JP2015053265A - Cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cable that favorably transmits a digital signal including video.SOLUTION: A cable is for transmitting a digital signal using a differential signal of a predetermined channel number from a transmitter to a receiver. The transmitter or receiver has an information provision function part that provides information showing a signal transmission ability of the cable.

Description

  The present invention relates to a cable, and more particularly to a cable for transmitting digital signals such as video.

  In recent years, HDMI (High Definition Multimedia Interface) has been widely used as a digital interface for connecting CE (Consumer Electronics) devices, and has become the de facto standard in the industry. For example, Non-Patent Document 1 describes the HDMI standard. In the HDMI standard, video, audio, and control signals are transmitted as digital signals using three data differential line pairs (TMDS Channel 0/1/2).

High-Definition Multimedia Interface Specification Version 1.4, June 5 2009

  At present, the value determined in the HDMI standard as the transmission speed of this digital signal is approximately 10.2 Gbps at the maximum. Considering high-quality 3D (3 dimension) video signals and future 4k2k (QFHD) and higher-quality video signals, HDMI will exceed the maximum value of current standards such as 15 Gbps and 20 Gbps. There is a need for future expansion.

  Two approaches are conceivable for speeding up the HDMI. One is a system that uses the current three data differential line pairs as they are, increases the clock speed for transmitting data, and increases the transmission rate accordingly. However, according to this method, it is difficult to expand the transmission band only by increasing the clock speed because of the physical limitation of using a differential pair of copper wires. Also, even if this method is possible, the transmission distance is assumed to be extremely short. That is, there is a problem that the length of the HDMI cable connecting the devices is limited.

  Another solution related to the present invention is to increase the current number of three data differential line pairs to four or more. Accordingly, the data rate can be increased by an increase in the number of lanes for transmitting data. However, in this method of increasing the data differential line pairs, compatibility with the current HDMI becomes a problem at that time. Specifically, for example, if the number of connector pins is increased from the conventional 19 pins by the number of data differential line pairs, it will be incompatible with the connection with the past device, which is misunderstood for the user. It causes confusion and is not suitable.

  A means for solving this problem is to maintain compatibility of connectors (plugs and receptacles). That is, it is necessary to consider wiring so that a functional failure does not occur in the cable itself without changing the connector from the conventional 19-pin connector.

  An object of the present invention is to provide a cable that can satisfactorily transmit digital signals such as video.

The concept of this invention is
A cable for transmitting a digital signal from a transmitting device to a receiving device by a differential signal of a predetermined number of channels,
The cable has an information providing function unit for providing information indicating the signal transmission capability of the cable to the transmitting device or the receiving device.

  For example, the information providing function unit provides information indicating the signal transmission capability of the cable to the receiving device or the transmitting device via the cable in response to a request from the receiving device or the transmitting device. For example, the information providing function unit rewrites a part of the capability information that the transmitting device reads from the receiving device via the cable. In addition, for example, the information providing function unit provides information indicating the signal transmission capability of the cable to the transmitting device or the receiving device through short-range wireless communication.

  According to the present invention, digital signals such as video can be transmitted satisfactorily.

1 is a block diagram showing a configuration example of an AV system as an embodiment of the present invention. It is a figure which shows the example of a combination of a source device, an HDMI cable, and a sink device. It is a figure which shows the structural example (at the time of the operation mode of the present HDMI) of the data transmission part of a source device, and the data reception part of a sink device. It is a figure which shows the structural example (at the time of the operation mode of new HDMI) of the data transmission part of a source device, and the data reception part of a sink device. It is a figure which shows the structural example of TMDS transmission data. It is a figure which compares and shows the pin assignment of current HDMI (Type A) and new HDMI. It is a figure which shows the pin arrangement | positioning of the receptacle of the source apparatus and sink apparatus of the present HDMI and new HDMI. It is a figure which shows the structural example of the existing HDMI cable. It is a figure which shows the structural example of a new HDMI cable. It is a figure which shows the other structural example of a new HDMI cable. It is a flowchart which shows an example of the process sequence of the operation mode control of the control part of a source device. It is a figure which shows an example of UI screen displayed on a display part (display) by control of the control part of a source device. It is a flowchart which shows the other example of the process sequence of the operation mode control of the control part of a source device. It is a figure which shows the example of the flag information newly defined on EDID. It is a figure for demonstrating the method of judgment whether the cable in a control part respond | corresponds to new HDMI, Comprising: It is a figure which shows that LSI is incorporated in the plug of a new HDMI cable. It is a figure for demonstrating the method of judgment whether the cable in a control part respond | corresponds to new HDMI, Comprising: It is a figure which shows an example of the EDID data rewriting circuit of LSI in a new HDMI cable. It is a figure for demonstrating the method of judgment whether the cable in a control part respond | corresponds to new HDMI, Comprising: It is a figure which shows that RF tag chip (LSI) is incorporated in the plug of new HDMI cable. . It is a figure for demonstrating the method of judgment whether the cable in a control part respond | corresponds to new HDMI, Comprising: By measuring the electrical property of a cable, whether a cable respond | corresponds to new HDMI It is a figure for demonstrating judging. It is a figure for demonstrating determining whether the cable respond | corresponds to new HDMI by measuring the electrical property of a cable. It is a figure for demonstrating the other example of the shape of a new HDMI cable plug and a receptacle. It is a perspective view of the plug of an existing HDMI cable and a new HDMI cable.

