis 204 and the Z axis 206, respectively. The lower case x is a rotation angle around the X axis 202. Similarly, y and θ are rotation angles around the Y axis 204 and the Z axis 206, respectively.

The first polarizer 40 is disposed so as to be orthogonal to the optical axis a, and the transmission axis is rotatable with respect to the optical axis a. Here, the actuator 46 rotates the transmission axis of the first polarizer 40.
Note that θ for the first polarizer 40 is a rotation angle around the optical axis a.

The polarization beam splitter 50 is, for example, a plate-shaped wire grid polarizer, and transmits light in the P direction component that is one direction, and reflects light in the S direction component orthogonal to the P direction. As shown in FIG. 2, the polarization beam splitter 50 is set to be inclined 45 degrees counterclockwise with respect to the optical axis a, and S of the light incident from the direction of 12:00 (upper side) along the optical axis a. The light of the direction component is reflected along the optical axis b in the direction of 3 o'clock (right side).
The plate surface of the polarizing beam splitter 50 rotates with respect to the normal line c, and the transmission axis direction (reflection axis direction) can be adjusted. The actuator 56 rotates the polarization beam splitter 50. Θ for the polarizing beam splitter 50 is a rotation angle around the normal line c.

  The phase difference compensation plate 60 is set in a holding unit (not shown) when the liquid crystal panel 10 is inspected, and compensates for the phase difference of the liquid crystal panel 10 according to the rotation angle about the optical axis a. Note that a quarter-wave plate is set in the holding unit before the liquid crystal panel 10 is inspected.

FIG. 3 is a diagram illustrating each axis and rotation of the phase difference compensation plate 60 set in the holding unit.
As shown in this figure, the phase difference compensation plate 60 is held rotatably about the X axis 262, the Y axis 264, and the Z axis 266. Here, the X axis 262 and the Y axis 264 define the plate surface of the phase difference compensation plate 60 in two dimensions, and the Z axis 266 coincides with the optical axis a. In addition, even when the quarter wavelength plate is set in the holding unit, the quarter wavelength plate is similarly held rotatably around the X axis 262, the Y axis 264, and the Z axis 266. .
Further, x for the phase difference compensation plate 60 (or ¼ wavelength plate) is a rotation angle around the X axis 262. Similarly, y and θ are rotation angles around the Y axis 264 and the Z axis 266, respectively.

The second polarizer 70 is disposed so as to be orthogonal to the optical axis b, and the transmission axis is rotatable with respect to the optical axis b. Here, the actuator 76 rotates the transmission axis of the second polarizer 70.
Note that θ for the second polarizer 70 is a rotation angle around the optical axis b.

  The light receiving unit 120 includes a sensor 122. The sensor 122 receives light transmitted through the second polarizer 70 along the optical axis b, detects, for example, illuminance (amount of light flux per unit area) of the light, and outputs the illuminance information.

FIG. 4 is a diagram showing an electrical configuration of the contrast inspection apparatus 1.
As shown in this figure, the adjustment unit 80 includes a connector 82. The connector 82 is connected to the terminal portion 24 of the liquid crystal panel 10 to be inspected. The adjustment unit 80 controls the rotation of the actuators 32, 34, 36, 46, 56, 62, 64, 66, 76, and inputs the illuminance information of the light receiving unit 120 and is connected to the connector 82. A contrast (ratio) of 10 is output based on the illuminance information. It is not the contrast inspection apparatus 1 but another apparatus that determines whether or not the contrast is within a non-defective range.

  Next, the operation of the contrast inspection apparatus 1 will be described with reference to FIG. First, prior to the inspection of the liquid crystal panel 10, the position adjustment of each part is executed. Specifically, in step Sa1, a dummy panel in which a mirror (mirror) is casing is set instead of the liquid crystal panel 10 in the holding portion of the inspection jig, and a quarter wavelength is used instead of the phase difference compensation plate 60. The board is set. The set may be performed manually by the inspector, but a configuration in which the inspection apparatus automatically performs the setting is desirable.

