Abstract:
A method and apparatus is provided for controlling a dual display using a Red, Green and Blue (RGB) interface in a mobile terminal with a projector module, in which the projector module expends a high-resolution image and projects the expended image to the outside, a display displays a menu image for operation of the projector module, an image processor has a first buffer assigned to the display for data transmission to the display, and a second buffer assigned to the projector module for data transmission to the projector module, and a controller transmits image data to the first and second buffers, and outputs control signals for activating both or a selected one of the first and second buffers, depending on selection of a display mode.

Description:
PRIORITY 
     This application claims priority to an application filed with the Korean Intellectual Property Office on Jul. 13, 2009 and assigned Serial No. 10-2009-0063499, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to an apparatus and method for controlling a dual display, and more particularly, to an apparatus and method for controlling a dual display in a mobile terminal with a projector module. 
     2. Description of the Related Art 
     In order to overcome the limitation of screen size of mobile terminals, a function capable of displaying information of the mobile terminals on large external display devices has been recently developed, such as the TV-OUT function, and the use of a connector connecting mobile terminals to the external projector devices has increased accordingly. 
     In addition to the above functions, a technology also has been developed that mounts a small projector module in mobile terminals instead of using the external projector devices. A mobile terminal with the projector module allows a user to view Digital Multimedia Broadcasting (DMB) images on large screens by projecting the DMB images onto any alternative screens such as A4 papers, walls and white shirts, mitigating the inconvenience of viewing the images on a small Liquid Crystal Display (LCD) screen. 
     When the mobile terminal includes a projector module, a user may input commands such as numbers and characters, by directly pressing buttons on a keypad of the mobile terminal in order to control the projector module. Recently, however, touch pad technology has been increasingly applied to most mobile terminals, and full-touch phones are becoming the trend of the next-generation mobile terminals. In this case, the user touches soft buttons displayed on the screen rather than pressing hard buttons on the existing keypad, and then the mobile terminal recognizes numbers, characters and commands corresponding to the touch inputs. 
     A full-touch LCD screen of the mobile terminal with a projector module should always be turned on in order to receive key inputs. In the conventional mobile terminal with a projector function shown in  FIG. 1 , for example, when a user desires to watch a DMB broadcast, an image  110  for the DMB broadcast may be projected onto a projector screen  100 , and volume information, channel change information and other control command buttons may be displayed on an LCD screen  120  of the mobile terminal. 
     In this case, there is a need to focus on controlling the data to be output through the LCD screen  120  and the data to be output through the projector screen  100 . With the development of multimedia, when large high-resolution images are processed, efficient data processing should also be considered. In images with a resolution of Wide Video Graphics Array (WVGA) (800×480 or 854×480 class), the existing Central Processing Unit (CPU) interface needs a Write Enable (WE) signal of about up to 43 nsec to transmit video data consisting of 30 frames per second to an LCD panel and a projector module. That is, if the resolution increases, the time required to display one frame should be reduced. In particular, an expensive Application Processor (AP) chip for fast signal processing is needed to avoid high power consumption. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention provides a control apparatus and method for outputting high-resolution images through an LCD panel and a projector module of a mobile terminal. 
     Another aspect of the present invention provides an apparatus and method for controlling a dual display in a mobile terminal with a projector module, in which a projector function can be implemented at a low cost by using the existing LCD panel and AP chip, and the projector module. 
     In accordance with an aspect of the present invention, there is provided an apparatus for controlling a dual display using a Red Green and Blue (RGB) interface in a mobile terminal with a projector module, in which the projector module expends a high-resolution image and projects the expended image to the outside, a display displays a menu image for operation of the projector module, an image processor has a first buffer assigned to the display for data transmission to the display and a second buffer assigned to the projector module for data transmission to the projector module, and a controller transmits image data to the first and second buffers, and outputs control signals for activating both or a selected one of the first and second buffers, depending on selection of a display mode. 
     In accordance with another aspect of the present invention, there is provided a method for controlling a dual display using an RGB interface in a mobile terminal having a display and a projector module, in which a display mode is determined when the projector module is in an ON state, control signals are output according to the display mode, to activate both or a selected one of a first buffer assigned to the display for data transmission to the display and a second buffer assigned to the projector module for data transmission to the projector module, and image data from the first and second buffers is output through the display and the projector module respectively, according to the control signals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates an operation of a conventional mobile terminal with a projector function; 
         FIG. 2  illustrates an internal structure of a mobile terminal with a projector function according to a first embodiment of the present invention; 
         FIG. 3  illustrates an internal structure of a mobile terminal with a projector function according to a second embodiment of the present invention; and 
         FIG. 4  illustrates an operation of a mobile terminal with a projector function according to the first embodiment of the present invention. 
     
    
    
     Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features and structures. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, specific details such as detailed configuration and components are merely provided to assist the overall understanding of embodiments of the present invention. Therefore, it should be apparent to those skilled in the art that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for the sake of clarity and conciseness. 
     The present invention provides a method for controlling a dual display in a mobile terminal with a projector module. In particular, the present invention may control each of a mobile terminal&#39;s screen and a projector screen in real time by using an RGB interface to support high-resolution images. To be specific, the present invention independently controls data transmitted to each of an LCD panel and a projector driver (or a projector module) of the mobile terminal, and uses Chip Select (CS) signals for this control. By doing so, same or different high-resolution images may be displayed on a mobile terminal&#39;s screen and a projector screen. 
     Prior to a description of the present invention, a brief description of the RGB interface used in the present invention will now be given. 
     Generally, a CPU interface and/or an RGB interface are used to display images on an LCD panel of a mobile terminal, and control signals and data are transmitted through such interfaces. The CPU interface is mainly used to display still images. The RGB interface may implement high-resolution videos because it scatters data in sync with an external clock. Thus, the RGB interface is suitable to display high-resolution images compared with the CPU interface. With the continuing development of multimedia, however, a method for displaying high-resolution images should be provided in mobile terminals to support the multimedia. 
     If a modem chip or AP chip supporting the actual resolution of QVGA (240×320) or WQVGA (240×400) is provided in a mobile terminal, the CPU interface is also available. However, if the CPU interface is used when the performance has been improved to the resolution of WVGA (800×480 or 854×480 class), there is needed a modem chip and an AP chip, which have a high-performance CPU, and the existing display panels cannot be used. Considering this, the present invention uses the RGB interface that can easily display high-resolution images compared with the CPU interface. 
     A description will now be made of a structure of a control apparatus for displaying high-resolution images through an LCD panel and a projector driver in a mobile terminal that supports a projector function using an RGB interface. 
     A first embodiment of the present invention controls images being transmitted to an LCD panel and a projector driver through their associated paths using CS signals. A second embodiment of the present invention controls data being transmitted to an LCD panel only when the LCD panel needs an image update while the projector function is in operation. 
       FIG. 2  illustrates an internal structure of a mobile terminal with a projector function according to the first embodiment of the present invention. 
     A dual-display control apparatus according to the first embodiment of the present invention essentially includes a controller  200 , an image processor  210 , a display  220 , and a projector module  230 . While only the blocks needed for a description of the first embodiment of the present invention are shown in  FIG. 2  for convenience, the present invention will not be limited to these blocks. Herein, the controller  200  may be realized using an application processor, and the image processor  210  may be implemented using an image control Integrated Circuit (IC). 
     The controller  200  serves to control the overall operation of the mobile terminal and a signal flow between the components. The controller  200  outputs control signals to the image processor  210  so that images may be displayed according to each of standards of the display  220  and the projector module  230 . 