Hereinafter, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described. The description will be given in the following order.
1. Embodiment 2. FIG. Modified example

<1. Embodiment>
[Example of AV system configuration]
FIG. 1 shows a configuration example of an AV (Audio and Visual) system 100 as an embodiment. The AV system 100 is configured by connecting a source device 110 and a sink device 120. The source device 110 is an AV source such as a game machine, a disc player, a set top box, a digital camera, or a mobile phone. The sink device 120 is, for example, a television receiver or a projector.

  The source device 110 and the sink device 120 are connected via the cable 200. The source device 110 is provided with a receptacle 111 constituting a connector, to which a data transmission unit 112 is connected. The sink device 120 is provided with a receptacle 121 constituting a connector, to which a data receiving unit 122 is connected. In addition, a plug 201 constituting a connector is provided at one end of the cable 200, and a plug 202 constituting a connector is provided at the other end. The plug 201 at one end of the cable 200 is connected to the receptacle 111 of the source device 110, and the plug 202 at the other end of the cable 200 is connected to the receptacle 121 of the sink device 120.

  The source device 110 has a control unit 113. The control unit 113 controls the entire source device 110. In this embodiment, the data transmission unit 112 of the source device 110 supports both current HDMI and new HDMI. When determining that the cable 200 is compatible with the new HDMI and the sink device 120 is compatible with the new HDMI, the control unit 113 controls the data transmission unit 112 to operate in the operation mode of the new HDMI. On the other hand, if the control unit 113 determines that at least the sink device 120 supports only the current HDMI, or determines that the cable 200 supports the current HDMI, the control unit 113 sets the data transmission unit 112 to the current HDMI. Control to operate in operation mode.

  The sink device 120 has a control unit 123. The control unit 123 controls the entire sink device 120. In this embodiment, the data receiving unit 122 of the sink device 120 supports only the current HDMI or both the current HDMI and the new HDMI. When the data receiving unit 122 is compatible with both the current HDMI and the new HDMI, the control unit 123 controls the data receiving unit 122 to operate in the same operation mode as the data transmitting unit 112 of the source device 110. . In this case, the control unit 123 controls the operation mode of the data reception unit 122 based on the determination result of the operation mode transmitted from the source device 110 through a line such as CEC. The cable 200 is compatible with current HDMI or new HDMI.

  In the AV system 100 shown in FIG. 1, when the cable 200 is compatible with the new HDMI and the sink device 120 is compatible with both the current HDMI and the new HDMI as shown in FIG. Data transmission is carried out. At this time, the data transmission unit 112 of the source device 110 and the data reception unit 122 of the sink device 120 are controlled so as to operate in the new HDMI operation mode.

  Further, in the AV system 100 shown in FIG. 1, as shown in FIGS. 2B to 2D, at least the cable 200 is compatible with the current HDMI, or the sink device 120 is only compatible with the current HDMI. Data transmission with the current HDMI is performed. At this time, the data transmission unit 112 of the source device 110 is controlled to operate in the current HDMI operation mode. In addition, the data reception unit 122 of the sink device 120 that supports both the current HDMI and the new HDMI is controlled to operate in the current HDMI operation mode. In the case of FIG. 2B, when the cable 200 is capable of new HDMI data transmission, for example, by lowering the data transfer rate, data transmission in the new HDMI mode may be performed.

[Configuration example of data transmitter and data receiver]
3 and 4 show configuration examples of the data transmission unit 112 of the source device 110 and the data reception unit 122 of the sink device 120 in the AV system 100 of FIG. The data transmission unit 112 transmits a differential signal corresponding to uncompressed video data for one screen to the data reception unit 122 in one direction in a plurality of channels in an effective image period (also referred to as “active video period”). Send.

  Here, the effective image section is a section obtained by removing the horizontal blanking section and the vertical blanking section from the section from one vertical synchronization signal to the next vertical synchronization signal. In addition, the data transmission unit 112 transmits at least a plurality of channels of differential signals corresponding to audio data, control data, and other auxiliary data associated with video data in a horizontal blanking interval or a vertical blanking interval. Transmit to the receiving unit 122 in one direction.

  The data reception unit 122 receives differential signals corresponding to video data transmitted in one direction from the data transmission unit 122 through a plurality of channels in the active video section. In addition, the data reception unit 122 receives differential signals corresponding to audio data and control data transmitted in one direction from the data transmission unit 112 through a plurality of channels in a horizontal blanking interval or a vertical blanking interval. Receive.

  The transmission channels of the HDMI system including the data transmission unit 112 and the data reception unit 122 include the following. First, there are differential signal channels (TMDS channel, TMDS clock channel) as transmission channels. The differential signal channels for transmitting digital signals such as video data are 3 channels in the current HDMI, but 6 channels in the new HDMI.

  A differential signal channel in the current HDMI will be described. As shown in FIG. 3, three TMDSs serving as transmission channels for serially transmitting video data and audio data in one direction in synchronization with the pixel clock from the data transmission unit 112 to the data reception unit 122. There are channels # 0 to # 2. There is also a TMDS clock channel as a transmission channel for transmitting the TMDS clock.

  The HDMI transmitter 81 of the data transmission unit 112 converts, for example, uncompressed video data into corresponding differential signals, and is connected via the cable 200 with three TMDS channels # 0, # 1, and # 2. Serial transmission is performed in one direction to the data receiving unit 122. The HDMI transmitter 81 converts audio data accompanying the uncompressed video data, necessary control data, and other auxiliary data into corresponding differential signals, and converts them into three TMDS channels # 0, # 1, # 2. Then, the data is serially transmitted to the data receiving unit 122 in one direction.

