JP2004236071A - Video signal transmission display system and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the data width of video data transmitted on a transmission path without degrading the resolution and reducing the number of color data, when video data are transmitted from a video image transmitting device such as a car navigation device to a display device. <P>SOLUTION: A video image transmitting device 41 makes a balanced serial signal contain a color number code of 4/8/16 bit widths identifying each pixel data and transmits the signal to a display device 45. A color palette is referred to on a reference table 55 in the display device 45 using a color number code in a serial LVDS signal as a reference key, and the color number code is converted into a 24-bit RGB888 data to display it on a liquid crystal display panel 57. According to the arrangement, a data width of the serial LVDS signal can be made small. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a video signal transmission / display system and a display device which are mounted on an automobile and transmit and display predetermined video data through a predetermined transmission path.
[0002]
[Prior art]
Conventionally, for example, when transmitting an image of a car navigation device digitally, when the display device and the car navigation device exist as separate electronic control units (ECUs), the image of the car navigation device is converted into an analog RGB format signal using a harness or the like. And has been displayed on a display at a resolution of QVGA (Quarter Video Graphics Array) or EGA (Enhanced Graphics Adapter).
[0003]
FIG. 2 is a block diagram showing a conventional analog display type video signal transmission / display system (prior art 1). In this video signal transmission and display system, first, on the car navigation device 1 side, the graphics unit 3 gives the RAM-DAC 5 an 8-bit color number code of PO0 to PO7 for each pixel, for example. Based on the reference, a reference table (LUT) 7 having a color palette in the RAM-DAC 5 is referred to, and the above-mentioned 8-bit color number code is converted into R (Red: Red) / G (Green: Green) / B ( Blue (blue) is converted into digital data of three color components of 8 bits (24 bits in total) (hereinafter referred to as “RGB888 data”), and then converted into analog RGB signals (analog R, analog G, The signal was converted to analog B) and input to the display device 11 together with the synchronization signal SYNC. In addition, recently, 16-bit wide RGB color has been applied to each pixel.
[0004]
Alternatively, recently, demands for higher-definition car navigation images have increased, and display on a wide VGA display has been performed.
[0005]
In order to take advantage of the high definition of the display, it is necessary to transmit video data as digital data from the car navigation device. Therefore, the physical layer of the transmission path is used for the TMDS method or the LVDS used in personal computers. A method can be considered.
[0006]
By the way, for example, in an in-vehicle system installed in a car, it is important to reduce the wiring of the harness. Not preferred.
[0007]
Here, in general, a balanced serial signal wire, that is, two serial differential signal wires may be used as a signal line (transmission path) for video digital transmission.
[0008]
FIG. 3 is a block diagram illustrating a video signal transmission display system for RGB888 data transmission (prior art 2) used in a personal computer. In this video signal transmission and display system, first, on the personal computer main body 21 side, an 8-bit width color number code of PO0 to PO7 is given to the reference table (LUT) 25 from the graphics unit 23 for each pixel, and the color of the reference table 25 is given. With reference to the palette, the image data is converted into RGB888 data which is digital data of a total of 24 bits of three color components. The RGB888 data is input to the transmitter 27, serialized by the transmitter 27, and transmitted to the display device 29 as a differential signal near gigahertz. On the display device 29 side, after serial-to-parallel conversion and decoding are performed by the receiver 31, the digital RGB signals (analog R, analog G, analog B) are displayed on a liquid crystal display panel (LCD) or the like. Note that, in this example, RGB888 data is described as an example. However, in an actual personal computer, data transmission such as 16-bit width, 24-bit width, and 32-bit width is performed for each color of RGB of each pixel. They are frequently used, and are selectively switched appropriately by software programs (drivers and firmware).
[0009]
Note that the applicant has not conducted a prior art document search on the related art in the present case.
[0010]
[Problems to be solved by the invention]
As in the above-described related art 2 (FIG. 3), when the transmitter 27 specializes in transmitting 24-bit fixed data of RGB888 data, which is a video signal, to the display device 29, the video signal is transmitted to the display device 29 on the receiving side. In order to reproduce the signal without any trouble, the effects of signal jitter (signal fluctuation) and skew (signal phase variation) on the receiving side should be reduced as much as possible, and the transition (signal polarity inversion) time should be reduced. It is necessary to increase the frequency of the transmission path. In this case, the frequency of the serial signal in the transmission path 37 is 24 bits × dot rate × k (where k is a coefficient in consideration of overhead), and the frequency is close to 1 GHz.
[0011]
As described above, in the system in which the data width of the transmitter 27 is fixed to 24 bits, when transmitting a high-frequency signal, in order to ensure video quality without lowering the resolution and the number of color data, it is necessary to use a transmission harness or a connector. Since the transmission loss of the transmission harness must be kept low, a high-grade material having low resistance must be used as the material of the transmission harness, which increases the cost.
