KR20160126119A - Optical HDMI cable that supports the DDC - Google Patents

Abstract

The present invention relates to an optical HDMI cable, and more particularly, to a new optical HDMI cable structure in which video and audio signals are transmitted unidirectionally from the video source side to the video display device side and the DDC and CEC information are transmitted bidirectionally without increasing the number of optical fiber cores .
The optical HDMI cable according to the present invention is characterized in that low-speed bidirectional DDC and CEC information are superimposed on a high-speed clock signal transmission line, transmitted, and then extracted again. For this purpose, we substitute a reflective semiconductor optical amplifier (R-SOA) with a light emitting element and a light receiving element for the conventional unidirectional clock transmission. CEC) signals electrically overlapping or separating signals.
The optical HDMI cable according to the present invention adds a bidirectional transmission function for low-speed data (DDC and CEC) signals to the function of an optical HDMI cable for down-transmitting only conventional video and audio signals, Control and HDCP video playback.

Description

Optical HDMI cable supporting DDC {Optical HDMI cable that supports the DDC}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical HDMI cable structure,

To optical signal processing supporting DDC.

In the meantime, high definition multi-media interface (HDMI) cables have been developed for delivering full high definition (FHD) high definition video signals and have been used in video servers, bluerayplayer, (Cable length) of up to several tens of Gbps, because the signal bandwidth of ultra-high-quality video is wide ranging from several tens to several tens of Gbps. meter. < / RTI > In recent years, optical HDMI cables have been developed that convert video signals to optical signals using the characteristics of optical fibers with a very low signal attenuation, extending the range of use from several hundred meters to several tens of kilometers. In order to transmit three high-speed signals and one synchronous high-speed clock signal required for video and audio signal transmission, the optical HDMI cable is equipped with a light emitting element and a light receiving element And has a structure in which devices are arranged and an optical fiber is interposed therebetween. Depending on the length of the optical HDMI cable, multimode optical fibers are used for short distances and single mode optical fibers are used for long distances. Optical transmission and reception components using wavelength multiplexing technology are used to reduce the number of cores in the optical fiber used A technique for reducing the number of core wires from four to two or one is being developed. However, the conventional optical HDMI cable does not transmit bi-directional display data channel (DDC) and consumer electronics control (CEC) information, only transmitting video and audio signals from the video source side to the video display device side, It has the disadvantage that it does not support. In other words, since it is impossible to exchange bi-directional DDC and CEC information between the video source and the video display device, identification, screen adjustment, and remote control of the video display device can not be performed. Especially, It can not be reproduced.

Disclosure of Invention Technical Problem [8] The present invention has been conceived to solve the problems of the conventional optical HDMI cable described above, and it is an object of the present invention to provide a method and apparatus for transmitting video and audio signals unidirectionally from an image source side to a video display device, The present invention provides a new optical HDMI cable structure for transmitting optical signals, and also provides a dual wavelength transmission of DDC and CEC information by a single optical device, thereby providing applicability of a wavelength multiplexing technique for reducing the number of optical fiber cores have.

In order to solve the above problems, the optical HDMI cable according to the present invention is applied to a high-speed clock signal transmission line for synchronization, which has a transmission speed of about 1/10 as compared with three high-speed signal transmission lines required for video and audio signal transmission And superimposes / extracts low-speed bidirectional DDC and CEC information. For this purpose, we substitute a reflective semiconductor optical amplifier (R-SOA) with a light emitting element and a light receiving element for the conventional unidirectional clock transmission. CEC) signals electrically overlapping or separating signals. Here, the high-speed clock signal is continuously transmitted (downward) continuously from the image source side to the image display device side, and the low-speed data signal is half-duplexed from the downward direction or upward direction (from the image display device side to the image source side).

The optical HDMI cable according to the present invention adds a bidirectional transmission function for low-speed data (DDC and CEC) signals to the function of an optical HDMI cable for down-transmitting only conventional video and audio signals, In addition, when adding bidirectional transmission function for low-speed data (DDC and CEC) signals, it is necessary to increase the number of optical fiber cores or to increase the number of light emitting devices, It can be easily implemented with a single type of optical element and an electric filter without using an optical fiber, which is economical and has a high advantage of applicability of a wavelength multiplexing technique to reduce the number of optical fiber cores in the future.

1 is an HDMI configuration diagram.
2 is a block diagram of a conventional optical HDMI cable.
3 is a block diagram of an optical HDMI cable of the present invention (clock channel).
FIG. 4 is a signal processing diagram according to the present invention (downlink clock, downlink data).
5 is a signal processing diagram according to the present invention (downward clock, upstream data).

