PATENT DOCUMENT

Publication Number: US-9584111-B2
Application Number: US-201414502883-A
Country: US
Kind Code: B2

Title: Systems and methods for improving energy efficiency of gate driver circuits

Abstract:
A gate drive circuit may include a latch circuit, a first transmission gate, and a second transmission gate. The first transmission gate and the second transmission gate may both be directly coupled to the latch circuit and may be directly coupled to a first gate line and a second gate line, respectively. The latch circuit may receive an electrical signal from a third gate line adjacent to the second gate line, such that the electrical signal is configured to reset a state of the latch circuit.

Claims:
What is claimed is: 
     
       1. A system, comprising:
 a first circuit configured to drive a first gate line and a second gate line within a display, wherein the first circuit comprises: 
 a first latch circuit configured to directly couple to a first transmission gate and a second transmission gate, wherein the first transmission gate is configured to directly couple to the first gate line, and wherein the second transmission gate is configured to directly couple to the second gate line; and 
 a second circuit configured to drive a third gate line and a fourth gate line within the display, wherein the second circuit comprises:
 a second latch circuit configured to directly couple to a third transmission gate and a fourth transmission gate, wherein the third transmission gate is configured to directly couple to the third gate line, and wherein the fourth transmission gate is configured to directly couple to the fourth gate line; 
 wherein the first gate line is configured to directly couple to the second latch circuit; and 
 
 a third latch circuit configured to directly couple to a fifth transmission gate and a sixth transmission gate; 
 wherein the fourth gate line is configured to directly couple to the first latch circuit and the third latch circuit. 
 
     
     
       2. The system of  claim 1 , wherein the first gate line is configured to provide a first electrical signal to the second latch circuit, wherein the first electrical signal is configured to change a state of the second latch. 
     
     
       3. The system of  claim 1 , wherein the fourth gate line is configured to provide a second electrical signal, and wherein the second electrical signal is configured to set the first latch circuit to an inactive state and set the third latch circuit to the active state. 
     
     
       4. The system of  claim 1 , wherein the first latch circuit is configured to set the first transmission gate and the second transmission gate to an active or an inactive state, and wherein the second latch circuit is configured to set the third transmission gate and the fourth transmission gate to the active or the inactive state. 
     
     
       5. The system of  claim 1 , comprising:
 a first bus line configured to provide a first clock signal from a first clock, wherein the first bus line is configured to directly couple to the first transmission gate; and 
 a second bus line configured to provide a second clock signal from a second clock, wherein the second bus line is configured to directly couple to the second transmission gate. 
 
     
     
       6. The system of  claim 5 , wherein the first clock signal is configured to cause the first transmission gate to send a first electrical signal to the first gate line, and wherein the second clock signal is configured to cause the second transmission gate to send a second electrical signal to the second gate line. 
     
     
       7. The system of  claim 5 , wherein the first clock signal comprises a first pulse having a duration, wherein the second clock signal comprises a second pulse that occurs after the duration expires at an end of the first pulse. 
     
     
       8. The system of  claim 7 , wherein the second pulse has a period that corresponds to the duration. 
     
     
       9. An electronic device, comprising:
 a display; and 
 a first gate drive circuit configured to drive a first set of gate lines of the display; and 
 a second gate drive circuit configured to drive a second set of gate lines of the display, wherein at least one gate line of the first set of gate lines is adjacent to at least one gate line of the second set of gate lines, and wherein the first gate drive circuit is configured to control a first operation of the second gate drive circuit. 
 
     
     
       10. The electronic device of  claim 9 , wherein the second gate drive circuit comprises at least one latch circuit configured to store an active state or an inactive state. 
     
     
       11. The electronic device of  claim 10 , wherein the first gate drive circuit is configured to control the first operation of the second gate drive circuit by changing the state of the at least one latch circuit. 
     
     
       12. The electronic device of  claim 9 , wherein the second gate drive circuit is configured to control a second operation of the first gate drive circuit. 
     
     
       13. The electronic device of  claim 9 , wherein the first gate drive circuit is disposed within a first bezel region of the electronic device, wherein the second gate drive circuit is disposed within a second bezel region of the electronic device, and wherein the first bezel region and the second bezel region are located on opposite sides of the electronic device. 
     
     
       14. The electronic device of  claim 9 , wherein the display is part of a media device, a laptop computer, a desktop computer, a tablet computer, a phone device, or any combination thereof. 
     
     
       15. A method, comprising:
 receiving, at a latch circuit, a set signal that causes the latch circuit to store state information; 
 sending, from the latch circuit, the state information to a first transmission gate and a second transmission gate, wherein the first transmission gate and the second transmission gate drive a first gate line and a second gate line associated with display when the state information corresponds to an active state; and 
 receiving, at the latch circuit, an electrical signal from directly via a third gate line associated with the display, wherein the third gate line is directly coupled to a third transmission gate, wherein the electrical signal causes the latch circuit to reset to an inactive state thereby deactivating the first transmission gate and the second transmission gate, and wherein the latch circuit, the first transmission gate, and the second transmission gate is disposed on a first side of the display and the third transmission gate is disposed on a second side of the display opposite the first side. 
 
