JPH06130920A - Automatic adjusting device for liquid crystal display panel - Google Patents

Abstract

PURPOSE:To automatically set flickers and contrasts at a good state by automatically adjusting the plural trimmers provided in a liquid crystal display panel. CONSTITUTION:An adjusting mechanism 50 for rotating the trimmers and an optical unit 20 are disposed near the liquid crystal display panel. The transmitted light emitted from liquid crystal display panel is condensed onto the surface of an on optical sensor 22 by a condenser lens 21 and the level of the transmitted light is detected by the optical sensor 22. The detection signal alpha outputted from the optical sensor 22 is subjected to signal processing in a signal processing circuit 30. The AC components of the detection signal are extracted at the time of the flicker adjustment. On the other hand, the DC components of the detection signal are extracted at the time of the contrast adjustment. A control circuit 40 is a circuit for forming an instruction for moving the adjusting mechanism 50 and determines the rotating angle of the corresponding trimmer according to the output signal of the signal processing circuit 30 after specifying the trimmer to be rotated according to the kind to be adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel automatic adjustment device for automatically adjusting a plurality of trimmers provided in a liquid crystal display panel to automatically set flicker and contrast to a good condition.

[0002]

2. Description of the Related Art In an active matrix type liquid crystal display panel or the like used in a liquid crystal television receiver, an AC voltage which is inverted in a field cycle is applied between a pixel electrode and a counter electrode. However, it is known that the transistor for driving the pixel electrode has variations in characteristics, and the AC voltage of the counter electrode deviates from the inversion center voltage, causing flicker in the liquid crystal display panel.

Therefore, in order to prevent the display quality of the liquid crystal display panel from deteriorating, the substrate is adjusted before shipment of the liquid crystal display panel so that there is no flicker. At this time, the contrast of the liquid crystal display panel is adjusted at the same time.

Conventionally, a method has been adopted in which the presence or absence of flicker and the degree of contrast are visually checked by an inspector, and when the inspector determines that it is necessary, the liquid crystal display panel is adjusted by himself. Further, JP-A 1-269991 (Japanese Patent Application No.
It is also possible to quantitatively measure the degree of flicker and contrast using the measuring device described in (63-98964), and the inspector can adjust the liquid crystal display panel based on the measurement result. It is also conceivable to use a camera instead of the measuring device.

[0005]

However, in the method that relies on the visual inspection of the inspector, it is not possible to accurately grasp the presence or absence of flicker and the degree of contrast due to individual differences and the brightness of the background, so it is necessary to make appropriate adjustments. Is impossible. Further, in the method using the above measuring device, not only the influence of the ambient light from the optical sensor but also the noise component is large because the peak and bottom hold circuits perform signal processing, and the degree of flicker and contrast can be accurately measured. It is difficult to do so, and in practice it is difficult to make appropriate adjustments. Furthermore, although the method using a camera is less susceptible to the influence of ambient light, it is also unsuitable for flicker measurement due to the long image signal capturing period, and the same as above can be said.

The present invention was created in view of the above background, and an object of the present invention is to provide a liquid crystal display panel automatic adjusting device capable of setting flicker and contrast in good condition. It is in.

[0007]

The liquid crystal display panel automatic adjusting device according to the present invention is an adjusting mechanism for rotating a trimmer, and a transmitted light emitted from the liquid crystal display panel is condensed on a surface of an optical sensor by a condenser lens. An optical unit that detects the level of transmitted light by a light sensor and a circuit that processes the detection signal output from the optical sensor. When the flicker adjustment is performed, the AC component of the detection signal is extracted while the contrast adjustment is performed. A signal processing circuit for extracting the DC component of the detection signal and a circuit for generating an instruction for moving the adjustment mechanism, which specifies the trimmer to be rotated according to the type of adjustment, and then responds to the output signal of the signal processing circuit. And a control circuit for determining the rotation angle of the trimmer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a liquid crystal display panel automatic adjusting device according to the present invention will be described below with reference to the drawings. 1 is a block diagram of a liquid crystal display panel automatic adjustment device, FIG. 2 is a block diagram of a signal processing circuit, FIG. 3 is a diagram showing an AC component of a detection signal at the time of flicker adjustment, and FIG. 4 is a P of the AC component of the detection signal.
FIG. 5 is a cross-sectional view of the liquid crystal display panel 10, FIG. 6 is a view showing an inversion signal and a detection signal of the optical sensor, and FIG. 7 is a detection signal at the time of contrast adjustment. It is a figure which shows a DC component.

