JP2002232898A - Image signal transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image signal transmitter that adopts a transmission system suitable for the resolution of an image signal to be transmitted and for the length of a cable so as to transmit the image signal. SOLUTION: An image transmission side device is provided with a single to biphase conversion circuit to separate parallel image data to be transmitted into even numbered data and odd numbered data, a 1st parallel to series conversion circuit, a 2nd parallel to series conversion circuit, and a changeover means that gives parallel image data to be transmitted to the 1st parallel to series conversion circuit when an operating mode control signal sent from an image receiver side device designates a 1st operating mode or gives the parallel image data to be transmitted to the single phase to biphase conversion circuit when the operating mode control signal sent from the image receiver side device designates a 2nd operating mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to transmitting an image signal generated by a personal computer to a display device such as a liquid crystal projector or a plasma display panel (PDP) which is relatively far from the personal computer. The present invention relates to an image signal transmission device used.

[0002]

2. Description of the Related Art When an image signal generated by a personal computer is transmitted to a display device using an analog transmission cable, image degradation is likely to occur when the analog transmission cable is long. In particular, 1024 × 768 pixels (XG
A) As in a display device of 1280 × 1024 pixels (SXGA), when the resolution becomes high, the image deterioration becomes more conspicuous.

Therefore, an image signal transmission device which does not cause image degradation even when the transmission cable length is long has been already developed. As one of the devices, "PanelLink" (Panel Link) developed by Silicon Image, Inc. in the United States has been developed. There is. this is
TMDS (Transition Minimized Differential Signalin
g) It was developed based on the signal transmission technology called.

[0004] TMDS is a signal transmission technique for serially transmitting red, blue and green signals (RGB) and a clock signal in a differential manner. The differential method is a method of transmitting one signal through two transmission lines, and realizes noise resistance and stable signal transmission, and achieves a higher transmission speed and a longer cable length. . However, even in this method, the resolution of the image data is 1600 × 1200 pixels (UXGA), 2048 ×
When the height is further increased (ultra high resolution) such as 1536 pixels (QXGA), the physical limit of the cable is reached and transmission becomes difficult.

[0005] To solve this, a standardization organization D
DWG (Digital Display Working Group)
l Visual Interface) "DualLi"
nk method ". Conventional" PanelLink "
(This is called "SingleLink" method for "DualLink" method). Instead of transmitting each RGB signal on one channel, that is, three channels, each RGB signal is converted to one phase and two phase. 2 channels each, ie 6
By transmitting as a channel, a bandwidth twice as large as that of the "SingleLink" system can be secured, so that image transmission of ultra-high resolution (UXGA-) can be performed. Further, since the transmission rate can be reduced by performing one-phase to two-phase conversion of the signal, transmission of a longer cable length can be performed.

FIG. 4 shows the configuration of a signal transmission device employing the "SingleLink" system, and FIG. 5 shows the configuration of a signal transmission device employing the "DualLink" system.

[0007] In a signal transmission device employing the "SingleLink" system, image data as a parallel signal is input to a PanelLink Transmitter 201 as shown in FIG. Pa
The nelLink 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 one signal line for transmitting a clock signal.
The PanelLink Receiver 203 performs serial-parallel conversion of the received serial signal into a parallel signal.

In a signal transmission device adopting the “DualLink” system, as shown in FIG. 5, even data of image data, which is a parallel signal, is input to a PanelLink Transmitter 301, and odd data is input to a PanelLink Transmitter 302. Each PanelLink Transmitter 301, 302
Performs parallel-serial conversion of image data from a parallel signal to a serial signal.

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 is a cable for transmitting image data.
It comprises a pair of signal lines and one signal line for transmitting a clock signal. Each PanelLink Receiver 304, 305
Performs a serial-parallel conversion of the received serial signal into a parallel signal.

In the "DualLink" system shown in FIG. 5, the RGB image data, which is a parallel signal, is not distributed to even-numbered data and odd-numbered data.
Input 1 and do not operate PanelLink Transmitter 302 (power down mode).
When only Panel 04 operates and PanelLink Receiver 305 is set to the power down mode, the operation becomes the same as the “SingleLink” system in FIG.

[0011]

In the "PanelLink" system, transmission of ultra-high resolution (UXGA-) and long-distance transmission have become difficult. Therefore, the "DualLink" method is effective for such ultra-high-resolution transmission or long-distance transmission.