  Further, the HDMI transmitter 81 transmits a TMDS clock synchronized with video data transmitted through the three TMDS channels # 0, # 1, and # 2 to the data transmission unit 122 through the TMDS clock channel. Here, in one TMDS channel #i (i = 0, 1, 2), 10-bit video data is transmitted during one TMDS clock.

  The HDMI receiver 82 of the data reception unit 122 transmits a differential signal corresponding to video data, audio data, and control data transmitted in one direction from the data transmission unit 112 through TMDS channels # 0, # 1, and # 2. A differential signal corresponding to is received. In this case, reception is performed in synchronization with the pixel clock (TMDS clock) transmitted from the data transmission unit 112 through the TMDS clock channel.

  Next, a differential signal channel in the new HDMI will be described. As shown in FIG. 4, six TMDS as transmission channels for serially transmitting video data and audio data in one direction in synchronization with the pixel clock from the data transmission unit 112 to the data reception unit 122. There are channels # 0 to # 5. In this new HDMI, the transmission of the TMDS clock is omitted, and a self-clock method is used in which the clock is reproduced from the received data on the receiving side.

  The HDMI transmitter 81 of the data transmission unit 112 converts, for example, uncompressed video data into corresponding differential signals, and is a data reception unit connected via the cable 200 with six TMDS channels # 0 to # 5. In 122, serial transmission is performed in one direction. The HDMI transmitter 81 converts audio data accompanying uncompressed video data, necessary control data and other auxiliary data into corresponding differential signals, and uses six TMDS channels # 0 to # 5. Serial transmission is performed in one direction to the data receiving unit 122.

  The HDMI receiver 82 of the data receiver 122 corresponds to differential signals corresponding to video data, audio data, and control data transmitted in one direction from the data transmitter 112 via TMDS channels # 0 to # 5. Receive differential signals. In this case, the HDMI receiver 82 reproduces the pixel clock from the received data and receives it in synchronization with the pixel clock (TMDS clock).

  In addition to the above-described TMDS channel and TMDS clock channel, there are transmission channels called DDC (Display Data Channel) and CEC line as transmission channels of the HDMI system. The DDC includes two signal lines (not shown) included in the cable 200. The DDC is used by the data transmission unit 112 to read E-EDID (Enhanced Extended Display Identification Data) from the data reception unit 122.

  That is, in addition to the HDMI receiver 82, the data receiving unit 122 has an EDID ROM (EEPROM) that stores E-EDID that is capability information related to its capability (Configuration / capability). For example, in response to a request from the control unit 113, the data transmission unit 112 reads the E-EDID from the data reception unit 122 connected via the cable 200 via the DDC.

  The data transmission unit 112 sends the read E-EDID to the control unit 113. The control unit 113 stores this E-EDID in a flash ROM or DRAM (not shown). The control unit 113 can recognize the setting of the capability of the data reception unit 122 based on the E-EDID. For example, the control unit 113 recognizes whether or not the sink device 120 including the data receiving unit 122 is compatible with new HDMI in addition to the current HDMI. The CEC line is composed of one signal line (not shown) included in the cable 200, and is used for bidirectional communication of control data between the data transmission unit 112 and the data reception unit 122.

  The cable 200 includes a line (HPD line) connected to a pin called HPD (Hot Plug Detect). The source device can detect the connection of the sink device using the HPD line. This HPD line is also used as a HEAC-line constituting a bidirectional communication path. The cable 200 includes a power line (+ 5V Power Line) used for supplying power from the source device to the sink device. Further, the cable 200 includes a utility line. This utility line is also used as a HEAC + line constituting a bidirectional communication path.

  FIG. 5 shows an example of the structure of TMDS transmission data. FIG. 5 shows sections of various transmission data when image data of horizontal x vertical B pixels x A lines is transmitted in TMDS channels # 0 to # 2 or TMDS channels # 0 to # 5. ing. There are three types of sections in a video field in which transmission data is transmitted using the HDMI TMDS channel, depending on the type of transmission data. These three types of sections are a video data period, a data island period, and a control period.

  Here, the video field period is a period from the rising edge (active edge) of a certain vertical synchronizing signal to the rising edge of the next vertical synchronizing signal. The video field period is divided into a horizontal blanking period (horizontal blanking), a vertical blanking period (vertical blanking), and an active video period (Active Video). In this active video section, a video data section that is a section obtained by removing the horizontal blanking period and the vertical blanking period from the video field section is assigned to the active video section. In this video data section, B pixel (pixel) × A pixel effective pixel (Active pixel) data constituting uncompressed image data for one screen is transmitted.

  The data island period and the control period are assigned to the horizontal blanking period and the vertical blanking period. In the data island section and the control section, auxiliary data (Auxiliary data) is transmitted. That is, the data island period is assigned to a part of the horizontal blanking period and the vertical blanking period. In this data island period, for example, audio data packets that are not related to the control among the auxiliary data are transmitted. The control period is allocated to other parts of the horizontal blanking period and the vertical blanking period. In this control period, for example, vertical synchronization signals, horizontal synchronization signals, control packets, and the like, which are data related to control, of auxiliary data are transmitted.

