This application claims priority to Chinese Patent Application Serial Number 201510124736.4, filed on Mar. 20, 2015, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to a shift register device and a display apparatus, and more particularly to a shift register device and a display apparatus which are able to reduce power consumption.
2. Description of Related Art
A flat panel display device, such as a liquid crystal display (LCD) device or an organic light-emitting diode (OLED) display device, usually has a lot of shift registers for controlling gray levels of all pixels in the display device displayed at the same time point. In response to energy issues followed by all sectors of the industry, the level of power consumption has also to be considered in a circuit design of a display device. Thus, how to design an electrical circuit of a shift register for saving power has become one of the major objectives for those skilled in the art. On the other hand, the accuracy of signals correspondingly outputted at each time point has to be considered in an electrical circuit design of a shift register for ensuring image display quality of a display device with such shift register.
The objective of the present invention is to provide a shift register device and a display apparatus for reducing power consumption and avoiding abnormal operation to ensure operational reliability.
One aspect of the present invention is directed to a shift register device. The shift register device includes N number of shift registers. An i-th shift register among the N number of shift registers includes a control circuit, an output stage circuit and a bias circuit. The control circuit is configured to receive a first control signal, a first input signal and a second input signal and output a second control signal via a first node. The output stage circuit is configured to receive a first clock signal, a second clock signal and the second control signal and output an i-th output signal via a second node. The bias circuit includes a first capacitor and a first transistor. The first capacitor has a first terminal configured to receive the first clock signal. The first transistor has a drain coupled to a second terminal of the first capacitor and configured to provide the first control signal, a gate coupled to the second node and a source configured to receive a reference voltage.
In one embodiment of the present invention, N is an integer greater than or equal to 5, the first input signal is an (i−2)th output signal outputted by an (i−2)th shift register among the N number of shift registers, the second input signal is an (i+2)th output signal outputted by an (i+2)th shift register among the N number of shift registers, wherein i is an integer greater than or equal to 3 and less than or equal to (N−2).
In one embodiment of the present invention, the first input signal is a starting signal, and the second input signal is an (i+2)th output signal outputted by an (i+2)th shift register among the N number of shift registers, wherein i is 1 or 2.
In one embodiment of the present invention, N is an integer greater than or equal to 5, the first input signal is an (i−2)th output signal outputted by an (i−2)th shift register among the N number of shift registers, and the second input signal is an ending signal, wherein i is N or (N−1).
In one embodiment of the present invention, the control circuit includes a second transistor, a third transistor and a fourth transistor. The second transistor has a drain coupled to the first node, a gate configured to receive the first input signal and a source configured to receive a forward voltage. The third transistor has a drain coupled to the drain of the second transistor, a gate configured to receive the second input signal and a source configured to receive a backward voltage. The fourth transistor has a drain coupled to the drain of the second transistor, a gate coupled to the drain of the first transistor and a source configured to receive the reference voltage.
In one embodiment of the present invention, the output stage circuit includes a fifth transistor, a second capacitor, a sixth transistor and a seventh transistor. The fifth transistor has a drain coupled to the second node, a gate coupled to the first node and a source configured to receive the first clock signal. The second capacitor has a first terminal coupled to the first node and a second terminal coupled to the second node. The sixth transistor has a drain coupled to the second node, a gate coupled to the drain of the first transistor and a source configured to receive the reference voltage. The seventh transistor has a drain coupled to the second node a gate configured to receive the second clock signal and a source configured to receive the reference voltage.
In one embodiment of the present invention, the shift register device further comprises four clock signal lines, wherein two of the clock signal lines are coupled to a j-th shift register among the N number of shift registers, and the other two of the clock signal lines are coupled to a (j+1)th shift register among the N number of shift registers, wherein j is an odd integer less than N.
In one embodiment of the present invention, the shift register device further comprises two starting signal lines, wherein one of the starting signal lines is coupled to a first shift register among the N number of shift registers, and the other of the starting signal lines is coupled to a second shift register among the N number of shift registers.
In one embodiment of the present invention, the shift register device further comprises two ending signal lines, wherein one of the ending signal lines is coupled to an (N−1)th shift register among the N number of shift registers, and the other of the ending signal lines is coupled to an N-th shift register among the N number of shift registers.