The liquid crystal display panel automatic adjusting apparatus listed here measures the presence or absence of flicker and the degree of contrast of an active matrix type liquid crystal display panel used in a liquid crystal television receiver, and the liquid crystal is measured according to the measurement result. A plurality of trimmers provided on the display panel are automatically adjusted to set flicker and contrast in good condition. The schematic configuration is shown in FIG.

Reference numeral 10 in the figure denotes a liquid crystal display panel set in the apparatus. In this state, the liquid crystal display panel 10 is energized.
In this embodiment, the backlight type is assumed, but other reflective type or the like can be applied.

An optical unit 20 is arranged so as to face the liquid crystal display panel 10. The optical unit 20 is a condenser lens
It is composed of 21 and an optical sensor 22, and a liquid crystal display panel 10
The transmitted light emitted from the optical system is condensed on the surface of the optical sensor 22 by the condenser lens 21, and the level of the transmitted light is detected by the optical sensor 22.

In this embodiment, in order to reduce the size of the device as a whole, only a part of the screen projected on the liquid crystal display panel 10 is taken into the optical sensor 22.

The detection signal α output from the optical sensor 22 is guided to the control circuit 40 through the signal processing circuit 30. First, the signal processing circuit 30 will be described with reference to FIG.

The signal processing circuit 30 includes an AC / DC signal switch 3
4, high-pass filter 31, low-pass filter 32, A / D
It is composed of a converter 33. AC / DC signal switch 34
Is a circuit for switching the detection signal α, and the contact output changes according to the setting of flicker adjustment or contrast adjustment.

The high-pass filter 31 is a circuit that removes the DC level contained in the detection signal α and extracts the AC component. The low-pass filter 32 is a circuit that removes spike-like noise components included in the detection signal α and extracts DC components. The A / D converter 33 is a circuit that digitally converts the signal that has passed through the low-pass filter 32 at a predetermined sampling period.

Returning to FIG. 1, the control circuit 40 will be described. The control circuit 40 is composed of a CPU unit 41 and a servo control unit 42, and is adapted to generate a command for moving an adjusting mechanism 50 arranged near the optical unit 20. The CPU unit 41 is prepared in advance with information as to what trimmer should be rotated according to the type of adjustment.

The adjusting mechanism 50 comprises an XY table 51 and an adjusting driver mechanism 52. XY table 51
By this operation, the tip of the driver portion of the adjusting driver mechanism 52 is positioned at the adjusting position of a trimmer (not shown) provided in the liquid crystal display panel 10. When the positioning is completed, the driver portion is rotated by the operation of the adjusting driver mechanism 52, and the trimmer is rotated.

Next, the operation of the liquid crystal display panel automatic adjusting device configured as described above will be described. In this embodiment, in order to perform highly accurate adjustment, contrast adjustment is first performed, and then flicker adjustment is subsequently performed.

At the time of flicker adjustment, the AC / DC signal switch 34 is switched to the AC side, the detection signal α is processed through the high pass filter 31, the low pass filter 32, and the A / D converter 33 in this order, and the detection signal α is AC. The components are extracted.
This signal is digitally introduced to the CPU unit 41. The CPU unit 41 sequentially obtains the P-P value of the AC component of the detection signal α (see FIG. 3).

On the other hand, the CPU unit 41 has in advance information on what trimmer should be rotated when performing flicker adjustment. Therefore, the trimmer is specified based on this information, and the XY table 51 is specified through the servo control unit 42.
Is operated to position the tip of the driver portion of the adjusting driver mechanism 52 at the adjusting position of the trimmer. After that, the adjusting driver mechanism 52 is operated to rotate the trimmer, but it is stopped when the PP value of the AC component of the detection signal α is the lowest (see FIG. 3). By determining the rotation angle of the trimmer in this way, the flicker adjustment of the liquid crystal display panel 10 is appropriately performed.

The cause of flicker on the liquid crystal display panel 10 will be described. FIG. 5 is a sectional view of the liquid crystal display panel 10. In the figure, 11 and 17 are upper and lower deflection plates, 12 and 16 are upper and lower glasses, 13 counter electrodes, 15 is a pixel driving transistor, 14 is a liquid crystal, and 18 is a backlight.

