Patent Publication Number: US-2009231175-A1

Title: Multimedia signal processing apparatus

Description:
BACKGROUND 
     The present invention relates to driving liquid crystal displays (LCDs), and more particularly, to multimedia signal processing apparatuses having an LCD panel. 
     Regarding small-sized LCD panels, like a 7-inch LCD panel for example, the most common resolution of the day for analog panels is typically (480*234) pixels. Here, the term “analog panels” represents the LCD panels with analog source driver integrated circuits (ICs). That is, the internal process scheme of the driver ICs for driving sources of display units of the LCD panels is analog. If a higher resolution such as (800*480) pixels is required, digital panels are typically utilized for implementation according to the related art. Here, the term “digital panels” represents the LCD panels with digital source driver ICs. That is, the internal process scheme of the driver ICs for driving the sources of the display units of the LCD panels is digital. 
     According to the related art, utilizing digital source driver ICs may have benefits such as better noise-resistant capabilities while implementing a small-sized LCD panel with a higher resolution. However, utilizing digital source driver ICs leads to disadvantages such as a higher cost of driver ICs, and a large number of data connections between the small-sized LCD panel and a printed circuit board (PCB) of a control circuit (e.g. the PCB for mounting an LCD control ASIC). For example, the number of data connections required for each of red, green, and blue channels (which are typically referred to as R/G/B channels) is six, the overall number of data connections between the small-sized LCD panel and the PCB with digital source driver ICs is eighteen, while the number of data connections for implementing a small-sized LCD panel by utilizing analog source driver ICs is merely three. Referring to  FIG. 1  illustrating a combination  100  of an LCD panel  110  and a control circuit  120  according to the related art, the LCD panel  110  is implemented by utilizing analog source driver ICs such as a set of LCD driver ICs (LDIs)  112 - 1 ,  112 - 2 , . . . , and  112 - 6 , and there are three data connections coupled between a digital-to-analog converter (DAC)  122  within the control circuit  120  and the first LDI  112 - 1  of the set of LDIs. 
     It is noted that no matter whether the internal process scheme of the source driver ICs is digital or analog, the source driver ICs typically drive the sources of the display units of the LCD panels by at least one analog driving voltage. As a result, utilizing digital source driver ICs may lead to another disadvantage such as requiring of a larger number of digital-to-analog converters (DACs) within the digital source driver ICs. 
     SUMMARY 
     It is an objective of the claimed invention to provide multimedia signal processing apparatuses, so that a small-sized liquid crystal display (LCD) panel with a higher resolution can be implemented by utilizing analog source driver integrated circuits (ICs). 
     An exemplary embodiment of a multimedia signal processing apparatus comprises: a scalar for performing a scaling operation of an image; a formatter, coupled to the scalar, for generating a first set of digital values and a second set of digital values according to a scaling result of the scaling operation, where the first set of digital values represents a first portion of the image, and the second set of digital values represents a second portion of the image; a first digital-to-analog converter (DAC), coupled to the formatter, for performing digital-to-analog conversion on the first set of digital values to generate a first set of analog signals; a second DAC, coupled to the formatter, for performing digital-to-analog conversion on the second set of digital values to generate a second set of analog signals; a panel for displaying the image; and a plurality of driver ICs, coupled to the first and the second DACs and the panel, for driving the panel according to the first and the second sets of analog signals, respectively. 
     An exemplary embodiment of a multimedia signal processing apparatus comprises: a first DAC for performing digital-to-analog conversion on a first set of digital values to generate a first set of analog signals, where the first set of digital values represents a first portion of an image; a second DAC for performing digital-to-analog conversion on a second set of digital values to generate a second set of analog signals, where the second set of digital values represents a second portion of the image; an analog panel for displaying the image; and a plurality of driver ICs, coupled to the first and the second DACs and the analog panel, for driving the analog panel according to the first and the second sets of analog signals, respectively. 
     An exemplary embodiment of a multimedia signal processing apparatus comprises: a first DAC for performing digital-to-analog conversion on a first set of digital values to generate a first set of analog signals, where the first set of digital values represents a first portion of an image to be displayed; a second DAC for performing digital-to-analog conversion on a second set of digital values to generate a second set of analog signals, where the second set of digital values represents a second portion of the image to be displayed; and a plurality of driver ICs, coupled to the first and the second DACs, for receiving the first and the second sets of analog signals and driving according to the first and the second sets of analog signals, respectively. 