[0012]
Therefore, in order to limit the frequency in the transmission path, it is conceivable to apply a method that does not particularly limit the bit width, such as the serial LVDS method or the serial gigabit Ethernet method, to the physical layer in the transmission physical layer in the transmission path. As one example, a method of applying serial differential transmission communication is conceivable (Patent Application 2002-376885: Proposed example). This serial differential transmission method (balanced serial signal) is a method in which a plurality of parallel data is serialized and transmitted through a one-channel transmission path, and it is possible to transmit video data using only a pair of cables. Therefore, the system can be configured with the minimum vehicle harness.
[0013]
The serial LVDS and serial Gigabit Ethernet systems in this proposal example do not specialize in video by defining the physical layer of transmission, and can transmit a signal having a width of 10 to 20 bits through a transmission path. The frequency of the signal may be set lower than that of a signal having a fixed data width of 24 bits as in the prior art 2. That is, since the NTSC signal can be originally represented by 8-bit or 16-bit YUV data, the 8-bit or 16-bit YUV data transmits video data as a signal having 20 bits or less per pixel. be able to. For this reason, it is possible to transmit video data from a peripheral viewing camera installed for safety confirmation around the vehicle and to transmit the current video video by a signal system such as a serial LVDS system or a gigabit Ethernet system. The frequency of the transmission path can be greatly reduced.
[0014]
However, in order to transmit video data of a wide VGA resolution of a car navigation device, a signal of 10 to 20 bits has a narrow bit width and requires processing such as time-division transmission. The frequency at the time cannot be kept low.
[0015]
Considering these facts, if it is possible to suppress the data width of the video data and reduce the frequency without lowering the resolution or the number of color data, use an inexpensive popular type product as the transmission harness. However, sufficient video quality can be ensured.
[0016]
Therefore, an object of the present invention is to provide a video data transmission device that transmits a video data from a video transmission device such as a car navigation device to a display device without reducing the resolution or the number of color data without reducing the data width of the video data transmitted on the transmission path. Another object of the present invention is to provide a video signal transmission / display system and a display device capable of suppressing frequency and frequency.
[0017]
[Means for Solving the Problems]
In order to solve the above problem, an invention according to claim 1 is a video signal transmission and display system for transmitting and displaying predetermined video data through a predetermined transmission path, wherein the video transmission transmits video data as a serial signal. Device, and a display device that performs video display based on the serial signal provided from the video transmission device through the transmission path, wherein the video transmission device specifies each pixel data of the video data by the serial signal. The display device includes a color number code for performing a predetermined operation by referring to a previously stored color palette using the color number code in the serial signal provided from the video transmission device through the transmission path as a reference key. And a reference table for converting the pixel data of the color component into the pixel data of the color component. Those comprising a video display means for displaying an image based on over data.
[0018]
The invention according to claim 2 is the video signal transmission display system according to claim 1, wherein the video transmission device outputs at least the color number code as each pixel data of video data, A transmitter for transmitting the serial signal to the display device through the transmission path based on the color number code from the graphics unit.
[0019]
The invention according to claim 3 is the video signal transmission / display system according to claim 1 or 2, wherein the pixel data of the color component is a three-color component having an 8-bit width or a 16-bit width per color. Wherein the color number code is 4-bit, 8-bit or 16-bit data, and the serial signal is a balanced serial signal.
[0020]
The invention according to claim 4 is the video signal transmission / display system according to claim 3, wherein the video transmission device uses the color signal having a width of 4 bits, 8 bits, or 16 bits in the serial signal. In addition to the number code, other signals are included and transmitted to the display device.
[0021]
The invention according to claim 5 is the video signal transmission display system according to any one of claims 1 to 4, wherein the color component transmitted from the look-up table to the video display means is provided. The pixel data is a parallel signal.
[0022]
According to a sixth aspect of the present invention, there is provided the video signal transmission / display system according to any one of the first to fifth aspects, wherein the video signal transmission / display system is mounted on an automobile.
[0023]
The invention according to claim 7 is the video signal transmission / display system according to claim 6, wherein the video transmission device is a car navigation device.
[0024]
The invention according to claim 8, wherein a display device that performs video display based on a serial signal of video data provided from a predetermined video transmission device via a transmission path, wherein the serial signal is a pixel data of video data. A reference table for converting pixel data of a predetermined color component with reference to a color pallet held in advance, using the color number code as a reference key, Video display means for displaying a video based on the pixel data of the color component.
[0025]
The invention according to claim 9 is the display device according to claim 8, wherein the pixel data of the color component is pixel data of a three-color component having an 8-bit width or a 16-bit width per color. The color number code is 4-bit, 8-bit or 16-bit data, and the serial signal is a balanced serial signal.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
A video signal transmission and display system according to one embodiment of the present invention is used for transmitting video data such as map information and character information from a video transmission device such as a car navigation device to a display device (display device). Instead of transmitting the analog RGB signal of the prior art 1, a color number code (pixel ID) having a small data width is transmitted, and a look-up table (LUT: look-up table) is displayed on the display device side based on the color number code. Table) is used to convert the data into color component data such as RGB888 data. In this embodiment, the RGB component data of 24 bits in total is described as an example of the color component data. However, it is needless to say that the present invention may be applied to the case of data of 16 bits for each color of RGB. .
