Display device and display control method for the display device

Abstract

By simplifying the reading and writing of data to and from memory when scrolling the image displayed on the light-emitting section, image scrolling control is simplified. [Solution] The display control unit of the display unit displays an image on the light-emitting unit, which includes multiple light-emitting elements, using data for one screen from memory each time it receives a screen display command. When the display control unit receives a screen display command after receiving a scroll command which includes the latest data set used for scrolling the image, it overwrites the memory storage area where the oldest data set that will not be used for the next image display from the data for one screen used for image display on the light-emitting unit is stored with the latest data set, and outputs multiple data sets read from memory to the drive unit so that an image using the new oldest data set from the latest data set stored in memory is displayed from the light-emitting element group at one end of the light-emitting unit to the light-emitting element group at the other end.

Description

[Technical Field]

[0001] The present disclosure relates to a display device and a display control method for a display device. [Background Art]

[0002] In a liquid crystal display device including a liquid crystal panel, a technique is known which reduces the amount of image data transferred to the liquid crystal panel and reduces power consumption by: receiving one frame of image data including a plurality of lines and writing the image data to the display panel, and then writing only changed lines, among the next received one frame of image data, to the display panel.

[0003] Furthermore, an LED display is known in which a plurality of display modules each having an LED light emitting unit including LEDs (Light Emitting Diodes) arranged in a matrix are arranged in one row. Each display module includes a display memory that holds data for one screen to be displayed on the LED light emitting unit, and a buffer memory that receives data for one row of the LED light emitting unit and transfers the data to the display memory.

[0004] After storing data for one screen in the display memory and displaying an image on the LED light emitting unit, the display module reads back data for one row from the display memory to the buffer memory, and repeats the operation of storing the data in an area of the display memory shifted by one row. At this time, the display module receives new data for one row, sets the data in the buffer memory, and stores the set data for one row in the display memory, thereby displaying an image scrolled by one row on the LED light emitting unit. [Prior Art Literature] [Patent Literature]

[0005] [Patent Literature 1] Japanese Patent Application Laid-Open No. 2002-287681 [Patent Literature 2] Japanese Patent Application Laid-Open No. 11-327509 [Summary of Invention] [Problems that the invention aims to solve]

[0006] The display module described above has a memory area in the display memory that stores one column of data, with each column of the LED light-emitting section corresponding to that area. Therefore, each time the image is scrolled, the data stored in the display memory must be read back into the buffer memory column by column, shifted, and stored back into the display memory. In other words, the display module needs to read and write one screen's worth of data to and from the display memory in order to scroll the image, which makes memory access complex.

[0007] This disclosure aims to simplify image scrolling control by simplifying the reading and writing of data to memory when scrolling an image displayed on the light-emitting unit. [Means for solving the problem]

[0008] A display device according to one embodiment of the present disclosure is a display device having at least one display unit on which an image is displayed, and a main control unit that controls the display unit, wherein the display unit includes a plurality of light-emitting elements arranged in a matrix, a light-emitting section that displays an image by the emission of light from the plurality of light-emitting elements, a memory that includes a plurality of storage areas each storing data groups that cause the light-emitting elements, which are the light-emitting elements arranged in one direction, to emit light, and is capable of storing data for one screen of the light-emitting section, a drive unit that drives the light-emitting section, and a display control unit that controls the display of an image by the light-emitting section by controlling the reading and writing of data to the memory, wherein the display control unit controls the display of an image by the light-emitting section each time it receives a screen display command from the main control unit, which stores the data for one screen stored in the memory The drive unit outputs data for each screen to cause the light-emitting unit to display an image. After receiving a scroll command that includes the latest data set used for scrolling the image displayed on the light-emitting unit, the drive unit receives a screen display command from the main control unit. In this case, the drive unit overwrites the storage area with the latest data set received with the oldest data set from the data for one screen that was used for image display by the light-emitting unit immediately before receiving the screen display command, and outputs a plurality of data sets read from the memory to the drive unit so that an image is displayed from the group of light-emitting elements at one end of the light-emitting unit to the group of light-emitting elements at the other end, using the latest data set stored in the memory to create a new oldest data set. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, the scrolling control of an image can be simplified by simplifying the reading and writing of data to and from memory when scrolling an image displayed on the light-emitting unit. [Brief explanation of the drawing]

[0010] [Figure 1] A block diagram showing an example of a display device according to one embodiment. [Figure 2] Figure 1 is a circuit block diagram showing an example of the display unit. [Figure 3]Figure 2 is a block diagram showing an example of the configuration of the display control unit. [Figure 4] Figure 2 is an explanatory diagram showing an example of the configuration of the LED light-emitting section. [Figure 5] This is an explanatory diagram illustrating an example of scrolling the image displayed on the LED light-emitting section of the display unit in Figure 2 to the left. [Figure 6] This is an explanatory diagram illustrating an example of scrolling the image displayed on the LED light-emitting section of the display unit in Figure 2 upwards. [Figure 7] This timing diagram shows an example of displaying a scrolling image on the LED light-emitting section without using the column and row receive buffers in the display device shown in Figure 1. [Figure 8] This is a timing diagram showing a continuation of Figure 7. [Figure 9] This timing diagram shows an example of scrolling an image displayed on the LED light-emitting section using a column receiving buffer in the display device shown in Figure 1. [Figure 10] This is a timing diagram showing a continuation of Figure 9. [Figure 11] Figure 10 is a timing diagram showing the operation of a portion of the area indicated by the dashed frame. [Figure 12] This diagram illustrates a comparison of data transfer times using the existing parallel transfer method, the existing serial transfer method, and the new serial transfer method described above when displaying images in a scrolling format. [Modes for carrying out the invention]

[0011] The following description will explain embodiments for carrying out the invention with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "up," "down," and other terms including these terms) will be used as needed. The use of these terms is for the purpose of facilitating the understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components.

[0012] Furthermore, the embodiments described below illustrate a display device and the like for embodying the technical idea of the present invention, and are not intended to limit the present invention to the following. In addition, unless specifically stated otherwise, the shapes, relative arrangements and the like of the components described below are not intended to limit the scope of the present invention thereto, but are intended to be illustrative. Furthermore, the content described in one embodiment is also applicable to other embodiments and modified examples. In addition, the sizes and positional relationships of members shown in the drawings may be exaggerated for clarity of explanation. Furthermore, in order to avoid excessive complexity of the drawings, schematic diagrams omitting the illustration of some elements may be used.

[0013] In addition, reference numerals denoting signals may be used as reference numerals denoting signal lines, signal terminals, or signal nodes. Signals include address signals, data signals, control signals, and the like. Reference numerals denoting power supply / voltage may be used as reference numerals denoting power supply lines / voltage lines, power supply terminals / voltage terminals, and power supply nodes / voltage nodes.

[0014] (Overview of Display Device) Fig. 1 is a block diagram showing an overview of a display device according to an embodiment. The display device 10 according to the present embodiment is installed outdoors, for example, and is used to provide various types of information to users of facilities and equipment. For example, the display device 10 may be installed downstream of a dam to display dam discharge information, hazard information, caution information, and weather information. In addition, the display device 10 may be installed on expressways, national highways, and the like to display traffic information and weather information. Note that the application of the display device 10 is not limited to the above, and any application that provides information to users is acceptable.

[0015] A display device 10 includes a display panel 20 having a plurality of display units 100 arranged in a matrix, and a control board 30 that controls the display panel 20. Each display unit 100 includes a plurality of unillustrated LEDs (Light Emitting Diodes) arranged in a matrix, and is capable of displaying an image including characters and the like by turning on the plurality of LEDs. Each display unit 100 also has a function of scroll-displaying an image such as characters. Examples of scroll display are described with reference to FIG. 5 and FIG. 6.

[0016] In FIG. 1, the display device 10 has 20 display units 100, with five display units arranged in the X direction and four arranged in the Y direction. Note that the number and arrangement of the display units 100 mounted on the display device 10 are not limited to those shown in FIG. 1. For example, the display units 100 may be arranged in one row in either the X direction or the Y direction. In the following description, the X direction is also referred to as the horizontal direction X, and the Y direction is also referred to as the vertical direction Y.

[0017] The display units 100 are sequentially connected via a serial interface SIF indicated by a double-headed arrow. Although not particularly limited, the operating frequency of the serial interface SIF may be 25 MHz, in which case the transfer time per bit is 40 ns. The display unit 100 closest to the control board 30 is connected to the control board 30 via the serial interface SIF.

[0018] In the example shown in FIG. 1, the display unit 100 connected to the control board 30 is sequentially connected to the display units 100 aligned in the horizontal direction X, and the display unit 100 at the end in the horizontal direction X is connected to the display unit 100 adjacent in the vertical direction Y. All the display units 100 are connected in a meandering pattern via the serial interface SIF, and transfer control information, image data, and the like to adjacent display units 100 via the serial interface SIF. In the following description, the image data is also simply referred to as data. Note that the connection order of the display units 100 is not limited to the example shown in FIG. 1.

[0019] The control board 30 has a controller such as a CPU (not shown) and sequentially transmits control information and image data to each display unit 100 via the serial interface SIF, thereby causing each display unit 100 to display an image. For example, the control board 30 may transmit a packet including a header and a payload to the display unit 100 via the serial interface SIF and receive packets from the display unit 100. The control board 30 and the controller mounted on the control board 30 are examples of main control units that control the display units 100.

[0020] Furthermore, the control board 30 can group any multiple display units 100 and control the display of the display units 100 on a group basis. For example, when the image displayed on a display unit 100 belonging to a group is changed, other display units 100 that do not belong to the group can continue to display the image they are currently displaying.

[0021] (Circuit block of the display unit) Figure 2 is a circuit block diagram showing an example of the display unit 100 in Figure 1. The display unit 100 has a communication unit 110 including interface (I / F) units 120 and 130. The interface unit 120 has an encoder / decoder 121, a serial-to-parallel (S / P) conversion unit 122, a parallel-to-serial (P / S) conversion unit 123, and a communication control unit 124. The communication control unit 124 has an ID (Identification) register and a group ID register. The ID register and group ID register are explained in Figures 7 and 8. For example, the interface unit 130 has the configuration of the interface unit 120 excluding the communication control unit 124.

[0022] The display unit 100 also includes a display control unit 140, column receive buffers RBUF1(V), RBUF2(V), RBUF3(V), row receive buffers RBUF1(H), RBUF2(H), RBUF3(H), and a multiplexer MUX1. The column receive buffers RBUF1(V) to RBUF3(V), row receive buffers RBUF1(H) to RBUF3(H), and the multiplexer MUX1 operate during scroll display mode.

[0023] Furthermore, the display unit 100 includes multiple scroll display data storage RAMs (Random Access Memory) 150, multiple display data storage RAMs 160, a multiplexer MUX2, a drive circuit 170, and an LED light-emitting unit 180. The column receive buffer RBUF1(V) and row receive buffer RBUF1(H) are examples of first-stage buffers, and the column receive buffer RBUF3(V) and row receive buffer RBUF3(H) are examples of final-stage buffers. Each scroll display data storage RAM 150 and each display data storage RAM 160 is a multi-port memory having a data write port and a data read port, and is an example of a memory capable of storing data for at least one screen.

[0024] The communication unit 110 has the function of decoding serial data packets received from the control board 30 or other display unit 100 via the serial interface SIF, and converting the decoded packets into parallel data. Furthermore, the communication unit 110 has the function of converting parallel data into serial data packets, encoding the converted serial data packets, and transmitting the encoded packets to the control board 30 or other display unit 100 via the serial interface SIF. In addition, the communication unit 110 has the function of relaying packets received via the serial interface SIF.