  In step Sa2, the adjustment unit 80 controls the rotation of the actuators 32, 34, 46, 56, 66, and 76 to adjust the position of each unit. For example, the adjustment unit 80 selects one of the actuators and rotates only the selected actuator to search for a point where the illuminance information of the light receiving unit 120 is the maximum value or the minimum value. When the maximum value or minimum value is reached, the adjustment unit 80 sets the selected actuator to the point where the maximum value or minimum value is reached, and this time, selects another actuator, and similarly selects only the selected actuator. To search for a point at which the illuminance information has the maximum value or the minimum value. Thus, when all of the actuators are selected and the illuminance information is set to the maximum value in each of the actuators, the set position is a position where the light receiving unit 120 receives the light output from the light source 110 most efficiently. The relationship, that is, the arrangement shown in FIG.

Of the light emitted from the light source 110, the linearly polarized light in the P direction transmitted through the first polarizer 40 and the polarizing beam splitter 50 is converted into circularly polarized light in one direction (for example, clockwise) by the quarter wavelength plate. , Reflect on the mirror. Since this becomes circularly polarized light in the reverse direction (counterclockwise) at the time of this reflection, it is converted to linearly polarized light in the S direction when passing through the quarter wavelength plate again. For this reason, when the light receiving unit 120 has the positional relationship in which the light output from the light source 110 is most efficiently received, the P direction, which is the transmission axis of the polarizing beam splitter 50, is aligned with the transmission axis of the first polarizer 40. In addition, the transmission axis of the second polarizer 70 coincides with the S direction, which is the reflection axis of the polarization beam splitter 50.
This state is a state in which the illuminance information by the light receiving unit 120 is brightest. Unlike the liquid crystal panel 10, the mirror of the dummy panel does not have a modulation function. For this reason, the adjusting unit 80 rotates, for example, one of the first polarizer 40 and the second polarizer 70 around the Z axis from the current state to create a black state by the polarizers. Thereby, since the light receiving unit 120 outputs the darkest illuminance information, the adjusting unit 80 outputs the ratio between the highest value and the lowest value of brightness, that is, the contrast of the mirror. This contrast serves as a reference for the contrast measured by the liquid crystal panel 10.

When the positional relationship is such that the light from the light source 110 is received most efficiently, in step Sa3, the adjustment unit 80 prohibits the actuators 46, 56, and 76 from rotating thereafter. As a result, the first polarizer (PL) 40, the polarization beam splitter (PBF) 50, and the second polarizer (PL) 60 are each fixed without adjusting their positions.
Next, in step Sa4, the phase difference compensation plate 60 is set instead of the quarter wavelength plate. Subsequently, in step Sa5, the liquid crystal panel 10 to be inspected is set in the holding portion of the inspection jig instead of the dummy panel. The set in steps Sa4 and Sa5 may be performed manually by the inspector, but a configuration in which the inspection apparatus automatically performs is desirable.

In step Sa6, the adjustment unit 80 first supplies a video signal and a control signal for displaying a white image in which all of the pixels are white pixels, for example, to the liquid crystal panel 10 in which the terminal unit 24 is connected to the connector 82. To do.
Secondly, the adjustment unit 80 controls the rotation of the actuators 32, 34, and 36, that is, rotates the liquid crystal panel 10 by x rotation, y rotation, and θ rotation, and receives the light output from the light source 110 as the light receiving unit 120. Adjust to the point where the illuminance information output by is the highest. Thus, the liquid crystal panel 10 is adjusted to a position where the display area is perpendicular to the diagonal center with respect to the optical axis a.
Third, the adjustment unit 80 supplies the liquid crystal panel 10 with a video signal and a control signal for alternately displaying a white image and a black image.
Fourthly, the adjusting unit 80 applies the illuminance information when the white image is displayed and the illuminance information when the black image is displayed from the light receiving unit 120 (sensor 122) to the displayed black image. Find the brightness ratio of the white image.
Fifth, the adjustment unit 80 operates the actuator 66 to rotate the phase difference compensation plate 60 by a minute angle (for example, 0.2 degrees) (for example, clockwise as viewed from the light source 110).
Thereafter, the adjusting unit 80 repeats the third to fifth operations until the ratio reaches the maximum value. When this operation is repeatedly executed, the ratio of the brightness of the white image to the black image is obtained in the liquid crystal panel 10 while the phase difference compensation plate 60 rotates by a minute angle. When the ratio reaches the maximum value, it can be considered that the phase difference compensation plate 60 is adjusted to a point where the phase difference of the liquid crystal panel 10 is optimally compensated. For this reason, the adjustment unit 80 outputs the maximum value of the ratio as the contrast (ratio) of the liquid crystal panel 10.
Although the phase difference of the liquid crystal panel 10 varies from one individual to another, it is almost limited to a certain range. Therefore, it is not necessary to rotate the phase difference compensator 60 by knowing 360 degrees all around. For this reason, the time required for the inspection is short.

