JP4799254B2 - Display device and display system - Google Patents

Description

  The present invention relates to a display device and a display system, and more particularly, to a display device that can be connected to an output device such as a DVD playback device through a digital interface such as HDMI (High Definition Multimedia Interface), and a display system including the device.

  Conventionally, a DVI (Digital Visual Interface) standard is known as an interface for transmitting a digitized video signal at high speed between a computer main body and a display. A digital connection standard called HDMI (High Definition Multimedia Interface), which is a further development of DVI, is known. The purpose of this is to digitally connect an output device such as an STB (Set Top Box) and a display in the home in response to changes such as digitization of TV broadcasting and switching of a display device to a flat panel.

  In this HDMI, a function for transmitting an audio signal and a control signal is added to satisfy the demand for TV use. Conventionally, multiple cables are used for video, audio, and control signals for connection between devices, but only one HDMI cable is required, and control signals are compatible with bidirectional transmission. By relaying a control signal to an output device such as an STB or DVD player connected via HDMI, it is possible to operate the entire AV system (home theater, etc.) with a single remote controller.

  In this way, prevention of duplication becomes more important when content is digitally transmitted. For this reason, HDMI employs HDCP (High-bandwidth Digital Contents Protection) as an unauthorized copy prevention function to prevent unauthorized copying.

  Furthermore, in consideration of user convenience, HDMI incorporates measures such as downsizing of the connector and simplification of handling. For example, a hot plug function that enables plugging / unplugging of the cable even during operation and a DDC / CI (Display Data Channel / Command Interface) function that automatically sets the optimum screen resolution are defined. Even can be connected without special knowledge.

  For example, Patent Document 1 and Patent Document 2 describe a system for receiving and displaying a video signal from an output device connected to an output device such as a DVD player by using the DVI standard or HDMI standard interface described above. ing.

  FIG. 3 is a block diagram illustrating a configuration example of a conventional transmission / reception system described in Patent Document 1. In FIG. In the figure, the transmission / reception system includes a transmission device 105 and a reception device 206. In the transmission / reception system, the transmission device 105 is a part of the transmission-side processing device 100 for reading video data recorded on a recording medium 103 such as a DVD and transmitting it as a digital video signal. The reception device 206 is a part of the display device 200 that displays the digital video signal received from the transmission side processing device 100, and is supplied in the form of a single LSI, for example.

  The transmission side processing device 100 and the display device 200 are connected to each other by a transmission line 300 compliant with the DVI standard. Here, the transmission-side processing device 100 is an output device such as a personal computer or a DVD player, and the display device 200 is a display device such as a television receiver or a liquid crystal monitor.

  The transmission-side processing apparatus 100 includes a first memory that holds the first device key 102, a transmission control unit 104, a transmission data processing unit 101 for processing a video signal recorded on the recording medium 103, and a transmission A transmission device 105 is connected to the control unit 104 and the transmission data processing unit 101, respectively, and encrypts and transmits a video signal.

  The transmission device 105 is connected to the transmission control unit 104, and includes an encryption control unit 105c for encrypting the video signal, a data encryption unit 105b connected to the transmission data processing unit 101, and a data encryption unit 105b. A data transmission unit 105a that outputs an encrypted video signal to the display device 200 via the high-speed bus 301 in the transmission path 300 is provided.

  On the other hand, the display device 200 receives the encrypted video signal and receives the reception device 206 for decrypting the video signal, the second memory for holding the second device key 204, and the reception side information 205. A third memory, a reception control means 203 connected to the second memory and the third memory, a reception data processing means 201 for processing the video signal decoded by the reception device 206, and a reception data processing means 201 And a display panel 202 for displaying the video signal processed in. Note that the third memory is connected to the transmission control unit 104 via the low-speed bus 302 in the transmission path 300.

  The receiving side information 205 includes EDID (Extended Display Identification Data). In particular, when the current DVI standard or HDMI standard is used, the EDID becomes the reception side information 205. This EDID includes information on the types of signals that can be processed by the display device 200, information such as the resolution of the display panel 202, information such as a pixel clock, a horizontal effective period, and a vertical effective period.

  The receiving device 206 is connected to the data receiving means 206a for receiving the encrypted video signal via the high-speed bus 301, the decryption control means 206c connected to the reception control means 203, and the data receiving means 206a. And data decrypting means 206b for decrypting the encrypted video signal.