     
     
       16. The method of  claim 15 , wherein the electrical signal drives the third gate line. 
     
     
       17. The method of  claim 15 , wherein the second gate line and the third gate line are directly adjacent to each other. 
     
     
       18. A gate drive circuit, comprising:
 a latch circuit; 
 a first transmission gate; and 
 a second transmission gate, wherein the first transmission gate and the second transmission gate are configured to couple to the latch circuit, and wherein the first transmission gate and the second transmission gate are configured to couple to a first gate line and a second gate line, respectively; 
 wherein the latch circuit is configured to receive an electrical signal from a third gate line adjacent to the second gate line, and wherein the electrical signal is configured to reset a state of the latch circuit. 
 
     
     
       19. The gate drive circuit of  claim 18 , wherein the latch circuit comprises a D flip-flop circuit. 
     
     
       20. The gate drive circuit of  claim 18 , wherein the latch circuit is configured to prevent itself from being in an active state when a preceding latch in the gate drive circuit and a subsequent latch in the gate drive circuit are both in the active state. 
     
     
       21. The gate drive circuit of  claim 18 , comprising a first bus line and a second bus line configured to provide first clock signal and a second clock signal to the first transmission gate and the second transmission gate, respectively. 
     
     
       22. An electronic display, comprising:
 a first gate drive circuit configured to drive a first set of gate lines of the display; and 
 a second gate drive circuit configured to drive a second set of gate lines of the display, wherein the first gate drive circuit is configured to control a first operation of the second gate drive circuit, and wherein the first gate drive circuit and the second gate drive circuit each comprises at least one latch circuit configured to directly couple to at least two transmission gates. 
 
     
     
       23. The electronic display of  claim 22 , wherein the first gate drive circuit and the second gate drive circuit each comprises at least four bus lines configured to provide at least four clock signals to the at least two transmission gates.

Description:
BACKGROUND 
     The present disclosure relates generally to electronic displays. More specifically, the present disclosure relates to improving the energy efficiency and/or profile (i.e., area occupied by gate drive circuit) of gate driver circuits used to illuminate pixels in an electronic display. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     The bezel region or border of an electronic device generally includes the area of the electronic device between the edge of the device itself and a display region of the electronic device. Disposed within this bezel region are a number of electronic components that facilitate the operation of the display region. For instance, electronic components, such as gate drive circuits, disposed within the bezel region of the electronic device may provide electrical signals to components (e.g., pixels) in the display region to depict images on the display region. To depict images on the display region, these electronic components generally use a number of energy-consuming components such as latch circuits, transmission gate circuits, clock buses, and the like. Each of these energy-consuming components is typically disposed within the bezel region of the electronic device. As such, the number of electronic components disposed within the bezel region of the electronic device is directly proportional to the size of the bezel region. 
     Keeping this in mind, users generally prefer to have a larger display area with their respective electronic device. As such, the bezel region surround a display region of an electronic device may consume a valuable portion of the surface area of the electronic device that may rather be used as part of the display region. By reducing the number of electronic components disposed within the bezel region of the electronic device, the electronic device may improve its efficiency with regard to consuming energy while increasing the relative amount of surface area of the electronic device that includes the display region. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     The present disclosure generally relates to improving the energy efficiency of a display within an electronic device while reducing the bezel region of the electronic device. In particular, the present disclosure relates to using a single latch circuit to control the operation of at least two transmission gate circuits used to provide power to pixels along at least two respective gate lines of a display. In one embodiment, the latch circuit may store state information (e.g., active or inactive) and may use the state information to enable the corresponding transmission gate circuits to provide power to the corresponding gate lines. Other gate driver circuits that are not the subject of this disclosure may use an individual latch circuit to control the state of an individual transmission gate circuit in a 1:1 proportion. However, by using just one latch circuit to control the state of at least two transmission gate circuits in a 2:1 proportion (or greater), the embodiments disclosed herein enable the electronic device to have a smaller bezel region. Moreover, the reduced number of latch circuits and the scheme in which the latch circuits operate may reduce the total amount of energy consumed by the electronic display. Additional details regarding how a single latch circuit may be employed to control the states of at least two transmission gate circuits will be described below with reference to  FIGS. 1-8 . 
     Various refinements of the features noted above may exist in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a block diagram of exemplary components of an electronic device, in accordance with an embodiment; 
         FIG. 2  is a front view of a handheld electronic device, in accordance with an embodiment; 
         FIG. 3  is a front view of a tablet electronic device, in accordance with an embodiment; 
         FIG. 4  is a view of a computer, in accordance with an embodiment; 
         FIG. 5  is a block diagram of a less efficient gate drive circuit coupled to a display of an electronic device, in accordance with an embodiment; 
         FIG. 6  is a timing diagram of clock signals that may correspond to the operation of the gate drive circuit of  FIG. 5 , in accordance with an embodiment; and 
         FIG. 7  is a block diagram of a gate drive circuit having improved energy efficiency as compared to the gate drive circuit of  FIG. 5 , in accordance with an embodiment; 
         FIG. 8  is a timing diagram of clock signals and states of various gate lines and transmission gate circuits that may operate as part of the gate drive circuit of  FIG. 7 , in accordance with an embodiment; and 
         FIG. 9  is a schematic diagram of a latch circuit in the gate drive circuit of  FIG. 7 , in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     A variety of electronic devices may incorporate systems and methods for providing an energy-efficient gate drive circuit to illuminate pixels along gate lines within a display of an electronic device. An example of a suitable electronic device may include various internal and/or external components, which contribute to the function of the device.  FIG. 1 , for example, is a block diagram illustrating the components that may be present in such an electronic device  10  and which may allow the electronic device  10  to function in accordance with the systems and techniques discussed herein. Those of ordinary skill in the art will appreciate that the various functional blocks shown in  FIG. 1  may include hardware elements (including circuitry), software elements (including computer code stored on a computer-readable medium), or a combination of both hardware and software elements. It should further be noted that  FIG. 1  is merely one example of a particular implementation and is merely intended to illustrate the types of components that may be present in the electronic device  10 . For example, in the presently illustrated embodiment, these components may include a display  12 , I/O ports  14 , input structures  16 , one or more processors  18 , a memory device  20 , a non-volatile storage  22 , a networking device  24 , a power source  26 , gate drive circuit  28 , and the like. 
     With regard to each of these components, the display  12  may be used to display various images generated by the electronic device  10 . Moreover, the display  12  may be a touch-screen liquid crystal display (LCD), for example, which may enable users to interact with a user interface of the electronic device  10 . In some embodiments, the display  12  may be a MultiTouch™ display that can detect multiple touches at once. In any case, the display  12  may be coupled to gate drive circuit  28 , which may provide electrical signals to the display  12 , such that one or more images may be depicted on the display  12 . That is, the gate drive circuit  28  may provide electrical signals to gate lines disposed within the display  12  to facilitate activation and deactivation of pixels along the respective gate lines within the display  12 . 
     The I/O ports  14  may include ports configured to connect to a variety of external I/O devices, such as a power source, headset or headphones, peripheral devices such as keyboards or mice, or other electronic devices  10  (such as handheld devices and/or computers, printers, projectors, external displays, modems, docking stations, and so forth). The input structures  16  may include the various devices, circuitry, and pathways by which user input or feedback is provided to the processor  18 . Such input structures  16  may be configured to control a function of the electronic device  10 , applications running on the electronic device  10 , and/or any interfaces or devices connected to or used by the electronic device  10 . 
     The processor(s)  18  may provide the processing capability to execute the operating system, programs, user and application interfaces, and any other functions of the electronic device  10 . The instructions or data to be processed by the processor(s)  18  may be stored in a computer-readable medium, such as the memory  20 . The memory  20  may be provided as a volatile memory, such as random access memory (RAM), and/or as a non-volatile memory, such as read-only memory (ROM). The components may further include other forms of computer-readable media, such as the non-volatile storage  22 , for persistent storage of data and/or instructions. The non-volatile storage  22  may include flash memory, a hard drive, or any other optical, magnetic, and/or solid-state storage media. The non-volatile storage  22  may be used to store firmware, data files, software, wireless connection information, and any other suitable data. 
     The network device  24  may include a network controller or a network interface card (NIC). Additionally, the network device  24  may be a Wi-Fi device, a radio frequency device, a Bluetooth® device, a cellular communication device, or the like. The network device  24  may allow the electronic device  10  to communicate over a network, such as a Local Area Network (LAN), Wide Area Network (WAN), or the Internet. The power source  26  may include a variety of power types such as a battery or AC power. 
     With the foregoing in mind,  FIG. 2  and  FIG. 3  illustrate an electronic device  10  in the form of a handheld device  34  and a tablet device  40 , respectively.  FIG. 2  illustrates a cellular telephone, but it should be noted that while the depicted handheld device  34  is provided in the context of a cellular telephone, other types of handheld devices (such as media players for playing music and/or video, personal data organizers, handheld game platforms, and/or combinations of such devices) may also be suitably provided as the electronic device  10 . As discussed with respect to the general electronic device  10  of  FIG. 1 , the handheld device  34  and the tablet device  40  may allow a user to connect to and communicate through the Internet or through other networks, such as local or wide area networks. The handheld electronic device  34  and the tablet device  40 , may also communicate with other devices using short-range connections, such as Bluetooth® and near field communication. By way of example, the handheld device  34  may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif. Similarly, by way of example, the tablet device  40  may be a model of an iPad® from Apple Inc. of Cupertino, Calif. 
     The handheld device  34  and the tablet device  40  include an enclosure or body that protects the interior components from physical damage and shields them from electromagnetic interference. The enclosure may be formed from any suitable material such as plastic, metal or a composite material and may allow certain frequencies of electromagnetic radiation to pass through to wireless communication circuitry within the handheld device  34  and the tablet device  40  to facilitate wireless communication. In the depicted embodiment, the enclosure includes user input structures  16  through which a user may interface with the device. Each user input structure  16  may be configured to help control a device function when actuated. The handheld electronic device  34  and the tablet device  40  also may include various input and output (I/O) ports that allow connection of the handheld device  34  and the tablet device  40  to external devices. 
     In addition to handheld device  34  and the tablet device  40 , the electronic device  10  may also take the form of a computer or other type of electronic device. Such computers may include computers that are generally portable (such as laptop, notebook, and tablet computers) as well as computers that are generally used in one place (such as desktop computers, workstations, and/or servers). In certain embodiments, the electronic device  10  in the form of a computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, iPad® or Mac Pro® available from Apple Inc. By way of example, an electronic device  10  in the form of a laptop computer  50  is illustrated in  FIG. 4  in accordance with one embodiment. The depicted computer  50  includes a housing  52 , a display  12 , a bezel region  36 , input structures  16 , and input/output ports  14 . 
     In one embodiment, the input structures  16  (such as a keyboard and/or touchpad) may be used to interact with the computer  50 , such as to start, control, or operate a GUI or applications running on the computer  50 . For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on the display  12 . 
     As depicted, the electronic device  10  in the form of the computer  50  may also include various input and output ports  14  to allow connection of additional devices. For example, the computer  50  may include an I/O port  14 , such as a USB port or other port, suitable for connecting to another electronic device, a projector, a supplemental display, and so forth. The computer  50  may include network connectivity, memory, and storage capabilities, as described with respect to  FIG. 1 . As a result, the computer  50  may store and execute a GUI and other applications. 
     In the depicted embodiments, the handheld device  34 , the tablet device  40 , and the computer  50  each includes the display  12 . The display  12  may be a touch-screen LCD used to display a graphical user interface (GUI) that allows a user to interact with the handheld device  34 , the tablet device  40 , or the computer  60 . A border region along each side of the display  12  may be characterized as a bezel region  36 . The bezel region  36  may include the area of the handheld device  34 , the tablet device  40 , or the computer  50  between the edge of the display  12  and the edge of the device itself. Generally, the gate drive circuit  28  may be disposed within the bezel region  36 . As such, the gate drive circuit  28  may provide gate drive signals to gate lines within the display  12 , thereby illuminating pixels disposed along the gate lines. 
     In operation, a source driver circuit may receive image data from the processor  18  and, based on the received data, outputs signals to control the pixels of the display  12 . To display the image data, the source driver circuit may adjust the voltage of pixel electrodes disposed along a row across the display  12 . To access an individual row of pixels, the gate drive circuit  28  may send an activation signal to thin film transistors (TFTs) associated with the particular row of pixels along a particular gate line. This activation signal may render the TFTs on the gate line conductive. Accordingly, the image data corresponding to the addressed row may be transmitted from the source driver circuit to each of the pixels along the gate lines via data lines disposed within the display  12 . Thereafter, the gate drive circuit  28  may deactivate TFTs in along the gate line, thereby impeding the pixels within that gate line from changing state until the next time they are addressed. As this process is repeated for each gate line (i.e., row) of pixels in display  12 , the display  12  may depict the image data as a viewable image. 
