JP2009015262A - Display control device, control method for display control device, control program for display control device, and computer-readable recording medium with the program recorded therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display control device for simultaneously displaying images on a plurality of display devices, the control device being designed to maintain the display quality of at least one of the display devices. <P>SOLUTION: The display control device includes: a writing section 133 for writing image data in a frame memory 15; a plurality of reading sections 17a, 17b, and 17c that read image data stored in the frame memory 15 and output them to the plurality of display devices; and a writing timing determination section 132 that selects, as a selected reading section, a reading section selected from them to output the image data to the selected display device, compares a writing speed, at which the writing section 133 writes the image data in the frame memory 15, with a reading speed, at which the selected reading section reads the image data from the frame memory 15, and determines the timing of writing the image data in the frame memory 15 by the writing section 133. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display control device that controls a display device, and more particularly to a display control device that can simultaneously display images on a plurality of display devices.

  In recent years, there are various display devices that display moving images and still images, and there are various screen sizes. For example, there are screens with a size of several inches that can be carried, while screens with a screen size of about 50 inches that can be installed in a living room at home.

  In some cases, the same moving image or still image is displayed on a plurality of display devices. For example, there is a case where an image viewed on a display device with a small screen size is displayed on a display device with a large screen size so that a plurality of people can see it.

  FIG. 13 shows an example of a conventional display control device that displays images on a plurality of display devices. As shown in FIG. 13, a conventional display control apparatus 301 includes an LCD (liquid crystal display) synchronization control unit 302 that is a liquid crystal synchronization control unit and a TV (television) synchronization that is a television synchronization control unit. A control unit 303, which respectively generate timing signals necessary for liquid crystal display and television display, and LCD layer 1 lead unit 307a, LCD layer 2 lead unit 307b, TV layer lead unit 307c, which are the respective lead units, Controls the timing of the color space conversion unit 308, the aspect conversion unit 309, the layer synthesis unit 310, the signal processing unit 311, and the like.

  Next, the image data placed on the frame memory 306 is read from the frame memory 306 by the read unit of each layer in accordance with the timing instructed by the respective synchronization control units. The image data read from the frame memory 306 is appropriately converted between RGB format data and YUV format data based on luminance and color difference by the color space conversion unit 308, and converted into data in a format required for output. Is done. That is, whether the data on the frame memory 306 is RGB data or YUV data, it is converted to RGB data for liquid crystal display and YUV data for television display.

  The image data converted by the color space conversion unit 308 is appropriately subjected to vertical enlargement / reduction, horizontal enlargement / reduction processing, and output by an aspect conversion unit 309. Then, the layer synthesis unit 20 selects which image data from a plurality of layers is to be output to the display device for each pixel, and selectively outputs the image data to the signal processing unit 311. Note that in the layer composition unit 310, the location and overlap information of a plurality of layers on the display device are set in advance. The signal processing unit 311 mainly performs processing such as γ correction of the display device, and outputs image data to the display device.

  The output data to the liquid crystal display device is output to the liquid crystal driver, and the liquid crystal driver converts the image data into an analog signal. Further, a timing signal necessary for the liquid crystal panel is generated from the timing signal received from the synchronization control unit, and is output and displayed on the liquid crystal panel.

  Output data to the television receiver is passed to the TV encoder, and the TV encoder converts the image data into an analog signal. In addition, necessary synchronization signals, color burst signals, and the like are added, and signals necessary for the television receiver, such as NTSC composite signals or component signals, are generated and output to the television receiver for display.

  A host CPU (central processing unit) 304 generates image data necessary for display, and refers to timing information of the LCD synchronization control unit 302 or the TV synchronization control unit 303 as necessary to display a host IF (interface). The image data is written into the frame memory 306 via 305.

  Next, FIG. 14 shows an example of a product on which the display control device is mounted. FIG. 14 shows an example in which the display control device is mounted on the mobile phone 140. The mobile phone 140 has a main body divided into two housings, an upper housing and a lower housing, and an operation unit arranged with buttons and the display unit arranged with a liquid crystal panel or the like are opposed to each other via hinges. Can be folded. In addition, when the folding is opened, the upper casing can be turned to the horizontal state by tilting it 90 degrees to the right via the rail or the second hinge provided on the back side of the display unit. It can be displayed in the landscape state. The liquid crystal panel has a source driver in the short side direction and a gate driver in the long side direction. When tilted 90 degrees to the right, the scanning direction of the liquid crystal scans from right to left and sequentially from right to left. It will be the direction to do. Here, the scanning direction is the order of data transmitted from the display control device to the liquid crystal panel as data displayed on the liquid crystal.

  In addition, the mobile phone 140 can be connected to the television receiver 141 via a connector and a cable. A composite signal or component signal output from the display control device built in the mobile phone 140 is output to the television receiver 141. The television receiver 141 is a horizontally long screen, and the scanning direction is a direction of scanning from the upper left to the upper right, and further from the upper to the lower.

  Here, an image of necessary image data on the frame memory 306 is shown in FIG. The image data of FIG. 15A is read into the LCD layer 1 read unit 307a, the image data of FIG. 15B is read into the LCD layer 2 read unit 307b, and the image data of FIG. The data is read by the unit 307c. The image data read by the LCD layer 1 read unit 307 a and the data read by the LCD layer 2 read unit 307 b are output to the layer synthesis unit 310. Then, the layer composition unit 310 pastes the image data of FIG. 15A on the center of the image data of FIG. 15B, generates image data according to the output image, and displays the image of the display image of FIG. Let

Patent Document 1 discloses a portable information processing apparatus that can selectively display display data on both an internal display device and an external display device.
JP 2000-66649 A (publication date: March 3, 2000)

  However, the above conventional configuration causes the following problems. That is, in the conventional display control device, when displaying an image on a plurality of display devices, the display quality of an image on an arbitrary display device cannot be maintained.

