Patent Publication Number: US-2016247473-A1

Title: Transmission device, reception device, transmission/reception system, and image display system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International Application No. PCT/JP2014/076161 filed Sep. 30, 2014, claiming priority based on Japanese Patent Application No. 2013-209354 filed Oct. 4, 2013, the contents of all of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a transmission device, a reception device, a transmission/reception system, and an image display system. 
     BACKGROUND ART 
     An image display system such as a liquid crystal display system includes a transmission device, a reception device, and an image display device. A clock may be transmitted through a signal line separate from a signal line through which data is transmitted from the transmission device to the reception device or data in which the clock is embedded may be transmitted from the transmission device to the reception device (see Non Patent Literatures 1 and 2). For the data in which the clock is embedded, a timing of transition from a first level to a second level is in each unit period and information of a predetermined number of bits is provided in the unit period starting from the timing of transition. Also, one of the first and second levels is a high level and the other is a low level. 
     The transmission device inputs an image signal or the like from an outside and transmits image data and control data to the reception device. The reception device receives the image data and the control data from the transmission device, performs control on the basis of the control data, and transmits the image signal to the image display device. The image display device displays an image on the basis of the image signal transmitted from the reception device. 
     In an image display system such as a liquid crystal display system, generally, the above-described transmission device or a device including the transmission device is referred to as a “timing controller” and the above-described reception device or a device including the reception device is referred to as a “driver.” Also, generally, a plurality of drivers are connected to one timing controller. 
     In a transmission/reception system including a transmission device and a reception device which transmit and receive such image data, an active period in which the image data is transmitted and received and a blank period in which no image data is transmitted or received are provided. Control data indicating a control signal (control command) for controlling the reception device is transmitted from the transmission device to the reception device during the blank period. 
     CITATION LIST 
     Non Patent Literature 
     
         
         [Non Patent Literature 1] Jeong-Ho Kang, et al, “A Clock-embedded Voltage Differential Signaling (CVDS) for the Chip-On-Glass Application of TFT-LCD,” SID 10 DIGEST, pp. 66-69 (2010). 
         [Non Patent Literature 2] Dong Hoon Baek, et al, “Late-NewsPaper: The Enhanced Reduced Voltage Differential Signaling (eRVDS) Interface With Clock Embedded Scheme for Chip-On-Glass TFT-LCD Applications,” SID 10 DIGEST, pp. 70-73 (2010) 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In the conventional transmission/reception system, a timing at which the control data is transmitted from the transmission device to the reception device is fixed to a specific timing during the blank period. The reception device designates data received at the fixed timing as the control data. Due to this, there is a problem in that the degree of freedom of control data transmission from the transmission device to the reception device is low, and, for example, the timing at which the reception device requires the control command and the transmission timing are different from each other or it is difficult to increase types and the number of control commands. 
     The present invention has been made to solve the above-described problem and an objective of the invention is to provide a transmission device and a reception device for increasing the degree of freedom of control data transmission from the transmission device to the reception device. Also, an objective of the invention is to provide a transmission/reception system including the transmission device and the reception device and an image display system including the transmission device, the reception device, and an image display device. 
     Solution to Problem 
     A transmission device of the present invention is a transmission device for transmitting serial data for which a timing of transition from a first level to a second level is in each unit period and which has information of a predetermined number of bits in the unit period starting from the transition timing to a reception device, the transmission device including: a transmission unit configured to transmit control data indicating a control signal for controlling the reception device and image data as the serial data to the reception device; and a transmission control unit configured to control data transmission by the transmission unit. Further, the transmission control unit causes the transmission unit to transmit the image data as a first type of data for which two or more transitions from the second level to the first level are in the unit period, and the transmission control unit causes the transmission unit to transmit the control data as a second type of data for which one transition from the second level to the first level is in the unit period and the number of bits having the second level in the unit period corresponds to the control signal. 
     A reception device of the present invention is a reception device for receiving serial data for which a timing of transition from a first level to a second level is in each unit period and which has information of a predetermined number of bits in the unit period starting from the transition timing from a transmission device, the reception device including: a reception unit configured to receive control data and image data as the serial data from the transmission device; and a reception control unit configured to perform control on the basis of the data received by the reception unit. Further, the reception control unit acquires the image data from the data when the serial data received by the reception unit is a first type of data for which two or more transitions from the second level to the first level are in the unit period, and the reception control unit performs control of content according to the number of bits having the second level in the data when the serial data received by the reception unit is a second type of data for which one transition from the second level to the first level is in the unit period. 
     In the transmission device of the present invention, preferably, the transmission control unit causes the transmission unit to transmit the control data as the second type of data in a plurality of continuous unit periods when the control data is transmitted to the reception device. In the reception device of the present invention, preferably, the reception control unit performs control of content according to the number of bits having the second level in each of a plurality of second types of data when the serial data received by the reception unit is the second type of data in a plurality of continuous unit periods. 
     In the transmission device of the present invention, preferably, when the image data is designated as the first type of data, the transmission control unit designates the image data as the first type of data by adding level inversion information to level-inverted data if the number of transitions from the second level to the first level in the unit period is larger for data obtained by inverting a level of a specific bit of original data than for the original data. In the reception device of the present invention, preferably, when the serial data received by the reception unit is the first type of data and level inversion information is included in the data, the image data is acquired from data obtained by inverting a level of a specific bit of the data. 
     A transmission/reception system of the present invention includes the transmission device of the present invention and the reception device of the present invention. An image display system of the present invention includes the transmission device of the present invention, the reception device of the present invention; and an image display device configured to display an image on the basis of the image data acquired by the reception device. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to increase the degree of freedom of control data transmission from a transmission device to a reception device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating a schematic configuration of an image display system  1  of the present embodiment. 
         FIG. 2  is a diagram illustrating a configuration of a transmission/reception system  2  of the present embodiment. 
         FIGS. 3A, 3B and 3C  are diagrams for describing data (a first type of data) and control data (a second type of data). 
         FIGS. 4A, 4B, 4C and 4D  are diagrams for describing image data (a first type of data). 
         FIGS. 5A, 5B, 5C and 5D  are diagrams for describing a timing of transmission/reception of each of the image data and the control data. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same elements in the description of the drawings are assigned the same reference signs and redundant description thereof will be omitted. 
       FIG. 1  is a diagram illustrating a schematic configuration of an image display system  1  of the present embodiment. The image display system  1  illustrated in  FIG. 1  includes a transmission device  10 , N reception devices  20   1  to  20   N , and an image display device  30 . The transmission device  10  and the N reception devices  20   1  to  20   N  constitute a transmission/reception system of the present embodiment. Here, N is an integer greater than or equal to 2 and n shown below is each integer greater than or equal to 1 and less than or equal to N. In  FIG. 1 , the illustration of a drive unit and a signal line for vertical scanning of an image in the image display device  30  is omitted. 
     The transmission device  10  inputs an image signal and a control signal (control command) from an outside and transmits image data and control data as serial data to each of the N reception devices  20   1  to  20   N . The image data is serial data generated on the basis of the image signal. The control data is serial data generated on the basis of the control signal. The serial data is data in which a clock is embedded, a timing of transition from a first level to a second level is provided in each unit period, and the serial data has information of a predetermined number of bits in the unit period starting from the timing of transition. One of the first level and the second level is a high level and the other is a low level. The transition from the first level to the second level at the starting timing of each unit period corresponds to the clock. 
     For example, the control signal includes a signal indicating the polarity of the image data transmitted from each reception device  20   n  to the image display device  30 , a signal indicating a start position of data writing to a register embedded in each reception device  20   n , a signal indicating a data header position during a blank period, and a signal indicating a frame start position. Also, the control signal also includes a training signal for each reception device  20   n  to perform clock training. 
     Each reception device  20   n  receives image data and control data arriving from the transmission device  10  through a first signal line  40   n . Each reception device  20   n  performs control of content indicated by received control data. Also, each reception device  20   n  transmits an image signal obtained by receiving the image data to the image display device  30 . The image display device  30  is, for example, a liquid crystal panel, and displays an image on the basis of image signals transmitted from the reception devices  20   1  to  20   N . 
     The transmission device  10  and each reception device  20   n  are connected by the first signal line  40   n . Each signal line  40   n  transmits the serial data transmitted from the transmission device  10  to the reception device  20   n . Each signal line  40   n  may be physically one line or a pair of lines for transmitting differential data. 
     Also, the transmission device  10  and the reception devices  20   1  to  20   N  are connected by a second signal line  50 , and can perform communication via the second signal line. This communication conforms to protocols of serial bus standards, for example, such as Inter-Integrated Circuit (I 2 C) and Serial Peripheral Interface (SPI). When the I 2 C standard is used as illustrated in  FIG. 1 , the second signal line  50  includes an SCL line through which a clock is transmitted and an SDA line through which data is transmitted. For example, the transmission device  10  can write data to a register embedded in each reception device  20   n  by performing communication according to a predetermined protocol via the second signal line  50 . Each reception device  20   n  can perform an operation according to the data written to the register. 