Next, in step Sa7, the liquid crystal panel 10 set on the holding part of the inspection jig is removed. The removal may be performed manually by the inspector, but a configuration in which the inspection apparatus automatically performs the removal is desirable.
Then, the processing procedure returns to step Sa5, and another liquid crystal panel 10 is set. Thereafter, steps Sa5 to Sa7 are repeatedly executed for each liquid crystal panel, and the contrast is obtained each time.

In this embodiment, prior to the inspection of the liquid crystal panel 10, a dummy panel having a mirror is set on the holding portion of the inspection jig, and the angles of the respective axes, that is, the rotation angles x and y of the liquid crystal panel 10, The rotation angle θ of the one polarizer 40, the rotation angle θ of the polarization beam splitter 50, the rotation angle θ of the quarter wave plate instead of the phase difference compensation plate 60, and the rotation angle θ of the second polarizer 70 A total of six rotation angles are adjusted in advance to optimum positions. When inspecting the liquid crystal panel 10, the Z axis (θ) of the liquid crystal panel 10, the rotation axes (θ) of the first polarizer 40, the polarization beam splitter 50, and the second polarizer 70, and the phase difference A total of six rotation axes including the X axis and the Y axis of the compensation plate 60 are fixed. Therefore, when the liquid crystal panel 10 is inspected, as shown by the solid line in FIG. 6, what is actually adjusted in the inspection of the liquid crystal panel 10 is the X axis, the Y axis, and the phase difference compensation plate There are only three rotation axes of the Z axis (θ) of 60, and the others are already adjusted to the optimum positions. Note that the X-axis and Y-axis of the phase difference compensation plate 60 are at the optimal positions because adjustment is not necessary in this embodiment.
Here, for example, when adjustment of one angle (one axis) requires 20 seconds (note that the rotation angle θ of the first polarizer 40, the rotation angle θ of the polarization beam splitter 50, and further the rotation of the second polarizer 70). Adjustment of the angle θ takes longer than 20 seconds, that is, the adjustment of these three axes takes 300 seconds or more because the optimum position cannot be determined unless the rotation angle θ is adjusted over several turns. In order to inspect the contrast, it is necessary to adjust six angles for each liquid crystal panel 10. For example, as shown in FIG. 8, if the angle around the Y axis of the liquid crystal panel 10 is deviated, a loss of light is generated before reaching the light receiving unit 120. This is because the contrast cannot be correctly inspected.
On the other hand, in this embodiment, when the mirror is first set, it takes 360 seconds (20 seconds × 3 + 300 seconds) to adjust the position of all six axes. Since only the three axes of the X axis and Y axis of the panel 10 and the Z axis (θ) of the phase difference compensation plate 60 are adjusted, 60 seconds (20 seconds × 20 seconds) per sheet of the liquid crystal panel 10 while maintaining the inspection accuracy. 3) is enough.
Therefore, according to the present embodiment, inspection efficiency can be greatly improved.

  In addition, when the liquid crystal panel 10 is set in the present embodiment, the rotation angle θ may not be adjusted with particular attention. This is because even if the phase difference direction of the liquid crystal panel 10 is different for each individual, it is corrected by adjusting the rotation angle θ that rotates the phase difference compensation plate 60 about the Z axis when the liquid crystal panel 10 is inspected.