  The operation of the conventional transmission / reception system having the reception device 206 and the transmission device 105 as main parts as described above will be described by taking as an example the case where video data recorded on a recording medium 103 such as a DVD is displayed on the display panel 202. .

  First, the video data recorded on the recording medium 103 is subjected to predetermined signal processing by the transmission data processing means 101. For example, the transmission data processing unit 101 performs a process of decoding video data recorded in a compressed state on the recording medium 103.

  Next, the video signal sent from the transmission data processing means 101 is encrypted by the data encryption means 105b using the above-mentioned HDCP. The encrypted video signal is sent to the data transmission unit 105a, and the data transmission unit 105a sends the encrypted video signal to the high-speed bus 301. Note that, in the DVI standard, transmission is performed by a method called TMDS (Transition Minimized Differential Signals). The high-speed bus 301 is a serial transmission path, and is provided with a transmission path for each of the red, green, and blue channels and a clock transmission path. The video signal separated into red, green, and blue is transmitted as a baseband signal in the transmission path.

  The maximum transfer speed of the high-speed bus 301 is about 750 Mbit / sec or more for each channel. In addition, since a differential signal is used in the TMDS system, resistance to noise and signal distortion is high.

  Next, the data receiving unit 206a receives the encrypted video signal via the high-speed bus 301, and sends this video signal to the data decrypting unit 206b. Next, the encrypted video signal is decrypted by the data decryption means 206b and restored to the original video signal. Thereafter, the restored video signal is sent to the reception data processing means 201. After predetermined signal processing is performed in the reception data processing means 201, an image is displayed from the display panel 202. The received data processing unit 201 performs processing such as gradation correction and optimization of signal output to the display panel 202 in accordance with the horizontal / vertical scanning cycle.

  In the DVI standard, a plug and play function is realized, and a video signal is transmitted in accordance with the resolution of a display panel to be used. In order to realize this plug and play, the transmission path 300 is provided with a low-speed bus 302. The low-speed bus 302 is called a DDC (Display Data Channel), and an I2C bus that is a bidirectional bus is used. This I2C bus is a low-speed serial bus having a maximum transfer clock frequency of 100 kHz. The transmission control means 104 acquires the receiving side information (EDID) 205 via the low-speed bus 302, thereby realizing a plug and play function.

  The low-speed bus 302 is also used for HDCP authentication processing. In HDCP, after authenticating that the receiving device is not an unauthorized device, encrypted transmission is started. Information necessary for this authentication process is transmitted via the low-speed bus 302.

The reception control unit 203 controls the decryption control unit 206c to perform an operation in a predetermined procedure using the second device key 204. The obtained calculation result is transmitted to the transmission control means 104 via the low speed bus 302. The transmission control unit 104 controls the encryption control unit 105 c to perform calculation in a predetermined procedure using the first device key 102. From the obtained calculation result and the calculation result from the reception control means 203, it is confirmed that the receiving (display) device is not an unauthorized device. For example, a microcomputer is used for the reception control unit 203 and the transmission control unit 104.
JP 2005-51558 A Utility Model Registration No. 3112392

  Some display devices including the above-described HDMI / DVI compatible devices have a power management function for the purpose of reducing power consumption during standby. According to the power management function, for example, when a signal from the PC is not detected on the display device side in a state where the PC and the display device are digitally connected, the display device is automatically turned off. be able to.

  However, conventionally, when the power management function is executed in digital connection such as HDMI / DVI, it is necessary to always turn on the power of the receiving means (TMDS receiver) in the display device in order to detect the digital signal. there were. Since this TMDS receiver is composed of an IC chip or the like, it is not preferable from the viewpoint of energy saving to always supply power to this TMDS receiver because it increases power consumption.

  The present invention has been made in view of the above circumstances, and monitors the access to a low-speed bus such as a DDC bus at the time of digital connection such as HDMI / DVI, and according to whether or not the low-speed bus is accessed. An object of the present invention is to provide a display device capable of controlling power supply to a receiving means (TMDS receiver) and a display system including the device.

In order to solve the above problems, a first technical means of the present invention is a display device for displaying a video signal, unrealized and DDC bus transmission speed is smaller than the digital signal transmission bus and the digital signal transfer bus DVI Means for connecting to a transmission path conforming to the standard or HDMI standard, receiving means for receiving a video signal via the digital signal transfer bus, and receiving an HDCP authentication request via the DDC bus ; and a monitoring means for monitoring the access to the DDC bus associated with receiving before the HDCP authentication request, if access to the DDC bus is detected by said monitoring means, and starts power supply to the receiving means , if access to the DDC bus is not detected a predetermined time, it was also characterized by stopping or limiting the power supply to the receiving means It is.

According to a second technical means, in the first technical means, when the access to the DDC bus is detected and power supply is started, the receiving means authenticates the display device based on the HDCP authentication request. The video signal is received later via the digital signal transfer bus.

A third technical means is an output device for outputting an image signal, a display device for displaying a video signal, or a digital signal transfer bus and said digital signal transfer unrealized DVI standard and a DDC bus transmission speed is smaller than the bus In a display system comprising a transmission line conforming to the HDMI standard, and wherein the output device and the display device are connected via the transmission line, the output device transmits a video signal via the digital signal transfer bus. And a transmission means for transmitting an HDCP authentication request via the DDC bus, wherein the display device receives the video signal via the digital signal transfer bus and sends the HDCP authentication request via the DDC bus. Bei receiving means for receiving, and monitoring means for monitoring the access to the DDC bus associated with the HDCP authentication request before reception of the video signal , If access to the DDC bus is detected by said monitoring means, and starts power supply to the receiving means, if access to the DDC bus is not detected a predetermined time, stops the power supply to the receiving means Or it is characterized by limiting .

According to a fourth technical means, in the third technical means, the output device detects the HDCP authentication request when access to the DDC bus is detected by the display device and power supply to the receiving means is started. The video signal is transmitted through the digital signal transfer bus after the authentication processing of the display device based on the above.

  According to the present invention, during digital connection such as HDMI / DVI, access to a low-speed bus such as a DDC bus is monitored, and power is supplied to a receiving means (TMDS receiver) depending on whether or not the low-speed bus is accessed. Therefore, it is not necessary to turn on the receiving means during standby or the like, and power consumption can be reduced to save energy.

  Hereinafter, preferred embodiments of a display device and a display system including the device according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a configuration example of a display system according to an embodiment of the present invention, in which 10 denotes a display device, 20 denotes an output device, and 30 denotes a digital transmission path. The display device 10 is digitally connected to the output device 20 via the digital transmission path 30. The display device 10 is a device that receives a video / audio signal. For example, the display device 10 is a television receiver having a thin display panel such as an LCD or a PDP, or a display device such as a projector that can be digitally connected. The output device 20 is a device that supplies video / audio signals. For example, all output devices that can be digitally connected, such as STBs, DVD players, and digital video cameras, are targeted. The digital transmission path 30 is a digital interface (hereinafter referred to as an HDMI cable 30) conforming to the above-described HDMI standard or DVI standard.

  Both the display device 10 and the output device 20 are provided with means for connecting the HDMI cable 30 (HDMI connectors 11 and 21 respectively) so that they can be digitally connected to each other. The HDMI cable 30 transmits more than the digital signal transfer bus 31 corresponding to the first bus of the present invention, which is a high-speed bus for transmitting video / audio signals as digital signals at high speed, and the digital signal transfer bus 31. And a DDC bus 32 corresponding to the second bus of the present invention which is a low-speed bus having a low speed. The DDC bus 32 is a bus used for HDCP authentication and enables bidirectional communication.

  The output device 20 transmits the video / audio signal via the HDMI connector 21 for connecting the HDMI cable 30 and the digital signal transfer bus 31, and transmits the HDCP authentication request via the DDC bus 32. Control the overall operation of the output device 20, the TMDS transmitter 22 corresponding to the transmission means, the video processing unit 23 for performing predetermined signal processing such as decoding of the compressed video signal recorded on the recording medium 25 such as a DVD, etc. And a CPU 24 for doing so.

  The TMDS transmitter 22 corresponds to the transmission device 105 shown in FIG. 3 described above, and encrypts the video / audio signal and sends it to the HDMI cable 30 via the HDMI connector 21. The output device 20 is controlled to perform the encrypted transmission for the first time after authenticating that the display device 10 is not an unauthorized device by HDCP authentication. At the time of HDCP authentication, the output device 20 can freely access the memory of the display device 10 via the DDC bus 32 and acquire information necessary for HDCP authentication. That is, information necessary for HDCP authentication is held in the memory of the display device 10, and the information is read from the memory of the display device 10 according to the authentication request from the output device 20, and is transmitted via the DDC bus 32. And transmitted to the TMDS transmitter 22.