     Four paths are formed for outputting the control signals and for data transmission. A path # 1  may be realized with 2 pins, and serves as a path for transmitting screen change information. Initial setting values such as an individual porch value and a resolution are transmitted through path # 1 . The term “porch value” as used herein refers to top, bottom, left and right margins of images displayed through the display  220  and the projector module  230 . A path # 3  may be realized with 24 pins, and serves as a path through which image data is transmitted. A path # 2  and a path # 4  are connected, respectively, to a first buffer  240  for storing data to be transmitted to the display  220  and a second buffer  250  for storing data to be transmitted to the projector module  230 . As control signals are transmitted from the controller  200  through the paths # 2  and # 4  and chip select signals CS 1  and CS 2  are both enabled through the paths # 2  and # 4 , data from the first and second buffers  240  and  250  may be simultaneously transmitted to the display  220  and the projector module  230  through paths # 5  and # 6 , respectively. By doing so, it is possible to output synchronized same images. 
     When the projector module  230  is in an OFF state, the first buffer  240  may not be used because it is not necessary to acquire synchronization with the projector module  230 . Thus, in this bypass mode, images are directly transmitted to the display  220  through a path # 3 - 1 . 
     However, when it is desired to display different images, the controller  200  alternately enables the chip select signals CS 1  and CS 2  through the paths # 2  and # 4  in a toggle manner. First, the controller  200  activates the first buffer  240  assigned to the display  220  by enabling the chip select signal CS 1  through path # 2 , and then instructs the display  220  to load data for a menu image from the first buffer  240 . Subsequently, the controller  200  disables the chip select signal CS 1  through the path # 2  and then enables the chip select signal CS 2  through the path # 4  so that data from the second buffer  250  may be transmitted to the projector module  230 . Thereafter, upon occurrence of an even in which a menu configuration of the display  220  should be changed, the controller  200  changes data displayed on the display  220  by disabling the chip select signal CS 2  through the path # 4  and enabling the chip select signal CS 1  through the path # 2  during one frame. By doing so, a menu image for operation of the projector module  230  is displayed on the display  220 , and videos may be projected onto the projector screen. 
     The image processor  210  serves to control data being transmitted to the display  220  and the projector module  230  under the control of the controller  200 , and for this control, includes two frame buffers  240  and  250 . By providing the first and second buffers  240  and  250 , it is possible to transmit different or same data to the display  220  and the projector module  230 , enabling independent control. This image processor  210  may feed back data from the controller  200  by the chip select signals through paths # 2  and # 4 . In case the image signals supported in the display  220  and the projector module  230  are incompatible with each other, the image processor  210  is adapted to enable independent settings, including self-generating RGB image signals supported in each of the display  220  and the projector module  230 , such as a back porch, a front porch and a sync signal. 
     The display  220  may be realized with an LCD panel, and if the LCD panel is realized in the form of a touch screen, the display  220  may also serve as an input means. The display  220  serves to display user input information or information provided to the user, including various menus of the mobile terminal. Particularly, the display  220  displays menus for operation of the projector module  230 , and may also display the same image as the image displayed through the projector module  230 . When displaying the same images, the display  220  may display the images without any loss in performance of the controller  200 . 
     The projector module  230  is provided in the mobile terminal and serves to expand images and project them onto external screens. 
     With reference to  FIG. 3 , a description will be made of the second embodiment of the present invention, in which data being transmitted to an LCD panel is controlled only when an image on the LCD panel needs to be updated while a projector function is in operation. 
     Referring to  FIG. 3 , unlike in the first embodiment of the present invention, the image processor  210  includes only one buffer  300  and uses no chip select signal, so only two paths exist between the controller  200  and the image processor  210 . A set value for controlling a menu image displayed on the display  220  and an update command, are transmitted through path # 1 . Image data is transmitted through path # 3 , and may be transmitted to the display  220  through the buffer  300 , or may be directly transmitted to the display  220  without passing through the buffer  300  in a bypass mode. At the same time, the image data may be transmitted even to the projector module  230  through path # 7 - 1 . This method excludes chip select signals, and reduces the number of output pints in the image processor  210 . 
     In this method, if the projector module  230  is in an OFF state, image data is directly transmitted to the display  220  through a path # 7 - 2  without passing through the buffer  300  in a bypass mode. That is, the display  220  is directly connected to the controller  200 , and displays data from the controller  200 . 