  Further, Patent Document 1 does not describe any display quality of images displayed on a plurality of display devices.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a display control device that displays images on a plurality of display devices at the same time, and can maintain the display quality of at least one display device. It is to realize a control device or the like.

  In order to solve the above problems, a display control device according to the present invention includes an image data storage unit that stores image data, and a plurality of display devices that display the same image data read from the image data storage unit. A display control device that outputs image data to an image data storage unit, and a plurality of image data writing units that read the image data stored in the image data storage unit and output the image data to the plurality of display devices, respectively. An image data reading unit, and selects, as the selected image data reading unit, an image data reading unit that outputs image data to a display device selected from the plurality of image data reading units. The writing speed at which the writing means writes the image data into the image data storage unit and the selected image data reading method Is compared with the reading speed at which the image data is read from the image data storage unit. If the writing speed is higher than the reading speed, the selected image data reading means finishes reading the image data. If the speed is slower than the reading speed, the writing timing determining means determines the time when the selected image data reading means starts reading the image data as the timing when the image data writing means writes the image data into the image data storage unit. Is further provided.

  In order to solve the above-described problem, a display control apparatus control method according to the present invention includes an image data storage unit that stores image data, and displays the same image data read from the image data storage unit as an image. A display control device control method for outputting to a plurality of display devices, the image data writing step for writing image data to the image data storage unit, and the image data stored in the image data storage unit are read out, A plurality of image data reading steps to be output to the display device, and the image data reading step for outputting the image data to the display device selected from the plurality of image data reading steps is selected image data reading step And the image data is stored in the image data writing step. The writing speed to write to the selected image data reading step and the reading speed to read image data from the image data storage unit are compared. If the writing speed is faster than the reading speed, the selected image data reading step If the writing speed is slower than the reading speed when the data reading is completed, the image data is converted into the image data in the image data writing step. It is characterized by further including a write timing determination step for determining the write timing in the storage unit.

  According to the above configuration and method, for image data of an image displayed on at least one display device, the writing timing of the image data depends on whether the writing speed of the image data is faster or slower than the reading speed of the image data. It is determined. The writing timing of the image data is as follows: when the writing speed is faster than the reading speed, when the reading of the image data is completed, and when the writing speed is slower than the reading speed, when the reading of the image data starts. Become.

  As a result, when the writing speed is slower than the reading speed, writing starts at the start of reading. Therefore, when reading the image data, the portion where writing has ended and the portion that has not ended are combined. Will not be read. When the writing speed is higher than the reading speed, writing starts when reading is completed. Therefore, when reading image data, a portion where writing has been completed and a portion where writing has not been completed are read together. There is nothing.

  Therefore, it is possible to maintain the display quality of at least one display device without reading out the portion where the writing of the image data is finished and the portion where the writing of the image data is not finished together.

  In addition, the display quality of the display device having the same relationship between the reading speed and the writing speed as the display device in which the display quality is maintained can be maintained.

  A configuration in which a plurality of image data reading means corresponding to one display device exist may be employed. In this case, one of the image data reading means corresponding to the display device is the selected image reading means. Thereby, there can exist an effect similar to the above.

  The display control device may be realized by a computer. In this case, a display control program for a display control device for realizing the display control device by a computer by causing the computer to operate as each of the means, and A computer-readable recording medium on which it is recorded also falls within the scope of the present invention.

  As described above, the display control device according to the present invention reads the image data writing means for writing the image data into the image data storage unit and the image data stored in the image data storage unit, and sends them to the plurality of display devices. A plurality of image data reading means for outputting, and from among the plurality of image data reading means, an image data reading means for outputting image data to a selected display device is selected as a selected image data reading means. The writing speed at which the image data writing means writes the image data to the image data storage section is compared with the reading speed at which the selected image data reading means reads the image data from the image data storage section. If it is faster than the speed, the selected image data reading means has finished reading the image data. If the writing speed is slower than the reading speed, the point when the selected image data reading means starts reading the image data is the timing at which the image data writing means writes the image data into the image data storage unit. It is the structure further provided with the write timing determination means to determine.

  The display control device control method according to the present invention includes an image data writing step for writing image data into the image data storage unit, and reading out the image data stored in the image data storage unit to each of the plurality of display devices. A plurality of image data reading steps to be output, and an image data reading step for outputting image data to one selected display device is selected as a selected image data reading step from the plurality of image data reading steps. The writing speed at which the image data is written to the image data storage unit at the image data writing step is compared with the reading speed at which the image data is read from the image data storage unit at the selected image data reading step. If the speed is higher than the speed, the selected image data reading step is performed. If the writing speed is slower than the reading speed at the time when the reading of the image data is completed, the image data is read at the image data writing step at the time when the reading of the image data is started at the selected image data reading step. It is a method further comprising a write timing determination step for determining the write timing in the image data storage unit.

  Accordingly, there is an effect that at least the display quality of the selected display device can be maintained without reading together the portion where the writing of the image data is finished and the portion where the writing is not finished.

  One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a display control apparatus 10 according to the present embodiment.

  As shown in FIG. 1, the display control apparatus 10 includes a liquid crystal synchronization control unit 11, a television synchronization control unit 12, a main control unit 13, an interface 14, a frame memory (image data storage unit) 15, and a rotation processing unit (rotation). Processing means) 16, liquid crystal first layer reading section (image data reading means) 17a, liquid crystal second layer reading section (image data reading means) 17b, television layer reading section (image data reading means) 17c, color space conversion section ( A color space conversion unit) 18, an aspect conversion unit (aspect conversion unit) 19, a layer synthesis unit (layer synthesis unit) 20, and a signal processing unit 21. Then, the rotation processing unit 16, the liquid crystal first layer reading unit 17a, the liquid crystal second layer reading unit 17b, the television layer reading unit 17c, the color space conversion unit 18, and the aspect conversion unit 19 are respectively connected to the liquid crystal first layer and the liquid crystal first layer. It is provided corresponding to two layers and a television layer.