       FIG. 2  is a diagram illustrating a configuration of a transmission/reception system  2  of the present embodiment. In  FIG. 2 , any one reception device  20  among the N reception devices  20   1  to  20   N  is illustrated and a configuration part corresponding to the reception device  20  in the transmission device  10  is illustrated. The transmission device  10  includes a transmission unit  11  and a transmission control unit  12 . The transmission unit  11  transmits control data and image data as serial data to the reception device  20 . The transmission control unit  12  controls data transmission by the transmission unit  11 . The reception device  20  includes a reception unit  21  and a reception control unit  22 . The reception unit  21  receives the control data and the image data as the serial data from the transmission device  10 . The reception control unit  22  performs control on the basis of data received by the reception unit  21 . 
     The serial data to be transmitted from the transmission unit  11  of the transmission device  10  to the reception unit  21  of the reception device  20  are a first type of data and a second type of data. For the first type of data, two or more transitions from the second level to the first level are in the unit period. For the second type of data, one transition from the second level to the first level is in the unit period. 
     The transmission device  10  causes the transmission unit  11  to transmit the image data as the first type of data. At this time, the transmission control unit  12  inputs an image signal from the outside and packetizes and encodes the image data on the basis of the image signal and the transmission unit  11  serializes the encoded data and transmits the image data as the first type of data. On the other hand, when the serial data received by the reception unit  21  is the first type of data, the reception device  20  acquires the image data from the data. At this time, the reception unit  21  de-serializes the received serial data to designate the de-serialized data as parallel data and the reception control unit  22  decodes the parallel data and further unpacketizes the decoded parallel data to acquire the image data. 
     The transmission control unit  12  of the transmission device  10  causes the transmission unit  11  to transmit control data as the second type of data. At this time, the transmission control unit  12  inputs a control signal (control command) from the outside and the number of bits having the second level in the unit period corresponds to the control signal (control command). On the other hand, the reception control unit  22  of the reception device  20  performs control of content corresponding to the number of bits having the second level in the data when the serial data received by the reception unit  21  is the second type of data. 
       FIGS. 3A to 3C  are diagrams for describing image data (a first type of data) and control data (a second type of data). In  FIGS. 3A to 3C , data for the two unit periods is illustrated. Also, in  FIG. 3C , dummy data (a first type of data) to be inserted during the transition from the blank period to the active period is also illustrated. The dummy data ( FIG. 3(C) ) is dummy data for excluding the disturbance of a data waveform during the transition from the blank period to the active period in the reception device  20 . 
     As illustrated in  FIGS. 3A to 3C , a start timing of each unit period is the timing (timing indicated by an upward arrow in  FIGS. 3A to 3C ) of transition from the low level (first level) to the high level (second level) in each of the image data (first type of data), the control data (second type of data), and the dummy data (first type of data). This data has 15-bit information in each unit period starting from the transition timing. 
     As illustrated in  FIG. 3(A) , image data per pixel has information of 24 bits (D 23  to D 00 ) and is represented by 30 bits for two unit periods by adding other bits thereto. The image data of each unit period includes one header bit having the high level, 12 bits (D 23  to D 12  or D 11  to D 00 ) indicating pixel information subsequent thereto, one bit (SMBU or SMBL) indicating predetermined information (to be described below) subsequent thereto, and one last bit having the low level. The image data to be transmitted from the transmission device  10  to the reception device  20  becomes the first type of data for which two or more transitions from the second level to the first level are in the unit period. 
     As illustrated in  FIG. 3(B) , control data of each unit period has the high level for a certain number of bits continuous from a header bit and has the low level until the last bit continuously thereafter. Thus, control data to be transmitted from the transmission device  10  to the reception device  20  becomes the second type of data for which one transition from the high level to the low level is in the unit period. Also, the control data is control data for which the number of bits having the high level in the unit period corresponds to the control signal (control command). In  FIG. 3(B) , the number of bits having the high level in each unit period is shown as any one of 4, 8, and 12 and it is possible to indicate three types of control signals (control commands) in each unit period. 
     The control data to be transmitted from the transmission device  10  to the reception device  20  may be a plurality of continuous second types of data. That is, the transmission control unit  12  of the transmission device  10  causes the transmission unit  11  to transmit the control data as the second type of data in a plurality of continuous unit periods when the control data is transmitted to the reception device  20 . On the other hand, the reception control unit  22  of the reception device  20  performs control of content according to the number of bits having the high level in each of the plurality of second types of data when the serial data received by the reception unit  21  is the second type of data in a plurality of continuous unit periods. In the example illustrated in  FIG. 3B , the second type of data is provided in two continuous unit periods and can indicate nine types of control signals (control commands). The control data (second types of data) may continue in three or more unit periods. When the number of continuous unit periods increases more, it is possible to transmit more various types of control signals (control commands). 