In one embodiment of the present invention, N is an integer multiple of 4.
Another aspect of the present invention is directed to a display apparatus. The display apparatus includes a display panel and a shift register device. The shift register device is configured to drive the display panel and includes N number of shift registers. An i-th shift register among the N number of shift registers includes a control circuit, an output stage circuit and a bias circuit. The control circuit is configured to receive a first control signal, a first input signal and a second input signal and output a second control signal via a first node. The output stage circuit is configured to receive a first clock signal, a second clock signal and the second control signal and output an i-th output signal via a second node. The bias circuit includes a first capacitor and a first transistor. The first capacitor has a first terminal configured to receive the first clock signal. The first transistor has a drain coupled to a second terminal of the first capacitor and configured to provide the first control signal, a gate coupled to the second node and a source configured to receive a reference voltage.
The foregoing aspects and many of the accompanying advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings.
The detailed explanation of the present invention is described as following. The described preferred embodiments are presented for purposes of illustrations and description, and they are not intended to limit the scope of the present invention.
Please refer to
Please refer to
The bias circuit 214 includes a capacitor CP1 and a transistor M4. The first terminal of the capacitor CP1 is configured to receive a clock signal CLK1. The drain of the transistor M4 is coupled to the second terminal of the capacitor CP1, providing the control signal CTRL1 to the gate of the transistor M3 and the output stage circuit 216. The gate of the transistor M4 is coupled to a node X2, and the source of the transistor M4 is configured to receive the reference voltage VSS.
The output stage circuit 216 includes a capacitor CP2 and transistors M5-M7. The drain of the transistor M5 is coupled to the node X2, the gate of the transistor M5 is coupled to the node X1, and the source of the transistor M5 is configured to receive the clock signal CLK1. The first terminal of the capacitor CP2 is coupled to the node X1, and the second terminal of the capacitor CP2 is coupled to the node X2. That is, the capacitor CP2 is coupled between the gate and the drain of the transistor M5. The drain of the transistor M6 is coupled to the node X2, the gate of the transistor M6 is coupled to the drain of the transistor M4, and the source of the transistor M6 is configured to receive the reference voltage VSS. The drain of the transistor M7 is coupled to the node X2, the gate of the transistor M7 is configured to receive the clock signal CLK2, and the source of the transistor M7 is configured to receive the reference voltage VSS.
If the shift register 210(i) illustrated in
If the shift register 210(i) illustrated in
If the shift register 210(i) illustrated in
If the shift register 210(i) illustrated in
If the shift register 210(i) illustrated in
As can be seen from the above, the clock signal CLK1 in the shift registers 210(1)-210(4) are sequentially the clock signals C1, C2, C3, C4, and the clock signal CLK2 in the shift registers 210(1)-210(4) are sequentially the clock signals C3, C4, C1, C2. In this embodiment, the clock signals CLK1 and CLK2 sequentially change with a period of four shift registers. In other words, the clock signal CLK1 in the shift registers 210(M−3)-210(M) (M is an integer multiple of 4) are sequentially the clock signal C1, C2, C3 and C4, and the clock signal CLK2 in the shift registers 210(M−3)-210(M) are sequentially the clock signal C3, C4, C1 and C2.
In the following embodiment, the forward voltage FW and the backward voltage BW are illustrated as high level and low level, respectively. Please refer to
At time t2, the starting signal STV1 falls to low level, the clock signal C1 rises to high level, and the clock signal C3 falls to low level. At this time, in the first stage shift register 210(1), the transistor M5 still remains on, and the output signal OUT(1) rises to high level because the clock signal C1 rises to high level. The voltage level of the control signal CTRL2 rises because of the coupling effect of the capacitor CP2. The transistor M4 is turned on because the output signal OUT(1) rises to high level, such that the control signal CTRL1 remains at low level. Meanwhile, the transistors M1, M2, M3, M6 and M7 are turned off.
