Image display device
View Patent ↗To provide an image display device having a circuit for solving burning phenomenon without increasing the size of the circuit. An image display device is provided having a display unit formed using display devices, a signal line for inputting a display signal voltage to the display unit, and a display control unit for controlling the display signal voltage, the image display device comprising a detection power source, a switch for causing a current of the detection power source to flow to the display device, a detection circuit for detecting the current, and a detection information storage circuit for storing information, and compensating the display signal voltage, using the information, wherein using a first reference voltage, and current detection is carried out, the detection circuit feeds back the current detected to set a second reference voltage different from the first reference voltage, and carries out current detection.
1. An image display device having a display unit comprising a plurality of display elements, a signal line configured to input a display signal voltage to the display unit, and a display control unit configured to control the display signal voltage, the image display device comprising:
a detection power source;
a switch configured to cause current from the detection power source to flow to the display elements of the plurality of display elements;
a detection circuit configured to detect a characteristic of each display elements of the plurality of display elements if the current is flowing to the display elements of the plurality of display elements; and
a detection information storage circuit configured to store information detected by the detection circuit, the information being usable to compensate the display signal voltage;
wherein the detection circuit comprises an A/D converter, the A/D converter being configured to the characteristic of the display element from an analog value to a digital value, and
wherein the detection circuit is configured to detect the characteristic of each display element of the plurality of display elements by:
performing a first detection operation of detecting the characteristic of each display element included in a first group of display elements of the plurality of display elements sequentially, the first detection operation being performed using a first reference voltage range between a first upper reference voltage and a first lower reference voltage applied to the A/D converter;
determining a second upper reference voltage based on a maximum characteristic value of the characteristics among the characteristics detected of the display elements of the first group of display elements;
determining a second lower reference voltage based on a minimum characteristic value of the characteristics among the characteristics detected of the display elements of the first group of display elements;
performing a second detection operation of detecting the characteristic of each display element of the first group of display elements, the second detection operation being performed under a common temperature condition with the first detection operation, the second detection operation being performed using a second reference voltage range between the second upper reference voltage and the second lower reference voltage applied to the A/D converter, the second reference voltage range being different from the first reference voltage range; and
outputting the characteristic of each display element of the first group of display elements detected during the second detection operation to the detection information storage circuit to be stored as the information detected by the detection circuit and used for compensating the display signal voltage.
2. The image display device according to claim 1 , wherein the switch is configured to connect the detection power source and at least one display element of the plurality of display elements during a period within one display period, the period being different from a period during which the display signal voltage is output.
3. The image display device according to claim 1 , wherein the detection power source is a constant current source, and the characteristic of each display element of the plurality of display elements is a voltage across a respective display element.
4. The image display device according to claim 1 , wherein the detection circuit is configured to determine a level of a deteriorated display element of the plurality of display elements, and the detection information storage circuit is configured to store a state of the deteriorated display element of the plurality of display element for one screen image based on the determined level.
5. The image display device according to claim 4 , wherein the display control circuit is configured to correct display data to be input to the deteriorated display element of the plurality of display elements.
6. The image display device according to claim 1 , further comprising
a switch configured to cause, in a time sharing manner, respective signals for red, green, and blue to be input to the display unit while the display signal voltage is input.
7. The image display device according to claim 1 , wherein the first detection operation is a temperature detection operation and wherein the second detection operation is a burning detection operation based on results obtained from the temperature detection operation.
8. An image display device having a display unit comprising a plurality of display elements, a data signal line configured to input a display signal voltage to the display unit, and a display control unit configured to control the display signal voltage, the image display device comprising:
a detection power source;
a switch configured to cause current from the detection power source to flow via a detection signal line to the display elements of the plurality of display elements;
a detection circuit configured to detect a characteristic of each display elements of the plurality of display elements if the current is flowing to the display elements of the plurality of display elements; and
a detection information storage circuit configured to store information detected by the detection circuit, the information being usable to compensate the display signal voltage;
wherein the data signal line and the detection signal line comprise a common signal line to be switched by a switching circuit,
wherein the detection circuit comprises an A/D converter, the A/D converter being configured to the characteristic of the display element from an analog value to a digital value, and
wherein the detection circuit is configured to detect the characteristic of each display element of the plurality of display elements by:
performing a first detection operation of detecting the characteristic of each display element included in a first group of display elements of the plurality of display elements sequentially, the first detection operation being performed using a first reference voltage range between a first upper reference voltage and a first lower reference voltage applied to the A/D converter;
determining a second upper reference voltage based on a maximum characteristic value of the characteristics among the characteristics detected of the display elements of the first group of display elements;
determining a second lower reference voltage based on a minimum characteristic value of the characteristics among the characteristics detected of the display elements of the first group of display elements;
performing a second detection operation of detecting the characteristic of each display element of the first group of display elements, the second detection operation being performed under a common temperature condition with the first detection operation, the second detection operation being performed using a second reference voltage range between the second upper reference voltage and the second lower reference voltage applied to the A/D converter, the second reference voltage range being different from the first reference voltage range; and
outputting the characteristic of each display element of the first group of display elements detected during the second detection operation to the detection information storage circuit to be stored as the information detected by the detection circuit and used for compensating the display signal voltage.
9. The image display device according to claim 8 , wherein the switch is configured to connect the detection power source and at least one display element of the plurality of display elements during a period within one display period, the period being different from a period during which the display signal voltage is output.
10. The image display device according to claim 8 , wherein the detection power source is a constant current source, and the characteristic of each display element of the plurality of display elements is a voltage across a respective display element.
11. The image display device according to claim 8 , wherein the detection circuit is configured to determine a level of a deteriorated display element of the plurality of display elements, and the detection information storage circuit is configured to store a state of the deteriorated display element of the plurality of display element for one screen image based on the determined level.
12. The image display device according to claim 11 , wherein the display control circuit is configured to correct display data to be input to the deteriorated display element of the plurality of display elements.
13. The image display device according to claim 8 , further comprising
a switch configured to cause, in a time sharing manner, respective signals for red, green, and blue to be input to the display unit while the display signal voltage is input.
14. The image display device according to claim 8 , wherein the first detection operation is a temperature detection operation and wherein the second detection operation is a burning detection operation based on results obtained from the temperature detection operation.