  Here, the pin assignment of the receptacle 111 will be described. First, the current HDMI pin assignment (type A) will be described. This current HDMI pin assignment constitutes the first pin assignment. FIG. 6A shows the pin assignment of this current HDMI. TMDS Data # i + and TMDS Data # i−, which are differential signals of TMDS channel #i (i = 0 to 2), are transmitted by two lines that are differential lines. Pins (pin numbers 7, 4, and 1) are assigned to TMDS Data # i +, and pins (pin numbers 9, 6, and 3) are assigned to TMDS Data # i−. The pins with pin numbers 8, 5, and 2 are assigned to TMDS Data # i Shield (i = 0 to 2).

  TMDS Clock + and TMDS Clock− which are differential signals of the TMDS clock channel are transmitted by two lines which are differential lines. The pin with pin number 10 is assigned to TMDS Clock +, and the pin with pin number 12 is assigned to TMDS Clock-. Note that the pin having the pin number 11 is assigned to the TMDS Clock Shield.

  Also, the CEC signal that is control data is transmitted through the CEC line. The pin with the pin number 13 is assigned to the CEC signal. An SDA (Serial Data) signal such as E-EDID is transmitted through the SDA line. A pin having a pin number of 16 is assigned to the SDA signal. Further, an SCL (Serial Clock) signal, which is a clock signal used for synchronization at the time of transmission / reception of the SDA signal, is transmitted through the SCL line. A pin with a pin number of 15 is assigned to the SCL. The DDC line described above is composed of an SDA line and an SCL line.

  A pin with a pin number of 19 is assigned to HPD / HEAC-. A pin with pin number 14 is assigned to utility / HEAC +. A pin with a pin number of 17 is assigned to DDC / CEC Ground / HEAC Shield. Furthermore, the pin with the pin number 18 is assigned to the power supply (+ 5V Power).

  Next, a new HDMI pin assignment will be described. This new HDMI pin assignment constitutes a second pin assignment. FIG. 6B shows the pin assignment of this new HDMI. TMDS Data # i + and TMDS Data # i−, which are differential signals of TMDS channel #i (i = 0 to 5), are transmitted by two lines which are differential lines. Pins (pin numbers 1, 4, 7, 10, 2, and 8) are assigned to TMDS Data # i +, and pins (pin numbers 3, 6, 9, 12, 5, and 11) are TMDS Data. Assigned to # i-.

  Also, the CEC signal that is control data is transmitted through the CEC line. The pin with the pin number 13 is assigned to the CEC signal. An SDA (Serial Data) signal such as E-EDID is transmitted through the SDA line. A pin having a pin number of 16 is assigned to the SDA signal. Further, an SCL (Serial Clock) signal, which is a clock signal used for synchronization at the time of transmission / reception of the SDA signal, is transmitted through the SCL line. A pin with a pin number of 15 is assigned to the SCL. The DDC line described above is composed of an SDA line and an SCL line.

  A pin with a pin number of 19 is assigned to HPD / HEAC-. A pin with pin number 14 is assigned to utility / HEAC +. A pin with a pin number of 17 is assigned to DDC / CEC Ground / HEAC Shield. Furthermore, the pin with the pin number 18 is assigned to the power supply (+ 5V Power).

  As described above, in the new HDMI pin assignment (see FIG. 6B), terminals (pin numbers 2, 5, and 5) used as shield terminals in the current HDMI pin assignment (see FIG. 6A). 8 and 11 pins) are used as data terminals. In the new HDMI pin assignment, a terminal (pin numbers 10 and 12) used as a signal terminal of a differential signal of a clock signal in the current HDMI pin assignment is used as a data terminal.

  When operating in the current HDMI operation mode, the data transmission unit 112 of the source device 110 selects the current HDMI pin assignment shown in FIG. 6A, and when operating in the new HDMI operation mode, FIG. The new HDMI pin assignment shown in FIG. In the above description, the pin assignment of the receptacle 111 of the source device 110 has been described. Although the detailed description is omitted, the same applies to the pin assignment of the receptacle 121 of the sink device 120 when the data receiving unit 122 of the sink device 120 supports both the current HDMI and the new HDMI.

  7A and 7B show the pin arrangement of the receptacle 111 of the source device 110. FIG. FIG. 7A shows the pin arrangement of the current HDMI, and FIG. 7B shows the pin arrangement of the new HDMI. When the current HDMI pin assignment is selected as the pin assignment of the receptacle 111, the pins with the pin numbers 2, 5, 8, and 11 are grounded in the source device 110 and the sink device 120, or the sink device. The ground state is set at 120, the high impedance state is set at the source device 110, the high impedance state is set at the sink device 120, and the ground state is set at the source device 110. Although not described in detail, the same applies to the pin arrangement of the receptacle 121 of the sink device 120 when the data receiving unit 122 of the sink device 120 supports both the current HDMI and the new HDMI.

  FIG. 8A shows a structure example of the current HDMI cable used as the cable 200. This current HDMI cable is configured as a shielded twisted pair portion so that each of the three data line pairs can obtain characteristics. The clock line pair and the utility and HPD line pair for the HEAC function are also configured as a shield twist pair.

  FIG. 8B shows a structural example of the shield twisted pair portion. The shield twisted pair portion has a structure in which two electric wires 3 and a drain wire 4 are covered with a shield member 5. The electric wire 3 is configured such that the core wire 1 is covered with a covering portion 2.