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing an HDMI configuration. Fig. 1 is a diagram showing an HDMI source 1 built in an image source device and a built- And an HDMI HDMI cable (5) connecting between the HDMI sockets (3). The electric HDMI cable 5 includes twisted pair 6 for three high-speed video / audio signal channels, twisted pair 7 for one high-speed clock channel, pair line 8 for DDC, and CEC (9). 2 is a block diagram of a conventional optical HDMI cable. In order to replace four super high-speed and high-speed twisted pair wires of an electric HDMI cable with an optical signal transmission system, a light emitting element driver 12 and a light emitting element 13 A light receiving element 15 and a signal amplifier 16 are disposed on the side of the HDMI sink 3 and an optical fiber 14 is connected between the light emitting and receiving elements on both sides. The optical HDMI cable 11 is provided at its both ends with an HDMI connector 17 for electrical connection between the HDMI source 1 side and the HDMI sink 3 side. The light emitting device 13 may be a VCSEL or an LD operating at wavelengths of 850 nm, 1300 nm, and 1550 nm. The light receiving device 15 may be a GaAs or InP photodiode depending on the wavelength of the light emitting device. The optical fiber 14 uses a single mode optical fiber (SMF) when the length of the optical HDMI cable is short to several hundred meters, and the multimode optical fiber (MMF) is several to several tens of km long. When the wavelengths of the light emitting devices 13 are different from each other, an optical sub-assembly in which two or four light emitting devices 13 and a light receiving device 15 are coupled to one optical fiber 14 by applying a wavelength division multiplexing (WDM) (OSA). In this case, the number of optical fibers 14 of the optical HDMI cable is two or one. FIG. 3 is a block diagram of an optical HDMI cable according to the present invention. The present invention has the same structure as that of the prior art in transmission of three high-speed optical signals required for transmission of video and audio signals, but it is also possible to superpose / extract low-speed bidirectional data (DDC and CEC information) . The reason for using the high-speed clock signal transmission line for bidirectional transmission of low-speed data below 10Mbps is that the clock signal speed is 165MHz (2k class FHD image transmission standard) to 600MHz (4k class UHD image transmission standard) 3 high-speed optical signal speeds are lower than 1 / 10th of 1.65Gbps ~ 6Gbps, while low-speed data rates are 10 times higher than 10Mbps, so that clocks and data can be superimposed or extracted with simple electric frequency filters. One of the other important features of the present invention is that the light emitting element 13 and the light receiving element 15 for the conventional unidirectional clock transmission are made of a reflective semiconductor optical amplifier (R-SOA) optical amplifier (30). That is, the reflection type optical amplifier 30 converts (or emits) an optical signal into an optical signal in accordance with an up-down high-speed clock signal and a low-speed data (DDC and CEC) And performs a function of converting (receiving) the optical signal back to an electrical signal. Here, the reflection type optical amplifier 30 has a basic light emitting operation characteristic of generating an optical signal by forward current modulation, and when receiving an optical signal from the outside in a state that a forward current is applied, And the light emission and the light receiving operation may occur at the same time. In addition, since a common VCSEL or LD has such a simultaneous light emission and light receiving characteristic, the fluctuation range of the light receiving voltage is small. Therefore, in the present invention, a reflection type optical amplifier 30 operating at a wavelength of 1550 nm will be used as a reference. 3, the high-speed clock signal transmitted continuously from the HDMI source 1 side to the HDMI sink 3 side is converted into a current modulation signal by the light-emitting element driver 12 and then transmitted through the RF mixer 22, Is converted into an optical signal by the optical fiber 30 and is transmitted through the optical fiber 14. The optical signal is converted into a voltage signal in the reflection type optical amplifier 30 on the side of the HDMI sink 3 and then passed through a clock high frequency pass filter 25 passing only a frequency of 25 MHz or more, Signal. (DDC and CEC) signals of the HDMI source 1 and the HDMI sink 3 are half-duplexed in the downward direction or the upward direction so that the signal control unit 20 disposed on the HDMI source 1 side and the HDMI sink 3 side It acts as a master and slave and handles signal transmission and reception. The signal controller 20 includes a multiplexing output stage 26 for multiplexing an input I ² C DDC signal and a general 1-wire serial CEC signal into a serial signal, a demultiplexer 26 for demultiplexing the inputted serial signal, Multiplexed input terminal 27 to output low-speed data in a downward or upward direction according to the control of the signal controller 20 serving as a master. The signal multiplexed in the signal controller 20 of the HDMI source 1 is converted into a current modulation signal in the low speed driver 21 and then transmitted through the RF mixer 22 to the reflection type optical amplifier 30 ) And is transmitted through the optical fiber 14. [ The optical signal is converted into a voltage signal by the reflection type optical amplifier 30 on the side of the HDMI sink 3 and then passed through a data low pass filter 23 and a low speed signal amplifier 24, And is demultiplexed by the control unit 20 into the original DDC signal and the CEC signal. The signal multiplexed by the signal controller 20 on the HDMI sink 3 side is converted into a current modulation signal by the low speed driver 21 and then converted into an optical signal by the reflection type optical amplifier 30 And is transmitted through the optical fiber 14. The optical signal is converted into a voltage signal in the reflection type optical amplifier 30 on the HDMI source 1 side and then passed through a low pass filter 23 for data and a low speed signal amplifier 24 for passing only a frequency of 10 MHz or less, And is demultiplexed by the control unit 20 into the original DDC signal and the CEC signal. When the low-speed data is transmitted downward by the master signal controller 20, the demultiplexing reception function of the master signal controller 20 and the multiplex transmission function of the slave signal controller 20 are turned off. On the contrary, when the slave signal controller 20 When the low-speed data is transmitted upward, the multiplexing transmission function of the master signal control unit 20 and the demultiplexing reception function of the slave signal control unit 20 are turned off. The RF mixer 22 has a function of superimposing a high-speed modulation current of 165 MHz and a low-speed modulation current of 10 Mbps or less, and is implemented as a passive RLC (resistor, inductor, capacitor) network or an RF mixing IC. The 25 MHz or more high-pass filter 25 and the 10 MHz or less low-pass filter 23 are implemented as a passive RLC network or an active IC filter for separating frequency components of an electric signal. Although the present invention describes an FHD-class optical HDMI cable with a clock speed of 165 MHz, it has the same effect even in an upper grade (for 4k class UHD) optical HMDI cable having a clock speed of 340 MHz and 600 MHz. That is, regardless of the class of the optical HMDI cable, the low-speed data is fixed at 10 Mbps or less, so that the bidirectional transmission / reception structure of the low-speed data of the present invention is the same, and only the clock transmission driver 12 and the amplifier 16 increase in speed do. At this time, the super high-speed signal rate for video and audio signals increases to 3.4 Gbps or 6 Gbps instead of 1.65 Gbps of the present invention. Also, the effects of the present invention are equally applied to a DVI including three high-speed video signals compatible with HDMI and one high-speed clock signal and a DDC signal. Considering the continuous downlink transmission of the high-speed clock signal and the time-division bidirectional transmission of the low-speed data signal, the DDC-supporting optical HDMI cable of the present invention has two operation states (downlink clock + downlink data) and downlink clock + 4 shows an operation example of (downward clock + downward data) operation of the reflection type optical amplifier 30 of the HDMI source 1 and the reflection function of the reflection side of the HDMI sink 3 side Type optical amplifier 30 performs a light receiving function. The reflection type optical amplifier 30 is composed of a pn junction active region 31 and a p-electrode 32 and an n-electrode 33 where optical / electric and electro-optical conversion takes place. An optical fiber 14, Respectively. On the HDMI source side, a high-speed clock signal and a low-speed data signal are converted into a current modulation signal through the drivers 12 and 21, respectively, and then converted into an optical signal by the reflection type optical amplifier 30 through the RF mixer 22 And is transmitted through the optical fiber 14. Here, the downlink optical signal is a form in which a high-speed clock signal is filled in the envelope of the low-speed data signal as shown in FIG. That is, the waveform amplitude of the high-speed clock signal becomes larger or smaller depending on the waveform of the low-speed data signal. When an optical signal is input in a state where forward DC current is applied to the reflection type optical amplifier 30 of the HDMI sink side, an optical signal amplification action occurs. Since the amplification of the optical signal occurs through the consumption of electrons and holes, the amount of charges in the pn junction active region 31 is reduced, which is a decrease in the applied voltage between the p-electrode 32 and the n-electrode 33 cause. Therefore, the downstream optical signal of FIG. 4 appears as a waveform-inverted voltage signal in the p-electrode 32 of the reflection type optical amplifier 30 of the HDMI sink side, and this is a principle in which the reflection type optical pulse fogger acts as a light receiving element. The received voltage signal is divided into a clock signal and a data signal through the high-pass filter 25 and the low-pass filter 23 of less than or equal to 25 MHz, respectively. Since each voltage signal at this time is weak in intensity, the clock signal is restored to the original clock signal through signal amplification and waveform reconstruction in the signal amplifier 16, and the data signal is transmitted to the signal controller 20 ), It is demultiplexed into the original DDC signal and the CEC signal after the waveform reversal.