[0025] In the communication unit 110, the encoder / decoder 121 decodes packets received from the control board 30 or the adjacent display unit 100 and outputs the decoded packets to the serial-to-parallel conversion unit 122. The encoder / decoder 121 also encodes packets received from the parallel-to-serial conversion unit 123 and transmits the encoded packets to the control board 30 or the adjacent display unit 100.

[0026] The serial-to-parallel conversion unit 122 converts the serial data packets received from the encoder / decoder 121 into parallel data packets and outputs them to the communication control unit 124. The parallel-to-serial conversion unit 123 converts the parallel data packets received from the communication control unit 124 into serial data packets and outputs them to the encoder / decoder 121.

[0027] The communication control unit 124 has the function of decoding packets received from the serial-to-parallel conversion unit 122 or packets received from the interface unit 130. If the identification information ID included in the header portion of the packet matches the ID stored in the ID register, the communication control unit 124 outputs the image data etc. included in the payload portion of the packet to the display control unit 140.

[0028] Furthermore, the communication control unit 124 relays packets by outputting packets received from the serial-to-parallel conversion unit 122 to the interface unit 130, and packets received from the interface unit 130 to the parallel-to-serial conversion unit 123. In addition, the communication control unit 124 generates packets containing information received from the display control unit 140, and outputs the generated packets toward the serial interface SIF on the control board 30.

[0029] The communication control unit 124 forwards packets received from one serial interface SIF to the other serial interface SIF, so that even when multiple display units 100 are connected in series via the serial interface SIF, packets can be forwarded to each display unit 100. Each display unit 100 can then perform image display processing on the LED light-emitting unit 180 based only on packets that indicate its own display unit.

[0030] The interface unit 130 converts packets received from the communication control unit 124 into serial data, decodes it, and outputs it to the serial interface SIF. The interface unit 130 encodes packets received from the serial interface SIF into parallel data and outputs it to the communication control unit 124.

[0031] The display control unit 140 controls the LED light-emitting unit 180 to display an image based on the control information and image data received from the communication control unit 124. The display control unit 140 also has a function to output information indicating the operating status of the drive circuit 170 or the LED light-emitting unit 180 to the communication unit 110. The communication unit 110 transmits the information received from the display control unit 140 as a packet to the control board 30. As a result, the controller such as the CPU mounted on the control board 30 in Figure 1 can recognize the status of each display unit 100.

[0032] For example, the display control unit 140 has a scroll display mode for scrolling the image displayed on the LED light-emitting unit 180. In the scroll display mode, when the display control unit 140 scrolls the image upwards or downwards, it stores the data corresponding to one row of images in the row receive buffer RBUF1(H) via the data line DT0. In the scroll display mode, when the display control unit 140 scrolls the image leftward or rightward, it stores the data corresponding to one column of images in the column receive buffer RBUF1(V) via the data line DT1.

[0033] In scroll display mode, when the display control unit 140 displays one screen's worth of image on the LED light-emitting unit 180 before scrolling, it outputs the data corresponding to one screen's worth of image to the multiplexer MUX1 via the data line DT2 and writes it to one of the scroll display data storage RAMs 150. By writing one screen's worth of image data to the scroll display data storage RAM 150 via the data line DT2, the control of the display control unit 140 can be simplified compared to when the image data is written to the scroll display data storage RAM 150 via the column receive buffers RBUF1(V), RBUF2(V), and RBUF3(V).

[0034] When the display control unit 140 displays an image for one screen on the LED light-emitting unit 180 in a normal display mode other than the scrolling display mode, it writes the data corresponding to the image for one screen to one of the display data storage RAMs 160 via the data line DT3. For example, if the number of bits for the grayscale data, as explained in Figure 4, is 8 bits, then each data line DT0, DT1, DT2, and DT3 has the same 8 bits of data. An example of the internal configuration of the display control unit 140 is shown in Figure 3.

[0035] The row receive buffers RBUF1(H), RBUF2(H), and RBUF3(H) are connected in series between the display control unit 140 and the multiplexer MUX1, and sequentially hold image data for one row used when scrolling the image upwards or downwards. The column receive buffers RBUF1(V), RBUF2(V), and RBUF3(V) are connected in series between the display control unit 140 and the multiplexer MUX1, and sequentially hold image data for one column used when scrolling the image leftward or rightward.

[0036] The row receive buffer RBUF2(H) holds the data output from the row receive buffer RBUF1(H) in synchronization with the control signal CNT2 generated by the display control unit 140. The column receive buffer RBUF2(V) holds the data output from the column receive buffer RBUF1(V) in synchronization with the control signal CNT2 generated by the display control unit 140.

[0037] The row receive buffer RBUF3(H) holds the data output from the row receive buffer RBUF2(H) in synchronization with the control signal CNT3 generated by the display control unit 140. The column receive buffer RBUF3(V) holds the data output from the column receive buffer RBUF2(V) in synchronization with the control signal CNT3 generated by the display control unit 140.

[0038] This prevents data DT1 in column receive buffer RBUF1(V) or column receive buffer RBUF2(V) from being overwritten and lost before it is written to the RAM 150 for storing scroll display data, thereby preventing the image from becoming unscrollable. Similarly, it prevents data DT0 in row receive buffer RBUF1(H) or row receive buffer RBUF2(H) from being overwritten and lost before it is written to the RAM 150 for storing scroll display data, thereby preventing the image from becoming unscrollable.

[0039] In this embodiment, one display cycle is required to update one column or one row of data in the RAM 150 for storing scroll display data. The display cycle indicates the period for displaying one screen's worth of image on the LED light-emitting unit 180, and the image continues to be displayed on the LED light-emitting unit 180 as the display cycle is repeated. If it is guaranteed that the period of the display packet VSC-PK for scrolling the image is longer than two display cycles, then even without the column receive buffer RBUF3(V) and row receive buffer RBUF3(H), the image data for one column or one row used for scrolling will not be overwritten and lost before it is written to the RAM 150 for storing scroll display data, and therefore the image will not become unusable. An example of the operation of the display control unit 140 based on the display packet VSC-PK for scrolling the image is shown in Figures 8 and 10.

[0040] To cause the multiplexer MUX1 to select the correct data, the display control unit 140 generates a selection signal SEL1 using the value held in the scroll execution register SPF. For example, the selection signal SEL1 is 2 bits. The multiplexer MUX1 is an example of a switching unit that connects either the output of the row receive buffer RBUF3(H), the output of the column receive buffer RBUF3(V), or the data line DT2 to the RAM 150 for storing scroll display data.

[0041] For example, if the selection signal SEL1 output from the display control unit 140 is "00b", the multiplexer MUX1 sequentially selects image data for one row output from the row receive buffer RBUF3(H) and outputs it to one of the scroll display data storage RAM 150. If the selection signal SEL1 is "01b", the multiplexer MUX1 sequentially selects image data for one column output from the column receive buffer RBUF3(V) and outputs it to one of the scroll display data storage RAM 150.

[0042] When the selection signal SEL1 is "10b", the multiplexer MUX1 sequentially selects data for one screen output from the display control unit 140 to the data line DT2 and outputs it to one of the scroll display data storage RAMs 150. The trailing "b" in "00b", "01b", "10b", etc., indicates that the value is in binary. By providing a multiplexer MUX1 that selects either the output of the data line DT2, the column receive buffer RBUF3(V), or the row receive buffer RBUF3(H), it is possible to select the data to write to the scroll display data storage RAM 150 according to the size of the received data and the scrolling direction.

[0043] Each scroll display data storage RAM 150 operates by receiving the address signal ADR, clock enable signal CE, and write enable signal WE, respectively, output from the display control unit 140. When the corresponding write enable signal WE is high, each scroll display data storage RAM 150 writes the image data received from the multiplexer MUX1 to the memory area indicated by the corresponding address signal ADR, in synchronization with the corresponding clock enable signal CE. When scrolling is performed, the display control unit 140 writes the image data for one column or one row of the LED light-emitting unit 180 that is newly displayed by scrolling to one of the scroll display data storage RAMs 150. On the other hand, the display control unit 140 does not write the image data corresponding to the image where only the display position on the LED light-emitting unit 180 changes due to scrolling to the scroll display data storage RAM 150.

[0044] Each scroll display data storage RAM 150 reads data from the memory area indicated by the corresponding address signal ADR in synchronization with the corresponding clock enable signal CE when the corresponding write enable signal WE is low, and outputs it to the multiplexer MUX2. When the display control unit 140 reads image data for one screen of the LED light-emitting unit 180 from one of the scroll display data storage RAMs 150 when scrolling an image, it changes the reading order of the data for each column or row read from one of the scroll display data storage RAMs 150 for each scroll. That is, when scrolling an image, the display control unit 140 changes the output order of the address signal ADR to the scroll display data storage RAM 150. Examples of writing data to and reading data from the scroll display data storage RAM 150 when scrolling an image are shown in Figures 5 and 6.

[0045] The write port of each display data storage RAM 160 is connected to the display control unit 140 via the data line DT3, and receives image data output from the display control unit 140. The read port of each display data storage RAM 160 is connected to the input of the multiplexer MUX2, and the image data read from each display data storage RAM 160 is output to the drive circuit 170 via the multiplexer MUX2. In Figure 2, the address signal ADR, clock enable signal CE, and write enable signal WE that control the write and read operations of each display data storage RAM 160 are omitted from the description, but each display data storage RAM 160 receives the address signal ADR, clock enable signal CE, and write enable signal WE, respectively, and performs the write and read operations, respectively. Note that the scroll display data storage RAM 150 may be used instead of the display data storage RAM 160. When using the scroll display data storage RAM 150 instead of the display data storage RAM 160, the multiplexer MUX1 selects data line DT2 and outputs the data received from data line DT2 to the scroll display data storage RAM 150 instead of data line DT3. This allows the scroll display data storage RAM 150 to operate in the same way as the display data storage RAM 160.

[0046] The multiplexer MUX2 selects either image data read from the RAM 150 for storing scroll display data or the RAM 160 for storing display data, according to the selection signal SEL2 output from the display control unit 140, and outputs the selected image data to the drive circuit 170.

[0047] The drive circuit 170 outputs a drive current to the LED light-emitting unit 180 to drive each LED in the LED light-emitting unit 180 according to the image data received via the multiplexer MUX2. The drive circuit 170 is an example of a drive unit that drives LEDs.

[0048] The LED light-emitting unit 180 lights up the LEDs with a brightness corresponding to the drive current for each LED output from the drive circuit 170. When the display control unit 140 is operating in scroll display mode, which scrolls the image displayed on the LED light-emitting unit 180, it writes new column data or new row data necessary for scrolling the image to one of the scroll display data storage RAMs 150. The display control unit 140 then repeatedly writes new data to one of the scroll display data storage RAMs 150 and reads out the data for one screen, including the new data, from the aforementioned one of the scroll display data storage RAMs 150 and outputs it to the drive circuit 170.

[0049] (Example of display control unit configuration) Figure 3 is a block diagram showing an example of the configuration of the display control unit 140 in Figure 2. The display control unit 140 has a scroll direction specification register SDR, a next scroll direction register NSD, an active scroll direction register PSD, a scroll waiting state register SWF, and a scroll execution register SPF. The display control unit 140 also has a read base address register BAS, a row offset amount register ROV, a column offset amount register COV, adders ADD1 and ADD2, an offset amount change control unit 141, a write address register WRA, and a multiplexer MUX3. In the following, the codes indicating various registers are also used as codes for the values ​​held in those registers.

[0050] The scroll direction specification register SDR stores information indicating the scroll direction received from the communication control unit 124 in Figure 2. Hereafter, the information indicating the scroll direction will also be simply referred to as the scroll direction. The scroll direction specification register SDR holds one of the four scroll directions: up, down, left, or right, and the setting can be changed even while controlling image scrolling. The information indicating the scroll direction is an example of direction information. The scroll direction specification register SDR is an example of a direction information holding unit that holds direction information indicating whether to sequentially update the images displayed in the pixel column or sequentially update the images displayed in the pixel row when scrolling an image.

[0051] The display control unit 140 determines the column receive buffer RBUF(V) or row receive buffer RBUF1(H) to write the received data to, based on the scroll direction information held in the scroll direction specification register SDR. If the number of pixels in the vertical direction of the LED light-emitting unit 180 differs from the number of pixels in the horizontal direction, the display control unit 140 may determine the column receive buffer RBUF(V) or row receive buffer RBUF1(H) to write the received data to, based on the data length information received from the communication control unit 124.

[0052] The display control unit 140 copies the scroll direction held in the scroll direction specification register SDR to the next scroll direction register NSD. This prevents a problem in which the image scroll direction immediately switches when a new scroll direction is stored in the scroll direction specification register SDR from the communication control unit 124.

[0053] The display control unit 140 copies the value of the next scroll direction register NSD to the currently running scroll direction register PSD. The currently running scroll direction register PSD outputs the held scroll direction to the offset amount change control unit 141. The display control unit 140 controls the scrolling of the image based on the scroll direction held in the currently running scroll direction register PSD. By pre-holding the next scroll direction in the next scroll direction register NSD, which is not overwritten by the communication control unit 124, the display control unit 140 can smoothly switch the scroll direction.

[0054] The scroll waiting state register SWF is set to a high level H, indicating the image is waiting to scroll, when it receives a display packet VSC-PK that causes the image displayed on the LED light-emitting unit 180 to scroll by column or row. Then, at the start of the display cycle cyc, which scrolls and displays one column or one row of data, the high level H of the scroll waiting state register SWF is copied to the scroll execution register SPF, and the scroll waiting state register SWF is reset to a low level L. The value held in the scroll execution register SPF is output to the offset amount change control unit 141. The display control unit 140 resets the scroll execution register SPF to "0" if the scroll waiting state register SWF is set to "0" before the start of the scroll display cycle cyc (Figure 10).

[0055] The read base address register BAS is sequentially set with addresses indicating the area of ​​the scroll display data storage RAM 150 for reading the grayscale data of each pixel. When the image is scrolled in the row direction, the row offset register ROV holds the offset amount, which is the amount of change in the row direction address for each scroll. Also, when the image is scrolled in the row direction, the column offset register COV holds the amount of change in the address caused by the column direction scrolling of the scroll display data storage RAM 150 that holds the data, and does not change during row direction scrolling.

[0056] When an image is scrolled in the column direction, the column offset register COV holds the offset amount, which is the change in the column-direction address for each scroll. Also, when an image is scrolled in the column direction, the row offset register ROV holds the change in address caused by row-direction scrolling in the scroll display data storage RAM 150, which holds the data, and does not change during column-direction scrolling.

[0057] At the start of each display cycle, if the high level "H" for scroll display is set to the scroll execution register SPF, the offset amount change control unit 141 increases or decreases the values ​​held in the row offset amount register ROV and the column offset amount register COV, respectively, according to the value of the scroll direction register PSD.

[0058] The offset amount change control unit 141 updates the read address RDA by the value held in the row offset amount register ROV each time a row of the image is scrolled, if the execution scroll direction register PSD indicates scrolling in the row direction (up or down).

[0059] The offset amount change control unit 141 updates the read address RDA by the value held in the column offset amount register COV each time the image column is scrolled, if the execution scroll direction register PSD indicates scrolling in the column direction (left or right).

[0060] The maximum increase or decrease in the row offset register ROV and the column offset register COV, respectively, depends on the row and column sizes of the LED matrix of the LED light-emitting unit 180.

[0061] When the image is scrolled in the row or column direction, the offset amount change control unit 141 adds the read base address BAS, the row offset amount ROV of the read address, and the column offset amount COV of the read address using adders ADD1 and ADD2 to generate a read address RDA to be output to the scroll display data storage RAM 150 from which the data is read. When the scroll display signal SCR is "1", the multiplexer MUX3 selects the read address RDA and outputs it as the address signal ADR.

[0062] The write address register WRA sequentially holds write addresses WRA that indicate the memory area of ​​the RAM 150 for storing scroll display data to which data is written. When the image is not scrolled, the write addresses WRA for writing the data used to display one screen of the LED light-emitting unit 180 are sequentially held in the write address register WRA corresponding to each LED.

[0063] The display control unit 140 sets the scroll display signal SCR to "1" when reading data from the scroll display data storage RAM 150, and sets the scroll display signal SCR to "0" when not reading data from the scroll display data storage RAM 150. When the scroll display signal SCR is "1", the multiplexer MUX3 selects the read address RDA generated by the offset amount change control unit 141 and outputs it as the address signal ADR. When the scroll display signal SCR is "0", the multiplexer MUX3 selects the write address WRA and outputs it as the address signal ADR. During the period when the scroll display signal SCR is "1", the display control unit 140 controls the scrolling of the image displayed on the LED light-emitting unit 180. During the period when the scroll display signal SCR is "0", the display control unit 140 stops controlling the scrolling of the image.

[0064] (Example of LED light-emitting section configuration) Figure 4 is an explanatory diagram showing an example of the configuration of the LED light-emitting unit 180 in Figure 2. The LED light-emitting unit 180 has a plurality of pixels PX arranged in a matrix. Each pixel PX has a red-emitting LED (R), a green-emitting LED (G), and a blue-emitting LED (B). The brightness of each LED (R), LED (G), and LED (B) can be set in 2 to the power of n ways based on n-bit gradation data. For example, if the gradation data for each RGB color is 8 bits (n=8), each of the red, green, and blue LEDs can emit light at 256 different brightness levels, and each pixel PX can display full color (16.77 million colors). The LED light-emitting unit 180 is an example of a light-emitting unit that displays an image, and the LEDs mounted on the LED light-emitting unit 180 are an example of light-emitting elements.

[0065] In Figure 4, the LED light-emitting unit 180 has 16 pixels PX in both the horizontal X direction and the vertical Y direction. However, the number of pixels in the horizontal X direction and the vertical Y direction only needs to be 2 or more. Also, the number of pixels in the horizontal X direction and the number of pixels in the vertical Y direction may differ from each other. In the following description, pixels PX arranged in a single column in the horizontal X direction will be referred to as a pixel row, and pixels PX arranged in a single column in the vertical Y direction will be referred to as a pixel column. A pixel row and a pixel column are examples of a group of light-emitting elements including LEDs arranged in one direction.

[0066] The drive circuit 170 in Figure 2 outputs a drive current to the LED light-emitting unit 180 to drive each LED based on the image data (grayscale value) for each pixel PX LED read from one of the scroll display data storage RAMs 150 or one of the display data storage RAMs 160, based on the control by the display control unit 140. For example, the drive circuit 170 displays one screen by performing a scan operation 16 times, sequentially lighting up 16 pixels PX arranged in the vertical direction Y, while switching the pixel rows. The drive circuit 170 drives the LED light-emitting unit 180 48 times in one scan operation, corresponding to 48 grayscale data (16 pixels × each RGB color).

[0067] Furthermore, the drive circuit 170 maintains the illumination state of the LED light-emitting unit 180 by repeatedly looping 16 scan operations based on the control of the display control unit 140. Note that in the scan operation of each pixel row, the pixels PX to be lit do not have to be in the order of arrangement of the pixels PX included in the pixel row. Also, the pixel rows to be sequentially lit do not have to be in the order of arrangement within the LED light-emitting unit 180. In the row-direction scan operation, the drive circuit 170 displays one screen by sequentially illuminating 16 pixels PX arranged in the horizontal direction X, similar to the column-direction scan operation, while switching pixel rows 16 times.

[0068] (Example of scrolling images left) Figure 5 is an explanatory diagram illustrating an example of left scrolling of the image displayed on the LED light-emitting unit 180 in the display unit 100 of Figure 2. In Figure 5, for the sake of clarity, it is assumed that the LED light-emitting unit 180 has 8 pixels PX in both the horizontal X direction and the vertical Y direction. The data used to display the image of each pixel row of the LED light-emitting unit 180 is denoted by codes A through J. In Figure 5, it is assumed that data is read from and written to one of the RAM 150 for storing scroll display data.

[0069] Furthermore, for the sake of clarity, the position of each pixel PX of the LED light-emitting unit 180 is shown below by column addresses 0 to 7 assigned to the horizontal direction X and row addresses 0 to 7 assigned to the vertical direction Y. The grayscale data for each LED of pixel PX is read from the storage area of ​​the scroll display data storage RAM 150, which is indicated by the read address RDA generated by the offset amount change control unit 141 corresponding to the combination of column address and row address.

[0070] First, the display control unit 140 uses the data line DT2 and the write address register WRA to sequentially write column data A to H, corresponding to eight pixel rows, to the scroll display data storage RAM 150 at column addresses 0 to 7. The data line DT2 is an example of a write path that allows writing of one screen's worth of data from the display control unit 140 to the scroll display data storage RAM 150 without going through the column receive buffers RBUF1(V) to RBUF3(V) and row receive buffers RBUF1(H) to RBUF3(H). The column data is an example of a data set that causes LEDs arranged in one direction to light up.

[0071] Next, the display control unit 140 repeatedly updates column addresses 0 to 7 for each display column 0 to 7, and outputs column data A to H for each LED, which are sequentially read from the RAM 150 for storing scroll display data, to the drive circuit 170. The display control unit 140 controls the drive circuit 170 to display images corresponding to column data A to H in each of the display columns 0 to 7 of the LED light-emitting unit 180. In the example shown in Figure 5, to make the scroll display easier to understand, the initial image displayed on the LED light-emitting unit 180 is a diagonal line going from the upper right to the lower left in Figure 5.

[0072] The drive circuit 170 drives display column 0 of the LED light-emitting unit 180 using the first column data (column data A for column 0) received from the scroll display data storage RAM 150. The drive circuit 170 drives display column 1 of the LED light-emitting unit 180 using the second column data (column data B for column 1) received from the scroll display data storage RAM 150. Then, the drive circuit 170 drives display column 7 of the LED light-emitting unit 180 using the eighth column data (column data H for column 7) received from the scroll display data storage RAM 150.

[0073] Next, a packet containing new column data I, which is necessary when scrolling the image to the left, is sent from the control board 30. The display control unit 140 sequentially stores the column data I received from the communication control unit 124 in the column receive buffers RBUF1(V), RBUF2(V), and RBUF3(V). The display control unit 140 writes the column data I held in the column receive buffer RBUF3(V) to the memory area at column address 0 of the scroll display data storage RAM 150. Before the column data I is written, the memory area at column address 0 of the scroll display data storage RAM 150 holds the oldest column data A, which will not be used for the next screen display due to the image scrolling to the left. In other words, during the first column scroll, the display control unit 140 overwrites the oldest column data A with the latest column data I.

[0074] Next, the display control unit 140 repeatedly updates row addresses 0 to 7 for each display column 1 to 7, outputting column data B to I for each LED sequentially read from the scroll display data storage RAM 150 to the drive circuit 170. The display control unit 140 controls the drive circuit 170 to display images corresponding to column data B to I in display columns 0 to 7 of the LED light-emitting unit 180. That is, images from the latest column data I to the oldest column data B stored in the scroll display data storage RAM 150 are displayed from display column 7 at one end of the LED light-emitting unit 180 to display column 0 at the other end.