       FIGS. 4A to 4D  are diagrams for describing image data (a first type of data). When the image data is the first type of data, it is preferable that the transmission control unit  12  of the transmission device  10  designate the image data as the first type of data by adding level inversion information (SMBU or SMBL) to level-inverted data if the number of transitions from the second level to the first level in the unit period is larger for data obtained by inverting a level of a specific bit of original data than for the original data. At this time, when the serial data received by the reception unit is the first type of data and the level inversion information is included in the data, the reception control unit  22  of the reception device  20  acquires image data from the data obtained by inverting the level of the specific bit of the data. 
     In the example illustrated in  FIGS. 4A to 4C , level-inverted bits among 15 bits of each unit period become a fourth bit, a fifth bit, an eighth bit, a ninth bit, a twelfth bit, and a thirteenth bit. 
     In  FIG. 4(A) , for control data to be transmitted from the transmission device  10  to the reception device  20 , original data for which the number of transitions from the second level to the first level is large is selected in any of a previous-stage unit period and a subsequent-stage unit period and an SMBU or SMBL of a fourteenth bit has the high level to indicate the original data. 
     In  FIG. 4(B) , control data to be transmitted from the transmission device  10  to the reception device  20  is original data for which the number of transitions from the second level to the first level is large in a previous-stage unit period and an SMBU of a fourteenth bit has the high level to indicate the original data. On the other hand, level-inverted data for which the number of transitions from the second level to the first level is large is selected in a subsequent-stage unit period and an SMBL of a fourteenth bit has the low level to indicate the selected level-inverted data. 
     In  FIG. 4(C) , for control data to be transmitted from the transmission device  10  to the reception device  20 , level-inverted data for which the number of transitions from the second level to the first level is large is selected in a previous-stage unit period and an SMBU of a fourteenth bit has the low level to indicate the selected level-inverted data. On the other hand, control data is original data for which the number of transitions from the second level to the first level is large in a subsequent-stage unit period and an SMBL of a fourteenth bit has the high level to indicate the original data. 
     In  FIG. 4(D) , for control data to be transmitted from the transmission device  10  to the reception device  20 , level-inverted data for which the number of transitions from the second level to the first level is large is selected in any of a previous-stage unit period and a subsequent-stage unit period and an SMBU or SMBL of a fourteenth bit has the low level to indicate the level-inverted data. 
       FIGS. 5A to 5C  are diagrams for describing a timing of transmission/reception of each of the image data and the control data. In  FIGS. 5A to 5C , an active period in which image data of a certain row is transmitted and received, an H blank period subsequent thereto, and an active period in which image data of the next row is transmitted and received are illustrated. Control data to be transmitted from the transmission device  10  to the reception device  20  may be transmitted and received immediately after the active period (during the start of the H active period) as illustrated in  FIG. 5(A)  and can be transmitted and received at any timing in the H active period as illustrated in  FIG. 5(B) . 
     Conventionally, the timing at which the control data is transmitted is fixed to a specific timing in the blank period as illustrated in  FIG. 5(A) . On the other hand, because it is possible to easily identify image data (the first type of data) and control data (the second type of data) in the reception device  20  in the present embodiment, the timing at which the control data is transmitted may be any timing in the active period as illustrated in  FIG. 5(B)  as well as the timing illustrated in  FIG. 5(A) . When the image data and the control data are transmitted at the timings of  FIG. 5(B) , the reception device  20  can acquire the image data from the data when the received serial data is the first type of data ( FIG. 5(C) ) and acquire the control data from the data when the received serial data is the second type of data ( FIG. 5(D) ). 
     Thus, in the present embodiment, the image data (first type of data) and the control data (second type of data) can be easily identified and the control data can be transmitted at any timing in the blank period. Therefore, the degree of freedom of control data transmission from the transmission device  10  to the reception device  20  is high. For example, the timing at which the reception device  20  requires the control command and the control data transmission timing can match each other and types and the number of control commands can increase. 
     Also, the following effects also occur due to the fact that the degree of freedom of control data transmission is increased. For example, an application for writing data to a lookup table embedded in the reception device  20  or a register such as a setting register is possible. It is possible to change content of control data for each line and dynamically change the control command. It is possible to change the timing at which the control data is inserted for each line and suppress an EMI. 
     REFERENCE SIGNS LIST 
     
         
           1  Image display system 
           2  Transmission/reception system 
           10  Transmission device 
           11  Transmission unit 
           12  Transmission control unit 
           20  Reception device 
           21  Reception unit 
           22  Reception control unit 
           30  Image display device 
           40  First signal line 
           50  Second signal line