  In the current HDMI cable, the drain wire constituting each shield twisted pair portion of data and clock is connected to a pin of a plug attached to the end portion of the cable. In this case, each drain line is connected to a pin (terminal) corresponding to each shield terminal (shield pin having pin numbers 2, 5, 8, and 11) of the above-described receptacle (current HDMI pin arrangement). . These shield terminals are grounded in the source device 110 and the sink device 120. As a result, the drain lines constituting the shield twisted pair portions of the data and the clock are grounded when the plug is connected to the receptacle (current HDMI pin arrangement).

  FIG. 9 shows a structure example of a new HDMI cable used as the cable 200. This new HDMI cable is configured as a shielded twisted pair portion so that each of the six data line pairs can obtain characteristics. For the HEAC function, the utility and HPD line pairs are also configured as shield twisted pairs.

  The new HDMI cable has an increased number of individual copper wires to be connected as compared with the current HDMI cable (see FIG. 8A). In this new HDMI cable, the drain wire constituting each shield twisted pair connected by the dedicated pins of the plug at both ends of the cable is connected to the metal shell of the plug. As a result, the shielding pins are opened, and an increase in the number of necessary pins of the plug is avoided, and the plug in the new HDMI cable is the same as the plug of the current HDMI cable. Thus, in the case where the drain wire constituting each shield twisted pair portion is connected to the metal shell of the plug, the receptacle shell into which the plug is inserted is connected to the ground level, so that the differential A pair line shield can be secured.

  FIG. 10 shows another structural example of the new HDMI cable used as the cable 200. The new HDMI cable has substantially the same structure as the new HDMI cable shown in FIG. 9 except that the cross-sectional shape is flattened. It is known that by flattening the cross-sectional shape in this way, the cross-sectional area can be reduced and impedance matching can be easily achieved.

[Operation mode control of current HDMI and new HDMI]
Next, the operation mode control of the control unit 113 of the source device 110 will be further described. As described above, when determining that the cable 200 is compatible with the new HDMI and the sink device 120 is compatible with the new HDMI, the control unit 113 controls the data transmission unit 112 to the operation mode of the new HDMI. In other cases, the control unit 113 controls the data transmission unit 112 to the current HDMI operation mode.

  The flowchart of FIG. 11 shows a processing procedure of operation mode control of the control unit 113. In step ST1, the control unit 113 starts processing, and then proceeds to processing in step ST2. In step ST2, the control unit 113 determines whether or not the source device 110, that is, the data transmission unit 112 is compatible with the new HDMI. Since the control unit 113 includes in advance capability information of the source device 110 (data transmission unit 112) in which the control unit 113 exists, this determination can be easily performed. In this embodiment, since it is clear that the source device 110 is compatible with the new HDMI, the control unit 113 may omit the determination process in step ST2.

  When determining that the source device 110 is compatible with the new HDMI, the control unit 113 determines whether or not the sink device 120, that is, the data receiving unit 113 is compatible with the new HDMI, in step ST3. Details of this determination will be described later. When determining that the sink device 120 is compatible with the new HDMI, the control unit 113 proceeds to the process of step ST4. In step ST4, the control unit 113 determines whether or not the cable 200 is compatible with the new HDMI. Details of this determination will be described later.

  When determining that the cable 200 is compatible with the new HDMI, the control unit 113 proceeds to the process of step ST5. In step ST5, the control unit 113 controls the data transmission unit 112 to operate in the new HDMI operation mode. When determining in step ST2, step ST3, and step ST4 that the source device 110, the sink device 120, and the cable 200 are not compatible with the new HDMI, the control unit 113 proceeds to the process of step ST6. In step ST6, the control unit 113 controls the data transmission unit 112 to operate in the current HDMI operation mode.

  For example, when it is determined in step ST3 that the sink device 120 is compatible with the new HDMI, the control unit 113 transmits the final operation mode determination result to the sink device 120 via the cable 200. . The determination result is transmitted as control information such as an info frame before data transmission from the source device 110, for example. In the sink device 120, based on the determination result of the operation mode from the source device 110, the control unit 123 controls the data reception unit 122 to operate in the same operation mode as the data transmission unit 112 of the source device 110. .

  Further, when the control unit 113 controls the data transmission unit 112 to operate in the new HDMI operation mode in step ST5, a UI screen indicating that is displayed, for example, as shown in FIG. You may control to display on a part (display). From this UI screen, the user can easily grasp that the source device 110 and the sink device 120 are connected by the new HDMI. The display unit (display) on which the UI screen is displayed is a display unit (display) (not shown) provided in the source device 110 or a display unit (display) (not shown) provided in the sink device 120. The same applies to the following UI displays.

  Further, when the control unit 113 determines in step ST4 that the cable 200 does not support the new HDMI and moves to the process of step ST6, a UI screen indicating that is shown in FIG. 12C, for example. In addition, it may be controlled to display on a display unit (display). With this UI screen, the user can easily recognize that the source device 110 and the sink device 120 are compatible with the new HDMI, but only the cable 200 is not compatible with the new HDMI. You can take measures such as replacing the

  Further, in the processing procedure of the flowchart of FIG. 11, when the control unit 113 determines in step ST4 that the cable 200 is compatible with the new HDMI, the control unit 113 immediately proceeds to step ST5 and the data transmission unit 112 operates in accordance with the new HDMI operation. Control to operate in mode. However, when the control unit 113 determines in advance in step ST4 that the cable 200 is compatible with the new HDMI by exchanging commands through a line such as CEC in advance before data transmission, the control unit 113 notifies the user of the new HDMI or the current HDMI. (Conventional HDMI) may be selected.