At time t4, the dock signal C1 falls to low level, and the dock signal C3 rises to high level. At this time, in the first stage shift register 210(1), the output signal OUT(1) falls to low level because the clock signal C1 falls to low level. Meanwhile, the output signal OUT(3) of the third stage shift register 210(3) rises to high level, such that the transistor M2 is turned on. As such, in the first stage shift register 210(1), the voltage level of the control signal CTRL2 falls by the coupling effect of the capacitor CP2 first, and then further falls to low level by the transistor M2 being turned on.
At time t6, the clock signal C1 rises to high level, and the clock signal C3 falls to low level. At this time, in the first stage shift register 210(1), the voltage of the control signal CTRL1 rises because of the coupling effect of the capacitor CP1, such that the transistors M3 and M6 are turned on and the output signal OUT(1) remains at low level. Meanwhile, a surge of the control signal CTRL2 appears because the clock signal C1 rises to high level, and then the voltage level of the control signal CTRL2 falls because the transistor M3 is turned on. In the first stage shift register 210(1), the switching status of the transistor M4 is controlled by the output signal OUT(1), and thus, the transistor M4 still remains off instead of being affected by the surge of the control signal CTRL2 to induce instantaneous conduction, thereby avoiding unnecessary power consumption in the bias circuit 214 and abnormal operation of the shift register device 200 by erroneous operation of the transistor M4.
Please refer to
At time t3, the starting signal STV2 falls to low level, the clock signal C2 rises to high level, and the clock signal C4 falls to low level. At this time, in the first stage shift register 210(2), the transistor M5 still remains on, and the output signal OUT(2) rises to high level because the clock signal C2 rises to high level. The voltage level of the control signal CTRL2 rises because of the coupling effect of the capacitor CP2. The transistor M4 is turned on because the output signal OUT(2) rises to high level, such that the control signal CTRL1 remains at low level. Meanwhile, the transistors M1, M2, M3, M6 and M7 are turned off.
At time t5, the clock signal C2 falls to low level, and the clock signal C4 rises to high level. At this time, in the second stage shift register 210(2), the output signal OUT(2) falls to low level because the clock signal C2 falls to low level. Meanwhile, the output signal OUT(4) of the fourth stage shift register 210(4) rises to high level, such that the transistor M2 is turned on. As such, in the second stage shift register 210(2), the voltage level of the control signal CTRL2 falls by the coupling effect of the capacitor CP2 first, and then further falls to low level by the transistor M2 being turned on.
At time t7, the clock signal C2 rises to high level, and the clock signal C4 falls to low level. At this time, in the second stage shift register 210(2), the voltage level of the control signal CTRL1 rises because of the coupling effect of the capacitor CP1, such that the transistors M3 and M6 are turned on and the output signal OUT(2) remains at low level. Meanwhile, a surge of the control signal CTRL2 appears because the clock signal C2 rises to high level, and then the voltage level of the control signal CTRL2 falls because the transistor M3 is turned on.
Similarly, in the second stage shift register 210(2), the switching status of the transistor M4 is controlled by the output signal OUT(2), and thus, the transistor M4 still remains off instead of being affected by the surge of the control signal CTRL2 to induce instantaneous conduction, thereby avoiding unnecessary power consumption in the bias circuit 214 and abnormal operation of the shift register device 200 by erroneous operation of the transistor M4.
In the foregoing embodiments, only the first stage shift register 210(1) and the second stage shift register 210(2) are illustrated. The operating method of the third stage to the N-th stage shift registers 210(3)-210(N) are similar to that of the first stage shift register 210(1) and the second stage shift register 210(2) and can be easily known by those skilled in the art by referencing the aforementioned embodiments, and thus the detailed description is not repeated herein. In addition, the forward voltage FW and the backward voltage BW may be changed to be lower level and high level, respectively, such that the output signals OUT(1)-OUT(N) of the shift register device 200 sequentially rise to high level in a reverse manner. That is, the output signal OUT(N) rises to high level first, and then the output signals OUT(N−1)-OUT(1) sequentially rise to high level.
Summing the above, the shift register device and the display apparatus using the same of the present invention can reduce power consumption and avoid abnormal operation of the shift register device by erroneous operation of the transistor in the shift register for ensuring operational reliability of the shift register device, thereby improving the image display quality of the display apparatus.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims.
Number | Date | Country | Kind |
---|---|---|---|
201510124736.4 | Mar 2015 | CN | national |