     An exemplary embodiment of a multimedia signal processing apparatus comprises: a first DAC for performing digital-to-analog conversion on a first set of digital values to generate a first set of analog signals, where the first set of digital values represents a first portion of an image; a second DAC for performing digital-to-analog conversion on a second set of digital values to generate a second set of analog signals, where the second set of digital values represents a second portion of the image; a panel for displaying the image; and a plurality of driver ICs, coupled to the first and the second DACs and the panel, for driving the panel according to the first and the second sets of analog signals, respectively. 
     An exemplary embodiment of a multimedia signal processing apparatus comprises: a first DAC for performing digital-to-analog conversion on a first set of digital values to generate a first set of analog signals, where the first set of digital values represents a first portion of an image to be displayed; a second DAC for performing digital-to-analog conversion on a second set of digital values to generate a second set of analog signals, where the second set of digital values represents a second portion of the image to be displayed; and a plurality of driver ICs, coupled to the first and the second DACs, for driving displaying of the image according to the first and the second sets of analog signals, respectively. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a liquid crystal display (LCD) panel and a control circuit according to the related art, where the LCD panel is implemented by utilizing analog source driver integrated circuits (ICs). 
         FIG. 2  is a diagram of a multimedia signal processing apparatus according to one embodiment of the present invention. 
         FIG. 3  is a diagram of the control circuit shown in  FIG. 2 . 
         FIG. 4  is a diagram of a multimedia signal processing apparatus according to another embodiment of the present invention. 
         FIG. 5  is a diagram of the control circuit shown in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, electronic equipment manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
     Please refer to  FIG. 2 .  FIG. 2  is a diagram of a multimedia signal processing apparatus  200  according to a first embodiment of the present invention, where the multimedia signal processing apparatus  200  comprises a liquid crystal display (LCD) panel  210  and a control circuit  220 . The multimedia signal processing apparatus  200  of this embodiment further comprises a plurality of driver integrated circuits (ICs) such as a first set of LCD driver ICs (LDIs)  212 - 1 ,  212 - 2 , and  212 - 3 , a second set of LDIs  214 - 1 ,  214 - 2 , and  214 - 3 , and another LDI  210 G, where the driver ICs are positioned on or within the LCD panel  210 , and are coupled to a plurality of display units (not shown) of the LCD panel  210 . For example, the driver ICs can be attached to and/or mounted on the LCD panel  210 . 
     In the first embodiment, an example of the multimedia signal processing apparatus  200  is a television (TV) receiver. Accordingly, the LCD panel  210  of this embodiment can be a small-sized LCD panel, for example, a 7-inch LCD panel whose resolution is (800*480) pixels, which means the number of the display units mentioned above is typically a multiple of (800*480). As shown in  FIG. 2 , the LCD panel  210  comprises a display area  210 A for displaying an image, and the display area  210 A represents the region where the display units described above are positioned. In addition, the two sets of LDIs of this embodiment are driver ICs for driving sources of these display units, and the LDI  210 G of this embodiment is utilized for driving gates of these display units. Additionally, the internal process scheme of the two sets of LDIs mentioned above is analog, which means the LCD panel  210  of this embodiment is an analog panel. 
     According to this embodiment, the control circuit  220  comprises a plurality of digital-to-analog converters (DACs)  222  and  224 , where there are three data connections coupled between the DAC  222  and the first LDI  212 - 1  of the first set of LDIs, and there are three data connections coupled between the DAC  224  and the first LDI  214 - 1  of the second set of LDIs. As shown in  FIG. 2 , the DAC  222  of this embodiment includes three output terminals  222 R,  222 G, and  222 B respectively corresponding to red, green, and blue channels (which are typically referred to as R/G/B channels), and the DAC  224  of this embodiment includes three output terminals  224 R,  224 G, and  224 B respectively corresponding to the red, green, and blue channels. 