[0075] As a result, the LED light-emitting unit 180 displays an image that has been scrolled to the left by one column. When the display control unit 140 displays new column data I for scrolling on the LED light-emitting unit 180, it shifts the column address from which it reads the column data from the scroll display data storage RAM 150 by one, as shown by the thick dashed arrow in Figure 5.

[0076] Even when displaying new column data I on the LED light-emitting unit 180, the drive circuit 170 uses the first column data (column data B for column 1) received from the scroll display data storage RAM 150 to drive display column 0 of the LED light-emitting unit 180. The drive circuit 170 uses the second column data (column data C for column 2) received from the scroll display data storage RAM 150 to drive display column 1 of the LED light-emitting unit 180. Then, the drive circuit 170 uses the eighth column data (column data I for column 0) received from the scroll display data storage RAM 150 to drive display column 7 of the LED light-emitting unit 180.

[0077] Next, a packet containing new column data J is transmitted from the control board 30. The display control unit 140 writes the column data J received from the communication control unit 124 to the memory area at column address 1 of the scroll display data storage RAM 150. Before the column data J is written, the memory area at column address 1 of the scroll display data storage RAM 150 holds the oldest column data B that will not be used for the next screen display due to the left scrolling of the image. In other words, in the second column scroll, the display control unit 140 overwrites the oldest column data B at that time with the latest column data J.

[0078] Next, the display control unit 140 repeatedly updates row addresses 0 to 7 for each display column 2 to 7, 0 to 1, and outputs column data C to J for each LED, which is sequentially read from the RAM 150 for storing scroll display data, to the drive circuit 170. Column addresses 2 to 7, 0 to 1 are read addresses obtained by sequentially shifting the column addresses 1 to 7, 0 from the previous column scroll. The display control unit 140 controls the drive circuit 170 to display images corresponding to column data C to J in display columns 0 to 7 of the LED light-emitting unit 180. In other words, the LED light-emitting unit 180 displays an image that has been scrolled one column further to the left.

[0079] Even when displaying new column data J on the LED light-emitting unit 180, the drive circuit 170 uses the first column data (column data C for column 2) received from the scroll display data storage RAM 150 to drive display column 0 of the LED light-emitting unit 180. The drive circuit 170 uses the second column data (column data D for column 3) received from the scroll display data storage RAM 150 to drive display column 1 of the LED light-emitting unit 180. Then, the drive circuit 170 uses the eighth column data (column data J for column 1) received from the scroll display data storage RAM 150 to drive display column 7 of the LED light-emitting unit 180. As shown by the thick dashed arrows in Figure 5, the drive circuit 170 shifts the display columns of the LEDs being driven one by one using the column data transferred from the scroll display data storage RAM 150.

[0080] (Example of scrolling images upwards) Figure 6 is an explanatory diagram illustrating an example of scrolling an image displayed on the LED light-emitting unit 180 in the display unit 100 of Figure 2 upwards. Detailed explanations of operations similar to those in Figure 5 are omitted. In Figure 6, for the sake of clarity, it is assumed that the LED light-emitting unit 180 has 8 pixels PX in both the horizontal X direction and the vertical Y direction. Also in Figure 6, it is assumed that data is read from and written to one of the RAM 150 for storing scroll display data.

[0081] First, the display control unit 140 uses the data line DT2 and the write address register WRA to sequentially write row data A to H, corresponding to eight pixel rows, to the scroll display data storage RAM 150 at row addresses 0 to 7. The row data is an example of a data set that causes LEDs arranged in one direction to light up.

[0082] Next, the display control unit 140 repeatedly updates row addresses 0 to 7 for each display row 0 to 7, and outputs row data A to H for each LED, which are sequentially read from the scroll display data storage RAM 150, to the drive circuit 170. The display control unit 140 controls the drive circuit 170 to display images corresponding to row data A to H on the LED light-emitting unit 180 for each of the display rows 0 to 7. In the example shown in Figure 6, as in Figure 5, the initial image displayed on the LED light-emitting unit 180 is a diagonal line that goes from the upper right to the lower left in Figure 6, in order to make the scroll display easier to understand.

[0083] The drive circuit 170 drives display row 0 of the LED light-emitting unit 180 using the first row data (row data A for row 0) received from the scroll display data storage RAM 150. The drive circuit 170 drives display row 1 of the LED light-emitting unit 180 using the second row data (row data B for row 1) received from the scroll display data storage RAM 150. Then, the drive circuit 170 drives display row 7 of the LED light-emitting unit 180 using the eighth row data (row data H for row 7) received from the scroll display data storage RAM 150.

[0084] Next, a packet containing new line data I, which is necessary when scrolling the image upwards, is transmitted from the control board 30. The display control unit 140 sequentially stores the line data I received from the communication control unit 124 in the line receive buffers RBUF1(H), RBUF2(H), and RBUF3(H). The display control unit 140 writes the line data I held in the line receive buffer RBUF3(H) to the memory area at line address 0 of the scroll display data storage RAM 150. Before the line data I is written, the memory area at line address 0 holds the oldest line data A, which will not be used for the next screen display due to scrolling the image upwards. That is, in the first line scroll, the display control unit 140 overwrites the oldest line data A with the latest line data I.

[0085] Next, the display control unit 140 repeatedly updates column addresses 0 to 7 for every 0 display rows 1 to 7, and outputs row data B to I for each LED, which is sequentially read from the scroll display data storage RAM 150, to the drive circuit 170. The display control unit 140 controls the drive circuit 170 to display the images corresponding to row data B to I on display rows 0 to 7 of the LED light-emitting unit 180. That is, the images from the latest row data I to the oldest column data B stored in the scroll display data storage RAM 150 are displayed on the LED light-emitting unit 180 from display row 7 on one end to display row 0 on the other end. As a result, the LED light-emitting unit 180 displays an image that has been scrolled up by one row.

[0086] Even when displaying new row data I on the LED light-emitting unit 180, the drive circuit 170 uses the first row data (column data B for row 1) received from the scroll display data storage RAM 150 to drive display row 0 of the LED light-emitting unit 180. The drive circuit 170 uses the second row data (row data C for row 2) received from the scroll display data storage RAM 150 to drive display row 1 of the LED light-emitting unit 180. Then, the drive circuit 170 uses the eighth row data (row data I for row 0) received from the scroll display data storage RAM 150 to drive display row 7 of the LED light-emitting unit 180.

[0087] Next, a packet containing new line data J is transmitted from the control board 30. The display control unit 140 writes the line data J received from the communication control unit 124 to the memory area at line address 1 of the scroll display data storage RAM 150. Before the line data J is written, the memory area at line address 1 of the scroll display data storage RAM 150 holds the oldest line data B that will not be used for the next screen display due to the image scrolling upwards. In other words, in the second line scroll, the display control unit 140 overwrites the oldest line data B at that time with the latest line data J.

[0088] Next, the display control unit 140 repeatedly updates column addresses 0 to 7 for each display row 2 to 7, 0 to 1, and outputs row data C to J for each LED, which is sequentially read from the RAM 150 for storing scroll display data, to the drive circuit 170. Row addresses 2 to 7, 0 to 1 are read addresses obtained by sequentially shifting row addresses 1 to 7, 0 from the previous row scroll. The display control unit 140 controls the drive circuit 170 to display images corresponding to row data C to J in each of the display rows 0 to 7 of the LED light-emitting unit 180. In other words, the LED light-emitting unit 180 displays an image that has been scrolled up by another row.

[0089] Even when displaying new row data J on the LED light-emitting unit 180, the drive circuit 170 uses the first row data (row data C for row 2) received from the scroll display data storage RAM 150 to drive display row 0 of the LED light-emitting unit 180. The drive circuit 170 uses the second row data (row data D for row 3) received from the scroll display data storage RAM 150 to drive display row 1 of the LED light-emitting unit 180. Then, the drive circuit 170 uses the eighth row data (row data J for row 1) received from the scroll display data storage RAM 150 to drive display row 7 of the LED light-emitting unit 180. As shown by the thick dashed arrows in Figure 6, the drive circuit 170 shifts the display rows of the LEDs driven by the row data transferred from the scroll display data storage RAM 150 one by one.

[0090] In this embodiment, as shown in Figure 5, the column number of the LED light-emitting unit 180 is rotated by one each time the scroll display data is stored in the RAM 150, thereby shifting the column number of the LED light-emitting unit 180 to which data is written. Similarly, as shown in Figure 6, the row number of the LED light-emitting unit 180 is rotated by one each time the scroll display data is stored in the RAM 150, thereby shifting the row number of the LED light-emitting unit 180 to which data is written. As a result, the image can be scrolled by simply rewriting one column or one row of data from the data for one screen held in the RAM 150. In other words, the image can be scrolled without writing the data for one screen to the RAM 150. As a result, the reading and writing of data to the RAM 150 when scrolling the image displayed on the LED light-emitting unit 180 can be simplified, and the image scrolling control can be simplified.

[0091] Furthermore, compared to the case where data for one screen is written to the RAM 150 for storing scroll display data each time the image is scrolled, the size of the scroll display data transmitted from the control board 30 to the multiple display units 100 can be reduced. As a result, the transfer time of the scroll display data to the last display unit 100 among the multiple display units 100 that are sequentially connected via the serial interface SIF can be shortened.

[0092] For example, as shown in equation (1), when the product of the transfer time (ms) of column data or row data per display unit 100 and the number of connected display units 100 within the display panel 20 is shorter than the scroll time (ms) for one column or one row, the image can be scrolled normally all the way to the last display unit 100. Transfer time for column or row data per display unit 100 (ms) × Number of connected display units 100 < Scroll time for one column or one row (ms) ... (1)

[0093] In this embodiment, the transfer time (ms) for column or row data per display unit 100 can be reduced, thereby increasing the number of display units 100 that can be connected and scrolled normally. Furthermore, since the display units 100 are connected via a serial interface SIF, the number of signal lines between display units can be reduced compared to when they are connected via a parallel interface. This reduces the cost of communication cables and other related components, and also reduces unwanted radiation.

[0094] (Example of receiving data for one screen and scrolling through the image) Figures 7 and 8 are timing diagrams showing an example of image scrolling display on the LED light-emitting section 180 without using the column receive buffers RBUF1(V) to RBUF3(V) and row receive buffers RBUF1(H) to RBUF3(H) in the display device 10 of Figure 1. Figures 7 and 8 show an example in which each display unit 100 performs image scrolling display when two display units 100 are connected in series to the control board 30 via the serial interface SIF. Figure 7 shows the period during which image scrolling display does not occur, and Figure 8 shows the period during which image scrolling display occurs.

[0095] First, in the initial state when the power supply of the display device 10 is turned on, the display control unit 140 of each display unit 100 operates in normal display mode and does not operate in scroll display mode. The control board 30 outputs an ID assignment packet ID-PK to the serial interface SIF, which assigns an individual ID to each display unit 100. The ID assignment packet ID-PK assigns ID#1 and ID#2 to the two display units 100, respectively. For example, the assigned ID#1 and ID#2 are stored in the ID register provided in the communication control unit 124 of each display unit 100. Although not particularly limited, the IDs of the display units 100 may be assigned in increments in order of proximity to the control board 30. ID#1 and ID#2 are examples of unit identification information that identifies the display unit 100, and the ID register is an example of an identification information holding unit. Note that when the power supply is turned on, no groups are set for any of the display units 100.

[0096] Furthermore, when the communication unit 110 receives various packets from one serial interface SIF, it transmits the received packets to the other serial interface SIF. This allows packets transmitted from the control board 30 to be sequentially forwarded to the terminal display units 100. In addition, packets generated by any of the display units 100 can be forwarded to the control board 30 via other display units 100.

[0097] Next, the control board 30 sequentially outputs a data writing packet DT-PK(ID#1) to the serial interface SIF, which causes the display unit 100 with ID#1 to display one screen's worth of image, and a data writing packet DT-PK(ID#2) to cause the display unit 100 with ID#2 to display an image.