  Then, the CPU 24 executes the authentication process of the display device 10 based on the information necessary for the HDCP authentication. When the display device 10 is authenticated as appropriate, the CPU 24 controls the TMDS transmitter 22 to The audio signal is encrypted and sent to the digital signal transfer bus 31.

  Further, the display device 10 receives the video / audio signal via the HDMI connector 11 for connecting the HDMI cable 30 and the digital signal transmission bus 31 and also receives the HDCP authentication request via the DDC bus 32. TMDS receiver 12 corresponding to the receiving means of the present invention and a predetermined signal such as tone correction for the received video signal and optimization of signal output to the display unit 17 described later according to the horizontal / vertical scanning cycle A video processing unit 13 that performs processing, a CPU 14 for controlling the overall operation of the display device 10, a memory 15 such as a flash memory or an EEPROM that holds information necessary for HDCP authentication, and a DDC bus 32 associated with HDCP authentication And an access monitoring means 16 for monitoring access to the display and a display unit 17 such as an LCD (liquid crystal display). That.

  The TMDS receiver 12 corresponds to the receiving device 206 shown in FIG. 3 described above, and performs processing for receiving and decrypting an encrypted video / audio signal and restoring the original video / audio signal. The memory 15 holds information necessary for HDCP authentication (hereinafter referred to as authentication information) and is freely accessed from the output device 20. That is, when receiving the HDCP authentication request from the output device 20, the TMDS receiver 12 performs a process of extracting authentication information in the memory 15 and transmitting it to the output device 20 via the DDC bus 32. As described above, at the time of HDCP authentication, encrypted transmission from the output device 20 becomes possible only after authenticating that the display device 10 is not an unauthorized device.

  An example of the operation of the CPU 14 and the access monitoring means 16, which are the main features of the present invention, will be described. The display device 10 includes a receiving unit (not shown) for receiving an operation input signal from a remote controller or the like that is an operation input means for operating the display device 10, and a CPU 14 that controls the receiving unit during standby or the like. Is always supplied with power (standby power). The access monitoring means 16 is controlled by the CPU 14 and monitors access to the DDC bus 32 accompanying the HDCP authentication request from the output device 20. Note that the CPU 14 actually functions as the access monitoring unit 16, but is illustrated as a unit different from the CPU 14 for explanation.

  Since the HDMI / DVI standard stipulates that HDCP authentication be performed, the output device 20 accesses the DDC bus 32 and authenticates from the display device 10 for HDCP authentication before transmitting the video / audio signal. Need to get information. Therefore, the power supply to the TMDS receiver 12 can be controlled by monitoring the access to the DDC bus 32 in the display device 10.

  When the display device 10 is on standby or the like, the access monitoring means 16 monitors access to the DDC bus 32. At this time, it is assumed that the power supply to the TMDS receiver 12 is stopped or restricted. For example, when the output device 20 is activated, an HDCP authentication request is transmitted to the display device 10 via the DDC bus 32. When the access monitoring means 16 detects this access to the DDC bus 32, the CPU 14 controls to start supplying power to the TMDS receiver 12.

  Further, the CPU 14 has a timer function, and counts an elapsed time after the access to the DDC bus 32 is stopped. When the CPU 14 determines that the access to the DDC bus 32 is not performed for a predetermined time, the CPU 14 controls to stop or limit the power supply to the TMDS receiver 12. Thereafter, the access to the DDC bus 32 is always monitored, and the power supply to the TMDS receiver 12 is controlled according to the presence or absence of the access.

  When access to the DDC bus 32 is detected and power supply is started, the TMDS receiver 12 receives a video signal via the digital signal transfer bus 31 after the authentication process of the display device 10 based on the HDCP authentication request. . That is, when the access to the DDC bus 32 is detected by the display device 10 and the power supply to the TMDS receiver 12 is started, the TMDS transmitter 22 performs the digital signal after the authentication processing of the display device 10 based on the HDCP authentication request. A video signal is transmitted via the transfer bus 31.

  In this way, during digital connection such as HDMI / DVI, access to the DDC bus can be monitored and power supply to the TMDS receiver can be controlled according to whether or not the DDC bus is accessed. The receiver does not have to be turned on, and power consumption can be reduced to save energy.