     The control circuit  220  of this embodiment is capable of generating a first set of digital values representing a first portion of an image to be displayed, and is capable of generating a second set of digital values representing a second portion of the image to be displayed. For example, the first portion is a partial image displayed on the left half of the display area  210 A, and the second portion is another partial image displayed on the right half of the display area  210 A, where the left half and the right half of the display area  210 A are seamless to a user viewing at a normal distance according to this embodiment. 
     The DAC  222  of this embodiment performs digital-to-analog conversion on the first set of digital values to generate a first set of analog signals, and outputs the first set of analog signals through the output terminals  222 R,  222 G, and  222 B, so the first set of LDIs  212 - 1 ,  212 - 2 , and  212 - 3  may receive the first set of analog signals, where the LDI  212 - 1  is coupled to the DAC  222  directly and the LDIs  212 - 2  and  212 - 3  are coupled to the DAC  222  indirectly, as shown in  FIG. 2 . In addition, the first set of LDIs  212 - 1 ,  212 - 2 , and  212 - 3  drives the LCD panel  210  according to the first set of analog signals. More particularly in this embodiment, the first set of LDIs  212 - 1 ,  212 - 2 , and  212 - 3  drives the display units corresponding to the left half of the display area  210 A according to the first set of analog signals. 
     Similarly, the DAC  224  of this embodiment performs digital-to-analog conversion on the second set of digital values to generate a second set of analog signals, and outputs the second set of analog signals through the output terminals  224 R,  224 G, and  224 B, so the second set of LDIs  214 - 1 ,  214 - 2 , and  214 - 3  may receive the second set of analog signals, where the LDI  214 - 1  is coupled to the DAC  224  directly and the LDIs  214 - 2  and  214 - 3  are coupled to the DAC  224  indirectly, as shown in  FIG. 2 . In addition, the second set of LDIs  214 - 1 ,  214 - 2 , and  214 - 3  drives the LCD panel  210  according to the second set of analog signals. More particularly in this embodiment, the second set of LDIs  214 - 1 ,  214 - 2 , and  214 - 3  drives the display units corresponding to the right half of the display area  210 A according to the second set of analog signals. 
     Please refer to  FIG. 3 .  FIG. 3  is a diagram of the control circuit  220  shown in  FIG. 2 , where the control circuit  220  comprises a scalar  310 , a formatter  312 , and two TV encoders (TVEs)  322  and  324 . The scalar  310  of this embodiment is capable of performing a scaling operation of an image according to the video data  308  thereof. Here, the video data  308  represents the source image data of the image to be displayed. The formatter  312  of this embodiment is capable of generating the first set of digital values and the second set of digital values according to a scaling result  311  of the scaling operation, where the first set of digital values can be output into the TVE  322  through an intermediate signal  321  according to a specific frame format, and the second set of digital values can be output into the TVE  324  through another intermediate signal  323  according to the specific frame format. 
     According to this embodiment, the formatter  312  outputs digital values corresponding to the partial image to be displayed on the left half of the display area  210 A as the first set of digital values, and outputs digital values corresponding to the partial image to be displayed on the right half of the display area  210 A as the second set of digital values. If the resolution of the whole image to be displayed on the display area  210 A is (800*480) pixels as mentioned, the resolution of each of the partial images to be displayed on the left and right halves can be (400*480) pixels respectively. 
     As shown in  FIG. 3 , each of the TVEs  322  and  324  is a  3 -channel TVE including three output terminals. The TVE  322  of this embodiment is capable of encoding the first set of digital values to output the first set of digital values through the three output terminals thereof according to a specific signal format. As a result, the DAC  222  performs digital-to-analog conversion on the first set of digital values from the TVE  322  to output the first set of analog signals through the output terminals  222 R,  222 G, and  222 B. Similarly, the TVE  324  of this embodiment is capable of encoding the second set of digital values to output the second set of digital values through the three output terminals thereof according to the specific signal format. As a result, the DAC  224  performs digital-to-analog conversion on the second set of digital values from the TVE  324  to output the second set of analog signals through the output terminals  224 R,  224 G, and  224 B. 