  The main control unit 13 includes a processing unit 131, a writing timing determining unit (writing timing determining unit) 132, and a writing unit (image data writing unit) 133.

  The liquid crystal synchronization control unit 11 generates a timing signal necessary for liquid crystal display, and performs a rotation processing unit 16, a liquid crystal first layer reading unit 17a, a liquid crystal second layer reading unit 17b, a color space conversion unit 18, and an aspect conversion unit 19. Control the block timing of the layer synthesis unit 20 and the signal processing unit 21. The television synchronization control unit 12 generates a timing signal necessary for television display, and each of the rotation processing unit 16, the television layer reading unit 17c, the color space conversion unit 18, the aspect conversion unit 19, and the signal processing unit 21 is provided. Control block timing.

  The processing unit 131 causes each block to execute each process of the display control apparatus 10. Further, image data necessary for display is generated and transmitted to the writing unit 133. Furthermore, the synchronization timing information of the liquid crystal synchronization control unit 11 or the television synchronization control unit 12 is referred to as necessary. Then, the referred synchronization timing information is transmitted to the write timing determination unit 132. Further, the vertical and horizontal directions of the display device connected to the display control device 10 are detected, it is determined whether the generated image is a vertically long image or a horizontally long image, and the rotation processing unit 16 determines whether or not to perform rotation processing. Then, the determined information is transmitted to the rotation processing unit 16 via the interface 14.

  In addition, the processing unit 131 includes a clock frequency of the writing unit 133 and a connection method between the writing unit 133 and the interface 14 (elements for determining the speed (writing speed) at which the writing unit 133 writes image data to the frame memory 15). Parallel interface or serial interface, synchronous or asynchronous), and transmits data indicating the contents to the write timing determination unit 132. In addition, the processing unit 131 reads the clock frequency of the reading unit 17 and the reading unit 17 from the frame memory 15 via the rotation processing unit 16, which are factors that determine the speed (reading speed) at which the reading unit 17 reads image data from the frame memory 15. 17 acquires the clock frequency of the bus for transmitting image data to 17 and the state of the bus (bit width, synchronous or asynchronous, cross bus or single bus, etc.), and transmits the data indicating the contents to the write timing determination unit 132 To do.

  The writing timing determination unit 132 selects a reading unit corresponding to the display device designated by the user from the liquid crystal first layer reading unit 17a, the liquid crystal second layer reading unit 17b, and the television layer reading unit 17c. Then, the writing unit 133 received from the processing unit 131 determines whether to write the image data from the frame memory 15 and the selected reading unit determines the speed at which the image data is read from the frame memory 15. It is determined whether the speed or the reading speed is faster. Then, the writing unit 133 determines the timing for writing image data to the frame memory 15 from the determined result and the synchronization timing information, and transmits the determined writing timing to the writing unit 133. Details of the determination of the write timing will be described later.

  The writing unit 133 writes the image data received from the processing unit 131 to the frame memory 15 according to the writing timing received from the writing timing determining unit 132. The frame memory 15 is a storage unit that stores image data.

  The rotation processing unit 16 converts the angle of the image, and converts the image data input in the horizontal position into image data to be displayed in the vertical position. This is transmitted to the reading unit 17 in a state where the memory direction of the received image data (direction in which the memory addresses are continuous) and the display scanning direction coincide with each other, or the memory direction and the display scanning direction are set in the vertical direction. As follows. The rotation processing unit 16 includes a line buffer 161 used for the rotation process. Details of the rotation process will be described later.

  Further, by providing the rotation processing unit 16, it is possible to read out by switching the scanning direction of the image data. Thereby, even if the display device can switch the display screen between a vertically long state and a horizontally long state, image data corresponding to each display screen can be output.

  Since the scanning direction can be switched and read out, it is not necessary to prepare image data having a different scanning direction in the frame memory 15, and the capacity of the frame memory 15 can be reduced.

  The liquid crystal first layer reading unit 17a, the liquid crystal second layer reading unit 17b, and the television layer reading unit 17c read image data from the frame memory 15 via the rotation processing unit 16. Then, the read image data is transmitted to the color space conversion unit 18. Note that the liquid crystal first layer reading unit 17a, the liquid crystal second layer reading unit 17b, and the television layer reading unit 17c may read image data from the frame memory 15 in an interlaced manner. Thereby, when the image data is image data of a moving image, flickering of the moving image displayed on the display device can be prevented.

  The color space conversion unit 18 applies RGB (red, green, blue) data and YUV (luminance signal) to the image data received from the liquid crystal first layer reading unit 17a, the liquid crystal second layer reading unit 17b, and the television layer reading unit 17c. , Blue color difference signal, red color difference signal). That is, even if the data on the frame memory 15 is RGB data or YUV data, it is converted into RGB data for liquid crystal display and YUV data for television display. Then, the converted image data is transmitted to the aspect conversion unit 19.

  Thereby, mutual conversion between RGB format data and YUV format data becomes possible. Then, regardless of whether the image data stored in the image data storage unit is in RGB format or YUV format, the image data corresponding to the RGB format display device and the YUV format display device is output. be able to. Therefore, it is not necessary to store the image data corresponding to the display device in the frame memory 15, and the capacity of the frame memory 15 can be reduced.

  The aspect conversion unit 19 performs vertical enlargement / reduction, horizontal enlargement / reduction processing of the image data received from the color space conversion unit 18. Then, the processed image data is transmitted to the layer composition unit 20 for the liquid crystal display and to the signal processing unit 21 for the television display.