  FIG. 2 is a flowchart for explaining an example of the flow of power control processing by the display system shown in FIG. In this example, the state in which power is not supplied to the TMDS receiver 12 will be described. First, the display device 10 determines whether or not there is an access to the DDC bus 32 accompanying the HDCP authentication request (step S1). When there is an access to the DDC bus 32 (in the case of YES), the display device 10 Power supply is started (step S2). In step S1, if there is no access to the DDC bus 32 (in the case of NO), a transition is made to a standby state in step S1, and access to the DDC bus 32 is monitored.

  Next, the display device 10 determines whether or not access to the DDC bus 32 is stopped (step S3). If access to the DDC bus 32 is stopped (in the case of YES), an elapsed time after the access is stopped. Is counted (step S4). If the access to the DDC bus 32 is not stopped at step S3 (in the case of NO), a transition is made to a standby state at step S3, and the access state to the DDC bus 32 is monitored.

  Next, the display device 10 determines whether or not a predetermined time has elapsed since the stop of access to the DDC bus 32 (step S5). If the predetermined time has elapsed (in the case of YES), the display device 10 supplies power to the TMDS receiver 12. Stop or limit (step S6), return to step S1, and monitor the access state to the DDC bus 32.

  On the other hand, in step S5, if the predetermined time has not elapsed (in the case of NO), it is determined whether or not there is access to the DDC bus 32 (step S7), and if there is access to the DDC bus 32 (in the case of YES) ) And return to step S3 to repeat the process. In step S7, if there is no access to the DDC bus 32 (NO), the process returns to step S5 and the process is repeated.

  As described above, according to the present invention, at the time of digital connection such as HDMI / DVI, the access to the low speed bus such as the DDC bus is monitored, and the receiving means (TMDS Since the power supply to the receiver) can be controlled, it is not necessary to turn on the receiving means during standby or the like, and power consumption can be reduced to save energy.

It is a block diagram which shows the structural example of the display system which concerns on one Embodiment of this invention. It is a flowchart for demonstrating an example of the flow of the power control process by the display system shown in FIG. It is a block diagram which shows the structural example of the conventional transmission / reception system described in patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Display apparatus, 11, 21 ... HDMI connector, 12 ... TMDS receiver, 13, 23 ... Image processing part, 14, 24 ... CPU, 15 ... Memory, 16 ... Access monitoring means, 17 ... Display part, 20 ... Output device , 22 TMDS transmitter, 25 recording medium, 30 digital transmission path (HDMI cable), 31 digital signal transfer bus, 32 DDC bus.

Claims (4)

In a display device that displays a video signal,
Means for connecting the digital signal transfer bus and DDC bus transmission speed is smaller than the digital signal transmission bus to the transmission path conforming to unrealized DVI standard or HDMI standard, receives a video signal via the digital signal transfer bus while, it comprises receiving means for receiving the HDCP authentication request via the DDC bus, and a monitoring means for monitoring the access to the DDC bus associated with the HDCP authentication request before reception of the video signal,
When access to the DDC bus is detected by the monitoring means, power supply to the receiving means is started, and when access to the DDC bus is not detected for a predetermined time, power supply to the receiving means is stopped or A display device characterized by limiting . 2. The display device according to claim 1 , wherein when the access to the DDC bus is detected and power supply is started, the receiving unit performs the digital device after authentication processing of the display device based on the HDCP authentication request. A display device that receives a video signal via a signal transfer bus. An output device for outputting a video signal, transmission path in accordance with a display device for displaying a video signal, a DDC bus transmission speed is smaller than the digital signal transmission bus and the digital signal transfer bus to unrealized DVI standard or HDMI standard In a display system in which the output device and the display device are connected via the transmission line,
The output device includes transmission means for transmitting a video signal via the digital signal transfer bus and transmitting an HDCP authentication request via the DDC bus,
The display device receives a video signal via the digital signal transfer bus and also receives a HDCP authentication request via the DDC bus, and the HDCP authentication request associated with the HDCP authentication request before receiving the video signal. Monitoring means for monitoring access to the DDC bus,
When access to the DDC bus is detected by the monitoring means, power supply to the receiving means is started, and when access to the DDC bus is not detected for a predetermined time, power supply to the receiving means is stopped or Display system characterized by limiting . 4. The display system according to claim 3 , wherein the output device detects the access based on the HDCP authentication request when the display device detects access to the DDC bus and starts supplying power to the receiving unit. A display system for transmitting a video signal through the digital signal transfer bus after authentication processing of the display device.

Images