[0098] The header portion of the data write packet DT-PK includes the ID (or group ID) of the controllable display unit 100, write information instructing the write operation, and the identification number of the RAM to which the data will be written. The payload portion of the data write packet DT-PK includes the image data for one screen to be displayed on the LED light-emitting unit 180 (gradation data for each RGB for all LEDs). The data contained in data write packets DT-PK(ID#1) and DT-PK(ID#2) may be the same or different. A data write packet DT-PK that displays one screen's worth of image is an example of a data write command.

[0099] When the communication control unit 124 of each display unit 100 receives a data write packet DT-PK, it compares the ID contained in the header with the ID held in the ID register. If the IDs match, the communication control unit 124 determines that the data write packet DT-PK is the target packet for its own display unit 100. The communication control unit 124 then transfers the write information and RAM identification information contained in the header, along with the image data contained in the payload, to the display control unit 140. In this example, the RAM identification information indicates the RAM 150 for storing scroll display data.

[0100] The display control unit 140, having received the information contained in the data writing packet DT-PK and the data for one screen, writes the received data DTa(ID#1) and DTa(ID#2) to the two scroll display data storage RAMs 150 via the data line DT2. DTa(ID#1) and DTa(ID#2) shown in the waveform of the scroll display data storage RAM 150 indicate the data writing period to each scroll display data storage RAM 150. The dashed line A shown on the right end of Figure 7 indicates the same timing as the dashed line A shown on the left end of Figure 8.

[0101] By writing image data for one screen to the scroll display data storage RAM 150 via the data line DT2, the control of the display control unit 140 can be simplified compared to the case where image data is written to the scroll display data storage RAM 150 via column receive buffers RBUF1(V), RBUF2(V), and RBUF3(V). In addition, the initial screen at the start of scrolling can be freely set.

[0102] When multiple display units 100 are grouped together, the control board 30 outputs a group ID assignment packet to the serial interface SIF. This assigns a common group ID to the multiple display units 100. For example, the assigned group ID is stored in the group ID register of the communication control unit 124 of each display unit 100. The group ID is an example of group identification information, and the group ID register that holds the group ID is an example of a group identification information holding unit.

[0103] The group ID register has multiple bits, each bit representing one group. For example, suppose the group ID register is 8 bits. For instance, when a group ID assignment packet is used, the group ID registers of display unit 100 for ID#1 and display unit 100 for ID#2 are set to "00000001b" (only the least significant bit being "1"), thereby assigning group ID=1 to both and setting them as a single group.

[0104] The communication control unit 124 of the display units 100 for ID#1 and ID#2 detects a match with the group ID held in the group ID register when the least significant bit of the group ID contained in the packet received via the serial interface SIF is "1". Therefore, the communication control unit 124 of the display units 100 for ID#1 and ID#2 determines that the received packet is a target packet for its own display unit 100. The communication control unit 124 then outputs the information (including data) contained in the received packet to the display control unit 140 and forwards the received packet to the next display unit 100. As a result, the same image is displayed on the LED light-emitting units 180 of the display units 100 of the same group. For example, a packet containing a group ID is a data write packet DT-PK or a display packet VSC-PK, etc., as described later.

[0105] If the least significant bit of the group ID contained in the data write packet DT-PK or display packet VSC-PK received via the serial interface SIF is "0", the communication control unit 124 determines that the received packet is not a target packet for the display unit 100 because it does not match the group ID held in the group ID register. In this case, the communication control unit 124 does not output the information (including data) contained in the received packet to the display control unit 140. The communication control unit 124 also outputs the packet containing the received group ID to the serial interface SIF on the opposite side of the receiving side.

[0106] For example, suppose the group ID packet GID-PK sets the group ID register of the display unit 100 for ID#3 and ID#4 to "00000010b" (only the second bit from the least significant bit being "1"). In this case, the communication control unit 124 of the display unit 100 for ID#3 and ID#4 determines that the received packet is a target packet for its own display unit 100 if the second bit of the group ID contained in the received data write packet DT-PK or display packet VSC-PK is "1".

[0107] Furthermore, if the first and second bits of the group ID included in the packet are "1", the display units 100 of ID#1, ID#2, ID#3, and ID#4 determine that the received data write packet DT-PK or display packet VSC-PK is the target packet for their own display unit 100. In this way, the number of display units 100 included in a group can be changed according to which bits of the 8 bits of the group ID included in the data write packet DT-PK or display packet VSC-PK are set to "1".

[0108] In Figure 8, the control board 30 outputs a display packet VSC-PK to the serial interface SIF, which causes the LED light-emitting unit 180 to display an image. For example, the display packet VSC-PK includes a group ID, illumination information indicating that the LED light-emitting unit 180 is lit, and a RAM identification number indicating the RAM 150 for storing scroll display data. The display packet VSC-PK is an example of a screen display command.

[0109] The communication control unit 124 of the display units 100, ID#1 and ID#2, which have sequentially received the display packets VSC-PK, compares the group ID (GR#1) contained in the display packets VSC-PK with the group ID held in the group register. If the group IDs match, the communication control unit 124 determines that the display packet VSC-PK is a target packet for its own display unit 100. The communication control unit 124 then transfers the illumination information contained in the header and the identification information in the RAM to the display control unit 140.

[0110] Each display control unit 140 belonging to the group determines that the information received from the communication control unit 124 includes lighting information, and therefore decides to read the corresponding scroll display data storage RAM 150. Based on the information received from the communication control unit 124, the display control unit 140 reads and accesses the corresponding scroll display data storage RAM 150. The display control unit 140 then outputs the display data DTa(ID#1) or DTa(ID#2) held in the corresponding scroll display data storage RAM 150 to the drive circuit 170, causing the LED light-emitting unit 180 to display an image.

[0111] Here, the display packet VSC-PK contains a group ID (GR#1) that matches the group IDs of the display units 100 with ID#1 and ID#2. Therefore, it operates almost in parallel with the display units 100 with ID#1 and ID#2, and lights up the LED light-emitting unit 180. Each display control unit 140 repeatedly reads data from the corresponding scroll display data storage RAM 150 and outputs it to the drive circuit 170. As a result, the LED light-emitting unit 180 continues to display the image over multiple display cycles (cyc).

[0112] By using a display packet VSC-PK that includes a group ID, a single display packet VSC-PK can display an image on the LED light-emitting sections 180 of multiple display units 100 belonging to the same group. This reduces the number of display packets VSC-PK transmitted by the control board 30, allowing for efficient use of the serial interface SIF.

[0113] Next, the control board 30 sequentially outputs a data writing packet DT-PK(ID#1) to the serial interface SIF, which will display an image on the display unit 100 with ID#1, and a data writing packet DT-PK(ID#2) to display an image on the display unit 100 with ID#2. For example, the data contained in each of the data writing packets DT-PK(ID#1) and DT-PK(ID#2) is the data for one screen to scroll and display an image on the LED light-emitting unit 180.

[0114] The display control unit 140, upon receiving the information and data contained in the data writing packet DT-PK, writes the received data DTb(ID#1) or DTb(ID#2) for one screen to the scroll display data storage RAM 150, which does not have data DTa(ID#1) or DTa(ID#2) written to it, via the data line DT2.

[0115] Subsequently, the control board 30 outputs a display packet VSC-PK to the serial interface SIF, which displays an image on the LED light-emitting unit 180. The communication control unit 124, because the group ID contained in the display packet VSC-PK indicates its own display unit 100, transfers the lighting information contained in the header and the identification information in RAM to the display control unit 140. Here, the reception period of the display packet VSC-PK indicates the image scrolling period.

[0116] Each display control unit 140 belonging to the group switches the scroll display data storage RAM 150 to which it reads and accesses the data DTb(ID#1) or DTb(ID#2) at the timing when the display cycle switches. Then, each display control unit 140 reads the display data DTb(ID#1) or DTb(ID#2) from the corresponding scroll display data storage RAM 150 and outputs it to the drive circuit 170, causing the LED light-emitting unit 180 to display the next image. As a result, even when the display unit 100 receives the display packet VSC-PK asynchronously with the display cycle cyc, it can switch the display of images in synchronization with the display cycle cyc.

[0117] Thereafter, each display control unit 140 belonging to the group continues to display the image already displayed on the LED light-emitting unit 180 using data DTb until the communication control unit 124 receives the next display packet VSC-PK. Furthermore, when the communication control unit 124 receives the next data write packet DT-PK and the next display packet VSC-PK from the control board 30, each display control unit 140 performs the operation to display the next image on the LED light-emitting unit 180.

[0118] (Example of receiving one column of data and scrolling through an image) Figures 9 and 10 are timing diagrams showing an example of scrolling an image displayed on the LED light-emitting unit 180 using the column receive buffers RBUF1(V)-RBUF3(V) in the display device 10 of Figure 1. Detailed explanations of operations similar to those in Figures 7 and 8 are omitted. Figures 9 and 10 show an example in which two display units 100 connected in series to the control board 30 via the serial interface SIF perform image scrolling. In Figures 9 and 10, the display units 100 are not grouped. Figure 9 shows the period during which image scrolling is not performed, and Figure 10 shows the period during which image scrolling is performed.

[0119] After the power of the display device 10 is turned on, the operation from the communication control unit 124 of the display unit 100 receiving the ID assignment packet ID-PK output by the control board 30 and storing ID#1 in the ID register is the same as in Figure 7. The control board 30 also outputs an ID assignment packet ID-PK for ID#2 (not shown) to the serial interface SIF.

[0120] Next, the control board 30 outputs a scroll direction specification packet SDR-PK (ID#1) containing information indicating left scrolling of the image to the serial interface SIF. The communication control unit 124 for ID#1 determines that the scroll direction specification packet SDR-PK is a target packet for the display unit 100 because ID#1 is included in the scroll direction specification packet SDR-PK. The communication control unit 124 then forwards the information indicating left scrolling (hereinafter referred to as left scrolling) contained in the header to the display control unit 140.

[0121] The display control unit 140 with ID#1 stores the left scroll information received from the communication control unit 124 in the scroll direction specification register SDR. For example, the value "00b" set in the scroll direction specification register SDR indicates left scroll (i.e., column scroll). When the display control unit 140 receives information indicating row scroll from the communication control unit 124, it stores the information indicating row scroll (up scroll or down scroll) in the scroll direction specification register SDR. By storing the scroll direction included in the scroll direction specification packet SDR-PK (ID#1) in the scroll direction specification register SDR, the display control unit 140 can scroll the image in the column direction or row direction, as shown in Figure 5 or Figure 6. Furthermore, by including the group ID in the scroll direction specification packet SDR-PK, the scroll direction of multiple display units 100 can be set at once.

[0122] Next, the control board 30 sequentially outputs data write packets DT-PK(ID#1) and DT-PK(ID#2) to the serial interface SIF. When the communication control unit 124 of ID#1 receives the data write packet DT-PK(ID#1), it forwards the write information contained in the header, the identification information of the scroll display data storage RAM 150 that reads and writes the data, and the data for one screen contained in the payload to the display control unit 140. The operation of the display unit 100 of ID#2 when it receives the data write packet DT-PK(ID#2) is the same as the operation of the display unit 100 of ID#1 when it receives the data write packet DT-PK(ID#1).

[0123] The display control unit 140, which has received the information contained in the data write packet DT-PK (ID#1) and the data for one screen, sets the scroll display signal SCR in Figure 3 to "0" because it is not controlling the scroll display. Based on the scroll display signal SCR of "0", the multiplexer MUX3 selects the write address WRA held in the write address register WRA and outputs it as the address signal ADR. Also, the display control unit 140, which has received the information and data of the data write packet DT-PK (ID#1) that writes the data for one screen to one of the RAM 150 for storing scroll display data, outputs a selection signal SEL1 to the multiplexer MUX1 to select the data line DT2.

