JP3857889B2 - Image signal transmission system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image transmission side device such as a personal computer, an image reception side device composed of a display device such as a liquid crystal projector or a plasma display panel (PDP), and digital image data and analog image data generated by the image transmission side device. The present invention relates to an image signal transmission system including an image signal transmission device having a function of transmitting to an image reception side device via a cable.
[0002]
[Prior art]
When an image signal created by a personal computer is transmitted to a display device using an analog transmission cable, image degradation is likely to occur if the analog transmission cable becomes longer. In particular, when the resolution is high, such as a display device of 1024 × 768 pixels (XGA) and 1280 × 1024 pixels (SXGA), the image deterioration becomes conspicuous.
[0003]
Therefore, an image signal transmission apparatus that does not cause image degradation even when the transmission cable length is long has already been developed, and one of them is “PanelLink” (panel link) developed by Silicon Image, Inc. of the United States. This was developed based on a signal transmission technology called TMDS (Transition Minimized Differential Signaling).
[0004]
TMDS is a signal transmission technique in which red, blue, and green signals (RGB) and a clock signal are serially transmitted in a differential manner. The differential system is a system that transmits one signal with two transmission lines. It realizes noise resistance and stable signal transmission, and achieves higher transmission speed and longer cable length. . However, even in this method, if the resolution of the image data becomes higher (ultra high resolution) such as 1600 × 1200 pixels (UXGA) and 2048 × 1536 pixels (QXGA), it will reach the physical limit of the cable and will be difficult to transmit. .
[0005]
To solve this problem, there is a so-called “DualLink method” proposed by the standardization group DDWG (Digital Display Working Group) in the DVI (Digital Visual Interface) specification. Rather than transmitting each RGB signal in one channel, that is, three channels as in the conventional "PanelLink" (this is called "SingleLink" method versus "DualLink" method), each RGB signal is one phase two By phase-converting and transmitting each channel as 2 channels, that is, 6 channels, it is possible to secure twice the bandwidth compared to the “SingleLink” system, thus enabling image transmission with ultra-high resolution (UXGA ~). Can do. In addition, since the transmission rate can be lowered by performing one-phase to two-phase conversion on the signal, transmission with a longer cable length can be enabled.
[0006]
FIG. 5 shows the configuration of a signal transmission apparatus adopting the “SingleLink” system, and FIG. 6 shows the configuration of a signal transmission apparatus adopting the “DualLink” system.
[0007]
In the signal transmission apparatus adopting the “SingleLink” method, image data that is a parallel signal is input to the PanelLink Transmitter 201 as shown in FIG. PanelLink Transmitter 201 performs parallel-serial conversion of image data from a parallel signal to a serial signal. The image data converted into the serial signal is transmitted through the cable 202 and sent to the PanelLink Receiver 203. The cable 202 includes three pairs of signal lines for transmitting image data and a pair of signal lines for transmitting clock signals. PanelLink Receiver 203 performs serial-parallel conversion of the received serial signal into a parallel signal.
[0008]
In the signal transmission apparatus adopting the “DualLink” method, as shown in FIG. 6, even data of image data which is a parallel signal is input to the PanelLink Transmitter 301 and odd data is input to the PanelLink Transmitter 302. Each of the PanelLink Transmitters 301 and 302 performs parallel-serial conversion of image data from a parallel signal to a serial signal.
[0009]
The even data of the image data converted into the serial signal by the PanelLink Transmitter 301 is transmitted through the cable 303 and sent to the PanelLink Receiver 304. The odd data of the image data converted into the serial signal by the PanelLink Transmitter 302 is transmitted through the cable 303 and sent to the PanelLink Receiver 305. The cable 303 includes six pairs of signal lines for transmitting image data and a pair of signal lines for transmitting clock signals. Each PanelLink Receiver 304, 305 performs serial-parallel conversion of the received serial signal into a parallel signal.
[0010]
In the “DualLink” system of FIG. 6, RGB image data that is a parallel signal is not distributed to even data and odd data, and is directly input to the PanelLink Transmitter 301 without operating the PanelLink Transmitter 302 (power down mode). By operating only the PanelLink Receiver 304 and setting the PanelLink Receiver 305 to the power down mode, the system is the same as the “SingleLink” method in FIG.
[0011]
[Problems to be solved by the invention]
By the way, DVI (Digital Visual Interface) stipulates “DVI-D” as a connector that has only a digital interface (“SingleLink” system or “DualLink” system). "DVI-I" is also specified as a connector that can be connected. This "DVI-I" can be connected to a conventional analog display device as it is.
[0012]
“DVI-D” has 24 connector pins, but “DVI-I” has 29 connector pins.
[0013]
FIG. 3 shows an arrangement of connector pins of the DVI-I connector 31 and an assignment table for each pin.
[0014]
The DVI-I connector 31 has 18 pins for TMDS (TMDS clock, data, shield), 5 pins for control (Display Data Channel, Hot Plug Detect, Power, GND), and analog (RGB, Return, 6 pins are available for H-Sync, V-Sync).
[0015]
If such a DVI-I connector 31 is used in a display device, the following image display can be performed.
[0016]
For example, two liquid crystal panels are installed in the image receiving side device. Then, digital image data and analog image data of the same content are sent from one PC to the image receiving side device via the DVI-I connector 31, and the digital image data is displayed on one of the liquid crystal panels. Is displayed on the other liquid crystal panel.
[0017]
Note that digital image data and analog image data of different contents are sent from one PC to the image receiving side device, one image is displayed on one liquid crystal panel, and the other image data is displayed on the other liquid crystal panel. You may do it.
[0018]
In addition, as shown in FIG. 7, the DVI-I connector is connected to the image receiving side device 503 having two liquid crystal panels, the digital connector (DVI-D connector or the like) is connected to the first PC 501, and the second PC 502 is connected. When an analog connector (VGA connector or the like) is provided and the connector of each of the PCs 501 and 502 is connected to the DVI-I connector of the image receiving side device 503, a digital image generated on the first PC 501 and an analog image generated on the second PC 502 Can be simultaneously sent to the image receiving side device 503 for display.
[0019]
However, as shown in FIG. 3, in the DVI-I connector 31, the digital connector pin and the analog connector pin are close to each other. In particular, in the case of DualLink transmission, the connector pins (pin numbers; 4) of the analog signal (RGB) connector pins (pin numbers; C1, C2, C3) and the digital signals (DATA0 to 5). , 5,12,13,20,21).
[0020]
The cable is designed to shield the paired signals so that the signals do not interfere with each other. However, if analog signals and digital signals (especially with DualLink) are input simultaneously, Interference on the substrate is unavoidable, and it is extremely difficult to separate signals on the substrate of the image receiving side device.
[0021]
For example, in order to separate the signals on the board wiring, it is necessary to wire both signal lines long, but the digital signal here is a high speed signal of several hundred bps to Gbps order. In other words, the signal quality is deteriorated.
[0022]
An object of the present invention is to provide an image signal transmission system capable of avoiding simultaneous input of an analog signal and a digital signal by DualLink transmission from an image transmission side device to an image reception side device.
[0023]
[Means for Solving the Problems]
An image signal transmission system according to the present invention has a function of transmitting digital image data and analog image data generated by an image transmission side device, an image reception side device, and an image transmission side device to the image reception side device via a cable. In an image signal transmission system that includes two operation modes, SingleLink mode and DualLink mode, as an operation mode for transmitting digital image data, the image signal transmission device includes: Digital detection means for detecting whether digital image data is sent by the image signal transmission device, Analog detection means for detecting whether analog image data is sent by the image signal transmission device, Digital image data Mode detection means for detecting the operation mode when And transmission means for transmitting the detection results of the digital detection means, the analog detection means, and the operation mode detection means to the image transmission side device. The image transmission side device is based on the received detection results. The digital image data and the analog image data are both sent to the image receiving side, and the determination means for determining whether or not the digital image data transmission operation mode is the DualLink mode. When both data are transmitted and the operation mode of the digital image data transmission is the DualLink mode, there is provided a means for switching the operation mode of the digital image data transmission to the SingleLink mode.
[0024]
As the transmission means for transmitting the detection result to the image transmission side device, one that transmits the detection result by wire or one that transmits the detection result by wireless is used.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS.
[0026]
[1] Description of configuration of image signal transmission system
FIG. 1 shows the configuration of an image signal transmission system according to the present invention.
[0028]
The image signal transmission system includes digital image data and analog image data generated by a personal computer (image transmission side device) 1, a liquid crystal projector (image reception side device) 20, and a personal computer (hereinafter referred to as PC) via a cable. And an image signal transmission device having a function of transmitting to the liquid crystal projector 20.
[0029]
The image signal transmission apparatus includes a transmission unit 10 attached to the PC 1, a reception side unit 105 attached to the liquid crystal projector 20, and a cable 30 connecting the transmission unit 10 and the reception side unit 105. The transmission unit 10 and the receiving unit 105 are provided with a DVI-I connector 31 as shown in FIG. As the cable 30, a DVI-I connector cable for connecting the DVI-I connector 31 of the transmission unit 10 and the DVI-I connector 31 of the receiving unit 105 is used.
[0030]
The transmission unit 10 includes a graphics controller (graphic board) 101, a switching circuit 102, a one-phase / two-phase conversion circuit 103, and a transmission side unit 104. The graphics controller 101 is connected to the main CPU 2 in the PC 1 via the bus 3 in the PC 1. A line receiver 145 is connected to the main CPU 2. The transmission side unit 104 includes a first PanelLink Transmitter 111 and a second PanelLink Transmitter 112.
[0031]
The reception side unit 105 in the liquid crystal projector 20 includes a first PanelLink Receiver 131, a second PanelLink Receiver 132, and an analog signal processing circuit 133. In the first PanelLink Receiver 131, a one-phase / two-phase conversion circuit 131a is provided. It is connected to a digital drive type liquid crystal panel 106 in the liquid crystal projector 20. The first PanelLink Receiver 131 and the second PanelLink Receiver 132 are connected to the first liquid crystal panel 106a. The analog signal processing circuit 133 is connected to the second liquid crystal panel 106b.
[0032]
In the liquid crystal projector 20, a digital detection circuit 141, a dual detection circuit 146, an analog detection circuit 142, a CPU 143, and a line driver 144 are provided.
[0033]
A transmission side unit 104 in the transmission unit 10 and a reception side unit 105 in the liquid crystal projector 20 are connected by a cable 30. The cable 30 includes six pairs of image data transmission signal lines, one pair of clock signal transmission signal lines, and a control signal line for digital transmission, and three image signals for analog transmission. A transmission signal line and control signal lines (H, V) are provided.
[0034]
This image signal transmission apparatus can transmit digital image data and analog image data. Also, there are two operation modes when transmitting digital image data: a DualLink mode in which transmission is performed using the DualLink method, and a SingleLink mode in which transmission is performed using the SingleLink method.
[0035]
[2] Description of operation during digital image signal transmission
[2-1] Explanation of operation in SingleLink mode [0037]
When the SingleLink mode is set as the operation mode, parallel digital image data (R, G, B) output from the graphics controller 101, clock signals and control signals (H, V, DE (Display Enable)) ) Is directly input to the first PanelLink Transmitter 111 without being sent to the one-phase / two-phase conversion circuit 103 via the switching circuit 102. In this case, the second PanelLink Transmitter 112 is not operating in the power down mode.
[0038]
The first PanelLink Transmitter 111 encodes image data and a clock signal and performs parallel-serial conversion to convert the image data from a parallel signal to a serial signal. The obtained RGB serial signals for each channel are transmitted through the cable 30 and sent to the first PanelLink Receiver 131 in the receiving unit 105. In this case, the second PanelLink Receiver 132 enters the power down mode and does not operate. The first PanelLink Receiver 131 performs data extraction, serial-parallel conversion, and decoding on the code sent from the first PanelLink Transmitter 111 in the transmission-side unit 104 to obtain parallel image data, H, V and DE are generated.
[0039]
When the first PanelLink Receiver 131 does not send an image signal to the second PanelLink Receiver 132 (SingleLink mode), the obtained parallel image signal is converted into a one-phase two-phase signal by a one-phase two-phase conversion circuit 131a. The RGB even data and odd data obtained thereby are sent to the first liquid crystal panel 106a. In addition, the first PanelLink Receiver 131 divides the generated H, V, DE and the received clock signal by 1/2 by the one-phase / two-phase conversion circuit 131a and sends it to the first liquid crystal panel 106a.
[0040]
Information on whether or not an image signal is sent to the second PanelLink Receiver 132 is sent from the second PanelLink Receiver 132 to the first PanelLink Receiver 131.
[0041]
When an image signal is sent to the second PanelLink Receiver 132 (DualLink mode), the first PanelLink Receiver 131 sends the obtained parallel signal as it is to the first liquid crystal panel 106a.
[0042]
[2-2] Explanation of operation in DualLink mode
When the DualLink mode is set as the operation mode, parallel digital image data (R, G, B) output from the graphics controller 101 is sent through the switching circuit 102 to the one-phase / two-phase conversion circuit 103. And is separated into even data and odd data. The even data is input to the first PanelLink Transmitter 111 in the transmission side unit 104. The odd data is input to the second PanelLink Transmitter 112 in the transmission side unit 104.