     However, if the projector module  230  is in an ON state, the controller  200  transmits an update command to the image processor  210  to control it only when information displayed on the display  220  is updated. An I2C command may be used as the update command. Specifically, the update command is transmitted to the image processor  210  through the path # 1 . Thus, the final image being projected or the image being updated is stored in the buffer  300  of the image processor  210 , and the buffer  300  generates an image signal to the display  220 , which has predetermined porch values. When the image needs to be updated, the image processor  210  may fetch data from the controller  200  by controlling path # 1 . 
     According to the second embodiment of the present invention, since data of the controller  200  can be directly transmitted to the projector module  230 , the image processor  210  can minimize the number of its output pins, contributing to a reduction in chip size and ensuring price competitiveness. Path # 7 - 1  may be connected to the buffer  300  instead of being connected in front of the image processor  210 , in which case the image processor  210  may directly generate output signals to the display  220  and the projector module  230  on behalf of the controller  200 , which removes the need to consider pan-out and load capacity of the controller  200 . 
     While it has been described in the first and second embodiments of the present invention that the image processor  210  is interposed between the controller  200  and the display  200  and the projector module  230 , the image processor  210  may also be integrated in controller  200 . That is, the image processor  210  may be built in the controller  200 . 
     An operation according to the first embodiment of the present invention will now be described with reference to  FIG. 4 . Referring to  FIG. 4 , if the projector module  230  is in an ON state in step  400 , the controller  200  provides screen change information to the image processor  210  through path # 1  in step  405 . Thereafter, the controller  200  determines in step  410  whether there is a selection to display the same images on the display  220  and the projector module  230 . If so, the controller  200  enables both of the chip select signals CS 1  and CS 2  in step  415 , and data from the first and second buffers  240  and  250  is transmitted to the display  220  and the projector module  230 , respectively, based on the enable signals in step  420 . In this case, the same RGB images are output to the display  220  and the projector module  230 . 
     In contrast, if there is no selection to display the same images, i.e., if there is a selection to display different images, the controller  200  selectively enables the chip select signals CS 1  and CS 2  in step  425 . In step  430 , the controller  200  outputs a menu image to the display  220  while the chip select signal CS 1  is enabled. In step  435 , the controller  200  enables the chip select signal CS 2  after disabling the chip select signal CS 1 , and outputs an RGB image to the projector module  230 . By doing so, the controller  200  outputs different images through the display  220  and the projector module  230 . 
     If a menu selection event is input from a user through the display  220  in step  440 , the controller  200  enables the chip select signal CS 1  after disabling the chip select signal CS 2  to output a changed menu image transmitted from the controller  200  to the display  220  in step  445 . Thus, a changed menu image is displayed on the display  220 . Thereafter, unless the projector module  230  is in an OFF state in step  450 , the controller  200  returns step  410  and repeats the proceeding steps, and if the projector module  230  is in the OFF state, the image processor  210  operates in a bypass mode in which the display  220  is directly connected to the controller  200 . Thus, the display  220  directly receives data from the controller  200  and displays the received data. 
     As is apparent from the foregoing description, according to an embodiment of the present invention, the mobile terminal may output high-resolution images through the LCD panel and the projector module even though it uses the RGB interface. In addition, the projector function may incur a low cost by using the existing LCD panel and AP chip and the projector module. 
     According to another embodiment of the present invention, the mobile terminal not only may display different images on the projector screen and the mobile terminal&#39;s screen, but also may output the same images during web browsing, despite using the RGB interface. According to the present invention, it is also possible to remove input pointing errors that may occur during web browsing. Moreover, even though an image control IC is added, compatibility with the existing LCD panel and AP chip is maintained, so they can be used without specification changes. Accordingly, it is not necessary to use high-performance AP chips, contributing to a reduction in the total cost of the system, and the existing intact platform can be used, shortening the development period. 
     While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.