The present invention is not limited to the above-described embodiments, and various applications and modifications are possible as follows.
The phase difference compensation plate 60 described above is a type in which the amount of phase difference compensation changes in accordance with the rotation angle θ about the Z axis that coincides with the optical axis a, but the phase difference compensation plate 60 of other types is also used. Application is also possible. For example, as shown in FIG. 7, the present invention can also be applied to a phase difference compensation plate 61 in which the phase difference compensation amount changes according to the rotation angle ψ of the optical axis 268 in the X and Y planes.
The optical axis 268 is a bisector of an angle formed by the X axis 262 and the Y axis 264, that is, an axis inclined by 45 degrees from the Y axis (X axis) on the plate surface of the phase difference compensation plate 61. Therefore, it is only necessary to hold the phase difference compensation plate 61 so that the axes (the fast axis, the slow axis, and the optical axis) coincide with the rotation axis of the holding unit. At this time, the adjustment unit 80 is preferably automatically switched so as to send a signal from the actuator 66 to the actuator 64 (62).
Even when the phase difference compensator 61 is used, it is necessary to replace the quarter wavelength plate before the inspection of the liquid crystal panel 10, so the rotational axis of the holder of the phase difference compensator 61 or the quarter wavelength plate is There are 4 axes. Further, when the contrast of the liquid crystal panel 10 is inspected, the phase difference compensation amount is adjusted by the rotation angle ψ.

  In the present invention, the inspection object may be a reflective liquid crystal panel, for example, a liquid crystal panel using a high temperature silicon process or a low temperature silicon process, or a so-called LCOS (Liquid) using a silicon substrate as an element substrate. Crystal on Silicon) type liquid crystal panel may be used.

DESCRIPTION OF SYMBOLS 1 ... Inspection apparatus, 10 ... Liquid crystal panel, 40 ... 1st polarizer, 50 ... Polarization beam splitter, 60 ... Phase difference compensation plate, 70 ... 2nd polarizer, 80 ... Adjustment part, 110 ... Light source, 120 ... Light receiving part .

Claims (4)

A light source that irradiates the inspection object with light;
A light receiving unit for receiving reflected light from the inspection object;
An optical member disposed on an optical axis from the light source to the inspection object, and from the inspection object to the light receiving unit;
A holding part that holds the optical member and each position of the inspection object in an adjustable manner with respect to the optical axis,
The optical member includes a first polarizer, a polarizing beam splitter, a phase difference compensation plate, and a second polarizing plate,
Irradiating the inspection object with light from the light source via the first polarizer, the polarization beam splitter, and the phase difference compensation plate;
The reflected light from the inspection object is received by the light receiving unit via the phase difference compensation plate, the polarization beam splitter, and the second polarizer,
An inspection method for inspecting the contrast of the inspection object based on reflected light received by the light receiving unit,
Before inspecting the panel to be inspected, hold a mirror instead of the panel, hold a quarter wave plate instead of the phase difference compensation plate, and adjust each position of the optical member,
When inspecting the panel to be inspected,
Instead of the mirror, hold the panel, hold the retardation compensation plate instead of the quarter-wave plate,
A contrast inspection method, wherein the position of the panel is adjusted, and the amount of phase difference compensation is adjusted according to the position of the phase difference compensation plate. An adjustment unit for adjusting each position of the first polarizing plate, the polarizing beam splitter, the phase difference compensation plate, the inspection object, and the second polarizing plate by the holding unit;
The said adjustment part prohibits adjustment of each position of a said 1st polarizing plate, the said polarizing beam splitter, and the said 2nd polarizing plate when test | inspecting the said panel to be examined. Contrast inspection method. The contrast adjustment method according to claim 2, wherein the adjustment unit adjusts to a point where the brightness of the light received by the light receiving unit is maximized. A light source that irradiates the inspection object with light;
A light receiving unit for receiving reflected light from the inspection object;
An optical member disposed on an optical axis from the light source to the inspection object, and from the inspection object to the light receiving unit;
A holding part that holds the optical member and each position of the inspection object in an adjustable manner with respect to the optical axis,
The optical member includes a first polarizer, a polarizing beam splitter, a phase difference compensation plate, and a second polarizing plate,
Irradiating the inspection object with light from the light source via the first polarizer, the polarization beam splitter, and the phase difference compensation plate;
The reflected light from the inspection object is received by the light receiving unit via the phase difference compensation plate, the polarization beam splitter, and the second polarizer,
An inspection apparatus for inspecting the contrast of the inspection object based on reflected light received by the light receiving unit,
Before inspecting the panel to be inspected, hold a mirror instead of the panel, hold a quarter wave plate instead of the phase difference compensation plate, and adjust each position of the optical member,
When inspecting the panel to be inspected,
Instead of the mirror, hold the panel, hold the retardation compensation plate instead of the quarter-wave plate,
The contrast inspection apparatus, wherein the position of the panel is adjusted and the amount of phase difference compensation is adjusted according to the position of the phase difference compensation plate.

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