US 5,293,178 AGranted

Display screen inspecting apparatus

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorAkira Kobayashi

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Abstract

A display screen inspecting apparatus is for inspecting a display screen of a liquid crystal display having image density which changes in proportion to change of a driving voltage applied to the display screen. A driving voltage changing device changes the driving voltage to actuate the display screen, an image pick-up device picks up an image of a displaying state of the display screen driven with different driving voltages, a storage device stores image data related to the image density of images picked up by the image pick-up device when different driving voltages are applied to the display screen, an image density ratio operating/storing device determines and stores a ratio of the image density of the images stored by the storage device, and a deciding device decides whether the display screen is acceptable or unacceptable on the basis of change of the image density ratio.

Claims5

Dependent claims

A display screen inspecting apparatus for inspecting a liquid crystal display having an image density which varies in proportion to a change in a drive voltage applied to the liquid crystal display, said apparatus comprising:

drive voltage varying means for applying plural different drive voltages to the liquid crystal display to obtain respective plural images on the liquid crystal display having different image densities;
image pick-up means for picking up an image of the respective plural images on the liquid crystal display having different image densities;
storage means for storing data indicative of the different image densities of the plural images picked up by said image pick-up means;
image density ratio means for determining a ratio of the different image densities stored in said storage means and for storing the thus determined image density ratio;
decision means for determining an acceptability of the liquid crystal display based on an extent of a variance in the image density ratio stored in said image density ratio means.

2 more elements

Dependencies are inferred from the claim text.