  As a result, the image data can be scaled independently vertically and horizontally. Therefore, even if the aspect ratio of the image data is different from the aspect ratio of the display screen of the display device, the image data can be output to the display device in accordance with the aspect ratio of the display screen of the display device.

  The layer synthesizing unit 20 selects a plurality of image data for each layer received from the aspect conversion unit 19 and outputs which layer of the image data for each pixel to the display device, and the selected image data is the signal processing unit. To 21. Alternatively, the image data obtained by weighted averaging the image data of each layer with a preset weight is transmitted to the signal processing unit 21. Note that the location of the plurality of layers on the display device and the overlap information are set in advance. As a result, a screen obtained by combining a plurality of image data can be displayed on the display device.

  The signal processing unit 21 performs processing such as gamma correction on the image data received from the layer synthesis unit 20 or the aspect conversion unit 19. Then, the image data is transmitted to the display device.

  The image data output to the liquid crystal display device 26 is transmitted to the liquid crystal driver 22, and the liquid crystal driver 22 converts the image data from digital data to analog signals. In addition, a timing signal necessary for the liquid crystal panel 23 is generated based on the timing signal from the liquid crystal synchronization control unit 11, and is output to the liquid crystal panel 23 for display.

  The image data output to the television receiver 27 is transmitted to the television encoder 24, and the television encoder 24 converts the image data from digital data to analog signals. In addition, a necessary synchronization signal, a color burst signal, and the like are added by a timing signal from the television synchronization control unit 12 to generate a necessary signal for the television receiver 27, for example, an NTSC composite signal or a component signal, and the television monitor. Is output to 25 and displayed.

  Next, the flow of processing in which the write timing determination unit 132 determines the write timing will be described with reference to FIG. FIG. 2 is a flowchart showing a flow of processing in which the write timing determination unit 132 determines the write timing.

  As shown in FIG. 2, the writing timing determination unit 132 selects a reading unit that outputs image data to the display device selected by the user (S201). Here, it is assumed that the liquid crystal first layer reading unit 17a is selected. Then, for the liquid crystal first layer reading unit 17a, the writing timing determining unit 132 determines whether or not the writing speed is faster than the reading speed (S202). If the writing speed is faster than the reading speed (YES in S202), the writing timing determination unit 132 determines the time point when the reading unit 17 finishes reading the image data as the writing timing (S203). Then, according to the determined timing, the writing unit 133 writes the image data into the frame memory 15 (S205). Then, the process returns to S201.

  On the other hand, if the writing speed is slower than the reading speed (NO in S202), the writing timing determination unit 132 determines the time point when the reading unit 17 starts reading the image data as the writing timing. Then, according to the determined timing, the writing unit 133 writes the image data into the frame memory 15 (S205). And go back to the beginning.

  Next, write timing will be described with reference to FIGS. 3 to 6 are diagrams showing the relationship between the timings of starting and ending the reading of image data and the starting and ending points of writing. In FIGS. 3 to 6, the vertical axis is the read address or the write address, and the horizontal axis is the time. A solid line represents an address read with time, and a broken line represents an address written with time.

  FIG. 3 is a diagram showing a case where the image data for one screen is updated and the writing speed is slower than the reading speed. Note that the writing unit 133 writes image data to the frame memory 15 so that one frame of image data can be written within two frame periods in each display device. Here, a case where the liquid crystal first layer reading unit 17a reads image data will be described.

  First, the liquid crystal first layer reading unit 17a notifies the processing unit 131 of an interruption from the liquid crystal synchronization control unit 11 when the image data reading starts. The processing unit 131 receives this interrupt and notifies the write timing determination unit 132 of it. When receiving this interrupt, the write timing determination unit 132 notifies the write unit 133 to start transmitting image data to the frame memory 15 via the interface 14. Then, transmission of image data for one frame is completed within a two-frame period of display on the liquid crystal display device 26.

  That is, first, the reading unit 17 starts reading image data at the point 3a in FIG. Then, in response to the instruction by the interrupt, the writing unit 133 starts writing the image data of the frame that is next read by the liquid crystal first layer reading unit 17a at the time point 3b. Then, the liquid crystal first layer reading unit 17a finishes reading the image data at the time point 3c, and starts reading the image data of the next frame at the time point 3d. Then, at the time 3e before the reading of the image data of the next frame is finished, the writing of the image data of the next frame by the writing unit 133 is finished. Thereafter, reading of the next frame is completed at 3f.

  In this way, as shown in FIG. 3, the writing unit 133 writes the image data to the frame memory 15 so as to follow the read address after starting the reading of the image data. When the liquid crystal first layer reading unit 17a reads the image data, the memory portion that has not been written and the memory portion that has been written are not read as image data of the same frame. Therefore, the boundary line in the scanning direction does not appear in the image displayed on the display device, and the display quality can be maintained.

  Next, a case where the image data for one screen is updated and the writing speed is faster than the reading speed will be described. FIG. 4 is a diagram showing a case where the image data for one screen is updated and the writing speed is faster than the reading speed.

  First, the liquid crystal first layer reading unit 17a notifies the processing unit 131 of an interruption from the liquid crystal synchronization control unit 11 when the reading of image data is completed. The processing unit 131 receives this interrupt and notifies the write timing determination unit 132 of it. When receiving this interrupt, the write timing determination unit 132 notifies the write unit 133 to start transmitting image data to the frame memory 15 via the interface 14. Since the writing speed is faster than the reading speed, the transmission of the image data is completed within one frame period.

  That is, first, the liquid crystal first layer reading unit 17a starts reading image data at the time point 4a and ends reading at the time point 4b. Then, in response to the instruction by the interrupt, the writing unit 133 starts writing the image data of the frame to be read next by the liquid crystal first layer reading unit 17a at the time point 4c. Then, the liquid crystal first layer reading unit 17a starts reading the image data of the next frame at the time point 4d, and the writing unit 133 performs the reading at the time point 4e before the reading of the image data of the next frame is finished. Writing of the image data for the next frame is completed. Thereafter, reading of the next frame is completed at the time point 4f.