5 shows an operation example of the downward clock + up data. Both the HDMI source 1 side and the reflection type optical amplifier 30 on the side of the HDMI sink 3 perform light emission and light reception functions at the same time. The downstream clock signal is converted into an optical signal in the reflection type optical amplifier 30 through the driver 12 and the RF mixer 22 and is transmitted in the form of a downstream optical signal through the optical fiber 14. [ The upstream data signal is converted into an optical signal by the reflective optical amplifier 30 through the driver 21 and transmitted through the optical fiber 14 in the form of an upstream optical signal. At this time, a voltage signal in which the light emitting signal and the light receiving signal are superimposed is displayed on the p-electrode 32 of the HDMI source side and the reflection type optical amplifier 30 of the HDMI sink side, Because. That is, since the voltage signal corresponding to the clock signal and the waveform inverted voltage signal of the data signal are superimposed on the p-electrode 32 of the reflection type optical amplifier 30 of the HDMI source side, the low-frequency pass filter 23 of less than 10 MHz Only the upstream data signal can be extracted. The extracted upstream data signal is demultiplexed into the original DDC signal and the CEC signal after the waveform reversal in the signal controller 20 via the low-speed signal amplifier 24. Similarly, since the voltage signal corresponding to the data signal and the waveform inverted voltage signal of the clock signal are superimposed on the p-electrode 32 of the reflection mirror type optical amplifier 30 of the HDMI sink side, the high- Only the downstream clock signal can be extracted. The extracted downstream clock signal is restored to the original clock signal through signal amplification and waveform reconstruction in the signal amplifier 16.