[0124] The display control unit 140 sets the write enable signal WE, which is output to the scroll display data storage RAM 150 where data is written, to a high level and generates a pulse for the clock enable signal CE. The display control unit 140 also sequentially generates the write address WRA, which is output to the scroll display data storage RAM 150 where data is written, and outputs it as the address signal ADR. Then, the display control unit 140 writes the data DTa(ID#1) that it receives sequentially from the communication control unit 124 to the scroll display data storage RAM 150 via the data line DT2, synchronized with the pulse for the clock enable signal CE. DTa(ID#1) shown in the waveform of the scroll display data storage RAM 150 indicates the writing period to the scroll display data storage RAM 150 where data for one screen is written.

[0125] The next scroll direction register NSD, the current scroll direction register PSD, the scroll waiting state register SWF, and the scroll execution register SPF are set to an undefined value XXb or a low level L, for example, when the power is started. The display control unit 140 does not use the column receive buffers RBUF1(V), RBUF2(V), and RBUF3(V), so it sets the control signals CNT2 and CNT3 to a low level L. The dashed line A shown on the far right of Figure 9 indicates the same timing as the dashed line A shown on the far left of Figure 10.

[0126] In Figure 10, the control board 30 outputs a display packet VSC-PK (ID#1) containing the identification number of the RAM 150 for storing scroll display data, which reads the lighting information and data, to the serial interface SIF. The communication control unit 124 of the display unit 100 with ID#1, which receives the display packet VSC-PK (ID#1), determines that the display packet VSC-PK (ID#1) is a target packet for its own display unit 100, and forwards the various information contained in the header to the display control unit 140.

[0127] The display control unit 140 for ID#1 stores the value "00b", which indicates left scrolling and is held in the scroll direction specification register SDR, into the next scroll direction register NSD, based on the information received from the communication control unit 124. The display control unit 140 for ID#1 also sequentially reads one screen's worth of data from the RAM 150 for storing scroll display data to be read, based on the information received from the communication control unit 124, and outputs it to the drive circuit 170, causing the LED light-emitting unit 180 to display an image. The display control unit 140 maintains the display of the image on the LED light-emitting unit 180 by repeatedly outputting the one screen's worth of data stored in the RAM 150 for storing scroll display data to be read to the drive circuit 170 for each display cycle cyc, until it receives the next display packet VSC-PK (ID#1).

[0128] Next, the control board 30 outputs a column data write packet VDT-PK (ID#1) to the serial interface SIF, which contains the identification number of the scroll display data storage RAM 150 and data for one column, in order to scroll the image displayed on the LED light-emitting unit 180 of ID#1. The column data write packet VDT-PK is an example of a scroll command containing the latest data set used for scrolling the image.

[0129] Upon receiving the column data write packet VDT-PK (ID#1), the communication control unit 124 of ID#1 forwards the various information contained in the header and the data for one column to the display control unit 140. The display control unit 140 stores the received data for one column, VDTnew (ID#1), in the column receive buffer RBUF1 (V) for column scrolling.

[0130] When the scroll direction specification packet SDR-PK(ID#1) in Figure 9 indicates line scrolling, the display control unit 140 receives a line data write packet HDT-PK(ID#1) containing one line of data HDTb(ID#1) (not shown) from the communication control unit 124. The display control unit 140 then stores the received one line of data HDTb(ID#1) in a line receive buffer RBUF1(H) for line scrolling (not shown).

[0131] Furthermore, the control board 30 outputs a column data write packet VDT-PK(ID#2) to the serial interface SIF, which includes ID#2, the identification number of the RAM 150 for storing scroll display data to which the scrolling data is written, the scrolling direction, and the data for one column, in order to scroll the image displayed on the LED light-emitting unit 180 of ID#2. The display unit 100 of ID#2 that receives the column data write packet VDT-PK(ID#2) operates in the same way as the display unit 100 of ID#1 that receives the column data write packet VDT-PK(ID#1).

[0132] Next, the control board 30 outputs a display packet VSC-PK (ID#1) to the serial interface SIF, which scrolls the image displayed on the LED light-emitting unit 180. The communication control unit 124 for ID#1 forwards the various information contained in the header to the display control unit 140 because the display packet VSC-PK (ID#1) is the target packet for its own display unit 100. The display packet VSC-PK is an example of a screen display command received after receiving the column data write packet VDT-PK (ID#1). Although not shown in the diagram, the reception period of the display packet VSC-PK indicates the image scrolling period.

[0133] The display control unit 140 for ID#1 stores "00b", which indicates left scrolling and is held in the scroll direction specification register SDR, into the next scroll direction register NSD, based on the information received from the communication control unit 124. The display control unit 140 for ID#1 also sets the scroll waiting state register SWF to high level H, putting the display control unit 140 into a scroll waiting state. The display control unit 140 for ID#1 generates a pulsed control signal CNT2 and saves the data VDTnew(ID#1) for one column held in the column receive buffer RBUF1(V) to the column receive buffer RBUF2(V).

[0134] Next, the display control unit 140 of ID#1 transfers the high level H of the scroll waiting state register SWF to the scroll execution register SPF after the execution of the display cycle cyc has finished. After transferring the high level H of the scroll waiting state register SWF to the scroll execution register SPF, the display control unit 140 resets the scroll waiting state register SWF to a low level L. Also, the display control unit 140 of ID#1 stores the scroll direction "00b" held in the next scroll direction register NSD into the execution scroll direction register PSD.

[0135] Based on the fact that the scroll execution register SPF has been set to a high level H, the display control unit 140 of ID#1 generates a pulsed control signal CNT3 and copies the data VDTnew(ID#1) for one column held in the column receive buffer RBUF2(V) to the column receive buffer RBUF3(V).

[0136] This prevents the data VDTnew (ID#1) from being overwritten before the data update in the RAM 150 used for storing scroll display data is completed. In this embodiment, one display cycle (1 cyc) is required to update one column of data for one screen held in the RAM 150 used for storing scroll display data. If the occurrence period of the command VSC is guaranteed to be longer than two display cycles (2 cyc), the column receive buffer RBUF3(V) and row receive buffer RBUF3(H) do not need to be provided. Furthermore, if the occurrence period of the column data write packet VDT-PK is longer than two display cycles (2 cyc), the column receive buffer RBUF2(V) and row receive buffer RBUF2(H) do not need to be provided, and one buffer between the display control unit 140 and MUX1 is sufficient. The scroll execution register SPF is reset to "0" after the rewriting of one column of data in the RAM 150 used for storing scroll display data is completed.

[0137] The offset amount change control unit 141 increases or decreases the row offset amount ROV and the column offset amount COV when the scroll execution register SPF is "1". The display unit 100 shown in Figure 2 has a receive buffer valid flag RBV (not shown) corresponding to the column receive buffers RBUF1(V) to RBUF3(V) and the row receive buffers RBUF1(H) to RBUF3(H), respectively. The display control unit 140 stores information in the receive buffer valid flag RBV indicating whether the data held in the corresponding column receive buffers RBUF1(V) to RBUF3(V) or row receive buffers RBUF1(H) to RBUF3(H) is valid or not.

[0138] Furthermore, the display unit 100 has buffer control registers BCNTR (not shown) corresponding to the column receive buffer RBUF3(V) and the row receive buffer RBUF3(H), respectively. The display control unit 140 stores information in the buffer control register BCNTR that, when a display packet VSC-PK is received while invalid data is held in the corresponding column receive buffer RBUF3(V) or row receive buffer RBUF3(H), allows the unit to choose whether to maintain the already held data without overwriting the invalid data held in the column receive buffer RBUF3(V) or row receive buffer RBUF3(H) in the corresponding scroll display data storage RAM 150, or to overwrite the corresponding scroll display data storage RAM 150 with the data for turning off one column or one row.

[0139] For example, if the buffer control register BCNTR corresponding to the column receive buffer RBUF3(V) holds information indicating the overwriting of unlit data, and the column receive buffer RBUF3(V) does not hold any valid new data for one column, and a display packet VSC-PK is received, then one column of unlit data will be displayed on the LED light-emitting unit 180. This prevents invalid data held in the column receive buffer RBUF3(V) from being displayed on the LED light-emitting unit 180, thus preventing a decrease in display quality.

[0140] Furthermore, for example, if the buffer control register BCNTR corresponding to the column receive buffer RBUF3(V) holds information to maintain the retention state of old data, and the display packet VSC-PK is repeatedly received, the image can be cycled and displayed on the display unit 100 that is the target of the display packet VSC-PK.

[0141] For example, when new data VDTnew with a valid data length is written to column receive buffer RBUF1(V), the receive buffer valid flag RBV1 corresponding to column receive buffer RBUF1(V) becomes valid. When new data VDTnew is transferred from column receive buffer RBUF1(V) to column receive buffer RBUF2(V), the value of the receive buffer valid flag RBV1 is copied to the receive buffer valid flag RBV2 corresponding to column receive buffer RBUF2(V), and the receive buffer valid flag RBV1 becomes invalid.

[0142] When new data VDTnew is transferred from column receive buffer RBUF2(V) to column receive buffer RBUF3(column), the value of the receive buffer valid flag RBV2 is copied to the receive buffer valid flag RBV3 corresponding to column receive buffer RBUF3(V), and the receive buffer valid flag RBV2 becomes invalid. Furthermore, when new data VDTnew is transferred from column receive buffer RBUF3(V) to the scroll display data storage RAM150 and the display cycle ends, the receive buffer valid flag RBV3 becomes invalid.

[0143] The display control unit 140 for ID#1 sets the selection signal SEL1 to "01b" for a predetermined period, causing the multiplexer MUX1 to select the output of the column receive buffer RBUF3(V). As a result, one column's worth of data VDTnew(ID#1) is sequentially output from the column receive buffer RBUF3(V). During the period when the selection signal SEL1 is set to "01b", the display control unit 140 for ID#1 temporarily sets the corresponding write enable signal WE to a high level and writes one column's worth of data VDTnew(ID#1) to the scroll display data storage RAM 150, which is the target of the writing, in synchronization with the pulse of the corresponding clock enable signal CE.

[0144] The memory area of ​​the scroll display data storage RAM 150, where one column of data VDTnew (ID#1) is written, is allocated to correspond to multiple LEDs arranged in the column direction (Y direction) of the LED light-emitting unit 180.

[0145] As a result, the oldest column of data in the RAM 150 for storing scroll display data that is to be written to is overwritten with the latest column of data VDTnew(ID#1). For example, in Figure 5, data A is overwritten with data I. The diagonal lines shown in Figure 10 for the RAM 150 for storing scroll display data indicate that the oldest column of data is overwritten with the data VDTnew(ID#1) for one column, and after scrolling one column, the data for the corresponding screen is retained. Then, the new image, after scrolling one column, is displayed on the LED light-emitting unit 180 from the display cycle cyc8 onwards. A timing diagram of a part of the area shown by the dashed frame in Figure 10 is shown in Figure 11.

[0146] Figure 11 is a timing diagram showing the operation of a portion of the area indicated by the dashed frame in Figure 10. In Figure 11, the code RD indicates the timing of reading data from the scroll display data storage RAM 150, and the code WR indicates the timing of writing new row or column display data to the scroll display data storage RAM 150. In Figure 11, the RAM data reading timing, it is assumed that in the scroll display data storage RAM 150 to be written, the oldest column data held in the memory area of ​​address signal ADR=ADR1 is overwritten with new column data VDTnew for scrolling. For the sake of clarity, in Figure 11, it is assumed that one column of data is written to the scroll display data storage RAM 150 to be written, or one column of data is read from the scroll display data storage RAM 150 to be read, in synchronization with the pulse of the clock enable signal CE which is synchronized with the clock signal CLK.