[0044]
The clock signal and control signal (H, V, DE (Display Enable)) output from the graphics controller 101 are sent to the one-phase / two-phase conversion circuit 103, divided by 1/2, and then sent to the transmission side. Input to the first PanelLink Transmitter 111 and the second PanelLink Transmitter 112 in the unit 104.
[0045]
The first PanelLink Transmitter 111 encodes even data and a clock signal and performs parallel-serial conversion to convert the even data from a parallel signal to a serial signal. The second PanelLink Transmitter 112 encodes the odd data and the clock signal and performs parallel-serial conversion to convert the odd data from the parallel signal to the serial signal.
[0046]
Serial signals of two RGB channels obtained by the first PanelLink Transmitter 111 and the second PanelLink Transmitter 112 are transmitted through the cable 30 and transmitted to the first PanelLink Receiver 131 and the second PanelLink Receiver 132 in the receiving unit 105. It is done.
[0047]
The first PanelLink Receiver 131 performs data extraction, serial-parallel conversion and decoding on the code sent from the first PanelLink Transmitter 111 to generate parallel signals, H, V, and DE for even data. To do. The second PanelLink Receiver 132 performs data extraction, serial-parallel conversion and decoding on the code transmitted from the second PanelLink Transmitter 112 to generate a parallel signal for odd data.
[0048]
Parallel signals (even data and odd data of each RGB) obtained by both PanelLink Receivers 131 and 132 are sent to the first liquid crystal panel 106a. Further, the H, V, DE generated by the first PanelLink Receiver 131 and the received clock signal are also sent to the first liquid crystal panel 106a.
[0049]
[3] Description of operation during analog image signal transmission
In analog signal transmission, analog image signals (R, G, B) and H, V signals output from the graphics controller 101 are sent to the analog signal processing circuit 133 in the receiving unit 105 via the cable 30.
[0051]
The analog signal processing circuit 133 performs A / D conversion on the received analog R, G, B data, performs scaling processing on a desired resolution and gradation, and sends the obtained image data to the second liquid crystal panel 106b. .
[0052]
[4] Description of Control Based on Detection Signals of Digital Detection Circuit 141, Dual Detection Circuit 146, and Analog Detection Circuit 142
The digital detection circuit 141 detects whether a digital image signal has been sent to the liquid crystal projector 20. The digital detection circuit 141 detects whether or not a digital image signal has been sent based on the clock CLK sent to the receiving side unit 105. As the digital detection circuit 141, a circuit that detects whether a digital image signal is transmitted based on a digital RGB signal may be used.
[0054]
The dual detection circuit 146 detects whether or not the operation mode of digital image signal transmission is the DualLink mode when a digital image signal is sent to the liquid crystal projector 20. The dual detection circuit 146 detects whether or not the operation mode of the digital image signal transmission is the DualLink mode based on the DATA5 signal sent to the receiving side unit 105. As the dual detection circuit 146, a circuit that detects whether or not the operation mode of digital image signal transmission is the DualLink mode based on the DATA3 or DATA4 signal may be used.
[0055]
The analog detection circuit 142 detects whether an analog image signal is sent to the liquid crystal projector 20. Based on the horizontal synchronization signal H, the analog detection circuit 142 detects whether an analog image signal is being sent. As the analog detection circuit 142, a circuit that detects whether or not an analog image signal is transmitted based on the analog RGB signal may be used.
[0056]
The detection result of the digital detection circuit 141, the detection result of the dual detection circuit 146, and the detection result of the analog detection circuit 142 are sent to the CPU 143. The CPU 143 feeds back the detection results to the line receiver 145 in the PC 1 on the transmission side via the line driver 144.
[0057]
The detection result received by the line receiver 145 in the PC 1 is input to the main CPU 2. The main CPU 2 determines an operation mode of digital image signal transmission based on the detection result sent from the CPU 143 in the liquid crystal projector 20 and sends a control signal corresponding to the operation mode to the graphics controller 101 via the bus 3.
[0058]
FIG. 2 shows an operation mode switching processing procedure by the main CPU 2.
[0059]
First, when image transmission is started (step 1), the CPU 143 in the liquid crystal projector 20 waits for an analog signal detection result, a digital signal detection result, and a digital image signal transmission operation mode detection result (step 1). 2). When the analog signal detection result, the digital signal detection result, and the digital image signal transmission operation mode detection result are sent, it is determined whether both the analog signal and the digital signal are detected (step 3).