  In this case, the control unit 113 performs control so that the UI screen for that purpose is displayed on a display unit (display) as shown in FIG. The user selects either new HDMI or current HDMI based on this UI screen. FIG. 12B shows a state where “new HDMI” is selected. The control unit 113 controls the data transmission unit 112 to operate in the new HDMI or current HDMI operation mode according to the user's selection.

  The flowchart of FIG. 13 shows a processing procedure of operation mode control of the control unit 113 in that case. In FIG. 13, portions corresponding to those in FIG. 11 are denoted by the same reference numerals, and detailed description thereof is omitted. When the control unit 113 determines in step ST4 that the cable 200 is compatible with the new HDMI, the control unit 113 proceeds to the process in step ST7. In step ST7, the control unit 113 controls the display unit (display) to display a UI screen for selecting either the new HDMI or the current HDMI. This UI display may be transmitted as a video signal by the source device 110 through the transmission path 200, or the sink device 120 may instruct the display to be displayed by itself.

  Thereafter, the control unit 113 proceeds to the process of step ST8. In step ST8, the control unit 123 notifies the operation of the user's remote control or the like through a line such as CEC, so that the control unit 113 determines whether the user has selected new HDMI or current HDMI. When the user selects new HDMI, in step ST5, the control unit 113 controls the data transmission unit 112 to operate in the new HDMI operation mode. On the other hand, when the user selects the current HDMI, in step ST6, the control unit 113 controls the data transmission unit 112 to operate in the operation mode of the current HDMI (conventional HDMI).

"Judgment of sink device to support new HDMI"
A method for determining whether or not the sink device 120 supports the new HDMI in the control unit 113 will be described. As this determination method, for example, there are the following first determination method and second determination method.

"First judgment method"
The control unit 113 determines whether or not the sink device 120 is compatible with the new HDMI based on the EDID read from the sink device 120 using the DDC line (SDA line and SCL line) of the cable 200. The EDID itself has a data structure defined on the format. Assume that new flag information indicating whether or not the sink device 120 is compatible with new HDMI (new transmission) is newly defined at a predetermined location of the EDID.

  FIG. 14 shows an example of flag information newly defined on the EDID. Originally, EDID is a data structure indicating the capabilities of various sink devices 120. FIG. 14 shows only the bytes of the EDID related to the present invention for the sake of simplification and is simplified to the minimum. In the second bit, 1-bit flag information “New Rx Sink” indicating whether or not the sink device 120 supports the new HDMI is described. Further, 1-bit flag information “New Cable” indicating whether or not the cable 200 is compatible with the new HDMI is newly defined in the first bit.

  When the above-described 1-bit flag information “New Rx Sink” is present in the EDID read from the sink device 122, the control unit 113 determines that the sink device 120 is compatible with the new HDMI. That is, when the sink device 120 supports only the current HDMI, the above-described 1-bit flag information “New Rx Sink” does not exist in the EDID read from the sink device 122.

"Second judgment method"
The control unit 113 performs communication with the sink device 120 through the cable 200 to determine whether or not the sink device 120 is compatible with the new HDMI. For example, the control unit 113 uses the CEC line to check whether the sink device 120 is compatible with the new HDMI on a command basis.

  Further, for example, the control unit 113 communicates with the sink device 120 using a bidirectional communication path (HEAC function) configured by a utility line and an HPD line, and the sink device 120 supports the new HDMI. Check if it is. Further, for example, the control unit 113 exchanges some signal using an unused line, for example, a utility line until transmission becomes valid, and determines whether or not the sink device 120 supports the new HDMI. Confirm.

"Judgment of cable compatibility with new HDMI"
Next, a method for determining whether or not the cable 200 is compatible with the new HDMI in the control unit 113 will be described. Examples of this determination method include the following first to fourth determination methods. The first to third determination methods are determination methods performed using the information providing function of the cable 200 when the cable 200 is a new HDMI cable.

"First judgment method"
In the case of this first determination method, as shown in FIG. 15, the new HDMI cable incorporates an LSI (Large Scale Integration) in a plug, for example. For example, in a state where +5 V is supplied from the source device 110, the sink device 120 requests the LSI to output using the CEC protocol while the HPD is dropped to L. Note that the sink device 120 in this case is a sink device compatible with the new HDMI. In response to an output request from the sink device 120, the LSI sends the register value (indicating that it is compatible with the new HDMI and cable characteristic data such as a transmittable data band) to the sink device 120. Report with CEC protocol.

  The sink device 120 adds the information reported from the LSI to its own EDID. The sink device 120 instructs the source device 110 to read the EDID by setting the HPD to H after the additional writing. Based on the EDID read from the sink device 120, the control unit 113 determines whether the cable 200 is compatible with the new HDMI. That is, the control unit 113 determines that the cable 200 is compatible with the new HDMI when information such as that the cable 200 is compatible with the new HDMI is included.

  In the above description, the sink device 120 has been described as requesting output from the LSI using the CEC protocol. However, the source device 110 itself requests an output from the LSI using the CEC protocol, and directly receives a report of a register value (indicating that it is compatible with the new HDMI and cable characteristic data such as a transmittable data band) from the LSI. It is also possible.