  In this way, when the liquid crystal first layer reading unit 17a reads image data from the frame memory 15, the memory part that has not been written and the memory part that has been written are used as image data of the same frame. There is no reading. Therefore, the boundary line in the scanning direction does not appear in the image displayed on the display device, and the display quality can be maintained.

  In addition, when updating only a part of the screen instead of the entire screen, the above-described write start timing may be set at the start or end of reading of the image data to be updated. FIG. 5 is a diagram showing a case where the writing speed is slower than the reading speed when a part of the image data is updated. FIG. 6 is a diagram showing a case where a part of image data is updated and the writing speed is faster than the reading speed.

  That is, when the writing speed is slower than the reading speed, as shown in FIG. 5, the liquid crystal first layer reading unit 17a starts reading the update area at the time 5a that is the reading start time of the update area. The writing unit 133 starts writing the image data in the update area of the next frame at the time point 5b according to the interrupt instruction by the start. At the time 5c, the reading of the update area is completed, and at the time 5d, the reading unit 17 starts reading the image data of the update area of the next frame. Then, the writing by the writing unit 133 is completed at time 5e before the reading is completed. Thereafter, the reading of the liquid crystal first layer reading unit 17a is completed.

  If the writing speed is faster than the reading speed, as shown in FIG. 6, the liquid crystal first layer reading unit 17a starts reading the update area at 6a and ends at 6b. Then, the writing unit 133 starts writing image data in the update area of the next frame at the time of 6c in response to an interrupt instruction upon completion of reading. Then, the writing ends at the time 6d, and the liquid crystal first layer reading unit 17a starts reading the update area of the next frame at the time 6e, and ends the reading at the time 6f.

  In this way, when the liquid crystal first layer reading unit 17a reads the image data from the frame memory 15, as in the case of updating all the one screen described above, the memory portion that has not been written and the writing are not completed. The timing for reading the completed memory portion as the same frame does not occur. Therefore, the boundary line in the scanning direction does not appear in the image displayed on the display device, and the display quality can be maintained.

  When the writing speed and the reading speed are the same, the writing timing may correspond to either the case where the writing speed is slower than the reading speed or the case where the writing speed is faster than the reading speed. This is because when the writing speed and the reading speed are the same, the memory portion that has not been written and the memory portion that has been written are read as image data of the same frame, regardless of when writing is started. This is because there is nothing.

  The reason why the display quality cannot be maintained unless the writing timing is determined at the above-mentioned timing is as follows.

  That is, when writing is started before the liquid crystal first layer reading unit 17a starts reading image data when the writing speed is slower than the reading speed, the memory portion that has not been written and the writing are completed. This memory portion is read as image data of the same frame. Thereby, a boundary line in the scanning direction appears in the image displayed on the display device, and the quality cannot be ensured.

  Further, when the writing speed is faster than the reading speed, when the writing is started after the liquid crystal first layer reading unit 17a starts reading the image data, the writing is finished and the memory portion where the writing is not finished. The memory portion is read as image data of the same frame. Thereby, a boundary line in the scanning direction appears in the image displayed on the display device, and the quality cannot be ensured.

  Here, FIG. 7 shows an image in which a boundary line in the scanning direction appears in the image and the quality of the image cannot be secured. FIG. 7 shows an example in which the reading direction matches the writing direction, and the writing speed is slower than the reading speed. When updating a moving image, an object with a large movement displays the previous frame data and the next frame data as one frame data. Thereby, it is displayed as if the screen is broken. FIG. 7 shows a case in which the upper half is the next frame data, the address read by the reading unit 17 in the middle of writing exceeds the write address, and the lower half reads the previous frame data. Note that, when a reading direction and a writing direction, which will be described later, are orthogonal, an image that is broken obliquely is displayed.

  In general, the frame rate is asynchronous between the liquid crystal display device and the television receiver, and if the quality of the liquid crystal display is maintained, the display quality of the television receiver cannot be maintained. This is because, in a television receiver, writing and reading of image data are asynchronous, and when reading, the timing to read the memory part that has not been written and the memory part that has been written as the same frame occurs. It is because it will do. As a result, a boundary line in the scanning direction appears in the displayed image, and the display quality cannot be ensured. On the other hand, if the display quality of the television receiver is maintained, the display quality on the liquid crystal display side cannot be ensured. However, by setting which display quality is prioritized, it is possible to maintain the display quality of either the liquid crystal display device or the television receiver.

  Next, the operation of the rotation processing unit 16 will be described with reference to FIG. FIG. 8 shows the frame memory 15, the line buffer 161 built in the rotation processing unit 16, and the output display data. Now, assume that image data of a horizontally long image is output to a vertically long display device while rotating in the scanning direction, and the horizontally long image data is stored on the frame memory 15 in the same direction as the memory direction as shown in FIG. Suppose that

  The required capacity of the frame memory 15 increases in proportion to the output image size, and generally occupies most of the cost of the display control device. Therefore, it is assumed that the frame memory 15 is configured as a DRAM (dynamic random access memory) in order to reduce the cost as much as possible. DRAM can be accessed at high speed if it is sequentially accessed in the memory direction, but access to discontinuous addresses is very slow. When the reading unit 17 of each layer tries to read the image data in the direction perpendicular to the memory direction, the address becomes discontinuous, and when the DRAM is accessed as it is, the access becomes slow. Alternatively, in order to secure the necessary bandwidth, the power consumption increases, such as increasing the clock frequency.

  In order to avoid this, a line buffer 161 constituted by SRAM (static random access memory) for several lines, for example, 16 lines, is built in the rotation processing unit 16. First, the image data on the frame memory 15 in FIG. 8 is transferred to the line buffer 161. At this time, as shown in FIG. 8, data is read in the same direction as the memory direction of the frame memory 15, and written in the line buffer 161 in a direction perpendicular to the memory direction of the line buffer 161. The line buffer 161 sequentially stores and outputs 16 lines of the image data stored in the frame memory 15. Finally, all the image data is stored and output.

  Since the SRAM does not decrease the speed even when accessing the discontinuous address, writing to the line buffer 161 accesses the discontinuous address, but does not decrease the speed. Thereafter, the data in the line buffer 161 is read out as shown in FIG. 8 and converted in the scanning direction as shown in the display data output of FIG. 8, and then the image data is outputted to the reading unit 17 of each layer.

  Accordingly, when the scanning direction of the image data read by the liquid crystal first layer reading unit 17a, the liquid crystal second layer reading unit 17b, and the television layer reading unit 17c is switched, a part of the image data is stored in the line buffer 161. be able to. Even if the storage medium of the frame memory 15 has a low access speed with respect to the discontinuous address as in the DRAM, the speed of the storage medium in the line buffer 161 does not decrease with respect to the discontinuous address as in the SRAM. By doing so, it is possible to switch the scanning direction of the image data to be read without a reduction in speed.

  More specifically, it is assumed that the frame memory 15 stores image data indicated by F1. Then, only 16 lines are copied to the line buffer 161. Here, it is assumed that the area corresponding to 16 lines is an area having approximately the same size as the area displayed as “Kashitsu” indicated by F1 (L1). Then, L1 stored in the line buffer 161 is read in a direction perpendicular to the writing direction (L2), and is set as output image data. As a result, the output image data becomes H1.

  Next, the area adjacent to the previously read area of the image data stored in the frame memory 15 is read for 16 lines (F2). Then, similarly to the previous time, reading (L4) is performed in a direction perpendicular to the writing direction (L3) and output (H2). By repeating this, the final area (F3) of the image data is finally copied to the line buffer 161 (L5), read in the direction perpendicular to the writing direction (L6), and output (H3). Thereby, the image data for one frame can be rotated by 90 °.

  If the number of pixels included in the burst access length of the DRAM of the frame memory 15 is equal to the number of lines of the line buffer 161, access to the DRAM and SRAM is not accompanied by a decrease in speed. In addition, the capacity of the SRAM, which is expensive in comparison, can be minimized. Furthermore, as a result, the data after each layer part can be converted into a data order perpendicular to the memory direction of the data in the frame memory 15. Further, in the example of FIG. 8, an example of rotating 90 ° to the left is shown, but 90 °, 180 ° to the right, mirror inversion, and the like can be similarly realized.

  Next, FIG. 9 shows an example of a product on which the display control device 10 is mounted. FIG. 9 shows an example in which the display control device 10 is mounted on a mobile phone (liquid crystal display device 26). The mobile phone is divided into two cases, an upper case and a lower case, and the operation unit arranged with buttons and the display unit arranged with the liquid crystal panel 23 and the like are opposed to each other via hinges. Can be folded. The mobile phone and the television receiver 27 are connected so that image data can be transmitted.

  The liquid crystal panel 23 is provided with a source driver in the short side direction and a gate driver in the long side direction, and the scanning direction of the liquid crystal is the direction of scanning from the upper left to the upper right and further from the upper to the lower. Here, the scanning direction is an order in which the display control device 10 transmits image data of an image displayed on the liquid crystal to the liquid crystal panel.

  Here, an image of necessary image data on the frame memory 15 is shown in FIG. The liquid crystal first layer reading unit 17a reads the image data of FIG. Then, the liquid crystal second layer and the television layer are set to the same address as the addresses on the same frame memory 15, and the liquid crystal second layer readout unit 17b and the television layer readout unit 17c are configured to use the same image for the image data in FIG. Read data. The image data read by the liquid crystal first layer reading unit 17a and the image data read by the liquid crystal second layer reading unit 17b are output to the layer combining unit 20. Then, the layer composition unit 20 pastes the image data of FIG. 10A on the center of the image data of FIG. 10B, generates image data according to the output image, and displays it on the liquid crystal panel 23 of FIG. The image data of the displayed display image is output.

  Then, the aspect conversion unit 19 of the liquid crystal first layer and the liquid crystal second layer is set to output the received image data as it is. That is, the image data on the frame memory 15 is output 1: 1 in both the vertical and horizontal directions without performing the enlargement / reduction processing in the horizontal direction or the vertical direction. On the other hand, the pixel aspect ratio of the television monitor 25 of the television receiver 27 is 9: 8. Therefore, if the pixel aspect ratio of the liquid crystal panel 23 is 1: 1, the pixel aspect ratio on the frame memory 15 is 1: 1, and the aspect ratio conversion unit 19 of the TV layer sets the ratio 1: 1 and 9 If the enlargement setting is set to / 8 times and the image is enlarged and output in the horizontal direction, the same content can be simultaneously displayed on the liquid crystal panel 23 and the television monitor 25 with the same aspect ratio.

  Further, if the image data in FIG. 10A is a natural image content such as a one-segment broadcasting image or a moving image reproduction image, the original data is often YUV format data obtained by decompressing the compressed data. Further, if the image data in FIG. 10B is a computer-generated image made up of character information and pictographic information, such as caption broadcasting and clock display, the original data is often RGB data. Here, if the image data in FIG. 10A is YUV format data and the image data in FIG. 10B is RGB format data, the color space conversion unit 18 of the liquid crystal first layer is not converted, and the liquid crystal second If the color space conversion unit 18 of the layer is set to YUV → RGB conversion and the color space conversion unit 18 of the television layer is not converted, the output to the liquid crystal display device 26 is RGB format and the output to the television receiver 27 is YUV format. Thus, the data format required by each display device is obtained.

