The present invention relates to an electrophoretic display apparatus and an image-updating method thereof, and more particularly to an electrophoretic display apparatus with a slim border design and an image-updating method thereof.
The inner circuit structure of the current source driver adopted in an electrophoretic display apparatus generally comprises a plurality of control circuits corresponding to the number of the source lines. For the common electrode above the electrophoretic film and biased by a DC voltage (i.e., DC-common), the pixel potential should have three levels, that is, high level, low level, and common level. The three levels are respectively used to move particles upward, to move particles downward and to hold particles at the same position. Therefore, two-bit data is needed. Because each of the control circuits must receive the image data with the two bits, each of the control circuits must use two same circuits to process the image data with the two bits, and each of the control circuits further comprises an additional decoding circuit to decode the image data with the two bits. Therefore, in the condition of having a plurality of pins, the circuit of the conventional source driver is very complex, and the size of the circuit of the source driver is very large. Furthermore, the width of the outer frame of the display panel is determined by the size of the source driver (which is more complex than the gate driver), thus it is difficult to reduce the width of the outer frame of the display panel because the source driver is very complex, and it goes against the trend of narrowing the frame of the display panel.
The present invention relates to an electrophoretic display apparatus, in which a source driver is simple, the size of the source driver is reduced so that the electrophoretic display apparatus fits with the trend of narrowing a frame thereof.
The present invention also relates to an image-updating method adapted to the electrophoretic display apparatus.
The present invention provides an electrophoretic display apparatus, which comprises a display panel and a source driver. The display panel comprises a plurality of pixels and a plurality of source lines. Each of the pixels is electrically coupled to a corresponding one of the source lines, and each of the pixels comprises a pixel electrode and a capacitor. The capacitor comprises a plurality of charged particles. The pixel electrode of each of the pixels is electrically coupled to an alternating current (AC) common voltage through a corresponding capacitor. The source driver is electrically coupled to the source lines. The source driver comprises a first data-latching circuit and a second data-latching circuit. The first data-latching circuit comprises a first transistor, a first capacitor and a first inverter. The first transistor has a first source/drain terminal, a second source/drain terminal and a gate terminal. The first source/drain terminal of the first transistor is configured for receiving image data, and the gate terminal of the first transistor is configured for receiving a data shift-register output pulse. The first capacitor is electrically coupled between the second source/drain terminal of the first transistor and a reference voltage. The first inverter has an input terminal and an output terminal. The input terminal of the first inverter is electrically coupled to the second source/drain terminal of the first transistor. The second data-latching circuit comprises a second transistor, a second capacitor and a second inverter. The second transistor has a first source/drain terminal, a second source/drain terminal and a gate terminal. The first source/drain terminal of the second transistor is electrically coupled to the output terminal of the first inverter, and the gate terminal of the second transistor is configured for receiving a latching-enable pulse. The second capacitor is electrically coupled between the second source/drain terminal of the second transistor and the reference voltage. The second inverter has an input terminal and an output terminal. The input terminal of the second inverter is electrically coupled to the second source/drain terminal of the second transistor, and the output terminal of the second inverter is electrically coupled to one of the source lines.
The present invention also provides an image-updating method for an electrophoretic display apparatus. The electrophoretic display apparatus comprises a display panel and a source driver. The display panel comprises a plurality of pixels and a plurality of source lines. Each of the pixels is electrically coupled to a corresponding one of the source lines, and each of the pixels comprises a pixel electrode and a capacitor. The capacitor comprises a plurality of charged particles. The source driver is electrically coupled to the source lines, and the source driver comprises a first data-latching circuit and a second data-latching circuit. The first data-latching circuit comprises a first transistor, a first capacitor and a first inverter. The first transistor has a first source/drain terminal, a second source/drain terminal and a gate terminal. The first source/drain terminal of the first transistor is configured for receiving image data, and the gate terminal of the first transistor is configured for receiving a data shift-register output pulse. The first capacitor is electrically coupled between the second source/drain terminal of the first transistor and a reference voltage. The first inverter has an input terminal and an output terminal. The input terminal of the first inverter is electrically coupled to the second source/drain terminal of the first transistor. The second data-latching circuit comprises a second transistor, a second capacitor and a second inverter. The second transistor has a first source/drain terminal, a second source/drain terminal and a gate terminal. The first source/drain terminal of the second transistor is electrically coupled to the output terminal of the first inverter, and the gate terminal of the second transistor is configured for receiving a latching-enable pulse. The second capacitor is electrically coupled between the second source/drain terminal of the second transistor and the reference voltage. The second inverter has an input terminal and an output terminal. The input terminal of the second inverter is electrically coupled to the second source/drain terminal of the second transistor, and the output terminal of the second inverter is electrically coupled to one of the source lines. The image-updating method comprises the following steps: providing an alternating current (AC) common voltage so that the particles in the electrophoretic film being driven by the electrical field caused by the common electrode and the pixel electrode; making the AC common voltage present a first potential, and making a voltage of the output terminal of the second inverter present a second potential, so as to erase a previous image; and making the AC common voltage present the second potential, and making the voltage of the output terminal of the second inverter drive a corresponding one of the pixels in three stages, wherein the voltage of the output terminal of the second inverter presents the first potential in a first stage, the voltage of the output terminal of the second inverter presents the second potential in a second stage, and the voltage of the output terminal of the second inverter presents the first potential in a third stage.
