JP4372378B2 - Method and apparatus for inspecting liquid crystal display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display element inspection method and apparatus.
[0002]
[Prior art]
Light, thin and flat liquid crystal display elements are used in many fields. Liquid crystal display elements used in various places such as personal computers, AV equipment, in-vehicle navigation, games, viewfinders, watches, etc., are classified into a reflection direct view type, a transmission type, a transmission reflection type, a projection type, and the like according to the operation method.
[0003]
The principle of the liquid crystal display element is well known, but the most representative field effect type TN (twisted nematic) type liquid crystal display element will be described. FIG. 1 is a conceptual diagram showing a state where an electric field is not applied to the TN type liquid crystal display element, and FIG. 2 is a conceptual diagram showing a state where an electric field is applied to the TN type liquid crystal display element.
[0004]
As shown in FIG. 1, the liquid crystal molecules are twisted and aligned according to the alignment direction of the surfaces of both substrates. When two polarizing plates are placed perpendicular to each other with the liquid crystal layer sandwiched, the light passing through the upper polarizing plate rotates along the twist of the liquid crystal molecules due to the optical anisotropy effect of the liquid crystal molecules and passes through the lower polarizing plate. Therefore, it is visually recognized as a bright state. When an electric field is applied to the liquid crystal layer, as shown in FIG. 2, the twisted orientation of the liquid crystal molecules is released and there is no effect of rotating the polarization plane, and the incident light is blocked by the lower polarizing plate and becomes dark.
[0005]
In manufacturing a liquid crystal display element, there is a step of inspecting whether the liquid crystal display element operates normally. The liquid crystal display element alone checks the polarization / non-polarization operation. In order to confirm the operation, the liquid crystal display element is irradiated with light, the liquid crystal display element is turned on / off, and the video signal is captured. Was automatically checked by counting the blinking of light from the liquid crystal display element.
[0006]
FIG. 3 is a block diagram for confirming the operation of the liquid crystal display element. The transmissive liquid crystal display element 1 is driven by the circuit 2. Light is emitted from the light source 3 to the liquid crystal display element 1. When the liquid crystal display element is turned ON / OFF by the circuit 2, light is transmitted and blocked by the shutter effect of the liquid crystal display element 1. The liquid crystal display element 1 is imaged by the camera 4, the video signal output from the camera 4 is processed by the image processing device 5, and the determination circuit 7 confirms whether or not the liquid crystal display element 1 has been turned ON / OFF a predetermined number of times. A pass / fail of 1 is determined. Reference numeral 6 denotes a monitor of the image processing apparatus 5.
[0007]
[Problems to be solved by the invention]
When the image processing apparatus is used in the inspection method as described above, specialized knowledge is required for changing the program of the image processing apparatus, and maintenance and inspection condition change at the time of trouble cannot be easily performed.
[0008]
An image processing apparatus is expensive, and it takes time and money to construct an inspection system.
[0009]
[Means for Solving the Problems]
At least, an imaging comprising the steps of Ru was repeated transmission and blocking of light by the shutter effect screen of the liquid crystal display device while irradiating light to the liquid crystal display element is periodically ON-OFF, the light from the liquid crystal display device and a step of displaying on the monitor, and a step of detecting by a photoelectric sensor the brightness change of the monitor, the quality of the liquid crystal display device by measuring the number of blinks of the liquid crystal display device based on the output of the photoelectric sensor determination And a liquid crystal display element inspection method.
[0010]
At least, imaging a light source for irradiating light to the liquid crystal display device, a circuit Ru was repeated transmission and blocking of light by the shutter effect screen of the liquid crystal display device is periodically ON-OFF, the liquid crystal display device The liquid crystal display by measuring an imaging device, a monitor that displays an output from the imaging device, a photoelectric sensor that detects a change in brightness of the monitor, and the number of blinks of the liquid crystal display element based on the output of the photoelectric sensor An inspection apparatus for a liquid crystal display element comprising a determination circuit for determining the quality of the element.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 4 is a block diagram for explaining the inspection method of the liquid crystal display element of the present invention, and shows the configuration of the inspection apparatus. The transmissive liquid crystal display element 1 is driven by the circuit 2. Light is emitted from the light source 3 to the liquid crystal display element 1. When the liquid crystal display element 1 is periodically turned on and off by the circuit 2 and the entire screen is repeatedly turned on and off, light is repeatedly transmitted and blocked by the shutter effect of the liquid crystal display element 1. The liquid crystal display element 1 is imaged by the camera 4, and a video signal output from the camera 4 is displayed on the monitor 6. Since the liquid crystal display element 1 is displayed on the monitor 6, the monitor 6 repeatedly displays light and dark. The monitor 6 is preferably a self-luminous display device, particularly a cathode ray tube. A photoelectric sensor 8 is disposed in front of the cathode ray tube as means for detecting a change in brightness of the cathode ray tube, and the output of the photoelectric sensor 8 is output to the determination circuit 7 through the amplifier 9. The determination circuit 7 counts the output from the amplifier 9 to check whether the liquid crystal display element 1 has been turned ON / OFF a specified number of times, thereby determining whether the liquid crystal display element 1 is good or bad.
