Driver of display unit
View Patent ↗According to one aspect of the present invention, there is provided a driver of a display unit including a latch circuit holding gradation information, a D/A converter outputting analog signal based on the gradation information held by the latch circuit, a test circuit provided between the latch circuit and the D/A converter, the test circuit inputting or outputting test signal regarding the latch circuit, a switch connecting voltage output of the D/A converter and a driver output terminal in normal operation, and a test switch connecting the test circuit and the driver output terminal in test operation and disconnecting the test circuit and the driver output terminal in normal operation.
1. A driver of a display unit, said driver comprising:
a latch circuit holding gradation information;
a D/A converter outputting an analog signal based on the gradation information held by the latch circuit;
a test circuit provided between the latch circuit and the D/A converter, the test circuit inputting or outputting a test signal regarding the latch circuit;
a switch connecting a positive voltage output of the D/A converter and a first driver output terminal and connecting a negative voltage output and a second driver output terminal in a normal operation; and
a test switch feeding back the first driver output terminal and the second driver output terminal to the test circuit in a test operation and disconnecting the test circuit and the first driver output terminal and the second driver output terminal in said normal operation.
2. The driver of the display unit according to claim 1 , further comprising an amplifier amplifying the analog signal,
wherein the switch sets an output stage in said test operation to a deactivation state.
3. The driver of the display unit according to claim 1 , further comprising an amplifier amplifying the analog signal,
wherein the test switch applies the test signal to an output stage of the amplifier in said test operation.
4. The driver of the display unit according to claim 1 , wherein the switch comprises a switching circuit outputting a positive voltage output of the D/A converter to a first driver output terminal and outputting a negative voltage output of the D/A converter to a second driver output terminal.
5. The driver of the display unit according to claim 1 , wherein the test circuit detects a match or a mismatch between sets of data.
6. The driver of the display unit according to claim 1 ,
wherein the test circuit is connected to a test signal line,
wherein the test signal comprises a low-level signal during said normal operation, and
wherein the test signal comprises a high-level signal during said test operation.
7. The driver of the display unit according to claim 1 , wherein the test circuit comprises a plurality of switches and said plurality of switches is controlled by test data.
8. The driver of the display unit according to claim 7 , wherein the plurality of switches comprises a first-stage switch, a second-stage switch, and a third-stage switch.
9. The driver of the display unit according to claim 1 , wherein said normal operation comprises an output driving period and a panel charge collecting period.
10. The driver of the display unit according to claim 8 , wherein when the test data is in a low level, a first input terminal input terminals of the first-stage switch is connected to an output terminal of the first stage switch, and
when the test data is in a high level, a second input terminal of the first-stage switch is connected to the output terminal of the first-stage switch.