FIG. 6A is a diagram showing the relationship between the inversion signal applied to the counter electrode and the potential of the pixel driving transistor. 6B to 6D are diagrams showing detection signals of the optical sensor. As shown in FIG. 6A, if the potential of the picture element drive transistor 15 is at the level of L1 shown by the solid line (center voltage of the inverted signal), an AC voltage having a positive peak value and a negative peak value is equal to the picture voltage. Since it is applied to the element driving transistor 52, flicker does not occur. At this time, the light transmission outputs in the t1 cycle and the t2 cycle are equal, and the level of the detection signal of the optical sensor 22 is low and the positive and negative peaks are also equal, as shown in FIG. 6B.

However, if the potential of the pixel driving transistor 15 is L2 and L3 shown by the broken line, an AC voltage having a positive peak value and a negative peak value that are significantly different from each other is applied to the pixel driving transistor 52, and flicker occurs. Occurs. That is, t1
The light transmission outputs of the cycle and t2 cycle are not equal, the level of the detection signal of the optical sensor 22 is high, and the positive and negative peak values are significantly different as shown in FIGS.

In this embodiment, the trimming driver mechanism 52 rotates the trimmer and stops it when the PP value of the AC component of the detection signal α is minimum. In other words, FIG.
As shown in (a), an AC voltage is applied to the picture element drive transistor 15 such that the potential of the picture element drive transistor 15 becomes the level of L1 shown by the solid line. Therefore, the flicker adjustment can be surely performed.

Next, the contrast adjustment will be described.
For contrast adjustment, AC / DC signal switch 34
Is switched to the DC side, and the detection signal α is a low-pass filter
32 and the A / D converter 33 are sequentially processed to extract the DC component of the detection signal α (see FIG. 7). This signal is digitally sequentially introduced to the CPU unit 41.

On the other hand, the CPU unit 41 has in advance information about what kind of trimmer should be rotated when performing contrast adjustment. Therefore, the trimmer is specified based on this information and flicker adjustment is performed in exactly the same manner as in the case of adjustment. The front end of the driver portion of the driver mechanism 52 is positioned at the trimmer adjustment position. After that, the adjusting driver mechanism 52 is operated to rotate the trimmer, but D of the detection signal α
It is stopped when the C component reaches a predetermined set value. In this way, the rotation angle of the trimmer is determined. Therefore,
The contrast of the liquid crystal display panel 10 is adjusted reliably.

Needless to say, the liquid crystal display panel automatic adjusting apparatus according to the present invention is not limited to the application to the active matrix type liquid crystal display panel.

[0028]

As described above, the liquid crystal display panel automatic adjusting device according to the present invention is affected by ambient light by condensing the transmitted light of the liquid crystal display panel on the surface of the photosensor using the condenser lens. In addition, since the detection signal of the optical sensor is appropriately signal-processed according to the type to be adjusted, the state of flicker and contrast can be accurately measured. Moreover, since the trimmer of the liquid crystal display panel is automatically rotated based on the measurement result, the flicker and the contrast of the liquid crystal display panel are set in good condition.

[Brief description of drawings]

FIG. 1 is a block diagram of a liquid crystal display panel automatic adjustment device.

FIG. 2 is a configuration diagram of a signal processing circuit.

FIG. 3 is a diagram showing an AC component of a detection signal during flicker adjustment.

FIG. 4 is a diagram showing a relationship between a PP value of an AC component of a detection signal and a trimmer rotation angle.

FIG. 5 is a cross-sectional view of a liquid crystal display panel.

FIG. 6 is a diagram showing an inversion signal and a detection signal of an optical sensor.

FIG. 7 is a diagram showing a DC component of a detection signal at the time of contrast adjustment.

[Explanation of symbols]

 10 Liquid crystal display panel 20 Optical unit 21 Condenser lens 22 Optical sensor 30 Signal processing circuit 40 Control circuit 50 Adjustment mechanism

Claims (1)

[Claims] 1. A liquid crystal display panel automatic adjusting device for automatically adjusting a plurality of trimmers provided in a liquid crystal display panel to set flicker and contrast in a good state, and an adjusting mechanism for rotating the trimmer and the liquid crystal. An optical unit that collects the transmitted light emitted from the display panel on the surface of the optical sensor by a condenser lens and detects the level of the transmitted light by the optical sensor, and a circuit that processes the detection signal output from the optical sensor. A signal processing circuit that extracts the AC component of the detection signal during flicker adjustment, and a DC component of the detection signal during contrast adjustment, and a circuit that generates a command for operating the adjustment mechanism. After specifying the trimmer to be rotated according to the type of adjustment, the trimmer is rotated according to the output signal of the signal processing circuit. A liquid crystal display panel automatic adjusting device, comprising: