The present invention relates to a driver controller for controlling multiple data drivers in a display panel, such as a PDP (plasma display panel) or an LCD (liquid crystal display).
In recent years, as the use of display panels, such as PDPs and LCDs, has become widespread, the screen size and the definition thereof have been increasing at a rapid pace. These display panels have hundreds to thousands of signal lines in the horizontal and vertical directions and realize panel display by driving these signal lines by associated multiple data drivers and a scanning driver.
Typically, a plurality of data drivers are cascade-connected to form data driver modules and the driving thereof is controlled by a corresponding driver controller. The cascade connection reduces the number of signals driven in parallel, but in a high-definition display panel, the driver controller needs to drive signals which range from several dozens to more than one hundred. In addition, as the display panel screen size has been increased, the load capacitances between the driver controller and the data driver modules have been increased, which requires the driver controller to have high output drive capability.
However, at the time when the driver controller drives more than one hundred signals by using its high output drive capability, if these signal lines change concurrently in the same direction depending upon display data, large amounts of transient current flow in output buffers in the driver controller. This causes power supply voltage and ground voltage supplied to the driver controller to vary greatly, which results in noise adversely affecting the driver controller itself and the peripheral devices thereof.
Therefore, according to a conventional technique, a delay circuit is inserted for each output bit so as to delay the points in time when respective output data change, so that the transient currents instantaneously passing through the output buffers reach their peaks at different points in time. This reduces noise occurring due to variation in power supply voltage and ground voltage in the driver controller (see Japanese Laid-Open Publication No. 2003-8424).
With the increase in the display panel screen size, signal line skews, resulting from the increased load capacitances between the driver controller and the data driver modules, have been increasing, while the operating frequency has been raised as performance has been enhanced. It has thus become difficult to satisfy AC timing of the data driver modules.
However, for the above-described conventional technique, which uses the delay circuits to delay the points in time when the respective data change, it is difficult to achieve highly-precise phase control, because of ambient temperature, voltage variation, and other conditions. In addition, the conventional technique has the drawback of lacking a mechanism for adjusting AC timing.
The present invention has been made to overcome the above problems, and it is therefore an object of the present invention to provide a driver controller, in which noise caused by variation in power supply voltage resulting from output concurrent change is reduced, and optimization of AC timing is achieved even when propagation skew among data driver modules is increased with increase in display panel size.
In order to achieve the object, according to the present invention, in driver-data output clock selection sections and driver data control sections, each equal in number to data driver modules that are connected to the driver controller, the phase of driver data is adjusted for each data driver module, while the phase of each driver clock is adjusted in driver-clock output clock selection sections and driver clock control sections. This allows outputs to the corresponding data driver modules to change at different points in time. Also, driver data output clocks are selected with propagation skew among the data driver modules being a phase difference for each driver data control section, whereby AC timing in all data driver modules is optimized.
According to the present invention, individual phase-adjustment is performed for the timing of the output of the respective driver data and respective driver clocks to the data driver modules. This permits the respective driver data to change at different points in time, whereby the occurrence of noise is reduced, and even if there is propagation skew, optimization of AC timing is achievable.
Hereinafter, the driver controller 600 according to an embodiment of the present invention will be described in detail with reference to
The reference numeral 101 indicates a clock generation section, which generates a system clock s101 for the driver controller 600, while generating a plurality of clocks s1011 to s101i having different phases (where i is an integer equal to or greater than 2) with the system clock s101 used as a reference phase. These clocks having different phases may be generated by a PLL or a DLL, for example.
The reference numeral 102 indicates driver-data output clock selection sections. The number of driver-data output clock selection sections provided is n so as to correspond to the n data driver modules 6011 to 601n. The driver-data output clock selection sections 1021 to 102n each select one of the clocks s1011 to s101i with different phases generated by the clock generation section 101, in accordance with an associated selection signal s106a1, . . . or s106an from a register control section 106 (which will be described later) and output a driver data output clock s1021, . . . or s102n.
The reference numeral 103 indicates driver-clock output clock selection sections. The number of driver-clock output clock selection sections provided is m so as to correspond to the m groups of the n data driver modules 6011 to 601n, that is, G6011 to G601m. The driver-clock output clock selection sections 1031 to 103m each select one of the clocks s1011 to s101i with different phases generated by the clock generation section 101, in accordance with an associated selection signal s106b1, . . . or s106bm from the register control section 106 and output a driver clock output clock s1031 to s103m.
The reference numeral 104 indicates driver data control sections. The number of driver data control sections provided is n so as to correspond to the n data driver modules 6011 to 601n. The driver data control sections 1041 to 104n latch the respective data signals s100a1 to s100an from the signal processing section 100 by the respective driver data output clocks s1021 to s102n from the driver-data output clock selection sections 1021 to 102n and each select either one of the latch signal and the associated data signal s100a1, . . . or s100an in accordance with an associated selection signal s106c1, . . . or s106cn from the register control section 106. Thereafter, the driver data control sections 1041 to 104n determine the drive capability of the respective selected signals in accordance with selection signals s106e1 to s106en from the register control section 106 and output, as driver data s1041 to s104n, the respective selected signals from their output ports to the corresponding data driver modules 6011 to 601n.
The reference numeral 105 denotes driver clock control sections. The number of driver clock control sections provided is m so as to correspond to the m groups of the n data driver modules 6011 to 601n, that is, G6011 to G601m. During a time period in which the output enable signal s100b from the signal processing section 100 indicates the active state, the driver clock control sections 1051 to 105m determine the drive capability of respective driver clocks s1051 to s105m in accordance with selection signals s106f1 to s106fm from the register control section 106 and thereafter output the driver clocks s105 to s105m from their respective output ports to the corresponding data driver module groups G6011 to G601m. Each of the driver clocks s105 to s105m is synchronized with either one of the system clock s101 and the associated driver clock output clock s1031, . . . or s103m according to an associated selection signal s106d1, . . . or s106dm from the register control section 106.
The reference numeral 106 denotes the register control section for outputting the above-mentioned various selection signals s106a1 to s106an, s106b1 to s106bm, s106c1 to s106cn, s106d1 to s106dm, s106e1 to s106en, and s106f1 to s106fm in response to inputs (e.g., I2C compatible serial inputs) from an external port 106i.
Now, the driver data control section 104n will be described in detail with reference to
The reference numeral 104nb indicates an output data selection section for selecting either the data signal s100an or the latch data in accordance with the selection signal s106cn and outputting the selected data.
The reference numeral 104nc denotes a driver data drive control section, which determines the drive capability of the selected data in accordance with the selection signal s106en and outputs, as the driver data s104n, the selected signal from the output port thereof to the corresponding data driver module 601n.
Now, the driver clock control section 105m will be described in detail with reference to
The reference numeral 105mb indicates a driver clock generation section, which outputs a pre-driver clock in synchronization with either the positive or negative edge of the base clock during a time period (e.g., a period H) in which the output enable signal s100b indicates the active state. The determination as to whether the pre-driver clock is synchronized with the positive or negative edge may be made in advance or may be made by the register control section 106.
The reference numeral 105mc denotes a driver clock drive control section, which determines the drive capability of the pre-driver clock in accordance with the selection signal s106fm and outputs, as the driver clock s105m, the pre-driver clock from the output port thereof to the corresponding data driver module group G601m.
Next, the operation of the driver controller 600 will be described in detail with reference to
The driver data control section 1041 drives the data latched by the driver data output clock s1021 and outputs the driver data s1041, while the driver data control section 104n drives the data latched by the driver data output clock s102n and outputs the driver data s104n. The driver data having the phase differences are thus output to the data driver modules to thereby allow the respective driver data to change at different points in time, whereby noise in power supply voltage or ground caused by transient current can be reduced. Also, by making it possible to set the drive capability of the respective driver data to any values, the drive capability can be optimized according to the load capacitances of the respective driver data output ports, thereby enabling the signal quality to be improved and unnecessary current consumption to be reduced.
In the driver data control sections 1041 to 104n, the data signals s100a1 to s100an synchronized with the system clock s101 may be selected instead of the latch data.
The driver clock control section 1051 outputs the driver clock s105 that is synchronized with the negative edge of the driver clock output clock s1031, while the driver clock control section 105m outputs the driver clock s105m that is synchronized with the negative edge of the driver clock output clock s103m. At this time, the driver clock s105 corresponds to the driver data s1041 and s1042, while the driver clock s105m corresponds to the driver data s104(n−1) and s104n. In this way, since the driver clocks can correspond to any multiple number of driver data, the number of driver clocks for driving the data driver modules 6011 to 601n can be smaller than the number of data driver modules 6011 to 601n. Also, in a case where propagation skew among the data driver modules is large, data driver modules whose skews are close to each other are grouped together and the driver clocks having phase differences are output to the data driver module groups G6011 to G601m, whereby noise reduction and optimization of AC timing are both achievable. In addition, by making it possible to set the output drive capability of the driver clocks to any values, the drive capability can be optimized according to the load capacitances of the driver clock output ports, whereby the signal quality can be improved, and even when many data driver modules are driven, the driving can be realized with a small number of components without adding an external drive buffer and the like.
It will easily be appreciated that the driver clock control sections 1051 to 105m may output the driver clocks synchronized with the positive edges of the respective driver clock output clocks s1031 to s103m.
As stated above, in the driver controller 600 according to the embodiment of the present invention, highly-precise individual phase-adjustment can be made for the timing of the output of the respective driver data and respective driver clocks to the data driver modules 6011 to 601n. As a result, the respective driver data change at different points in time, whereby the occurrence of noise is reduced, and even in the case of large propagation skew, optimization of AC timing is achieved by appropriately combining the driver data and the driver clocks.
Next, a first modified example of the above-described embodiment will be described with reference to
Specifically, in
Now, the driver clock control section 205m will be described with reference to
The reference numeral 205mc denotes a driver clock drive control section, which determines the drive capability of the differential pre-driver clocks in accordance with the selection signal s106fm and outputs, as the differential driver clocks s205mp and s205nm, the pre-driver clocks from the output ports thereof to the corresponding data driver module group G601m.
The driver clock control section 205m outputs the differential driver clocks s205mp and s205nm having the ½ frequency and synchronized with the negative edge of the driver clock output clock s103m. At this time, the differential driver clocks s205mp and s205nm correspond to the driver data s104(n−1) and s104n. In this way, the driver clocks become the differential clocks having the ½ frequency, which enables the adjustment of AC timing to be made easily.
It will easily be appreciated that the driver clock control sections 2051 to 205m may output the driver clocks that are synchronized with the positive edges of the respective driver clock output clocks s1031 to s103m.
Next, a second modified example of the above-described embodiment will be described with reference to
Specifically, in
The reference numeral 304 denotes driver data control sections. The number of driver data control sections provided is n so as to correspond to the n data driver modules 6011 to 601n. The driver data control sections 3041 to 304n each latch the associated k-bit data signal s100a1, . . . or s100an from the signal processing section 100 by the associated k driver data output clocks s3021, . . . or s302n from the associated driver-data output clock selection sections 3021, . . . or 302n for each bit and select either one of the latch signal and the data signal s100a1, . . . or s100an for each bit in accordance with an associated selection signal s306c1, . . . or s306cn from the register control section 306. Thereafter, the driver data control sections 3041 to 304n determine the drive capability of the respective selected signals for each bit in accordance with respective selection signals s306e1 to s306en from the register control section 306 and output, as k-bit driver data s3041 to s304n, the respective selected signals from the output ports thereof to the corresponding data driver modules 6011 to 601n.
Now, the driver data control section 304n will be described with reference to
The reference numeral 304nb indicates an output data selection section, which selects either the data signal s100an or the latch data for each bit in accordance with the selection signal s306cn and outputs the selected data.
The reference numeral 304nc denotes a driver data drive control section, which determines the drive capability of the selected data for each bit in accordance with the selection signal s306en and outputs, as the k-bit driver data s304n, the selected data from the output port thereof to the corresponding data driver module 601n.
Therefore, in this modified example, it is possible to perform phase control and drive capability control for each bit in the data driver modules, which enhances the effect of reducing noise.
Next, a third modified example of the above-described embodiment will be described with reference to
Specifically, in
The reference numeral 404 denotes driver data control sections. The number of driver data control sections provided is n so as to correspond to the n data driver modules 6011 to 601n. The driver data control sections 4041 to 404n latch the respective k-bit data signals s100a1 to s100an from the signal processing section 100 by the respective driver data output clocks s1021 to s102n from the driver-data output clock selection sections 1021 to 102n, each select either one of the latch signal and the associated data signal s100a1, . . . or s100an in accordance with an associated selection signal s106c1, . . . or s106cn from a register control section 406, and perform delay control for each bit in accordance with an associated control signal s406g1, . . . or s406gn from the register control section 406. Thereafter, the driver data control sections 4041 to 404n determine the drive capability of the respective selected signals for each bit according to respective selection signals s306e1 to s306en from the register control section 406 and output, as k-bit driver data s4041 to s404n, the respective selected signals from the output ports thereof to the corresponding data driver modules 6011 to 601n.
Now, the driver data control section 404n will be described with reference to
The reference numeral 304nc denotes a driver data drive control section, which determines the drive capability of the delayed data for each bit in accordance with the selection signal s306en and outputs, as the k-bit driver data s404n, the delayed data from the output port thereof to the corresponding data driver module 601n.
Therefore, in this modified example, the phase control for each bit in the data driver modules is performed after the latching, and thus can be carried out in a wider range, which allows coarse adjustment to be made in the output data selection section and fine adjustment to be made in the data delay control section.
Next, a fourth modified example of the above-described embodiment will be described with reference to
Specifically, in
Therefore, in this modified example, it is possible to generate any test data signals irrespective of the data signals, whereby conditions for AC timing evaluation can be set easily. Also, in some display panels, noise can be reduced further by fixing unused driver data output.
As described above, according to the present invention, individual phase-adjustment is performed for the timing of the output of the respective driver data and respective driver clocks to the data driver modules. This allows the respective driver data to change at different points in time, whereby the occurrence of noise is reduced, and even if there is propagation skew, optimization of AC timing is achievable. The present invention is thus applicable to driver controllers for controlling a plurality of data driver modules in display panels, such as PDPs and LCDs.
Number | Date | Country | Kind |
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2006-145748 | May 2006 | JP | national |
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