"Second judgment method"
Also in the case of this second determination method, as shown in FIG. 15, the new HDMI cable includes an LSI in a plug, for example. The source device 110 reads and acquires the EDID indicating the capability from the sink device 120, for example, at the timing when the HPD changes from L to H. In this case, the EDID is notified to the source side by serially transmitting the data written in the EEPROM of the sink device 120 using the SDA / SCL line.

  The LSI observes a line through which EDID information is transmitted, that is, an SDA / SCL signal during EDID transmission. Then, when the flag information (the first bit of the predetermined byte in FIG. 14) indicating whether or not the cable 200 is compatible with the new HDMI is transmitted, the LSI sets the bit value to the new HDMI. Change to a compatible state, that is, a flag is set. That is, the data on the EDIDROM (EEPROM) of the sink device 120 is “00000100”, but becomes “00000110” when the LSI in the cable rewrites the data during transmission and the source device 110 receives the data.

  Based on the EDID read from the sink device 120, the control unit 113 determines whether the cable 200 is compatible with the new HDMI. That is, when the flag information (first bit of the predetermined byte in FIG. 14) indicating whether or not the cable 200 is compatible with the new HDMI is in a state corresponding to the new HDMI, the control unit 113 It is determined that the cable 200 is compatible with the new HDMI.

  FIG. 16 shows an example of the EDID data rewriting circuit of the LSI in the cable. This LSI has a counter that counts clocks on the SCL line and a driver that rewrites data on the SDA line based on the count value of the counter.

“Third Judgment Method”
In the case of this third determination method, as shown in FIG. 17, the new HDMI cable has an RF tag chip (LSI) in which information such as the plug is compatible with the new HDMI and information such as a transmittable data band is stored. Is built-in. In addition, an RF tag read chip (LSI) is built in the receptacle 111 of the source device 110. In this case, short-range wireless communication is performed between the RF tag reading chip of the receptacle 111 and the RF tag chip of the plug, and information stored in the RF tag chip is read by the RF tag reading chip.

  The control unit 113 determines whether or not the cable 200 is compatible with the new HDMI based on information read by the RF tag reading chip. That is, the control unit 113 determines that the cable 200 is compatible with the new HDMI when information such as that the cable 200 is compatible with the new HDMI is read by the RF tag reading chip.

  In the above description, short-range wireless communication is performed between the RF tag reading chip of the receptacle 111 of the source device 110 and the RF tag chip of the plug so that the information stored in the RF tag chip is read on the source device 110 side. Explained. However, for example, short-range wireless communication is performed between the RF tag reading chip of the receptacle 121 of the sink device 120 and the RF tag chip of the plug, and information stored in the RF tag chip is read on the sink device 120 side. It is conceivable that the information is then provided to the source device 110 side.

“Fourth Judgment Method”
In the case of this fourth determination method, the control unit 113 determines whether the cable 200 is compatible with the new HDMI by measuring the electrical characteristics of the cable 200. As shown in FIG. 18, the control unit 113 of the source device 110 transmits a measurement / detection test signal (digital signal) to the pins 2 and 5, and the control unit 123 of the sink device 120 outputs the signal. Receive. In the current HDMI cable, the pair of signal lines connected to the pins 2 and 5 do not constitute a differential signal transmission path, but in the new HDMI cable, the pair of signal lines connected to the pins 2 and 5 Constitutes a differential signal transmission path (see FIGS. 6A and 6B).

  The control unit 123 of the sink device 120 notifies the source device 110 of the received digital signal through another path (for example, an HDMI DDC line indicated by SCL / SDA, a CEC line, a utility line, or the like). The control unit 113 of the source device 110 determines whether or not the cable 200 is compatible with the new HDMI by confirming that the digital signal notified from the sink device 120 matches the digital signal transmitted by itself. . That is, the control unit 113 determines that the cable 200 is compatible with the new HDMI when the received digital signal matches the transmitted digital signal.

  As shown in FIG. 19A, when the cable 200 is a current HDMI cable, the pair of signal lines connected to the pins 2 and 5 are not shielded twisted pair wires. For this reason, the fact that the cable 200 is compatible with the current HDMI is used as “a high-speed test signal cannot be transmitted”. At this time, by applying a signal unrelated to the pin 2 to the pin 1 or the pin 3 related to the pin 2, the interference can be used. This interference makes high-speed test signals more difficult to transmit.

  On the other hand, as shown in FIG. 19B, when the cable 200 is a new HDMI cable, the pair of signal lines connected to the pins 2 and 5 are shielded twisted pair wires. For this reason, the determination that the cable 200 is compatible with the new HDMI cable uses “high-speed test signal can be transmitted”. At this time, even if a signal unrelated to the pin 2 is applied to the pin 1 or the pin 3, they are shielded independently, and the applied signal and the pin 2 do not interfere with each other. And does not affect the transmission of the test signal.

Here, the test signal is, for example, the fastest data that can be output by the source device 110 and random data that is long enough to evaluate 10 ⁻⁹ guaranteed by HDMI as the bit error rate. Since the sink device 120 has a built-in frame buffer memory for normal video reproduction, a memory dedicated for this transmission test may not be necessary.

  In the above description, the control unit 113 determines that the cable 200 is compatible with the new HDMI only when the received digital signal matches the transmitted digital signal. The control unit 113 performs a similar test by reducing the data transfer rate, and repeats the above determination process until they match, thereby determining the cable performance and determining that it is compatible with the new HDMI. You may make it perform the transmission which can be performed within the transmission speed. In this case, the current HDMI cable may be determined to be compatible with the new HDMI.