On the other hand, the "SingleLink" system is sufficient for transmitting low-resolution signals such as VGA. In addition, image transmission-side devices such as personal computers and image reception-side devices such as liquid crystal projectors are also becoming more portable.
It is important to reduce power consumption, and when transmitting a resolution signal or when long-distance transmission is not required, "S
Better to use ingleLink "transmission.

An object of the present invention is to provide an image signal transmission apparatus which can transmit an image signal by a transmission method suitable for the resolution of an image signal to be transmitted and the length of a cable.

[0014]

An image signal transmitting apparatus according to the present invention converts parallel image data from parallel to serial in an image transmitting apparatus, and then transmits the parallel image data to an image receiving apparatus via a cable. In the image signal transmission device for performing serial-parallel conversion of the image data received in the above, the image reception side device detects a level of a signal transmitted from the image transmission side device to the image reception side device via the cable, and detects the detected signal. Means for designating a first operation mode when the level is greater than a predetermined value, and generating an operation mode control signal for designating a second operation mode when the detected signal level is less than or equal to the predetermined value; Means for transmitting to the transmitting device, the image transmitting device comprising: a one-phase two-phase device for separating parallel image data to be transmitted into even data and odd data; Conversion circuit, the first parallel-serial conversion circuit, the second parallel-serial conversion circuit, and when the operation mode control signal sent from the image receiving side device specifies the first operation mode, The parallel image data to be transmitted is sent to the first parallel-serial conversion circuit. If the operation mode control signal sent from the image receiving side device specifies the second operation mode, the parallel image data to be transmitted is transmitted. A switching unit for transmitting the image data to the one-phase-two-phase conversion circuit, and when the operation mode control signal transmitted from the image receiving side device specifies the second operation mode, It is characterized in that even data obtained by the conversion circuit is sent to one of the first and second parallel-serial conversion circuits, and odd data is sent to the other parallel-serial conversion circuit. To.

The image receiving side device includes a first serial-to-parallel conversion circuit for converting serial data sent from the first parallel-to-serial conversion circuit via a cable into parallel data, and a second parallel-to-parallel conversion circuit. A second serial-parallel conversion circuit for converting serial data sent from the serial conversion circuit via the cable into parallel data;

When the first resolution is set, the first serial-to-parallel conversion circuit converts the parallel data obtained by the serial-to-parallel conversion into one-phase and two-phase to separate even-numbered data and odd-numbered data. A means for outputting is provided.

The means for transmitting the operation mode control signal to the image transmitting apparatus may be a means for transmitting the operation mode control signal by wire or a means for transmitting the operation mode control signal wirelessly.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the configuration of a digital image signal transmission device according to the present invention.

The image signal transmission apparatus includes a transmission unit 10 mounted on a personal computer (PC) 1, a receiving unit 105 mounted on a liquid crystal projector 20, and a cable 30 connecting the transmission unit 10 and the receiving unit 105. Consists of

The transmission unit 10 includes a graphics controller (a graphic board) 101 and a switching circuit 10
2, 1-phase to 2-phase conversion circuit 103 and transmission side unit 10
4 is provided. Graphics controller 101
Is the main CPU in the PC 1 via the bus 3 in the PC 1
2 are connected. A line receiver 146 is connected to the main CPU 2. Transmission unit 104
Are the first PanelLink Transmitter 111 and the second
PanelLink Transmitter 112 is provided.

The receiving unit 105 in the liquid crystal projector 20 is connected to a digitally driven liquid crystal panel 106 in the liquid crystal projector 20. The receiving unit 105 includes a first PanelLink Receiver 131 and a second Pa
A nelLink Receiver 132 and a coupler 141 are provided. In the first PanelLink Receiver 131, a one-phase to two-phase conversion circuit 131a is provided. In the liquid crystal projector 20, a detection circuit 142, an A / D converter 14
3, a CPU 144 and a line driver 145 are provided.

The transmission unit 10 in the transmission unit 10
4 and the receiving unit 105 in the liquid crystal projector 20
Are connected by a cable 30. Cable 3
Numeral 0 comprises six pairs of signal lines for transmitting image data and one signal line for transmitting a clock signal.

This image signal transmission apparatus has two operation modes, a DualLink mode in which transmission is performed according to the DualLink system, and a Singing mode.
There is a SingleLink mode in which transmission is performed using the leLink method.

When the SingleLink mode is set as the operation mode, the parallel image data (R, G, B) output from the graphics controller 101, the clock signal and the control signal (H, V, DE (Display En)
able)) is directly sent to the first PanelLink without being sent to the one-phase / two-phase conversion circuit 103 via the switching circuit 102.
Input to Transmitter 111. In this case, the second Pane
lLink Transmitter 112 is not operating in power down mode.