     Less Efficient Gate Drive Circuitry 
     Keeping the foregoing in mind,  FIG. 5  illustrates a block diagram of two gate drive circuits  60  that are provided as examples of less efficient circuitry than the efficient gate drive circuitry of  FIG. 7 , which is the subject of this disclosure. As will be appreciated, the more efficient gate drive circuitry of  FIG. 7  may consume less energy and use fewer parts as compared to the less efficient gate drive circuitry of  FIG. 5 . 
     Referring now to  FIG. 5 , the less efficient gate drive circuits  60  that may drive gate lines  62  of the display  12 . As such, the gate drive circuit  60  may include a number of latch circuits  64  and an equal number of transmission gates  66 . Each latch circuit  64  and transmission gate  66  pair may be used to drive a respective gate line  62  of the display  12 . As shown in  FIG. 5 , one gate drive circuit  60  is provided on both sides of the display  12 , and each gate drive circuit  60  may drive every other gate line  62  of the display  12 . That is, for example, the gate drive circuit  60  on the left side of the display  12  may drive odd-numbered gate lines  62  (e.g., 1, 3, 5, . . . N−1) while the gate drive circuit  60  on the right side of the display  12  may drive even-numbered gate lines  62  (e.g., 2, 4, 6, . . . N). 
     Generally, the latch circuit  64  may be a flip-flop circuit, such as a D flip-flop circuit, that may store state information (e.g., on/off, high/low, active/inactive etc.). The latch circuit  64  may then use the stored state to control the operation of a corresponding transmission gate  66 . The transmission gate  66  may be coupled to a corresponding gate line  62  and may provide the corresponding gate line  62  with an electrical signal to drive or illuminate one or more pixels located along the respective gate line  62  of the display  12 . 
     When initializing its state, the latch circuit  64  may use a clock signal received via bus lines  68 . As shown in  FIG. 5 , each of the bus lines  68  may be associated with a particular clock signal. Generally, one side of the display  12  may include bus lines  68  that provide two clock signals (e.g., clock  1  and clock  2 ) while the other side of the display  12  may include bus lines  70  that provide another two clock signals (e.g., clock  3  and clock  4 ). A timing diagram illustrating an example of four clock signals associated with the four clocks of bus lines  68  and  70  is provided in  FIG. 6 . 
     In operation, the latch circuit  64  may receive a pulse from a first clock signal that may cause the latch circuit  64  to change states (e.g., from inactive to active). The latch circuit  64  may then transfer the new state status to a respective transmission gate  66 . At that time, or after receiving the new state status, the transmission gate  66  may be prepared to drive a respective gate line  62  based on a second clock signal. In addition to being coupled to a respective gate line  62 , the output of the transmission gate  66  may be coupled to another latch circuit  64  and may cause the other latch circuit  64  to change states (e.g., from inactive to active). In some instances, the output of the transmission gate  66  may also be coupled to a latch circuit  64  associated with an immediately preceding gate line. In this way, the output of the transmission gate  66  may be used to reset or change the state of the latch circuit  64  associated with the immediately preceding gate line back to an inactive state. 
     To further illustrate the operation of the gate drive circuit  60 , the following discussion with regard to the operations of certain latch circuits  64  and transmission gates  66  is provided. Accordingly, by way of example, latch  1 , as illustrated in  FIG. 6 , may receive a first clock signal from clock  1 . Upon receiving the first clock signal, latch  1  may become set or change states from inactive to active. Latch  1  may then forward the new state information (e.g., active) to transmission gate  1 , such that transmission gate  1  is active and ready to drive gate line  1 . Once active, transmission gate  1  may receive a second clock signal from clock  2  that may cause transmission gate  1  to drive gate line  1 . 
     The next latch circuit  62 , or latch  3 , may be coupled to the output of transmission gate  1 . As such, upon receiving the output from the transmission gate  1 , latch  3  may enter into an active state. Latch  3  may then, in turn, activate transmission gate  3  according to its active state. As shown in  FIG. 5 , transmission gate  3  may be coupled to clock  1  and thus may drive gate line  3  based on the first clock signal received via clock  1 . Like the output of transmission gate  1 , the output of the transmission gate  3  may be coupled to the next latch (e.g., latch  5 ) of the gate drive circuit  60  causing latch  5  to set when transmission gate  3  outputs an electrical signal to gate line  3 . In addition being coupled to the next latch, the output of transmission gate  3  may be coupled to latch  1 . As such, since latch  1  is active prior to when transmission gate  3  outputs an electrical signal to gate line  3 , once transmission gate  3  outputs the electrical signal to gate line  3 , the electrical signal may also be provided to latch  1 , thereby causing latch  1  to reset. The remaining latch circuits  64  and transmission gates  66  may be configured according to the same wiring scheme described above. As such, each transmission gate  66  of the gate drive circuit  60  may drive a respective gate line  62  of the display  12 . The above process then continuously repeats to continuously display images on the display  12 . 
     With the foregoing in mind, it is apparent that the gate drive circuit  60  disposed either side of the display  12  operates independently with respect to each other. That is, the gate drive circuit  60  disposed on the left side of the display  12  may operate based on clock signals received via bus lines  68 , while the gate drive circuit  60  disposed on the right side of the display  12  may operate based on clock signals received via bus lines  70 . As can be appreciated, to ensure that two gate lines are not driven by two different gate circuit drives  60  at the same time, the clock signals from clocks  1 - 4  may be selected to ensure that one gate drive line  62  is driven at any given time. For instance, as shown in  FIG. 8 , each clock signal from clocks  1 - 4  occurs during distinct time intervals. In this way, the gate drive circuit  60  driving the odd-numbered gate drive lines  62  are not related to the gate drive circuit driving the even-numbered gate drive lines  62 , except for that the clock signals that drive each respective side of the display  12  are coordinated not to interfere with each other. 
     It should be noted that when using the clock signals to drive each latch circuit  64 , each latch circuit  64  may continuously consume energy when a clock signal is being input into the latch circuit  64  even though the respective latch circuit  64  may be in an inactive state. That is, the clock signals provided to the latch circuits  64  drive a drain side of input transistors in each respective latch circuit  64 . The drain side of the input transistor corresponds to a fringe capacitor that consumes energy inefficiently. Considering the total number of latch circuits  64  present in the gate drive circuit  60 , it is apparent that each latch circuit  64  consumes energy inefficiently by using the clock signals to drive the respective latch circuit  64 . Moreover, since the clock signals are used to drive the latch circuit  64  and the transmission gates  66 , two different pairs of bus lines  68  are used to provide the clock signals to the latch circuits  64  and the transmission gates  66 . By using two different pairs of bus lines to provide the same clock signals, the gate drive circuitry  60  again consumes energy inefficiently by losing energy via resistive properties of each bus line. 
     More Efficient Gate Drive Circuitry 
     Keeping the foregoing in mind,  FIG. 7  illustrates one embodiment in which gate drive circuit  80  and gate drive circuit  82  may not drive the latch circuits  64  using clock signals, as compared to the gate drive circuit  60  of  FIG. 5 . Instead, as depicted in  FIG. 7 , the output of one transmission gate  66  of one gate drive circuit (e.g., gate drive circuit  80 ) may be used to drive a latch circuit  64  disposed within another gate drive circuit (e.g., gate drive circuit  82 ). As such, clock signals are not used to drive each of the latch circuits  64  of the gate drive circuit  80  or the gate drive circuit  82 . As a result, each latch circuit  64  does not operate as a fringe capacitor, and thus does not consume energy inefficiently. 
     As an advantage to not driving latch circuits  64  with clock signals, gate drive circuits  80  and  82  include just one pair of bus lines  68  or  70 . That is, since the latch circuits  64  are no longer driven by clock signals, clock signal bus lines dedicated to driving latch circuits  64  are obsolete. Moreover, in addition to not driving the latch circuits  64  with clock signals, the gate drive circuit  80  and the gate drive circuit  82  may each employ just one respective latch circuit  64  to control the operation of two respective transmission gates  66 . Accordingly, by having fewer clock signal bus lines and half as many latch circuits  64  in the gate drive circuits  80  and  82 , the electronic device  10  may have a smaller bezel region or border surrounding the display  12  of the electronic device  10 , thereby enhancing a user&#39;s experience with the display  12 . 
     Additionally, by removing the fringe capacitance operation of the latch circuits  64  and by reducing the total number of latch circuits used in the gate drive circuits  80  and  82 , the electronic device  10  may operate the display  12  more efficiently with respect to energy as compared to a corresponding electronic device  10  employing the gate drive circuit  60 . 
     Referring now to  FIG. 7 , each latch circuit  64  may use stored states to control the operation of two transmission gates  66 . For example, latch  1  may receive a set signal via data line  84 . The set signal may be used to initialize the display  12  to begin depicting images. As such, the set signal may be provided via the processor  18  or the like when attempting to display images via the display  12 . As shown in  FIG. 7 , in one embodiment, the set signal may be provided to the first latch circuit  64  and to the last latch circuit  64  of the gate drive circuitry  80  or  82 . In this way, the gate lines  62  may be driven from the top of the display  12  to the bottom or from the bottom of the display  12  to the top. 
     In one embodiment, the set signal may cause the latch circuit (e.g., latch  1 ) to change states (e.g., from inactive to active). Once activated, latch  1  may transfer the new state status to transmission gate  1  and transmission gate  3 , both of which are coupled to latch  1 . As such, transmission gate  1  and transmission gate  3  may be active or prepared to drive gate line  1  and gate line  3 , respectively. As shown in  FIG. 7 , transmission gate  1  is coupled to clock  1  and transmission gate  3  is coupled to clock  2 , such that transmission gate  1  may drive gate line  1  according to the clock signal from clock  1  and transmission gate  3  may drive gate line  3  according to the clock signal from clock  2 . 
     After illuminating the pixels disposed on gate line  1 , the electrical signal driving gate line  1  may be provided to latch  2  to set latch  2 . That is, gate line  1  may be coupled to latch  2  of the gate drive circuit  82  on the right side of the display  12 . As such, upon receiving the electrical signal from gate line  1 , latch  2 , in turn, may transfer the new state status to transmission gate  2  and transmission gate  4 , both of which are coupled to latch  2 . Transmission gate  2  and transmission gate  4  may then be active or prepared to drive gate line  2  and gate line  4 , respectively. Since transmission gate  2  is coupled to clock  3  and transmission gate  4  is coupled to clock  4 , transmission gate  2  may drive gate line  2  according to the clock signal from clock  3  and transmission gate  4  may drive gate line  4  according to the clock signal from clock  4 . 
     To continue driving the subsequent gate lines  62 , gate line  4  may be coupled to latch  1  and latch  3  of the gate drive circuit  80 . As such, the electrical signal driving gate line  4  may reset latch  1 , thereby causing latch  1  to turn to an inactive state. The same electrical signal driving gate line  4  may also set latch  3 , thereby causing latch  3  to turn to active state. After latch  3  becomes active, latch  3  may transfer the active state to transmission gate  5  and transmission gate  7 , as described above with respect to transmission gate  1  and transmission gate  3 . The remaining latch circuits  64  and transmission gates  66  of the gate drive circuit  80  and the gate drive circuit  82  may be arranged according to the scheme described above and illustrated in  FIG. 7 . 
     By employing the scheme illustrated in  FIG. 7 , the gate drive circuit  80  and the gate drive circuit  82  operate in conjunction with each other. That is, most latch circuits  64  of the gate drive circuit  80  may be set and reset by various gate lines  62  driven by transmission gates  66  of the gate drive circuit  82 . In this way, instead of operating independently of each other, the gate drive circuit  82  may coordinate or contribute to the operation of the gate drive circuit  80 . As such, the gate drive circuit  80  and the gate drive circuit  82  may drive the gate lines  62  without relying on just clock signals to coordinate the operations of the transmission gates  66 . 
     Referring briefly back to the convention gate drive circuit  60  of  FIG. 5 , the transmission gates  66  drive the gate lines  62  according to the clock signals received from clocks  1 - 4  via bus lines  68  and bus lines  70 . As such, if any clock signal was altered due to noise or resistance along the bus lines  68  or the bus lines  70 , the likelihood of two different gate lines  62  driven at the same time may increase. Moreover, since each gate drive circuit  60  of  FIG. 5  operate independently of each other, both gate drive circuitries  60  may not be aware or have any way to prevent gate lines  62  from being driven at the same time from both sides of the display  12 . 
     In contrast to the gate drive circuit  60 , by using the electrical signal driving the gate line  62  from one side of the display  12  to control the latch circuit  64  located on the other side of the display  12 , the gate drive circuit  80  and the gate drive circuit  82  provides additional protection with regard to preventing multiple transmission gates  66  on either side of the display  12  from driving multiple gate lines  62  at the same time. Moreover, by reducing the number of latch circuits  64  employed in the gate drive circuit  80  and the gate drive circuit  82 , the bezel region or border of the display  12  may be reduced since fewer electrical components may reside in the region. Additionally, by driving the latch circuits  64  using data line  84  or gate lines  62 , and not using clock signals, each latch circuit  64  of the gate drive circuits  80  and  82  consume significantly less energy as compared to the gate drive circuit  60  of  FIG. 5 . Moreover, since clock signals are not provided as inputs to the latch circuits  64 , each gate drive circuit  80  and  82  does not include more than one bus line  68  or  70  providing the same clock signal. As such, since the bezel region of the electronic device  10  does not include the additional bus lines  68  or  70 , the bezel region may be reduced even further, thereby providing additional space on the electronic device  10  for the display  12 . 
     Although the embodiments discussed herein have been described as using one latch circuit  64  for two transmission gates  66  and one bus line  68  or  70  for each gate drive circuit  80  or  82 , it should be noted that the embodiments discussed herein are not limited to this schematic. That is, in other embodiments, one latch circuit  64  for more than two transmission gates  66 . In the same manner, additional bus lines  68  or  70  that may include additional clock signals may be provided for each gate drive circuit  80  or  82  to have a lower latch circuit to transmission gate ratio. For example, by adding one additional bus line that provides two additional clock signals to the gate drive circuit  80  or  82 , one latch circuit  64  may be used to control the operation of four transmission gate  66  if the clock signals are positioned properly. 
     Keeping the foregoing in mind,  FIG. 8  illustrates a timing diagram that describes how the electrical signal associated with one gate line  62  driven by one transmission gate  66  may control the operation of another transmission gate  66  located on the opposite side of the display  12 . Referring now to  FIG. 8 , the clock signals  1 - 4  are illustrated such that each clock signal occurs during a distinct time period. Moreover, each clock signal is scheduled such that a gate line  62  from one side of the display  12  is driven and then a gate line  62  from the opposite side of the display  12  is driven immediately thereafter. 
     For example, referring to latch  3  of  FIG. 7  and the timing diagram of  FIG. 8 , after gate line  4  is driven by transmission gate  4 , the electrical signal associated with gate line  4  may be provided to latch  3  as a set signal. As such, upon receiving the clock signal from clock  4  at time t 1 , the state of transmission gates  5  and  7 , which are coupled to latch  3 , may be set to active or high, as shown in  FIG. 8 . 
     Once the state of transmission gates  5  and  7  are active, the clock signal input into transmission gate  5  from clock  1  may cause the transmission gate  5  to drive gate line  5 . That is, the clock signal of clock  1  at time t 2  is transmitted through transmission gate  5  to drive gate line  5  since transmission gate  5  is in an active state between time t 1  and time t 5 . 
     After gate line  5  is driven by transmission gate  5 , the electrical signal associated with gate line  5  may be provided to latch  4  as a set signal. At approximately the same time, the electrical signal associated with gate line  5  may be provided to latch  2  as a reset signal. In this way, transmission gates  2  and  4  may be reset to a non-active state, thereby preventing gate lines  2  and  4  from being driven until latch  2  again receives a set signal. Referring back to latch  4 , upon receiving the clock signal from clock  4  at time t 1 , the state of transmission gates  6  and  8 , which are coupled to latch  4 , may be set to active or high. Transmission gate  6  may then drive gate line  6  according to the clock signal received at time t 3  from clock  3 . 
     After transmission gate  6  drives gate line  6 , transmission gate  7  may drive gate line  7  based on a clock signal received at time t 4  from clock  2 . In the same manner, after transmission gate  7  drives gate line  7 , transmission gate  8  may drive gate line  8  based on a clock signal received at time t 5  from clock  4 . At approximately the same time that gate line  8  is driven, the electrical signal driving gate line  8  is provided to latch  3 , thereby resetting latch  3  to an inactive state at time t 5  and turning transmission gates  5  and  7  to an off or inactive state. 
     In addition to being coupled to latch  3 , gate line  8  may also be coupled to the next latch circuit  64  (e.g., latch  5 ) of the gate drive circuit  80 . As such, the electrical signal driving gate line  8  may cause the next latch circuit  64  to change states. By employing the scheme described above for activating and deactivating latch circuits  64 , each gate drive circuit  80  and  82  may have just one latch circuit  64  active at any given time. As a result, the probability of driving two gate lines  62  by one gate drive circuit  80  or  82  is reduced as compared to the gate drive circuit  60 . 
     In certain embodiments, it may be beneficial to include a data line  86  that provides a reset signal to each respective latch circuit  64  of the gate drive circuits  80  and  82 . As such, the processor  18  may reset each latch circuit  64  via the data line  84  to ensure that the driving scheme described above is implemented effectively. That is, by sending a hard reset signal to each latch circuit  64 , the processor  18  may ensure that none of the latch circuits  64  are operating in an incorrect state when the gate drive circuits  80  and  82  are employed to depict images on the display  12 . 
     Although the gate drive circuits  80  and  82  may provide an improved manner in which to ensure that two gate lines  62  are not driven at the same time, in certain embodiments, the latch circuits  64  of the gate drive circuits  60 ,  80 , and  82  of  FIGS. 5 and 7  may be designed according to logic schematic  90  of  FIG. 9 . Referring to  FIG. 9 , the latch circuit  64  may include a D flip-flop circuit  92 , an inverter  94 , an inverter  96 , and a switch  98 . 
     Generally, by employing the logic schematic  90  of  FIG. 9  for the latch circuit  64 , the latch circuit  64  may provide additional protection to prevent two gate lines  62  of the display  12  being driven at the same time. That is, the logic schematic  90  uses state information regarding the state of a previous latch circuit  64  and a subsequent latch circuit  64  to ensure that a respective latch circuit  64  will not cause more than one gate line  62  from being driven at the same time. 
     Generally, the truth table for the logic schematic  90  may be summarized according to the following table. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Truth Table 
               