  In addition, as shown in FIG. 11, when the cellular phone is folded, the upper casing is further tilted 90 ° to the right via a rail or a second hinge provided on the back side of the display unit. It can be in a landscape state, and a landscape image can be displayed in a landscape state. Since the liquid crystal panel 23 is provided with a source driver in the short side direction and a gate driver in the long side direction, the liquid crystal scanning direction in the state tilted 90 ° to the right is from the upper right to the lower right and further to the right. From left to right.

  Here, an image of necessary image data on the frame memory 15 is shown in FIG. FIG. 12B reads the image data by the liquid crystal first layer reading unit 17a, sets the same address as the addresses on the same frame memory 15 in the liquid crystal second layer and the television layer, and FIG. The two-layer reading unit 17b and the television layer reading unit 17c read the same image data. The image data read by the liquid crystal first layer reading unit 17a and the data read by the liquid crystal second layer reading unit 17b are output to the layer combining unit 20. Then, the layer synthesis unit 20 pastes the image data of FIG. 12A on the center of the image data of FIG. 12B, generates image data according to the output image, and displays the image data of the display image of FIG. Is output.

  Then, the aspect conversion unit 19 of the liquid crystal first layer and the liquid crystal second layer is set to output the received image data as it is. That is, the image data on the frame memory 15 is output 1: 1 in both the vertical and horizontal directions without performing the enlargement / reduction processing in the horizontal direction or the vertical direction. On the other hand, the aspect conversion unit 19 of the TV layer displays the same content on the liquid crystal display device 26 and the television receiver 27 at the same aspect ratio with the 1: 1 vertical setting and the 9/8 horizontal setting. If the image data in FIG. 10A is YUV format data and the image data in FIG. 10B is RGB format data, the color space conversion unit 18 of the liquid crystal first layer is not converted, and the color of the liquid crystal second layer When the space conversion unit 18 is set to YUV → RGB conversion and the color space conversion unit 18 of the television layer is not converted, the output to the liquid crystal display device 26 is in RGB format, and the output to the television receiver 27 is in YUV format. The data format required by the display device is obtained.

  At this time, the rotation processing unit 16 of the liquid crystal first layer and the liquid crystal second layer is set to rotate 90 ° to the left. That is, the image data read in the liquid crystal first layer and the liquid crystal second layer is rotated 90 ° to the left via the line buffer 161 built in the rotation processing unit 16 as shown in FIG. Is obtained in the direction perpendicular to the memory direction of the frame buffer. By doing in this way, the image display of the display image shown in FIG. 11 can be obtained.

  In the liquid crystal display device 26, there are two states, a state 1 in which the liquid crystal panel 23 is in a vertically long state as shown in FIG. 9 and a state 2 in which the liquid crystal panel 23 is in a horizontally long state as shown in FIG. . In state 1, the memory direction of the frame memory 15, the scanning direction of the liquid crystal display device 26, and the scanning direction of the television receiver 27 can all be matched. In state 2, when the memory direction of the frame memory 15 and the scanning direction of the television receiver 27 are matched, the memory direction of the frame memory 15 and the scanning direction of the liquid crystal display device 26 are orthogonal to each other. Conversely, when the memory direction of the frame memory 15 and the scanning direction of the liquid crystal display device 26 are matched, the memory direction of the frame memory 15 and the scanning direction of the television receiver 27 are orthogonal to each other. As described above, when the orthogonal relationship is established, the rotation processing unit 16 can display the image data according to the display device by rotating the image data.

  Further, in the state 2, the display device in which the memory direction of the frame memory 15 and the scanning direction are orthogonal to each other indicates that the memory portion where writing has not been completed and the memory portion where writing has been completed are the same during reading. Timing to read as a frame occurs. As a result, oblique lines appear in the displayed image, and the quality cannot be ensured.

  That is, when the image data writing and the image data reading are orthogonal to each other in the scanning direction, when the image display with a high update rate such as a moving image is performed, the memory portion in which the writing is not completed at the time of reading. Then, the timing of reading the memory portion in which writing has been completed as the same frame occurs, oblique lines appear on the display, and the quality cannot be ensured.

  However, a display device in which the memory direction and the scanning direction of the image data coincide with each other can control the writing start timing according to the above-described writing timing to ensure display quality. For example, in the example of FIG. 12, the display quality on the television receiver 27 is ensured by aligning the image data in the frame memory 15 with the scanning direction on the television receiver 27 side.

  If the memory direction of the image data in the frame memory 15 is aligned with the scanning direction of the liquid crystal display device 26 and the scanning direction of the television receiver 27 is orthogonal to the memory direction, the display quality of the liquid crystal display device 26 can be ensured. it can.

  Therefore, by setting which display quality of the liquid crystal display device 26 or the television receiver 27 is prioritized, it is possible to maintain either display quality.

  Finally, each block of the display control device 10, particularly the main control unit 13 (processing unit 131, writing timing determination unit 132, writing unit 133), rotation processing unit 16, reading unit 17, color space conversion unit 18, aspect conversion unit 19, the layer synthesis unit 20 and the signal processing unit 21 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the display control device 10 includes a CPU that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, a RAM (random access memory) that expands the program, the program, and various types A storage device (recording medium) such as a memory for storing data is provided. An object of the present invention is a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program of the display control apparatus 10 which is software for realizing the functions described above is recorded so as to be readable by a computer. This can also be achieved by supplying the display control apparatus 10 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU (microprocessor unit)).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, a CD-ROM (compact disc read-only memory) / MO (magneto-optical) / Disc systems including optical disks such as MD (Mini Disc) / DVD (digital video disk) / CD-R (CD Recordable), card systems such as IC cards (including memory cards) / optical cards, or mask ROM / EPROM ( An erasable programmable read-only memory) / EEPROM (electrically erasable and programmable read-only memory) / semiconductor memory system such as a flash ROM can be used.