     In the first embodiment, an operation frequency of the DAC  222  is equal to an operation frequency of the DAC  224 . According to a variation of the first embodiment, a left partial image and a right partial image to be respectively displayed on different portions of the display area  210 A of the LCD panel  210  are not necessarily of the same resolution, so an operation frequency of the DAC  222  is not necessarily equal to an operation frequency of the DAC  224 . For example, the resolution of the left partial image to be displayed is approximately twice as high as the resolution of the right partial image to be displayed, the coupling between the source driver ICs may be varied according to the resolutions of the left and right partial images. As a result, within the first set of LDIs of this variation, there are four LDIs that are coupled to the DAC  222  directly or indirectly, and within the second set of LDIs of this variation, there are two LDIs that are coupled to the DAC  224  directly or indirectly, where the operation frequency of the DAC  222  is approximately twice as high as the operation frequency of the DAC  224 . 
     According to another variation of the first embodiment, the multimedia signal processing apparatus  200  can be a portable multimedia player supporting still image playback. According to another variation of the first embodiment, the multimedia signal processing apparatus  200  can be a cellular phone. Yet according to another variation of the first embodiment, the multimedia signal processing apparatus  200  can be a portable digital versatile disc (DVD) player, and the multimedia signal processing apparatus  200  further comprises a disc loader (not shown) for accessing an optical disc. 
     According to the first embodiment, the multimedia signal processing apparatus  200  drives displaying of the image according to the first and the second sets of analog signals, respectively. According to other embodiments of the present invention, the number of DACs respectively outputting different sets of analog signals to be received by corresponding sets of source driver ICs can be greater than two. Please refer to  FIG. 4  illustrating a diagram of a multimedia signal processing apparatus  400  according to a second embodiment of the present invention, where the second embodiment is also a variation of the first embodiment. The differences between the first and the second embodiments are described as follows. 
     According to the second embodiment, the multimedia signal processing apparatus  400  comprises three sets of source driver ICs comprising a first set of LDIs  412 - 1 ,  412 - 2 , and  412 - 3 , a second set of LDIs  414 - 1 ,  414 - 2 , and  414 - 3 , and a third set of LDIs  416 - 1 ,  416 - 2 , and  416 - 3 . In this embodiment, the three sets of LDIs mentioned above drive sources of a plurality of display units corresponding to a left region, a central region, and a right region of a display area  410 A of an LCD panel  410  of the multimedia signal processing apparatus  400  according to three sets of analog signals generated by three DACs  422 ,  424 , and  426  of a control circuit  420  of the multimedia signal processing apparatus  400 , respectively. For example, the resolution of an image to be displayed on the display area  410 A is (1280*800) pixels, and the resolution of each of the left and central regions can be (427*800) pixels, and the resolution of the right region can be (426*800) pixels. 
     As shown in  FIG. 5 , a formatter  512  of the control circuit  420  of the second embodiment generates three sets of digital values according to a scaling result  511  of the scaling operation performed by a scalar  510  of the control circuit  420 , and outputs digital values representing a left portion of the image to be displayed on the display area  410 A (e.g. a left partial image to be displayed on the left region) as a first set of digital values, and outputs digital values representing a central portion of the image to be displayed on the display area  410 A (e.g. a central partial image to be displayed on the central region) as a second set of digital values, and further outputs digital values representing a right portion of the image to be displayed on the display area  410 A (e.g. a right partial image to be displayed on the right region) as a third set of digital values. 
     In addition, the control circuit  420  of this embodiment comprises three TVEs  522 ,  524 , and  526  respectively encoding the first, second, and third sets of digital values from the formatter  512  to respectively output the first, second, and third sets of digital values into the DACs  422 ,  424 , and  426  according to a specific signal format. As a result, the DACs  422 ,  424 , and  426  perform digital-to-analog conversion on the first, second, and third sets of digital values to generate and output the first, second, and third sets of analog signals into the three sets of LDIs mentioned above, respectively. 
     In contrast to the related art, a small-sized LCD panel with a higher resolution can be implemented by utilizing analog source driver ICs according to the present invention. Therefore, the disadvantages of utilizing digital source driver ICs, for example, a higher cost of driver ICs, a large number of data connections between the small-sized LCD panel and a printed circuit board (PCB) of a control circuit, and a larger number of DACs within the digital source driver ICs, can be avoided. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.