[0147] The display control unit 140 generates low-level write enable signal WE and clock enable signal CE pulses for operations on columns where data is not rewritten. The display control unit 140 then reads the column data (VDT0, VDT2, etc.) held in the memory area indicated by the address signal ADR in the RAM 150 for storing scroll display data to be read, and outputs it to the drive circuit 170.

[0148] When rewriting data for one column, the display control unit 140 generates high-level write enable signal WE and clock enable signal CE pulses corresponding to the scroll display data storage RAM 150 to be written, and then generates low-level write enable signal WE and clock enable signal CE pulses. The selection signal SEL1 is set to "01b" to cause the multiplexer MUX1 to select the output of the column receive buffer RBUF3(V) during the period when data for one column is being rewritten.

[0149] As a result, the display control unit 140 can, during a memory access cycle in which it sets address ADR1, which reads the oldest column data from the scroll display data storage RAM 150, to the scroll display data storage RAM 150, overwrite the storage area of ​​the scroll display data storage RAM 150 that stores the oldest column data with the new column data VDTnew, and read the column data VDTnew that was overwritten in the storage area from the scroll display data storage RAM 150. In other words, the display control unit 140 can perform a write cycle in the background of a read cycle, and can rewrite the oldest column data held in the scroll display data storage RAM 150 with the new column data VDTnew without adding an additional write cycle. After this, the display control unit 140 reads the new column data VDTnew written to the scroll display data storage RAM 150 and outputs it to the drive circuit 170.

[0150] The display control unit 140 drives the LED light-emitting unit 180 via the drive circuit 170 according to the column data read from the scroll display data storage RAM 150, thereby lighting up the LED light-emitting unit 180 for each column. Then, within the display cycle in which the new column data VDTnew is written to the scroll display data storage RAM 150, the display control unit 140 starts displaying the image including the new column data VDTnew. Note that the update of the scroll display data storage RAM 150 is completed within the next display cycle cyc following the display cycle cyc in which VSC-PK was received.

[0151] (Comparison of data transfer times by transfer method) Figure 12 is an explanatory diagram showing a comparison of data transfer times for the existing parallel transfer method, the existing serial transfer method, and the new serial transfer method described above when displaying a scrolling image. In the existing parallel transfer method and the existing serial transfer method, as in Figures 7 and 8, data for one screen is transferred from the control board to the display unit each time the image is scrolled. In the new serial transfer method, data for one column or one row is transferred from the control board to the display unit each time the image is scrolled.

[0152] The data transfer time of the existing serial transfer method is 992% compared to the existing parallel transfer method, which is set at 100%. In contrast, the data transfer time of the new serial transfer method is 99%, equivalent to the existing parallel transfer method.

[0153] Based on the existing parallel transfer method, the data transfer time for the same data size is approximately 10 times longer for the existing serial transfer method, and approximately 1 time longer for the new serial transfer method. Based on the existing serial transfer method, the data transfer time for the same data size is approximately 1 / 10th of the data transfer time for both the existing parallel transfer method and the new serial transfer method.

[0154] In this embodiment, when the display control unit 140 receives the display packet VSC-PK after receiving the latest column data for scrolling contained in the data writing packet DT-PK, it overwrites the oldest column data stored in the scroll display data storage RAM 150 with the latest column data. The display control unit 140 then outputs multiple column data read from the scroll display data storage RAM 150 to the drive circuit 170 so that an image using the new oldest column data, based on the latest column data stored in the scroll display data storage RAM 150, is displayed on the LED light-emitting unit 180 from the first column to the last column.

[0155] Similarly, if the display control unit 140 receives the display packet VSC-PK after receiving the latest row data for scrolling contained in the data writing packet DT-PK, it overwrites the oldest row data stored in the scroll display data storage RAM 150 with the latest row data. The display control unit 140 then outputs multiple row data read from the scroll display data storage RAM 150 to the drive circuit 170 so that an image consisting of the latest row data stored in the scroll display data storage RAM 150 and the new oldest row data is displayed on the LED light-emitting unit 180 from the first row to the last row.

[0156] This simplifies the reading and writing of data to the RAM 150 for storing scroll display data when scrolling the image displayed on the LED light-emitting unit 180, thereby simplifying the image scrolling control.

[0157] When scrolling a column of an image, the display control unit 140 shifts the column address from which to read column data from the scroll display data storage RAM 150 by one for each scroll, and outputs the data for one screen read from the scroll display data storage RAM 150 to the drive circuit 170. Similarly, when scrolling a row of an image, the display control unit 140 shifts the row address from which to read row data from the scroll display data storage RAM 150 by one for each scroll, and outputs the data for one screen read from the scroll display data storage RAM 150 to the drive circuit 170.

[0158] This allows the image to be scrolled by simply rewriting one column or one row of data from the scroll display data storage RAM 150 that is held for one screen. In other words, the image can be scrolled without writing the data for one screen to the scroll display data storage RAM 150. As a result, the reading and writing of data to the memory 150 when scrolling the image displayed on the LED light-emitting unit 180 can be simplified, and the image scrolling control can be simplified.

[0159] The display control unit 140 performs the following processes during a memory access cycle: overwriting the oldest column data with new column data and reading the overwritten column data from the scroll display data storage RAM 150. This allows the display control unit 140 to perform a write cycle in the background of a read cycle, and to replace the oldest column data held in the scroll display data storage RAM 150 with new column data VDTnew without adding an additional write cycle.

[0160] The display control unit 140 stores new data for scrolling, VDTnew(ID#1), in the column receive buffer RBUF1(V) based on the column data write packet VDT-PK(ID#1), and then repeatedly displays the image before scrolling on the LED light-emitting unit 180 until it receives the display packet VSC-PK(ID#1). This allows the image displayed on the LED light-emitting unit 180 to scroll without interruption.

[0161] When the display control unit 140 receives a display packet VSC-PK (ID#1) for scrolling, it transfers the data VDTnew (ID#1) held in the column receive buffer RBUF1 (V) to the column receive buffer RBUF2 (V). This prevents the data VDTnew (ID#1) in the column receive buffer RBUF1 (V) from being overwritten and lost before it is written to the RAM 150 for storing scroll display data, thereby preventing the image from becoming unscrollable.

[0162] By writing image data for one screen to the scroll display data storage RAM 150 via the data line DT2, the control of the display control unit 140 can be simplified compared to the case where image data is written to the scroll display data storage RAM 150 via the column receive buffers RBUF1(V), RBUF2(V), and RBUF3(V).

[0163] By providing a multiplexer MUX1 that selects either the output of the data line DT2, the column receive buffer RBUF3(V), or the row receive buffer RBUF3(H), it is possible to select the data to be written to the RAM 150 for storing scroll display data according to the size of the received data and the scroll direction.

[0164] The communication control unit 124 forwards packets received from one serial interface SIF to the other serial interface SIF, so that even when multiple display units 100 are connected in series via the serial interface SIF, packets can be forwarded to each display unit 100. Each display unit 100 can then perform image display processing on the LED light-emitting unit 180 based only on packets that indicate its own display unit.

[0165] By using a display packet VSC-PK that includes a group ID, a single display packet VSC-PK can display an image on the LED light-emitting sections 180 of multiple display units 100 belonging to the same group. This reduces the number of display packets VSC-PK transmitted by the control board 30, allowing for efficient use of the serial interface SIF.

[0166] By storing the scroll direction included in the scroll direction specification packet SDR-PK (ID#1) in the scroll direction specification register SDR, the display control unit 140 can scroll the image in the column direction or row direction, as shown in Figure 5 or Figure 6.

[0167] Although preferred embodiments have been described in detail above, the invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims.

[0168] In addition to the embodiments described above, the following further notes are disclosed. (Note 1) A display device comprising at least one display unit on which an image is displayed, and a main control unit for controlling the display unit, The aforementioned display unit is A light-emitting unit that includes a plurality of light-emitting elements arranged in a matrix, and displays an image by the light emitted from the plurality of light-emitting elements, The memory includes a plurality of storage areas, each storing a data set for causing the group of light-emitting elements, which are arranged in one direction, to emit light, and is capable of storing data for one screen of the light-emitting unit. A drive unit for driving the light-emitting unit, The system includes a display control unit that controls the reading and writing of data to the memory and controls the display of an image by the light-emitting unit, The display control unit, each time it receives a screen display command from the main control unit, outputs the data for one screen stored in the memory to the drive unit, thereby causing the light-emitting unit to display an image. If, after receiving a scroll command containing the latest data set used for scrolling the image displayed on the light-emitting unit, the main control unit receives the screen display command, The latest data set received overwrites the oldest data set that will not be used for the next image display among the data for one screen used for image display by the light-emitting unit immediately before receiving the screen display command in the memory area. A display device that outputs a plurality of data sets read from the memory to the drive unit such that an image is displayed from the group of light-emitting elements at one end of the light-emitting unit to the group of light-emitting elements at the other end, using the newest data set stored in the memory as the newest data set. (Note 2) Each of the aforementioned multiple memory areas is assigned an address. The display control unit, When the latest data set is received from the main control unit, the address to which the received latest data set is written is set to the address of the storage area that stores the oldest data set. The display device according to Appendix 1, wherein each of the multiple addresses used to read a plurality of data groups representing an image to be displayed from the group of light-emitting elements at one end of the light-emitting section to the group of light-emitting elements at the other end is sequentially shifted relative to the previous read address. (Note 3) In a display cycle in which the light-emitting unit displays an image for one screen, the display control unit, The aforementioned data set is read sequentially from the memory while shifting the addresses and output to the drive unit. The display device according to Appendix 2, which, during a memory access cycle in which an address for reading the oldest data set from the memory area is set in the memory, overwrites the memory area storing the oldest data set with the latest data set and reads the latest data set that has been overwritten into the memory area. (Note 4) The display device according to any one of Appendix 1 to Appendix 3, wherein the display control unit causes the light-emitting unit to maintain the display of an image by repeatedly outputting the data for one screen stored in the memory to the drive unit until it receives the next screen display command. (Note 5) The display unit further includes a plurality of buffers connected in series that sequentially hold the data group received from the main control unit, The display control unit, The latest data set included in the scroll command is written to the first buffer. The display device according to any one of the appendices 1 to 4, wherein when the main control unit receives the screen display command, the light-emitting unit starts control to display the image for one screen, transfers the latest data set stored in the first-stage buffer to the subsequent-stage buffer, and overwrites one of the storage areas with the latest data set transferred to the final-stage buffer. (Note 6) The display unit further has a write path that allows the display control unit to write the data for one screen to the memory without going through the buffer, The display device according to Appendix 5, wherein when the display control unit receives a data write command from the main control unit to write the data for one screen to the memory, it writes the data for one screen included in the data write command to the memory via the write path. (Note 7) The display unit further includes a switching unit that connects either the output path or the write path of the final stage buffer to the memory. The display control unit, When the scroll command is received from the main control unit, the output path of the final stage buffer is connected to the memory via the switching unit, and the latest data set included in the scroll command is written to the memory. The display device according to Appendix 6, which, upon receiving the data writing command from the main control unit, connects the writing path to the memory via the switching unit and sequentially writes multiple data groups for one screen of the light-emitting unit included in the data writing command to the memory. (Note 8) The display unit has multiple units arranged in a matrix and sequentially connected by a serial interface, One of the multiple display units is connected to the main control unit via a serial interface. Each of the multiple display units is It has an identification information holding unit that holds unit identification information to identify the self-displaying unit, When the main control unit receives the screen display command, which includes unit identification information indicating the display unit, via the serial interface, the light-emitting unit is controlled to display an image. When the main control unit receives the scroll command, which includes unit identification information indicating the display unit, via the serial interface, the light-emitting unit performs control to scroll the image displayed on it. The display device according to any one of the appendices 1 to 7, wherein when the main control unit receives the screen display command or scroll command, which includes unit identification information that does not indicate the display unit itself, via the serial interface, the display device forwards the received screen display command or scroll command to the subsequent display unit. (Note 9) Each of the multiple display units is It further includes a group identification information holding unit that holds group identification information to identify the group to which the self-display unit belongs, When the display unit receives a screen display command from the main control unit via the serial interface, including the group identification information to which it belongs, it controls the light-emitting unit to display an image. When the display unit receives the scroll command, which includes group identification information to which it belongs, from the main control unit via the serial interface, it performs control to scroll the image displayed on the light-emitting unit. The display device according to Appendix 8, which, when it receives the screen display command or scroll command containing group identification information to which the display unit does not belong from the main control unit via the serial interface, forwards the received screen display command or scroll command to the subsequent display unit. (Note 10) The display device according to Appendix 8 or Appendix 9, wherein each of the plurality of display units forwards the received screen display command and the scroll command to a subsequent display unit, respectively. (Note 11) The group of light-emitting elements includes a plurality of light-emitting elements arranged in the vertical or horizontal direction of the light-emitting section, The storage area of ​​the memory is allocated in accordance with the direction in which the light-emitting elements are arranged in the group of light-emitting elements. The display control unit, The device further includes a direction information holding unit that holds direction information indicating whether the group of light-emitting elements is a vertical column or a horizontal row in the light-emitting unit, A display device according to any one of the appendices 1 to 10, which reads and writes the data group to the storage area allocated in correspondence with the arrangement direction of the light-emitting elements indicated by the direction information held in the direction information holding unit. (Note 12) A display control method for a display device comprising: at least one display unit on which an image is displayed; a main control unit for controlling the display unit, wherein the display unit includes a plurality of light-emitting elements arranged in a matrix, and the light-emitting section displays an image by the emission of light from the plurality of light-emitting elements; a memory that includes a plurality of storage areas each storing a data group for causing the group of light-emitting elements, which are arranged in one direction, to emit light, and is capable of storing data for one screen of the light-emitting section; a drive unit for driving the light-emitting section; and a display control unit that controls the reading and writing of data to the memory and controls the display of an image by the light-emitting section, wherein The display control unit, Each time a screen display command is received from the main control unit, the drive unit outputs the data for one screen stored in the memory, thereby causing the light-emitting unit to display an image. If, after receiving a scroll command containing the latest data set used for scrolling the image displayed on the light-emitting unit, the main control unit receives the screen display command, The latest received data set overwrites the oldest data set that will not be used for the next image display among the data for one screen used for image display by the light-emitting unit immediately before receiving the screen display command in the storage area where the oldest data set is stored. A display control method for a display device, comprising outputting a plurality of data sets read from the memory to the drive unit such that an image is displayed from the group of light-emitting elements at one end of the light-emitting unit to the group of light-emitting elements at the other end, using the oldest data set from the newest data set stored in the memory. [Explanation of Symbols]