  Further, the display control device 10 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN (local area network), ISDN (integrated services digital network), VAN (value-added network), CATV (community antenna television) communication. A network, a virtual private network, a telephone line network, a mobile communication network, a satellite communication network, etc. can be used. In addition, the transmission medium constituting the communication network is not particularly limited. For example, IEEE (institute of electrical and electronic engineers) 1394, USB, power line carrier, cable TV line, telephone line, ADSL (asynchronous digital subscriber loop) line Wireless such as IrDA (infrared data association) and remote control such as remote control, Bluetooth (registered trademark), 802.11 wireless, HDR (high data rate), mobile phone network, satellite line, terrestrial digital network, etc. But it is available. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  In a display control apparatus that displays images on a plurality of display devices at the same time, the display quality of at least one display device can be maintained. Therefore, the present invention can be applied to a display device that displays images on a plurality of display devices at the same time. This is suitable for a device that displays an image and displays the same image on other display devices.

1, showing an embodiment of the present invention, is a block diagram illustrating a configuration of a main part of a display control device. FIG. It is a flowchart which shows the flow of the process which determines the write-in timing in the said embodiment. It is a figure which shows the timing relationship between the read start and end time of image data and the start and end time of writing in the above embodiment, and the writing speed when updating for one screen is slower than the reading speed FIG. It is a figure which shows the timing relationship between the read start and end time of image data, and the start and end time of writing in the above embodiment, and the writing speed when updating for one screen is faster than the reading speed FIG. It is a figure which shows the relationship of the timing of the reading start and completion | finish time of image data, and writing start and completion | finish time in the said embodiment, and when writing speed is slower than reading speed when performing partial update of a screen FIG. It is a figure which shows the relationship of the timing of the reading start and completion | finish time of image data, and the writing start and completion | finish time in the said embodiment, and when writing speed is faster than reading speed when performing partial update of a screen FIG. It is an image which shows a display when the quality of a display image in the said embodiment cannot be maintained. It is a figure which shows the process at the time of using a line buffer when performing a rotation process in the said embodiment. It is a figure which shows the case where the said embodiment is used for a mobile telephone. It is a figure which shows the image data required for a frame memory at the time of using for the said mobile telephone, (a) is the image data used by a liquid crystal 2nd layer and a television layer, (b) is the image data used by a liquid crystal 1st layer. FIG. It is a figure which shows the case where the said embodiment is used for a mobile telephone. It is a figure which shows the image data required for a frame memory at the time of using for the said mobile telephone, (a) is the image data used by a liquid crystal 2nd layer and a television layer, (b) is the image data used by a liquid crystal 1st layer. FIG. It is a block diagram which shows a prior art and shows the principal part structure of a display control apparatus. It is a figure which shows the case where the said prior art is used for a mobile telephone. In the said prior art, it is a figure which shows the image data required for a frame memory, (a) is the image data used by LCD layer 1, (b) is the image data used by LCD layer 2, (c) is used by TV layer It is a figure which shows image data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Display control apparatus 11 Liquid crystal synchronization control part 12 Television synchronization control part 13 Main control part 14 Interface 15 Frame memory (image data storage part)
16 Rotation processing part (Rotation processing means)
17a Liquid crystal first layer reading unit (image data reading means)
17b Liquid crystal second layer reading unit (image data reading means)
17c TV layer reading unit (image data reading means)
18 Color space conversion unit (Color space conversion means)
19 Aspect converter (Aspect converter)
20 layer composition unit (layer composition means)
DESCRIPTION OF SYMBOLS 21 Signal processing part 22 Liquid crystal driver 23 Liquid crystal panel 24 Television encoder 25 Television monitor 26 Liquid crystal display device 27 Television receiver 131 Processing part 132 Writing timing determination part (writing timing determination means)
133 Writing unit (image data writing means)

Claims (4)

A display control device that includes an image data storage unit that stores image data, and outputs the same image data read from the image data storage unit to a plurality of display devices that display images,
Image data writing means for writing image data to the image data storage unit;
A plurality of image data reading means for reading the image data stored in the image data storage unit and outputting the image data to the plurality of display devices,
Image data reading means for outputting image data to a display device selected from the plurality of image data reading means is selected image data reading means,
Comparing the writing speed at which the image data writing means writes image data into the image data storage section and the reading speed at which the selected image data reading means reads image data from the image data storage section;
If the writing speed is faster than the reading speed, the selected image data reading means finishes reading the image data,
If the writing speed is slower than the reading speed, the time point when the selected image data reading means starts reading the image data,
A display control apparatus, further comprising: a writing timing determining unit that determines the timing at which the image data writing unit writes image data to the image data storage unit.   A display control program for operating the display control device according to claim 1, wherein the computer functions as each of the means.   A computer-readable recording medium on which the display control program according to claim 2 is recorded. A control method for a display control device, comprising an image data storage unit for storing image data, and outputting the same image data read from the image data storage unit to a plurality of display devices for displaying images,
An image data writing step of writing the image data into the image data storage unit;
A plurality of image data reading steps for reading the image data stored in the image data storage unit and outputting the image data to the plurality of display devices,
While selecting the image data reading step for outputting the image data to the display device selected from the plurality of image data reading steps as the selected image data reading step,
Comparing the writing speed for writing image data to the image data storage section in the image data writing step and the reading speed for reading image data from the image data storage section in the selected image data reading step;
If the writing speed is faster than the reading speed, the time point when reading of the image data is finished in the selected image data reading step is as follows:
If the writing speed is slower than the reading speed, the time point when reading of the image data is started in the selected image data reading step,
A control method for a display control apparatus, further comprising a write timing determination step for determining the timing at which image data is written in an image data storage unit in the image data writing step.

Images