Image display device
View Patent ↗The present invention provides an image display device that reduces variations in brightness of the light emitting elements included in the device due to a voltage drop on the power source line of the device and TFT threshold voltage variations and displays good quality images. The image display device is equipped with a pixel circuit voltage detecting means to selectively output a voltage internal to a pixel circuit included in each of a plurality of pixels of the device to a signal line to which the pixel circuit connects. Its drive circuit is equipped with a voltage addition means to add the signal line voltage and a signal voltage corresponding to image data to be displayed and output a sum voltage to the signal line again.
1. An image display device comprising:
an image display portion in which a plurality of pixels are arranged in a matrix;
a plurality of signal lines wired in said image display portion to carry a voltage signal to said pixels; and
a drive circuit to control voltage on each said signal line,
wherein each said pixel comprises a light emitting element and a pixel circuit which controls the intensity of light emission of said light emitting element,
the image display device is equipped with a pixel circuit voltage detecting circuit for placing the pixel circuit included in each said pixel in at least one of a disconnection state from said signal line, a connection state to said signal line, and resistive connection state wherein said pixel circuit connects to said signal line with a sufficiently higher value of resistance than in said connection state, and
the image display device is equipped with a voltage addition means to add the voltage on said signal line and a signal voltage corresponding to image data to be displayed and output a sum voltage to said signal line again.
2. The image display device according to claim 1 , wherein: said pixel circuit voltage detecting means comprises a resistor and switching transistors connected in parallel to the resistor.
3. The image display device according to claim 1 , wherein: said pixel circuit is equipped with a current holding circuit to supply a constant current to said light emitting element.
4. The image display device according to claim 1 , wherein: said drive circuit comprises a sampling circuit to hold the voltage on said signal line and an adder circuit to add the voltage thus held and an image signal voltage.
5. The image display device according to claim 1 , wherein: said drive circuit comprises a driver IC to output an analog voltage and a capacitor connected between said driver IC and said signal line.
6. The image display device according to claim 1 , wherein: said light emitting element is a light-emitting diode element.
7. The image display device according to claim 1 , wherein: said pixel circuit and said pixel circuit voltage detecting means are configured with thin-film transistors.
8. The image display device according to claim 7 , wherein: said pixel circuit is configured with either n-channel or p-channel thin-film transistors.
9. An image display device comprising:
an image display portion in which, a plurality of pixels are arranged in a matrix;
a plurality of signal lines wired in said image display portion to carry a voltage signal to said pixels; and
a drive circuit to control an analog voltage on each said signal line, wherein each said pixel comprises a light emitting element and a pixel circuit which controls the intensity of light emission of said light emitting element, and
the image display device further includes a plurality of resistive wiring lines having a higher value of resistance than said signal lines and wired in parallel with said signal lines, a plurality of first switching means to control connection between each said signal line and each said resistive wiring line, and a plurality of second switching means to control connection between each said resistive wiring line and each said pixel circuit.
10. The image display device according to claim 9 , wherein:
said drive circuit is equipped with a voltage addition means to add the voltage on said signal line and a signal voltage corresponding to image data to be displayed and output a sum voltage to said signal line again.
11. The image display device according to claim 9 , wherein: the image display device is equipped with a control circuit which controls said first and second switching means to change a value of resistance between said signal line and said pixel circuit in at least two levels.
12. The image display device according to claim 9 , wherein: said signal line and said resistive wiring line are formed so as to be overlapped in a region and isolated by an insulation layer which is formed therebetween.
13. The image display device according to claim 9 , wherein: said resistive wiring line is made of a polycrystalline silicon thin film.
14. The image display device according to claim 9 , wherein: said light emitting element is a light-emitting diode element.
15. The image display device according to claim 9 , wherein: said pixel circuit and said first and second switching means are configured with thin-film transistors.
16. The image display device according to claim 15 , wherein: said pixel circuit is configured with either n-channel or p-channel thin-film transistors.