Abstract:
A display controller for a communication terminal is connected to a base station through a radio channel for making radio communications with the base station. A first display control unit displays a moving image on a display unit. A second display unit has a first storage unit for storing a plurality of color numbers, and a second storage unit for storing color data in correspondence to each of the color numbers, and displays color data corresponding to a color number read from the first storage unit on the display unit as a graphics image. A determination unit determines, when the moving image and the graphics image are displayed on the display unit, which of the moving image and the graphics image is preferentially displayed depending on whether or not the color number read from the first storage unit is a predetermined number.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-333068, filed Oct. 31, 2000, the entire contents of which are incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a radio communication terminal, and more particularly to a display controller for a radio communication terminal which is connected to a base station through a radio channel to make radio communications with the base station.  
           [0004]    2. Description of the Related Art  
           [0005]    [0005]FIGS. 8A to  8 D are diagrams illustrating outer appearances of a conventional portable radio communication terminal. FIG. 8A is a front view; FIG. 8B is a side view, FIG. 8C is a cross-sectional view of a back light in FIG. 8A taken along a line A-A; and FIG. 8D is a cross-sectional view of a front light in FIG. 8A taken along the line A-A.  
           [0006]    A camera  101  is provided for photographing the face of a user, landscape, and the like. An antenna  102  has function of transmitting a transmission signal sent from a radio unit within a housing  107 , and a function of receiving a signal sent from the outside and routing the signal to the inside of the housing  107 . A speaker  103  transduces a received audio signal to a speech. A display  104  displays a manipulation made on the camera  101 , an image captured by the camera  101 , and an image received through the antenna  102 .  
           [0007]    A key manipulation unit  105  receives a telephone number entered by a user, and a menu selected by the user. The display  104  may be irradiated with light from the back side (back light), or with light from the front side (front light), when viewed in a cross-sectional view taken along a line A-A. A back light  108  is provided for the former irradiation method, while a front light  111  is provided for the latter irradiation method. The back light  108  and front light  111  are each provided with an LCD  109  and a protection cover  110 .  
           [0008]    The housing  107  also contains a video transmitter for transmitting an image captured by the camera  101  to a remote terminal, and a video receiver for receiving an image from a remote terminal.  
           [0009]    [0009]FIG. 9 illustrates the configuration of a video transceiver as mentioned.  
           [0010]    An RF unit  201  is provided for transmission and reception at a predetermined frequency. An RF control unit  202  acts to modulate a baseband signal and route the modulated signal to the RF unit  201 , and conversely, to demodulate a signal sent from the RF unit  201  into a baseband signal. A general control unit  203  acts to control the overall video transceiver.  
           [0011]    A camera  204  photographs a landscape and the like and outputs a video signal. Keys  212  permit a user to enter a telephone number, search a telephone book, and enter a simple mail or the like. An LCD control unit  205  controls an LCD  206 . The LCD  206  displays an image output from the camera  204 , and information represented by a telephone number, which is manipulated by the keys  212 . The video transceiver also comprises a microphone  207 , and an audio codec  208  for compressing an audio signal when it is to be transmitted and for decompressing an audio signal when it is received.  
           [0012]    The video transceiver further comprises a speaker  209 , and a multiplexer/demultiplexer  210  for multi-plexing an audio signal, a video signal and data into a single signal and for demultiplexing a multiplexed signal into an audio signal, a video signal and data. An MM processing unit  211  compresses and decompresses a video signal in accordance with an appropriate scheme represented by H.263 and MPEG-4. An LCD light  213  is arranged to irradiate the LCD  206  from the back when it is a transmission type and to irradiate the LCD  206  from the front when it is a reflection type. A light control unit  214  turns ON/OFF the LCD light  213  in response to a light ON/OFF control signal sent from the general control unit  203 .  
           [0013]    In the following, description will be made on the operation of the video transceiver configured as described above. As the user manipulates the keys  212  for transmission or reception, a communication is started. Upon starting a communication, the MM processing unit  211  compresses a video signal sent from the camera  204 , and sends the compressed video signal to the multiplexer/demultiplexer  210 . An audio signal sent from the microphone  207  is compressed by the audio codec  208 , and sent to the multiplexer/demultiplexer  210 . Data for control is added to the video signal and audio signal sent to the multiplexer/demultiplexer  210 , and these signals are multiplexed into a single signal. Then, the multiplexed signal is sent to the RF control unit  202  through the general control unit  203  for modulation, and the modulated signal is converted to radio waves by the RF unit  201  for transmission to a destination.  
           [0014]    On the other hand, a received signal, passing through the RF unit  201 , is demodulated to a digital signal by the RF control unit  202 , and sent to the multiplexer/demultiplexer  210 . The multiplexer/demultiplexer  210  demultiplexes the demodulated digital signal into a video signal, an audio signal and data for control. The video signal is sent to the MM processing unit  211 , while the audio signal is sent to the audio codec  208 . The video signal sent to the MM processing unit  211  is decompressed thereby, and sent to the LCD control unit  205  for display on the LCD  206 .  
           [0015]    The audio signal sent to the audio codec  208  in turn is decompressed thereby, and sent to the speaker  209  for generating a speech. In this event, as a key  212  is depressed, the general control unit  203  outputs a light ON signal to turn the LCD light  213  ON. After a predetermined time period has passed, the general control unit  203  outputs a light OFF signal to turn the LCD light  213  OFF.  
           [0016]    [0016]FIG. 10 is a diagram for explaining video and audio as well as the mechanism of data communication. The three types of data are multiplexed/demultiplexed (in accordance with H.233 or the like) in the multiplexer/demultiplexer  210  illustrated in FIG. 9. The data pass through the general control unit  203 , RF control unit  202  and RF unit  201  for radio communication, so that two terminals are interconnected through a radio-based switched line communication network. A terminal  1  ( 300 ) and a terminal  2  ( 304 ) in FIG. 10 are interconnected on physical layers (specifically, radio switched network)  303 ,  307  for communication in units of packets called MUX-PDU. AL/MUX layers (specifically, the multiplexer/demultiplexer)  302 ,  306  exist above the physical layers  303 ,  307  for generating the foregoing MUX-PDU.  
           [0017]    Higher rank layers  301 ,  305  exist above the AL/MUX layers  302 ,  306 , and the two layers are interconnected through a video channel, an audio channel, and a control/data channel. The higher rank layers  301 ,  305  are comprised of the MM processing unit (video channel)  211  and the audio codec (audio channel)  208  in FIG. 9, and a data communication unit (communication/data channel) not shown in FIG. 9.  
           [0018]    Video data sent from the MM processing unit  211  is multiplexed by the AL/MUX layers  302 ,  306 , embedded in MUX-PDU, transmitted from the terminal  1  ( 300 ) to the terminal  2  ( 304 ) through the physical layers  303 ,  307 , and sent to the higher rank layers  301 ,  305  through the reverse process for transmission and reception of video.  
           [0019]    The MUX-PDU is comprised of a flag located at the head thereof for identifying the start of a frame; a header indicative of contents of MUX-PDU; and mixed data including audio, control and video data. The MUX-PDU is arranged in accordance with a table which has been initially defined by both terminals  300 ,  304 . Video data are multiplexed and sent to a higher rank layer as a video channel which is embedded with an MPEG-4 stream. In the MPEG-4 stream, an I-frame (overall video) is followed by a P-frame (difference), and a reduced version of the I-frame, called the “macro-block,” is periodically sent, such that one image can be sent every  133  frames.  
           [0020]    While an image can be displayed by the configuration described above, no display controller has conventionally been provided for optimally and efficiently displaying a moving image and a graphics image on a display unit. No specific method has either been proposed for saving the power consumption of such a display controller.  
           [0021]    The present invention has been made in view of the challenge as mentioned, and it is an object of the present invention to provide a display controller for a radio communication terminal which is capable of optimally and efficiently displaying a moving image and a graphics image on a display unit.  
           [0022]    It is another object of the present invention to provide a display controller for a radio communication terminal which is capable of saving the power consumption of the display controller.  
         BRIEF SUMMARY OF THE INVENTION  
         [0023]    To achieve the above objects, in a first aspect, the present invention provides a display controller for a radio communication terminal connected to a base station through a radio channel for making radio communications with the base station. The display controller includes a first display control unit for displaying a moving image on a display unit, a second display control unit having a first storage unit for storing a plurality of color numbers and a second storage unit for storing color data in correspondence to each of the color numbers, for displaying color data corresponding to a color number read from the first storage unit on the display unit as a graphics image, and a determination unit operable when the moving image and the graphics image are displayed on the display unit for determining which of the moving image and the graphics image is preferentially displayed depending on whether or not the color number read from the first storage unit is a predetermined number.  
           [0024]    In a second aspect, the display controller for a radio communication terminal of the first aspect further includes a multimedia processing unit for performing signal processing on the moving image, wherein the first display control unit supplies the multimedia processing unit with control signals including a timing clock and synchronization signals when moving image data is acquired from the multimedia processing unit.  
           [0025]    Also, in a third aspect, in the display controller for a radio communication terminal of the second aspect, a parameter value associated with a timing at which the first display control unit acquires moving image data from the multimedia processing unit is programmable.  
           [0026]    Further, in a fourth aspect, in the display controller for a radio communication terminal of the first aspect, control signals including a display clock and synchronization signals are supplied in addition to RGB color data when the moving image and the graphics image are displayed on the display unit.  
           [0027]    Further, in a fifth aspect, in the display controller for a radio communication terminal of the fourth aspect, a parameter for use in displaying the moving image and the graphics image on the display unit is programmable.  
           [0028]    In a sixth aspect, the present invention provides a display controller for a radio communication terminal connected to a base station through a radio channel for making radio communications with the base station. The display controller includes a first display control unit for displaying a moving image on a display unit, and a second display control unit having a storage unit for storing data having a predetermined number of bits indicative of each of RGB color data, for displaying color data read from the storage unit on the display unit as a graphics image.  
           [0029]    Also, in a seventh aspect in the display controller for a radio communication terminal of the sixth aspect, the display controller determines which of the moving image and the graphics image is preferentially displayed depending on whether or not data representative of each color data is predetermined data.  
           [0030]    Further, in an eighth aspect, in the display controller for a radio communication terminal of the sixth aspect, a display control bit is added to one arbitrary color data having a predetermined number of bits representative of a color, wherein the display controller determines which of the moving image and the graphics image is preferentially displayed in accordance with the state of the display control bit.  
           [0031]    In a ninth aspect, the present invention provides a display controller for a radio communication terminal connected to a base station through a radio channel for making radio communications with the base station. The display controller includes a first display control unit for displaying a moving image on a display unit, a second display control unit for displaying a graphic image on the display unit, and a divider circuit for dividing a clock at an arbitrary frequency supplied from the outside for operating the display controller by an arbitrary division ratio to generate a clock frequency required for internal operations.  
           [0032]    In a tenth aspect, the present invention provides a display controller for a radio communication terminal connected to a base station through a radio channel for making radio communications with the base station. The display controller includes a first display control unit for displaying a moving image on a display unit, a second display control unit for displaying a graphic image on the display unit, and a register unit having a first register for actually setting data therein, and a second register for storing addresses of the first register, and capable of programmably setting data therein, wherein an address of the first register is written into the second register, and data is subsequently written into the second register to transfer the data to the first register for setting the data.  
           [0033]    In an eleventh aspect, in the display controller for a radio communication terminal of the tenth aspect, as an address of the first register is written into the second register, contents of the first register are transferred to the second register for reading data.  
           [0034]    In a twelfth aspect, the present invention provides a display controller for a radio communication terminal connected to a base station through a radio channel for making radio communications with the base station. The display controller includes a first display control unit for displaying a moving image on a display unit, a second display control unit for displaying a graphics image on the display unit, and a control unit operable when the moving image or the graphics image is displayed on the display unit for reducing a display speed of the display unit when the graphics image is only displayed, as compared with displaying an image including the moving image.  
           [0035]    In a thirteenth aspect, the present invention provides a display controller for a radio communication terminal connected to a base station through a radio channel for making radio communications with the base station. The display controller includes a first display control unit for displaying a moving image on a display unit, a second display control unit for displaying a graphics image on the display unit, a sleep mode setting unit capable of setting a sleep mode, and a control unit, responsive to recognition of the sleep mode set by the sleep mode setting unit, for stopping predetermined operations other than a sleep release recognition function after completing a sequence of operations which have been executed at the time of recognition.  
           [0036]    Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0037]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
         [0038]    [0038]FIG. 1 is a block diagram illustrating the configuration of an LCD control unit and components associated therewith according to one embodiment of the present invention;  
         [0039]    [0039]FIGS. 2A to  2 D are diagrams showing combinations of images displayed on an LCD  404 ;  
         [0040]    [0040]FIG. 3 is a diagram for explaining how a moving image is displayed;  
         [0041]    [0041]FIG. 4 is a diagram for explaining the relationship between synchronization signals and a moving image;  
         [0042]    [0042]FIG. 5 is a diagram showing the flow of operation in displaying a graphics image when a lookup table method is used;  
         [0043]    [0043]FIG. 6 is a diagram for explaining how an operation clock required by an LCD control unit  403  is set;  
         [0044]    [0044]FIG. 7 is a diagram for explaining a register setting procedure;  
         [0045]    [0045]FIGS. 8A to  8 D are diagrams illustrating outer appearances of a conventional portable radio communication unit;  
         [0046]    [0046]FIG. 9 is a block diagram illustrating the configuration of a video transceiver; and  
         [0047]    [0047]FIG. 10 is a diagram for explaining video and audio as well as the mechanism of data communication. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0048]    In the following, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. In a radio communication terminal for transmitting/receiving video data according to this embodiment, a video signal received from the MM processing unit  211  and a video signal from the camera  204  in FIG. 9 are sent to the LCD control unit  205  in the form of YUV video signal. The LCD control unit  205  converts these video signals to RGB signals for display on the LCD  206 .  
         [0049]    [0049]FIG. 1 is a block diagram illustrating the configuration of an LCD control unit and components associated therewith according to this embodiment of the present invention. Also, FIGS. 2A, 2B,  2 C and  2 D show possible combinations of images displayed on an LCD  404 . FIG. 2A shows a displayed moving image  50  which may be sent from a remote terminal or shot by an associated camera. Similarly, FIG. 2B shows characters  51  which are displayed through a CPU  400  that functions as a general control unit. FIG. 2C shows an animation  52  and characters  51  displayed in combination. While a combination of the moving image  50  and the animation  52  or the characters  51  is additionally contemplated, this may be regarded as a combination of the moving image  50  and a graphics image  53  as shown in FIG. 2D.  
         [0050]    Next, description will be made on the operation of an LCD controller for displaying the combined images as mentioned. First, how to display a moving image will be explained with reference to FIG. 3.  
         [0051]    An MM processing unit  401  outputs a YUV signal, which is a chroma signal of a moving image, to an LCD control unit  403  in this embodiment. The YUV signal is serially output in synchronism with DSYNC and DCLK applied from the LCD control unit  403  to the MM processing unit  401 . Here, DSYNC includes a vertical synchronization signal and a horizontal synchronization signal for providing one image of a moving image, and DCLK is a timing clock for outputting a YUV serial signal.  
         [0052]    [0052]FIG. 4 is a diagram for explaining the relationship between synchronization signals and a moving image. As described above, moving image YUV data is stored in a memory of the MM processing unit  401 , and the LCD control unit  403  applies the MM processing unit  401  with the horizontal synchronization signal, vertical synchronization signal and timing clock for retrieving the YUV data. In response, the MM processing unit  401  enters one horizontal period of a moving image sequence for staring the delivery of YUV data of a moving image when a predetermined number of horizontal periods of the moving image sequence have passed, i.e., when a vertical blanking period has passed after it had received the vertical synchronization signal.  
         [0053]    Similarly to the vertical period, horizontal moving image YUV data is sent after the horizontal synchronization signal period and the horizontal blank period in one horizontal period of the moving image sequence in which the MM processing unit  401  sends YUV data. In sequence, as a scan in the horizontal direction is completed for a vertical size of the moving image, a horizontal scanning period continues, in which no YUV data is sent, until entering the aforementioned horizontal period of the moving image sequence of the next frame, in which the MM processing unit  401  starts sending the YUV data. In the following, similar operations are repeated to send continuous moving image YUV data.  
         [0054]    For the LCD control unit  403 , the operation of sending data in the MM processing unit  401  corresponds to the operation of receiving the data. Therefore, the MM processing unit  401  and the LCD control unit  403  require that a variety of parameter values are identical, including the horizontal synchronization signal period; horizontal blanking period; horizontal size of the moving image; one horizontal period of the moving image sequence; vertical synchronization signal period; vertical blank period; vertical size of the moving image; and one vertical period of the moving image sequence. When these parameter values are fixed in the MM processing unit  401 , the LCD control unit  403  also performs hardware and software operations in accordance with the parameter values. However, since this results in a combination of the MM processing unit  401  and the LCD control unit  403  fixed in one-to-one correspondence, these settings are made programmable in the LCD control unit  403  such that the values are written into registers of the LCD control unit  403  from a higher rank layer.  
         [0055]    In this way, as illustrated in FIG. 3, the LCD control unit  403  serially receives a YUV signal from the MM processing unit  401 , and converts the received YUV signal to an RGB signal by an RGB converter unit  403 - 1 . Then, the LCD control unit  403  supplies the LCD  404  with the RGB signal, a display control signal (Ctrl), a display clock (LCLK), and a display synchronization signal (LSYNC).  
         [0056]    Completely in a similar manner to retrieval of moving image data from the MM processing unit  401 , a variety of parameter values inherent to the LCD  404  must have been determined when the LCD control unit  403  supplies the LCD  404  with RGB display data.  
         [0057]    There are a horizontal synchronization signal period; vertical blank period; horizontal size of a panel; display system—horizontal period; vertical synchronization signal period; vertical blank period; vertical size of the panel; display system—vertical period, and the like, the values of which depend on the size and characteristics of the LCD  404 . Therefore, these values are made arbitrarily settable in registers in the LCD control unit  403 , so that a variety of LDC displays can be provided by writing data from the higher rank CPU.  
         [0058]    Next, description will be made how to display a graphics image. Graphics image data is written from the CPU  400  into a frame memory (first storage unit)  403 - 2  in the LCD control unit  403  in a bit map form. The number of pixels in the frame memory  403 - 2  corresponds to at least the number of pixels on the LCD  404 .  
         [0059]    Next, description will be made on how data is written into the frame memory  403 - 2  and the data is displayed.  
         [0060]    1. Lookup table method  
         [0061]    [0061]FIG. 5 shows the flow of operations when a lookup table method is employed. First, data is written from the CPU  400  into the frame memory  403 - 2  in the LCD control unit  403  ({circle over (1)}). The data may be, for example, an 8-bit color number. Therefore, 256 different colors are available. A lookup table (second storage unit)  403 - 3  stores each RGB color data corresponding to the color number, so that for displaying, a color number is read from a certain bit in the frame memory  403 - 2  ({circle over (2)}) to retrieve RGB color data corresponding to the read color number from the lookup table  403 - 3 . Next, the resulting RGB color data is supplied to the LCD  404  together with other signals ({circle over (3)}). In this event, assuming that RGB color data are each represented by six bits, 262144 possible combinations of colors are provided, where this embodiment features in selecting 256 colors from them.  
         [0062]    2. Color data writing method  
         [0063]    While the lookup table method involves writing a color number into the frame memory  403 - 2 , the color data writing method directly writes color data into the frame memory  403 - 2 . For example, assuming that each RGB color data has six bits, one pixel is represented by 19 bits which consist of 18-bit color data and one display control bit, later described, in the frame memory  403 - 2 . For displaying, RGB color data may be directly retrieved sequentially from the frame memory  403 - 2  subsequent to an LSYNC signal, and output to the LCD  404 .  
         [0064]    Description will be next made on a simultaneous display of a moving image and a graphics image. As illustrated in FIG. 2D, a moving image and a graphics image may be simultaneously displayed on the LCD  404 . For implementing this simultaneous display, in this embodiment, a selection is made as to which is preferentially displayed when determining moving image color data and graphics image color data to be displayed at an arbitrary pixel on the LCD  404 .  
         [0065]    The aforementioned lookup table method provides 256 color numbers, from which an arbitrary number is assigned to a color number with which a moving image is preferentially displayed. For example, assuming that color number  0  is assigned, when the color number 0 is written into the frame memory  403 - 2 , moving image color data is output for that pixel. When no moving image is displayed, the function of color number 0 is lost, and it may be used as a normal color pallet.  
         [0066]    Description will be next made on how color data is directly written into the frame memory  403 - 2 . Likewise, in this case, discriminatory data, corresponding to color number 0 in the lookup table method, is required for discriminating from other color numbers. Here, the number of bits for one of RGB color data is increased by one bit which is added to the most significant bit side, such that the preference for displaying a moving image is identified by checking whether or not the additional bit is “1”. For example, assuming that RGB color data each have four bits, R color data, which should essentially have four bits, is increased by one bit to have five bits. The color data is represented by the four least significant bits, with the fifth bit functioning as a display control bit or a moving image display preference bit. A moving image is preferentially displayed when this bit is “1” or “0”. While the 4-bit color data is herein taken as an example, the number of bits of the color data is arbitrary.  
         [0067]    Alternatively, instead of adding the display control bit for determining whether or not a moving image is preferentially displayed, a moving image may be preferentially displayed when RGB color data themselves are predetermined data.  
         [0068]    Next, referring to FIG. 6, description will be made on how to set an operation clock required by the LCD control unit  403 . A clock SYSCLK required by the LCD control unit  403  for its internal operation is supplied from the outside or generated by a built-in clock generator. Described herein is the clock supplied from the outside. The LCD control unit  403  also requires a clock LCDCCLK which is the basis of the timing at which moving image data is captured, and color data is sent to the LCD  404 . SYSCLK and LCDCCLK at high frequencies are not preferable for saving the power consumption of the LCD control unit  403 .  
         [0069]    However, the LCD control unit  403  may not often be supplied with a clock at a desired frequency for reasons of the system. Thus, before the LCD controller  403  is powered to start the operation, an externally supplied clock SYSCLKO is divided by an arbitrary division ratio. After the completion of setting, SYSCLK is generated from SYSCLK 0  and supplied to respective circuits in the LCD control unit  403 .  
         [0070]    The same concept can be applied to LCDCCLK. Specifically, immediately after the LCD control unit  403  is powered, a division ratio is set for LCDCCLK 0  supplied from the outside. Then, the LCD control unit  403  starts operating and can be provided with the required LCDCCLK. When LCDCCLK is set identical to SYSCLK, a circuit for generating LCDCCLK is not required, in which case the single clock SYSCLK may be connected to lines to circuits, which would otherwise require LCDCCLK, within the LCD control unit  403 .  
         [0071]    In the following, description will be made on a method of setting registers. As will be understood from the foregoing description, the LCD control unit  403  has a number of various parameter values to be stored. Data pertinent to the MM processing unit  401  such as the horizontal synchronization signal period, horizontal blank period, horizontal size of a moving image, one horizontal period of the moving image sequence, and so on, and data pertinent to the LCD  404  are written through registers. Also, an internal operation mode is set through a register, and graphics image data is also written through registers. These values, though some of them may be set by default, cannot be fixed, so that they must be able to be programmably set in registers, including those values which may be set by default. When there are such a large number of registers which should be set, this embodiment sets the registers in the following procedure.  
         [0072]    [0072]FIG. 7 is a diagram for explaining a register setting procedure. The LCD control unit  403  is provided with an address register  403 - 4  and an internal register  403 - 5 . Data is actually set in the internal register  403 - 5  which does not allow an external CPU and the like to directly write data thereinto or read data therefrom. The CPU  400  reads and writes data from and into the internal register  403 - 5  by writing an address of the internal register  403 - 5  into the address register  403 - 4 .  
         [0073]    The address register  403 - 4  is assigned addresses of the internal register  403 - 5 , and the CPU  400  writes an address of the internal register  403 - 5  into the address register  403 - 4  in a manner similar to a general data write with I/O. In this embodiment, the internal register  403 - 5  has addresses 000-255, which are represented by an 8-bit address signal, as an example. The addresses in the internal register  403 - 5 , however, may be increased or decreased as required.  
         [0074]    For writing data into a specified address in the internal register  403 - 5  after writing the address of the internal register  403 - 5 , desired data is sequentially written into the address register  403 - 4 , causing the data to be transferred to the specified address of the internal register  403 - 5 . The data written into the internal register  403 - 5  in this way is referenced in an internal operation of the LCD control unit  403  as required.  
         [0075]    On the other hand, for reading data from the internal register  403 - 5  in which the status indicative of a situation of internal operation has been written, or for referencing previously written data, an address of the internal register  403 - 5  is written into the address register  403 - 4 , and subsequently, the address register  403 - 4  is read.  
         [0076]    When data is either written into or read from the internal register  403 - 5 , associated data in the internal register  403 - 5  is transferred to the address register  403 - 4  after an address of the internal register  403 - 5  is written into the address register  403 - 4  in order to minimize a time required for such operations. In this way, in reading data from the internal register  403 - 5 , data to be read has already been set in the address register  403 - 4 .  
         [0077]    A location of the address register  403 - 4  into which an address of the internal register  403 - 5  is written may be identical to or different from a location of the address register  403 - 4  in which data read from the internal register  403 - 5  is stored.  
         [0078]    Described next is an LCD display speed control. As previously described, images displayed on the LCD  404  include a moving image and a graphics image. In comparison of display speed between a moving image and a graphics image, a higher speed is required for displaying the moving image. Since the LCD control unit  403  can recognize whether or not moving image data is being displayed on the LCD  404 , the LCD control unit  403  increases the LCD display speed in this situation such that a natural moving image is displayed. On the other hand, when a graphics image is only displayed, the LCD control unit  403  reduces the LCD display speed in accordance with the characteristics of the LCD  404 , and a flicker characteristic of the image to save the power consumption. This may be implemented by reducing the frequency of LCLK, previously described, and correspondingly reducing the period of LSYNC.  
         [0079]    In addition, a sleep mode is provided for saving the power consumption of the LCD control unit  403  itself. A sleep mode setting bit is assigned to a certain register, such that as the bit indicates a transition to the sleep mode under the control of the CPU  400 , the LCD control unit  403  entirely stops supplying the clock to circuits other than those associated with an interface with the CPU  400  for receiving a release from the sleep mode. By the time the sleep mode is entered from the time the sleep mode was set, image frame data which had existed at the time of setting should have been output to the LCD  404 . For releasing the sleep mode, on the other hand, a release of the sleep mode can be accepted since a circuit which recognizes the release of the sleep mode is in a normal state even in the sleep mode. Upon receipt of the release of the sleep mode under the control of the CPU  400 , the LCD control unit  403  resumes supplying the clock to those circuits to which no clock has been supplied in the sleep mode.  
         [0080]    According to the present invention, a display controller for a radio communication terminal can be provided for optimally and efficiently displaying a moving image and a graphics image on a display unit.  
         [0081]    Also, according to the present invention, a display controller for a radio communication terminal can be provided for saving the power consumption of the display controller.  
         [0082]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.