  In the above description, the pins 2 and 5 are used. However, instead of these pins, the pins 8 and 11 having the same relationship as these pins between the current HDMI cable and the new HDMI cable may be used. That is, the pair of signal lines connected to the pins 8 and 11 in the current HDMI cable does not constitute a differential signal transmission path, but the pair of signal lines connected to the pins 8 and 11 in the new HDMI cable. Constitutes a differential signal transmission path (see FIGS. 6A and 6B).

  In the above description, the sink device 120 that has received the digital signal (test signal) sent from the source device 110 to the sink device is notified to the source device 110, and the source device 110 determines whether it is correct or not. showed that. However, by transmitting a predetermined pattern as a digital signal (test signal), the sink device 120 determines whether the received digital signal is correct, and notifies only the result to the source device 110 through a line such as CEC. Alternatively, the information may be added to its own E-EDID.

  As described above, in the AV system 100 shown in FIG. 1, the data transmission unit 112 of the source device 110 has an operation mode of the new HDMI mode in addition to the current HDMI operation mode. Here, the differential signal channel for transmitting digital signals such as video data is 3 channels in the current HDMI, but 6 channels in the new HDMI. Therefore, signal transmission at a high data rate becomes possible by using the new HDMI. Further, when the sink device 120 and the cable 200 do not support the new HDMI, the backward compatibility is ensured by using the current HDMI (conventional HDMI).

<2. Modification>
In the above embodiment, the plug shape of the new HDMI cable is the same as the plug shape of the current HDMI cable (conventional HDMI cable). However, the shape of the plug of the new HDMI cable is made different from the shape of the plug of the current HDMI cable so that when one of the source device and the sink device does not support the new HDMI, they are not connected with the new HDMI cable. You can also.

  FIG. 20A shows the shape of the plug of the current HDMI cable, and FIG. 20B shows the shape of the receptacle of the source device or sink device that supports only the current HDMI. On the other hand, FIG. 20C shows the shape of the plug of the new HDMI cable, and FIG. 20D shows an example of the shape of the receptacle of the source device or sink device corresponding to the new HDMI. 21A is a perspective view of the plug of the current HDMI cable, and FIG. 21B is a perspective view of the plug of the new HDMI cable.

  The plug of the new HDMI cable is provided with a convex portion (indicated by an arrow P). The receptacle of the source device or sink device compatible with the new HDMI is provided with a concave portion (indicated by an arrow Q) corresponding to the convex portion of the plug. In this case, the shape of the receptacle of the source device or sink device corresponding to the new HDMI matches the shape of the plug of the new HDMI cable, and includes the shape of the plug of the current HDMI cable.

  By setting the shape of the plug of the new HDMI cable and the shape of the receptacle of the source device or sink device compatible with the new HDMI as described above, the new HDMI cable can be used as a receptacle of the source device or sink device compatible with the new HDMI. Can connect. However, the new HDMI cable cannot be connected to a receptacle of a source device or a sink device that supports only the current HDMI. Thus, when one of the source device and the sink device does not support the new HDMI, they are not connected by the new HDMI cable. In other words, only when both the source device and the sink device are compatible with the new HDMI, these connections can be made with the new HDMI cable.

  As described above, the shape of the receptacle of the source device or sink device that also supports the new HDMI matches the shape of the plug of the new HDMI cable, and includes the shape of the plug of the current HDMI cable. Therefore, the current HDMI cable can be connected not only to a receptacle of a source device and a sink device compatible only with the current HDMI, but also to a receptacle of a source device and a sink device compatible with the new HDMI.

  In the above-described embodiment, there are three differential signal channels for transmitting digital signals such as video data in the current HDMI, whereas the new HDMI has six differential signal channels. showed that. However, the number of differential signal channels for transmitting digital signals such as video data is not limited to 6 channels, and 4 channels, 5 channels, 7 channels, and the like are also conceivable. For example, the number of differential signal channels for transmitting digital signals such as video data is set to 5 channels, and the clock frequency is increased to about 1.2 times to obtain a data transfer rate equivalent to that of 6 channels. It becomes possible.

  In the above-described embodiment, the present invention is applied to an AV system in which a source device and a sink device are connected by a digital interface of the HDMI standard. The present invention can be similarly applied to AV systems connected by other similar digital interfaces.

  The present invention can be applied to, for example, an AV system in which a source device and a sink device are connected via a digital interface.

81 ... HDMI transmitter 82 ... HDMI receiver 100 ... AV system 110 ... Source device 111 ... Receptacle 112 ... Data transmission unit 113 ... Control unit 120 ... Sink device 121 ..Receptacle 122 ... Data receiving unit 123 ... Control unit 200 ... Cable 201, 202 ... Plug

Claims (4)

A cable for transmitting a digital signal from a transmitting device to a receiving device by a differential signal of a predetermined number of channels,
A cable having an information providing function unit for providing information indicating the signal transmission capability of the cable to the transmitting device or the receiving device. The information providing function unit provides information indicating the signal transmission capability of the cable to the receiving device or the transmitting device via the cable in response to a request from the receiving device or the transmitting device. The cable according to 1. The cable according to claim 1, wherein the information providing function unit rewrites part of the capability information that the transmitting device reads from the receiving device via the cable. The cable according to claim 1, wherein the information providing function unit provides the transmitting device or the receiving device with information indicating the signal transmission capability of the cable through short-range wireless communication.