DESCRIPTION OF THE REFERENCE NUMERALS
1: HDMI source 2: HDMI sink
5: Electrical HDMI cable 11: Optical HDMI cable
14: optical fiber 20: signal control section
23: low-pass filter 25: high-pass filter
30: reflection type optical amplifier

Claims (6)

An HDMI connector 17 for electrical connection is provided at both ends and a driver 12 and a light emitting element 13 are connected to the HDMI source 1 and a light receiving element 15 and a signal amplifier 16 are connected to the HDMI sink 3, And an optical fiber 14 between the light emitting and receiving elements on both sides of the HDMI source 1. The FHD-class optical HDMI cable has three optical transmission lines for video and audio transmission at a speed of 1,65 Gbps. The device driver 12, the RF mixer 22 and the reflection type optical amplifier 30 are connected to the reflection type optical amplifier 30, the 25 MHz or higher high-frequency pass filter 25 and the signal amplifier 16 and an optical transmission line for a 165 MHz clock signal for connecting the two reflection type optical amplifiers 30 to each other with an optical fiber 14 are added and a signal control unit 20 serving as a master is disposed on the HDMI source 1 side The output of the multiplexing output stage 26 is input to the RF mixer 22 via the low-speed driver 21. The voltage signal of the reflection-type optical amplifier 30 is 10 MHz Via a low-pass filter 23 and low-speed signal amplifier 24 is input to the demultiplexer input 27
A signal controller 20 serving as a slave is disposed on the HDMI sink 3 side and an output of the multiplexer 26 is input to a reflective optical amplifier 30 through a low- (30) is input to a demultiplexing input (27) via a low-pass filter (23) and a low-speed signal amplifier (24) of 10 MHz or less.
The optical HDMI cable according to claim 1, wherein a semiconductor optical device such as a VCSEL or an LD is used in place of the reflective optical amplifier (30).
The method according to claim 1,
Wherein the optical fiber (14) is a single mode optical fiber, a multimode optical fiber, or a large diameter plastic optical fiber.
The method according to claim 1,
Four wavelengths of light emitting elements on the side of the HDMI source 1 were cross-arranged at 1310 nm and 1550 nm, and then optical sub-assemblies were applied using a multiplexing technique for two wavelengths to reduce the number of optical fiber core wires to two, The optical HDMI cable is fabricated from an optical sub-assembly employing multiple techniques for four wavelengths after different placement, thereby reducing the number of optical fiber cores to one.
The method according to claim 1,
The optical HMDI cable for a 4k class UHD is characterized in that the speed of the driver 12 for clock transmission and the speed of the amplifier 16 are increased to 340 MHz or 600 MHz and the super high speed signal speed for video and voice signals is increased to 3.4 Gbps or 6 Gbps.
The method according to claim 1,
Wherein the connection of the HDMI connector (17) is replaced by a DVI connector.

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