[0012]
FIG. 5 shows a counter circuit used in the determination circuit. The counter receives a reset signal from the CPU simultaneously with the start input. The output 9A from the amplifier 9 is input to the counter circuit 7A. The counter circuit 7A has a predetermined number N set in advance, and when the counter circuit 7A counts N times, an OK signal 7B is output.
[0013]
FIG. 6 is a block diagram for explaining an inspection method when the liquid crystal display element is of a reflective type, and shows a part of the configuration of the inspection apparatus. The reflective liquid crystal display element 10 is driven by the circuit 2. Light from the light source 3 is reflected by the half mirror 11 and applied to the reflective liquid crystal display element 10. When the reflective liquid crystal display element 10 is turned ON / OFF by the circuit 2, light is reflected / blocked by the shutter effect of the reflective liquid crystal display element 10. The imaging of the reflective liquid crystal display element 10 by the camera 4 and the display of the video signal output from the camera 4 on the monitor is the same as in the inspection apparatus for the transmissive liquid crystal display element.
[0014]
FIG. 7 is an inspection flowchart of the liquid crystal display element inspection apparatus according to the present invention. When the inspection is started, the photoelectric sensor detects a change in brightness of the monitor. The output signal that has detected a change in brightness is amplified by an amplifier and input to the determination circuit 7. The determination circuit 7 includes a signal detection circuit, a counting circuit, a count value coincidence detection circuit, and a specified time timer. The signal input to the determination circuit is input to the signal detection circuit. The detected signal is input to the counting circuit and counted. The number counted by the counting circuit is compared by the count value coincidence detection circuit, and if it matches the set value, a non-defective product is determined. Thus, the inspection of one product is completed. Further, the counter is reset to the set value N at the next measurement start signal.
[0015]
If no signal is detected by the signal detection circuit, a failure is determined when the set time of the specified time timer elapses. Further, even when the coincidence detection signal (non-defective product determination) is not output from the count value coincidence detection circuit, the failure determination is made after the set time of the specified time timer has elapsed.
[0016]
【The invention's effect】
According to the inspection method for a liquid crystal display element of the present invention, since the polarization state of the liquid crystal display element can be inspected by replacing it with the light and darkness of the cathode ray tube, the quality of the liquid crystal display element can be easily determined.
[0017]
According to the liquid crystal display element inspection apparatus of the present invention, since the polarization state of the liquid crystal display element can be inspected by the photoelectric sensor, an image processing apparatus is not required and an inexpensive liquid crystal display element inspection apparatus can be obtained.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a state where an electric field is not applied to a TN type liquid crystal display element. FIG. 2 is a conceptual diagram showing a state where an electric field is applied to a TN type liquid crystal display element. FIG. 4 is a block diagram for explaining an inspection method for a liquid crystal display element of the present invention. FIG. 5 is a counter circuit used in a determination circuit. FIG. 6 is an inspection when the liquid crystal display element is a reflection type. FIG. 7 is a block diagram for explaining the method. FIG. 7 is an inspection flowchart of the liquid crystal display element inspection apparatus according to the invention.
DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 2 Circuit 3 Light source 4 Camera 5 Image processing apparatus 6 Monitor 7 Judgment circuit 7A Counter circuit 7B OK signal 8 Light-dark change detection means (photoelectric sensor)
9 Amplifier 9A Output from amplifier 10 Reflective liquid crystal display element 11 Half mirror

Claims (2)

At least, an imaging comprising the steps of Ru was repeated transmission and blocking of light by the shutter effect screen of the liquid crystal display device while irradiating light to the liquid crystal display element is periodically ON-OFF, the light from the liquid crystal display device and a step of displaying on the monitor, and a step of detecting by a photoelectric sensor the brightness change of the monitor, the quality of the liquid crystal display device by measuring the number of blinks of the liquid crystal display device based on the output of the photoelectric sensor determination And a liquid crystal display element inspection method. At least, imaging a light source for irradiating light to the liquid crystal display device, a circuit Ru was repeated transmission and blocking of light by the shutter effect screen of the liquid crystal display device is periodically ON-OFF, the liquid crystal display device The liquid crystal display by measuring an imaging device, a monitor that displays an output from the imaging device, a photoelectric sensor that detects a change in brightness of the monitor, and the number of blinks of the liquid crystal display element based on the output of the photoelectric sensor An inspection apparatus for a liquid crystal display element, comprising: a determination circuit that determines whether the element is good or bad.

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