The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:
The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.
Referring to
From the above description, it can be seen that each of output terminals of the source driver 110 only needs to output two different potentials to perform the driving mode of the conventional source driver in three stages. With AC common driving, at the end of shaking phase (i.e., the first potential of the AC common voltage), particles may stay at the bottom of electrophoretic films. In the following phase-writing phase, the AC common voltage presents a second potential. Therefore, the pixel electrode only needs to provide two potentials, that is, high potential and low potential, and thus the source driver only requires one-bit data input. The following will describe some exemplary embodiments of the source driver in detail.
The second data-latching circuit 420 comprises a transistor 421, a transistor 422, a capacitor 423, an inverter 424 and an inverter 425. A source/drain terminal of the transistor 421 is electrically coupled to the output terminal of the inverter 415, and a gate terminal of the transistor 421 is configured for receiving a latching-enable pulse LE. Two source/drain terminals of the transistor 422 are both electrically coupled to the other source/drain terminal of the transistor 421, and a gate terminal of the transistor 422 is configured for receiving an inverted signal LE_Bar. The latching-enable pulse LE and the inverted signal LE_Bar have opposite phases. The capacitor 423 is electrically coupled between the other source/drain terminal of the transistor 421 and the ground voltage GND. An input terminal of the inverter 424 is electrically coupled to the other source/drain terminal of the transistor 421. An input terminal of the inverter 425 is electrically coupled to an output terminal of the inverter 424, and an output terminal of the inverter 425 is electrically coupled to a source line 132 through an output terminal 480 of the control circuit (which is served as an output terminal of the source driver 110). In addition, all of the transistors as shown in
It should be noted that both of the transistors 412 and 422 of
Referring to
The second exemplary embodiment may also be illustrated by
When the input voltage Vin is in the high potential, the transistor 608 is turned on. At the moment, the effect of the transistor 608 for pulling down the output voltage Vout is larger than the effect of the transistor 604 for pulling up the output voltage Vout. Thus, the output voltage Vout is close to the reference voltage VSS, and the voltage of the node Q is Vdd−Vth. When the input voltage Vin transits to the low potential, the transistor 608 is turned off. At the moment, the transistor 604 pulls up the output voltage Vout to the potential of the power voltage Vdd. Since the voltage across the capacitor cannot be altered instantaneously, the voltage of the node Q is pulled up over the potential of the power potential Vdd, so that the transistor 602 is turned off. The transistor 602 is turned off so that the voltage of the node Q may keep in a period. Thus, even if the output voltage Vout is the value of reducing the voltage of the node Q by the threshold voltage of the transistor 604, the output voltage Vout is prone to reach the potential of the power voltage Vdd.
From the above description, it can be seen that when the transistor 608 is turned off from turned on, the voltage of the node Q is pulled up over the potential of the power voltage Vdd, so that the driving capability of the transistor 604 is greatly improved, and the output voltage of the whole inverter reaches the potential of the power voltage Vdd (that is, the output voltage thereof may reach positive saturation). Thus, the boost inverter has an enough capability to drive a next-stage circuit without employing the transistor with the large size, and the preceding-stage circuit of the boost inverter may obtain a small size. Therefore, the present invention may employ the boost inverter to further reduce the size of the source driver 110, and the driving capability of the source driver 110 employing the boost inverter is more powerful than that of the conventional source driver.
It should be noted that although all of the inverters are boost inverters in the exemplary embodiment, the present invention is not limited herein. For example, in other design, only the last inverter (the inverter 425) of the second data-latching circuit 420 employs a boost inverter, and other inverters are inverters of any type.