The first PanelLink Transmitter 111
The image data and the clock signal are encoded, and parallel-serial conversion is performed to convert the image data from a parallel signal to a serial signal. The obtained one-channel RGB serial signal is transmitted through the cable 30 and received by the receiving unit 105.
Is sent to the first PanelLink Receiver 131. In this case, the second PanelLink Receiver 132 enters the power down mode and does not operate. First PanelLink Receiver
131 is the first PanelLink in the transmitting unit 104
Data extraction, serial-parallel conversion, and decoding are performed on the code sent from the Transmitter 111 to generate parallel image data, H, V, and DE.

The first PanelLink Receiver 131 has a second
When the image signal is not sent to the PanelLink Receiver 132 of the above, the obtained parallel image signal is subjected to one-phase / two-phase conversion by the one-phase / two-phase conversion circuit 131a, and the obtained even-numbered data of each RGB is The odd data is sent to the liquid crystal panel 106. Also, the first PanelLink Receiv
The er 131 divides the generated H, V, and DE and the received clock signal by に よ っ て using the one-phase to two-phase conversion circuit 131a and sends the frequency to the liquid crystal panel 106.

Information on whether or not an image signal has been sent to the second PanelLink Receiver 132 is described in the second PanelLink Receiver.
The message is sent from the receiver 132 to the first PanelLink Receiver 131.

When an image signal is being sent to the second PanelLink Receiver 132, the first PanelLin
k Receiver 131 sends the obtained parallel signal to liquid crystal panel 106 as it is.

When the DualLink mode is set as the operation mode, the parallel image data (R, G, B) output from the graphics controller 101 is
The data is sent to the one-phase / two-phase conversion circuit 103 via the switching circuit 102 and is separated into even data and odd data. The even-numbered data is stored in the first PanelLink Tr in the transmitting unit 104.
Input to ansmitter 111. The odd data is input to the second PanelLink Transmitter 112 in the transmitting unit 104.

The graphics controller 101
Clock signal and control signal (H, V,
DE (Display Enable) is a one-phase to two-phase conversion circuit 103
Is sent to the transmission unit 104
A first PanelLink Transmitter 111 and a second
Input to PanelLink Transmitter 112.

The first PanelLink Transmitter 111 has:
The even data and the clock signal are encoded and parallel-to-serial conversion is performed to convert the even data from a parallel signal to a serial signal. Second PanelLink Transmitter 112
Encodes odd data and a clock signal, and performs parallel-serial conversion to convert the odd data from a parallel signal to a serial signal.

The two-channel RGB serial signals obtained by the first PanelLink Transmitter 111 and the second PanelLink Transmitter 112 are connected to the cable 30.
And the first PanelLink in the receiving unit 105.
Receiver 131 and second PanelLink Receiver 132
Sent to

The first PanelLink Receiver 131 has the first
Performs data extraction, serial-parallel conversion, and decoding on the code transmitted from the PanelLink Transmitter 111, and outputs a parallel signal, H, V,
Generate DE. The second PanelLink Receiver 132
Data extraction, serial-parallel conversion, and decoding are performed on the code transmitted from the second PanelLink Transmitter 112 to generate a parallel signal for odd-numbered data.

The parallel signals (even and odd data of each RGB) obtained by both PanelLink Receivers 131 and 132 are sent to the liquid crystal panel 106. The H, V, and DE generated by the first PanelLink Receiver 131 and the received clock signal are also sent to the liquid crystal panel 106.

By the way, three pairs of image data of R, G, and B signals transmitted from the transmitting unit 104 to the receiving unit 105 and a pair of clock signals are transmitted in pairs by differential signals, respectively. Each signal level is almost equal. The transmission speed of digital image data (serial image data) transmitted through the cable 30 is, for example, UXG
In the case of A, the speed is 1.65 Gbps in the SingleLink mode, and is 825 Mbps, which is そ の of that in the DualLink mode.

As shown in FIG. 2, in this example, the coupler 141 is arranged on a signal line of one signal CLK− of the differential signal pair CLK + and CLK− of the received clock signal. The coupling output is input to the detection circuit 142. The characteristic impedance of each signal line of CLK + and CLK− is 50Ω at single end, and the terminating resistor 141a of the coupler 141 is, for example, 50Ω.
It is.

The CLK-coupled output signal is converted by a detection circuit 142 into an analog signal of a direct current (DC) voltage proportional to the amplitude level of the signal. Detection circuit 1
As the 42, for example, an AD8313 IC provided by Analog Devices, Inc. can be used.

The detection signal output from the detection circuit 142 is converted into a digital signal by the A / D conversion circuit 143 and then input to the input port of the CPU 144. CPU
At 144, the control signal for switching the operation mode (SingleLink mode or DualLink mode) is output by comparing the CLK-received signal level with a predetermined threshold value, This is fed back to the receiver 146.

The control signal corresponding to the received signal level transmitted to the line receiver 146 in the PC 1 is, for example, a DVI (Digital Visual Interface) defined as a digital interface between the PC and a liquid crystal projector in the United States.
face) If a standard 24-pin connector is used, the 1-bit control signal can be transmitted serially from this 8-pin terminal (NC) by using the vacant terminal without the need for new wiring. Can be. Note that a new signal wiring may be provided as an interface for transmitting a control signal.

The control signal received by the line receiver 146 in the PC 1 is input to the main CPU 2. PC1
Is based on the control signal input to the main CPU 2
An operation mode switching signal for switching between the ngleLink mode and the DualLink mode is sent to the graphics controller 101 via the bus 3. Upon receiving the operation mode switching signal, the graphics controller 101 sends a control signal corresponding to the operation mode switching signal to the switching circuit 102.

In this embodiment, the initial setting of the operation mode of the transmission unit 10 is set to the SingleLink mode. Then, when the transmission of the image data to the liquid crystal projector 20 is first started after the power of the transmission unit 10 is turned on, the operation mode determining process is performed.

When a short cable of 3 m or less is used as the cable 30, the type of the image signal is SingleLink.
Even if a UXGA high-resolution image signal with a transmission speed of 1.65 Gbps is used in the system, the attenuation of each signal on the cable 30 is 5 to 6 dB or less, and C / C sufficient for reproducing the received signal even in the SingleLink mode. The N ratio is obtained, and the received signal is reproduced without error.

In such a case, the C of the coupler 141
The amplitude of the LK- coupling output signal increases, and the amplitude level of the detection circuit 142 signal also increases. Therefore, CP
A control signal for setting the operation mode to the SingleLink mode is output from U144. This control signal is transmitted to the transmission side via the line driver 145. PC
When such a control signal is received, the main CPU 2 in 1 determines the operation mode as the SingleLink mode, and outputs an operation mode switching signal corresponding to the operation mode to the graphics controller 101. The graphics controller 101 outputs a switching control signal for the SingleLink mode to the switching circuit 102. As a result, the operation mode (SingleLink mode) set in the initial setting is maintained.

When a long cable of 10 m or more is used as the cable 30, if the image signal is a UXGA high-resolution image signal having a transmission rate of 1.65 Gbps in the SingleLink system, each signal of the cable 30 is used. Is about 20 dB. For this reason, in the SingleLink mode, a C / N ratio sufficient to reproduce the received signal cannot be obtained, and the received signal cannot be normally reproduced.

In such a case, the C of the coupler 141
The amplitude of the LK- coupling output signal becomes small, and the amplitude level of the detection circuit 142 signal becomes small. Therefore, CP
A control signal for setting the operation mode to the DualLink mode is output from U144. This control signal is transmitted to the transmission side via the line driver 145. PC1
When the main CPU 2 receives such a control signal, it determines the operation mode as the DualLink mode,
An operation mode switching signal corresponding thereto is output to the graphics controller 101. The graphics controller 101 outputs a switching control signal for the DualLink mode to the switching circuit 102. As a result, the operation mode (SingleLink mode) set in the initial setting
Mode.

As described above, when the operation mode is switched to the DualLink mode, the transmission speed of the signal transmitted to the cable 30 is reduced to 825 Mbps, the attenuation of each signal is reduced to, for example, about 10 dB, and the received signal is reproduced. , A sufficient C / N ratio can be obtained.

When a 5 m cable is used as the cable 30, the signal of UXGA resolution is "SingleLink".
However, in the case of a signal having the resolution of QXGA, the transmission speed is further increased and the coupler 141
The amplitude of the CLK- coupling output signal becomes small,
In response to the decrease in the amplitude level of the output signal of the detection circuit 142, the same procedure as described above is used to switch from SingleLink mode to Du.
The operation mode is automatically switched to alLink mode, and the received signal can be reproduced without error.

