CURRENT DRIVE CIRCUIT AND DISPLAY APPARATUS

1 . A current drive circuit for supplying a driving current to a pixel portion included in a current-driven display panel, the current drive circuit comprising:

a driving current generator including an output terminal for supplying the driving current; and

a protective transistor having a drain connected to the pixel portion, a source connected to the output terminal, and a gate to which a first bias voltage is supplied,

wherein the first bias voltage has a voltage level lower than or equal to a voltage level obtained by adding a threshold voltage of the protective transistor to a breakdown voltage of the driving current generator.

2 . The current drive circuit of claim 1 , further comprising a control transistor interposed between the pixel portion and the protective transistor,

wherein the control transistor has a drain connected to the pixel portion, a source connected to the drain of the protective transistor, and a gate to which a control signal for controlling ON/OFF of the control transistor is supplied.

3 . The current drive circuit of claim 2 , further comprising a compensation transistor having a drain, a source and a gate, the drain and the source of the compensation transistor being connected to the source of the control transistor, the gate of the compensation transistor receiving a compensation signal,

wherein the compensation signal is a signal for controlling ON/OFF of the compensation transistor, and

a voltage level of the compensation signal varies inversely with a variation of the control signal.

4 . The current drive circuit of claim 1 , wherein the first bias voltage is supplied concurrently with, or before, start-up of the driving current generator.

5 . The current drive circuit of claim 1 , further comprising a clamping transistor interposed between the pixel portion and the protective transistor,

wherein the clamping transistor has a drain connected to the pixel portion, a source connected to the drain of the protective transistor, and a gate to which a second bias voltage having a voltage level lower than or equal to a voltage level obtained by adding a threshold voltage of the clamping transistor to a breakdown voltage of the protective transistor is supplied.

6 . The current drive circuit of claim 5 , further comprising a control transistor interposed between the pixel portion and the clamping transistor,

wherein the control transistor has a drain connected to the pixel portion, a source connected to the drain of the clamping transistor, and a gate to which a control signal for controlling ON/OFF of the control transistor is supplied.

7 . The current drive circuit of claim 6 , further comprising a compensation transistor having a drain, a source and a gate, the drain and the source of the compensation transistor being connected to the source of the control transistor, the gate of the compensation transistor receiving a compensation signal,

wherein the compensation signal is a signal for controlling ON/OFF of the compensation transistor, and

a voltage level of the compensation signal varies inversely with a variation of the control signal.

8 . The current drive circuit of claim 1 , wherein a control signal for controlling ON/OFF of the protective transistor is supplied to the gate of the protective transistor, and

a voltage level of the control signal varies in a range between a non-conducting level at which the protective transistor is OFF and a conducting level lower than or equal to a voltage level obtained by adding a threshold voltage of the protective transistor to a breakdown level of the driving current generator.

9 . The current drive circuit of claim 8 , further comprising a compensation transistor having a drain, a source and a gate, the drain and the source of the compensation transistor being connected to the source of the protective transistor, the gate of the compensation transistor receiving a compensation signal,

wherein the compensation signal is a signal for controlling ON/OFF of the compensation transistor, and

a voltage level of the compensation signal varies inversely with a variation of the control signal.

10 . A display apparatus, comprising:

the current drive circuit recited in claim 1 ; and

the display panel recited in claim 1 .

11 . A current drive circuit for supplying a driving current to a pixel portion included in a current-driven display panel, the current drive circuit comprising:

a plurality of drive transistors; and

a plurality of switching transistors each connected between an associated one of the drive transistors and an output terminal for supplying the driving current,

wherein each of the switching transistors has a drain connected to the output terminal, a source connected to a drain of an associated one of the drive transistors, and a gate to which a selection signal for controlling ON/OFF of the switching transistor is supplied, and

a voltage level of the selection signal varies in a range between a non-conducting level at which the switching transistor is OFF and a conducting level lower than or equal to a voltage level obtained by adding a threshold voltage of the switching transistor to a breakdown level of the drive transistor.

12 . A display apparatus, comprising:

the current drive circuit recited in claim 11 ; and

the display panel recited in claim 11 .

13 . A current-driven display panel driven by a driving current supplied from an output terminal of a current drive circuit, the display panel comprising:

a pixel portion to which the driving current is supplied; and

a protective transistor having a drain connected to the pixel portion, a source connected to the output terminal, and a gate to which a bias voltage is supplied,

wherein the bias voltage has a voltage level lower than or equal to a voltage level obtained by adding a threshold voltage of the protective transistor to a breakdown voltage of the current drive circuit.