There is a disadvantage for the source driver 110 of the second exemplary embodiment, that is, the boost inverter thereof may not perform the pull-up operation for a long time, which will be described by
If the current value of the image data B0 is 0 (that is, the low potential), a voltage outputted from the first data-latching circuit 710 is pulled up to the power voltage Vdd. Thus, when the transistor 720-1 is turned on, the gate terminal of the transistor 722-1 will receive a voltage equal to the power voltage Vdd, so that the transistor 722-1 is completely turned on, and a voltage outputted from the second data-latching circuit 720 is pulled down to a voltage close to the reference voltage VSS. Then, if the current value of the image data B0 is changed from 0 to 1 (that is, the high potential), the voltage outputted from the first data-latching circuit 710 is pulled down to a voltage close to the reference voltage VSS. Thus, when the transistor 720-1 is turned on, the gate terminal of the transistor 722-1 will receive a voltage close to the reference voltage VSS, so that the transistor 722-1 is half turned off (that is, half turned on) from completely turned on, and the voltage of the node Q is pulled up over the power voltage Vdd. Therefore, the voltage outputted from the second data-latching circuit 720 reaches the potential of the power voltage Vdd.
From the above description of the exemplary embodiments, it can conclude an image-updating method of an electrophoretic display apparatus of the present invention.
The image-updating method thereof comprises the following steps: providing an alternating current (AC) common voltage so that the particles in the electrophoretic film can be driven by the electrical field caused by the AC common voltage and the pixel electrode (as shown in Step S902); making the AC common voltage present a first potential, and making a voltage of the output terminal of the second inverter present a second potential, so as to erase a previous image (as shown in Step S904); and making the AC common voltage present a second potential, and making the voltage of the output terminal of the second inverter drive the corresponding pixel in three stage. Wherein in a first stage, the voltage of the output terminal of the second inverter presents the first potential. In a second stage, the voltage of the output terminal of the second inverter presents the second potential. In a third stage, the voltage of the output terminal of the second inverter presents the first potential (as shown in Step S906).
In summary, for solving the above problem, the display panel of the present invention employs an AC common voltage with two potentials, thus each of the output terminals of the source driver of the present invention can output the two potentials to perform the driving mode of the conventional source driver for driving the pixels in the three stages. Since each of the output terminals of the source driver only needs to output the two potentials, each control circuit corresponding to an output terminal only needs to receive the image data with the one bit for controlling the output voltage thereof. Since each control circuit only needs to receive the data image with one bit for controlling the output voltage thereof, the first data-latching circuit and the second data-latching circuit of each control circuit only needs one circuit instead of two same circuits. Furthermore, each control circuit does not need to employ any decoding circuit to perform the decoding operation. Therefore, the source driver is simple, and the size of the source driver may be greatly reduced, thus the electrophoretic display apparatus of the present invention can fit with the trend of narrowing the frame thereof.
In addition, the common inverter of the source driver may be replaced by a boost inverter, thus the size of the source driver may be further reduced. Since the voltage of the gate terminal of the boost inverter may be pulled up over the power voltage Vdd, to enhance the driving current thereof, the boost inverter does not need to employ the transistor with the large size and has enough capability to drive the next-stage circuit. Furthermore, the size of the preceding-stage circuit is also reduced. According to an embodiment of the invention, when AC common driving is adopted, the size of the source driver can be reduced. In addition, adopting boost inverter can reduce the total circuit area of the source driver to a more practical level. Therefore, the slim boarder design can be achieved. Certainly, a gate driver can also be integrated into the display panel. Thus, the cost of the electrophoretic display will be reduced, and it facilitates the future demonstration in flexible displays.
While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.
Number | Date | Country | Kind |
---|---|---|---|
100113929 A | Apr 2011 | TW | national |
Number | Name | Date | Kind |
---|---|---|---|
3912948 | Bapat | Oct 1975 | A |
20020005832 | Katase | Jan 2002 | A1 |
20040257136 | Osame et al. | Dec 2004 | A1 |
20080143668 | Shin et al. | Jun 2008 | A1 |
20080143700 | Shin et al. | Jun 2008 | A1 |
20100134504 | Nam et al. | Jun 2010 | A1 |
20110096053 | Yamazaki | Apr 2011 | A1 |
Number | Date | Country | |
---|---|---|---|
20120268442 A1 | Oct 2012 | US |