[0169] 10 Display device 20 Display Panel 30 control boards 100 display units, self-display units 110 Communications Department 120, 130 Interface section 121 Decoder 122 Serial-to-Parallel Conversion Unit 123 Parallel-to-Serial Conversion Unit 124 Communication Control Unit 140 Display Control Unit 141 Offset Amount Change Control Unit 150 RAM for storing scroll display data 160 RAM for storing display data 170 Drive Circuit 180 LED light-emitting section ADD1, ADD2 Adder ADR Address Signal BAS Base Address Register CE Clock Enable Signal CNT2, CNT3 control signals COV Column Offset Amount Register cyc display cycle DT image data DT0, DT1, DT2, DT3 data lines DT, DTa, DTb data DT-PK Data Write Packet HDT Data ID identification information ID-PK ID Assignment Packet MUX1, MUX2, MUX3 Multiplexer NSD Next Scroll Direction Register PSD execution scroll direction register PX pixels RBUF1(V)~RBUF3(V) Column Receive Buffers RBUF1(H)~RBUF3(H) row receive buffer RD RAM data read timing RDA read address ROV row offset register SCR scrolling display signal SDR Scroll Direction Register SDR-PK Scroll Direction Specification Packet SEL1, SEL2 selection signal SIF Serial Interface SPF Scrolling Execution Registers SWF Scroll Wait State Register VDT, VDTnew column data VDT-PK Display Data Writing Packet VSC-PK Display Packet WE Light Enable Signal WR New row / new column display data writing timing WRA write address register, write address X horizontal direction Y (vertical direction)

Claims

1. A display device comprising at least one display unit on which an image is displayed, and a main control unit for controlling the display unit, The aforementioned display unit is A light-emitting unit that includes a plurality of light-emitting elements arranged in a matrix, and displays an image by the light emitted from the plurality of light-emitting elements, The memory includes a plurality of storage areas, each storing a data set for causing the group of light-emitting elements, which are arranged in one direction, to emit light, and is capable of storing data for one screen of the light-emitting unit. A drive unit for driving the light-emitting unit, The system includes a display control unit that controls the reading and writing of data to the memory and controls the display of an image by the light-emitting unit, The display control unit, each time it receives a screen display command from the main control unit, outputs the data for one screen stored in the memory to the drive unit, thereby causing the light-emitting unit to display an image. If, after receiving a scroll command containing the latest data set used for scrolling the image displayed on the light-emitting unit, the main control unit receives the screen display command, The latest data set received overwrites the oldest data set that will not be used for the next image display among the data for one screen used for image display by the light-emitting unit immediately before receiving the screen display command in the storage area. A display device that outputs a plurality of data sets read from the memory to the drive unit such that an image is displayed from the group of light-emitting elements at one end of the light-emitting unit to the group of light-emitting elements at the other end, using the newest data set stored in the memory as the newest data set.

2. Each of the aforementioned multiple memory areas is assigned an address. The display control unit, When the latest data set is received from the main control unit, the address to which the received latest data set is written is set to the address of the storage area that stores the oldest data set. The display device according to claim 1, wherein each of the multiple addresses from which a plurality of data groups indicating an image to be displayed from the group of light-emitting elements at one end of the light-emitting section to the group of light-emitting elements at the other end is read from a plurality of storage areas is sequentially shifted relative to the previous read address.

3. In a display cycle in which the light-emitting unit displays an image for one screen, the display control unit, The aforementioned data set is read sequentially from the memory while shifting the addresses and output to the drive unit. The display device according to claim 2, wherein during a memory access cycle in which an address for reading the oldest data set from the memory area is set in the memory, the latest data set is overwritten into the memory area storing the oldest data set, and the latest data set that has been overwritten into the memory area is read out.

4. The display device according to any one of claims 1 to 3, wherein the display control unit causes the light-emitting unit to maintain the display of an image by repeatedly outputting the data for one screen stored in the memory to the drive unit until it receives the next screen display command.

5. The display unit further includes a plurality of buffers connected in series that sequentially hold the data group received from the main control unit, The display control unit, The latest data set included in the scroll command is written to the first buffer. The display device according to any one of claims 1 to 3, wherein when the main control unit receives the screen display command, the light-emitting unit starts control to display the image for one screen, transfers the latest data set stored in the first stage buffer to the subsequent stage buffer, and overwrites one of the storage areas with the latest data set transferred to the final stage buffer.

6. The display unit further has a write path that allows the display control unit to write the data for one screen to the memory without going through the buffer, The display device according to claim 5, wherein when the display control unit receives a data writing command from the main control unit to write the data for one screen to the memory, it writes the data for one screen included in the data writing command to the memory via the writing path.

7. The display unit further includes a switching unit that connects either the output path or the write path of the final stage buffer to the memory. The display control unit, When the scroll command is received from the main control unit, the output path of the final stage buffer is connected to the memory via the switching unit, and the latest data set included in the scroll command is written to the memory. The display device according to claim 6, wherein when the main control unit receives the data writing command, the switching unit connects the writing path to the memory and sequentially writes the multiple data groups for one screen of the light-emitting unit included in the data writing command to the memory.

8. The display unit has multiple units arranged in a matrix and sequentially connected by a serial interface, One of the multiple display units is connected to the main control unit via a serial interface. Each of the multiple display units is It has an identification information holding unit that holds unit identification information to identify the self-displaying unit, When the main control unit receives the screen display command, which includes unit identification information indicating the display unit, via the serial interface, the light-emitting unit is controlled to display an image. When the main control unit receives the scroll command, which includes unit identification information indicating the display unit, via the serial interface, the light-emitting unit performs control to scroll the image displayed on it. The display device according to any one of claims 1 to 3, wherein when the main control unit receives the screen display command or scroll command, which includes unit identification information that does not indicate the display unit itself, via the serial interface, the received screen display command or scroll command is forwarded to the subsequent display unit.

9. Each of the multiple display units is It further includes a group identification information holding unit that holds group identification information to identify the group to which the self-display unit belongs, When the display unit receives a screen display command from the main control unit via the serial interface, including the group identification information to which it belongs, it controls the light-emitting unit to display an image. When the display unit receives the scroll command, which includes group identification information to which it belongs, from the main control unit via the serial interface, it performs control to scroll the image displayed on the light-emitting unit. The display device according to claim 8, wherein when the main control unit receives the screen display command or scroll command, which includes group identification information to which the display unit does not belong, via the serial interface, the display device forwards the received screen display command or scroll command to a subsequent display unit.

10. The display device according to claim 8, wherein each of the plurality of display units transfers the received screen display command and the scroll command to a subsequent display unit, respectively.

11. The group of light-emitting elements includes a plurality of light-emitting elements arranged in the vertical or horizontal direction of the light-emitting section, The storage area of ​​the memory is allocated in accordance with the direction in which the light-emitting elements are arranged in the group of light-emitting elements. The display control unit, The device further includes a direction information holding unit that holds direction information indicating whether the group of light-emitting elements is a vertical column or a horizontal row in the light-emitting unit, The display device according to any one of claims 1 to 3, which reads and writes the data group to the storage area allocated in correspondence with the arrangement direction of the light-emitting elements indicated by the direction information held in the direction information holding unit.

12. A display control method for a display device comprising: at least one display unit on which an image is displayed; a main control unit for controlling the display unit, wherein the display unit includes a plurality of light-emitting elements arranged in a matrix, and the light-emitting section displays an image by the emission of light from the plurality of light-emitting elements; a memory that includes a plurality of storage areas each storing a data group for causing the group of light-emitting elements, which are arranged in one direction, to emit light, and is capable of storing data for one screen of the light-emitting section; a drive unit for driving the light-emitting section; and a display control unit that controls the reading and writing of data to the memory and controls the display of an image by the light-emitting section, wherein The display control unit, Each time a screen display command is received from the main control unit, the drive unit outputs the data for one screen stored in the memory, thereby causing the light-emitting unit to display an image. If, after receiving a scroll command containing the latest data set used for scrolling the image displayed on the light-emitting unit, the main control unit receives the screen display command, The latest received data set overwrites the oldest data set that will not be used for the next image display among the data for one screen used for image display by the light-emitting unit immediately before receiving the screen display command in the storage area where the oldest data set is stored. A display control method for a display device, comprising outputting a plurality of data sets read from the memory to the drive unit, such that an image is displayed from the group of light-emitting elements at one end of the light-emitting unit to the group of light-emitting elements at the other end, using the newest data set stored in the memory and the oldest data set.

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