According to the above-described embodiment, the "SingleLink system" and "Dua"
lLink method "and automatically select the appropriate transmission method.

In the above embodiment, the coupler 141 is
Although arranged on the LK- signal line, it may be arranged on the CLK + signal line, or may be arranged on another image signal line RXR.
+, RXR-, RXG +, RXG-, RXB +, RXB
− May be arranged on any of the signal lines.

Further, as shown in FIG. 3, as a transmission method of a control signal transmitted from the liquid crystal projector 20 on the receiving side to the PC 1 on the transmitting side, a wireless interface is used.
The control signal output from the PU 144 may be transmitted from the wireless transmitter 147 and received by the wireless receiver 148.

[0052]

According to the present invention, a transmission method suitable for the resolution of an image signal to be transmitted and the length of a cable can be used.
Image signals can be transmitted.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital image signal transmission device.

FIG. 2 is a block diagram showing a configuration of signal level detection.

FIG. 3 is a block diagram illustrating a configuration of another image transmission system.

FIG. 4 is a block diagram showing a configuration of an image signal transmission device adopting the “Single Link” method.

FIG. 5 is a block diagram showing a configuration of an image signal transmission device adopting a “Dual Link system” system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PC 2 Main CPU 10 Transmission unit 20 Liquid crystal projector 30 Cable 101 Graphics controller 102 Switching circuit 103 One-phase two-phase conversion circuit 104 Transmission unit 111, 112 PanelLink Transmitter 105 Reception unit 131, 132 PanelLink Receiver 131a One-phase two-phase Conversion circuit 106 Liquid crystal panel 141 Coupler 142 Detection circuit 144 CPU 145 Line driver 146 Line receiver 147 Radio transmitter 148 Radio receiver

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 7/081 F term (Reference) 5B069 AA17 BA04 KA04 LA02 5B077 AA04 AA18 NN02 5C057 AA03 BA01 DA01 EL01 GH01 GH05 5C063 AA01 AB03 AB07 AC02 CA03 CA09 CA23 CA29 CA36 DA07 DA13

Claims (5)

[Claims] An image signal for performing parallel-to-serial conversion of parallel image data by an image transmission side device, transmitting the parallel image data to an image reception side device via a cable, and performing serial-to-parallel conversion of the image data received by the image reception side device. In the transmission device, the image receiving device detects a level of a signal transmitted from the image transmitting device to the image receiving device via the cable,
Means for generating an operation mode control signal for specifying the first operation mode when the detected signal level is higher than a predetermined value, and specifying the second operation mode when the detected signal level is lower than the predetermined value, and operation mode control Means for transmitting a signal to the image transmitting device, the image transmitting device comprising: a one-phase to two-phase conversion circuit for separating parallel image data to be transmitted into even data and odd data; A serial conversion circuit, a second parallel-serial conversion circuit, and, when the operation mode control signal transmitted from the image receiving side device specifies the first operation mode, the parallel image data to be transmitted is transmitted. If the operation mode control signal sent to the first parallel-serial conversion circuit and sent from the image receiving side device specifies the second operation mode, the parallel image to be transmitted is transmitted. A switching unit for transmitting the image data to the one-phase to two-phase conversion circuit; and when the operation mode control signal transmitted from the image receiving side device designates the second operation mode,
It is assumed that the even data obtained by the phase conversion circuit is sent to one of the first and second parallel-serial conversion circuits and the odd data is sent to the other parallel-serial conversion circuit. Characteristic image signal transmission device. 2. An image receiving-side device comprising: a first serial-to-parallel converter for converting serial data sent from a first parallel-to-serial converter via a cable into parallel data; and a second serial-to-parallel converter. 2. A second serial-to-parallel conversion circuit for converting serial data sent from the parallel-to-serial conversion circuit via a cable into parallel data, and a second serial-to-parallel conversion circuit. Signal transmission device. 3. The first serial-to-parallel conversion circuit, when the first resolution is set, converts the parallel data obtained by the serial-to-parallel conversion into one-phase and two-phase to separate even-number data and odd-number data. 3. The image signal transmission device according to claim 2, further comprising a unit for outputting the image signal. 4. The image signal transmission apparatus according to claim 1, wherein the means for transmitting the operation mode control signal to the image transmission side device transmits the operation mode control signal by wire. 5. The image signal transmission device according to claim 1, wherein the means for transmitting the operation mode control signal to the image transmission side device transmits the operation mode control signal wirelessly.