            
           
           
               
               
               
               
               
            
               
                   
                 N − 1 
                 N + 1 
                 Q_BAR 
                 Q 
               
               
                   
                   
               
               
                   
                 1 
                 0 
                 0 
                 1 
               
               
                   
                 0 
                 0 
                 Hold 
                 Hold 
               
               
                   
                 0 
                 1 
                 1 
                 0 
               
               
                   
                 1 
                 1 
                 1 
                 0 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table 1, when the preceding latch circuit  64  (i.e., N−1) is active (i.e., 1) and the subsequent latch circuit  64  (i.e., N+1) is inactive, the Q line is high, thereby allowing the respective latch circuit  64  (i.e., N) to set or become active. However, when both the preceding latch circuit  64  and the subsequent latch circuit  64  are inactive, the Q line and the Q_bar line wait in a hold position. As such, the respective latch circuit  64  may not change states, and instead may just remain in its present state. 
     When the preceding latch circuit  64  is inactive and the subsequent latch circuit  64  is active, the Q line is active and the Q_bar line is inactive. As such, the respective latch circuit  64  is reset to its original state. Finally, when the preceding latch circuit  64  and the subsequent latch circuit  64  are both active, the Q line is active and the Q_bar line is inactive. As such, the respective latch circuit  64  is again reset to its original state, thereby preventing two latch circuits  64  from being active at the same time. 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Metadata:
Filing Date: 20140930
Publication Date: 20170228
Grant Date: 20170228
Priority Date: 20140930
Inventors: CHANG TING-KUO
JAMSHIDI-ROUDBARI ABBAS
YEH SHIN-HUNG
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G3/3677", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K17/56", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G3/3677", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K17/56", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 55585558