[0060]
If both analog and digital signals are not detected, that is, if only one or both of the analog and digital signals are detected, the current operation The mode switching process ends.
[0061]
When both the analog signal and the digital signal are detected, it is determined whether or not the operation mode of digital image signal transmission is the DualLink mode (step 4).
[0062]
When the operation mode of digital image signal transmission is not the DualLink mode, that is, when the operation mode is the SingleLink mode, the current operation mode switching process ends.
[0063]
When the digital image signal transmission operation mode is the DualLink mode, a command for switching the digital image signal transmission operation mode from the DualLink mode to the SingleLink mode is output to the graphics controller 101 (step 5). Upon receiving this command, the graphics controller 101 outputs an operation mode switching control signal to the switching circuit 102 so that the operation mode of digital image signal transmission becomes the SingleLink mode. Thereby, the operation mode of digital image signal transmission is switched to the SingleLink mode.
[0064]
According to the above embodiment, when both the digital image data and the analog image data are sent to the liquid crystal projector 20 and the operation mode of the digital image signal transmission is the DualLink mode, it is attached to the personal computer (PC) 1. In the transmission unit 10, the digital image signal transmission operation mode is switched to the SingleLink mode. As a result, it is avoided that the analog image data interferes with the digital image data by the DualLink transmission on the liquid crystal projector 20 side.
[0065]
As shown in FIG. 4, a wireless transmission method may be adopted as a transmission method of a detection result transmitted from the liquid crystal projector 20 on the reception side to the PC 1 on the transmission side. In FIG. 4, the detection result output from the CPU 143 is transmitted from the wireless transmitter 147 and received by the wireless receiver 148.
[0066]
The present invention can also be applied to a system as shown in FIG. 7, that is, an image signal transmission system in which the image transmission side device is configured by two PCs.
[0067]
【The invention's effect】
According to the present invention, it is possible to avoid simultaneous input of an analog signal and a digital signal by DualLink transmission from the image transmission side device to the image reception side device.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an image signal transmission system.
FIG. 2 is a flowchart showing an image output selection processing procedure performed by the main CPU 2;
FIG. 3 is a schematic diagram showing an arrangement of connector pins of DVI-I and an assignment table of each pin.
FIG. 4 is a block diagram illustrating a configuration of another image transmission system.
FIG. 5 is a block diagram showing a configuration of an image signal transmission apparatus adopting a “Single Link” method.
FIG. 6 is a block diagram showing a configuration of an image signal transmission apparatus adopting a “Dual Link scheme” scheme.
FIG. 7 is a block diagram showing an image signal transmission system in which the image transmission side device is composed of two PCs.
1 PC
2 Main CPU
DESCRIPTION OF SYMBOLS 10 Transmission unit 20 Liquid crystal projector 30 Cable 101 Graphics controller 104 Transmission side unit 111, 112 PanelLink Transmitter
105 Receiver unit 131, 132 PanelLink Receiver
133 Analog signal processing circuits 106a and 106b Liquid crystal panel 141 Digital detection circuit 142 Analog detection circuit 143 CPU
144 Line driver 145 Line receiver 146 Dual detection circuit 147 Wireless transmitter 148 Wireless receiver

Claims (3)

An image transmission side device, an image reception side device, and an image signal transmission device having a function of transmitting digital image data and analog image data generated by the image transmission side device to the image reception side device via a cable. The signal transmission apparatus is an image signal transmission system having two operation modes, SingleLink mode and DualLink mode, as operation modes when transmitting digital image data.
The image receiving side device is a digital detection means for detecting whether or not digital image data is sent by the image signal transmission device, and an analog detection for detecting whether or not analog image data is sent by the image signal transmission device. Means for detecting the operation mode when digital image data is sent, and a transmission means for transmitting the detection results of the digital detection means, the analog detection means and the operation mode detection means to the image transmission side device. And
Based on the received detection results, the image transmission side device sends both digital image data and analog image data to the image reception side device, and whether the operation mode of digital image data transmission is the DualLink mode or not. When the digital image data and the analog image data are both sent to the image receiving side device and the operation mode of the digital image data transmission is the DualLink mode, the operation of the digital image data transmission An image signal transmission system comprising means for switching the mode to the SingleLink mode. The image signal transmission system according to claim 1, wherein the transmission means for transmitting the detection result to the image transmission side device transmits the detection result by wire. 2. The image signal transmission system according to claim 1, wherein the transmission means for transmitting the detection results to the image transmission side device transmits the detection results by radio.

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