[0027]
FIG. 1 is a block diagram showing a video signal transmission and display system according to one embodiment of the present invention. As shown in FIG. 1, the video signal transmission and display system includes a video transmission device (car navigation device) 41 and a reference table 55 based on color number codes PO0 to PO7 in a serial signal provided from the video transmission device 41. A display device (display device) 45 for performing a color restoration by referring to the image display.
[0028]
The video transmission device 41 includes a graphics unit 51 that generates video data, and a serial differential signal transmitter (transmitter) that converts color data provided from the graphics unit 51 into a serial LVDS signal that is a balanced serial signal. ) 53.
[0029]
The graphics section 51 converts the generated video data into 8-bit color number codes PO0 to PO7, a synchronization signal SYNC for defining the video synchronization of the color number codes PO0 to PO7, This is output to the serial differential signal transmitter 53 as a pixel clock signal DOTCLK that defines a clock cycle.
[0030]
The serial differential signal transmitter 53 serializes a parallel signal including the 8-bit color number codes PO0 to PO7, the synchronization signal SYNC, and the pixel clock signal DOTCLK provided from the graphics unit 51, and causes loss of a transmission line harness and a connector. , Transmission loss is less likely to occur (output to the transmission line 59 as a serial signal of 500 MHz or less). As described above, the serial signal communicated on the transmission path 59 includes an 8-bit color number code PO0 to PO7, a 1-bit synchronization signal SYNC, a 1-2-bit pixel clock signal DOTCLK, and a synchronization signal. , An attribute signal, an audio signal, an LUT rewrite signal, and other control signals having a 2-bit width or a 2-bit width.
[0031]
The display device 45 receives a differential transmission type receiver (serial signal receiving means) 43 for receiving and deserializing a serial signal given from the transmission path 59 and a color number code PO0 to PO7 given from the receiver 43. A reference table (LUT) 55 for converting RGB888 data (pixel data) as a parallel signal and a liquid crystal display panel (LCD: video display means) 57 are provided.
[0032]
The receiver 43 deserializes the serial signal provided from the serial differential signal transmitter 53 of the video transmission device 41 through the transmission path 59, and outputs 8-bit color number codes PO0 to PO7, a synchronization signal SYNC, and a pixel clock signal DOTCLK. And a parallel signal including other control signals. Among them, the color number codes PO0 to PO7 are output to the reference table 55, and the synchronization signal SYNC and the pixel clock signal DOTCLK are output directly to the liquid crystal display panel 57. Other control signals such as a synchronization signal, an attribute signal, an audio signal, and an LUT rewrite signal are output to a microcomputer chip or the like (not shown).
[0033]
The reference table 55 has a color palette in which 8-bit color number codes PO0 to PO7 are associated with 24-bit (R: 8 bits + G: 8 bits + B: 8 bits) RGB888 data. Using the given color number codes PO0 to PO7 as reference keys, the corresponding RGB888 data is output to the liquid crystal display panel 57 as a parallel signal in which the ports are divided for each of the three RGB components. The reference table 55 can be rewritten according to various uses. Specifically, the color data is rewritten during the vertical synchronization period of the video signal of the serial differential transmission system from the video transmission device 41 as a car navigation device or during the invalid video period for displaying a black screen on the display. Can be rewritten and external image files can be displayed. In this case, a plurality of reference tables 55 that are known in advance are provided on the display device 45 side, and these are selectively switched. In this case, a signal of the serial differential transmission system or an individual signal may be provided from the video transmission device 41 to select one of the plurality of reference tables 55.
[0034]
The operation of the video signal transmission / display system having the above configuration will be described.
[0035]
First, the graphics unit 51 of the video transmission device 41 converts the generated video data into 8-bit color number codes PO0 to PO7, a synchronization signal SYNC for defining video synchronization of the color number codes PO0 to PO7, The pixel clock signal DOTCLK defining the clock cycle of each pixel in the video and other control signals are output to the serial differential signal transmitter 53.
[0036]
The serial differential signal transmitter 53 serializes a parallel signal including the 8-bit color number codes PO0 to PO7, the synchronizing signal SYNC, the pixel clock signal DOTCLK, and other control signals provided from the graphics unit 51, and operates at 500 MHz or less. The signal is output to the transmission line 59 as a serial signal.
[0037]
Here, as described above, the serial signal communicated on the transmission path 59 includes an 8-bit color number code PO0 to PO7, a 1- or 2-bit synchronization signal SYNC, a 1-bit pixel clock signal DOTCLK, and others. Is a signal of 10 to 20 bits in total.
[0038]
Here, finally, 24-bit RGB888 data can be expressed by 8-bit color number codes PO0 to PO7 when an image is expressed by characters or animation as in a car navigation device, as in a live-action image. This is because it is not necessary to use all the colors of the RGB888 data of bits, and even if only a limited number of the colors are used, it is possible to sufficiently express a video. However, in comparison with, for example, pixel data of 16 colors (4 bits), in the case of RGB888 data, beautiful color expression such as not only primary colors but also mixed colors is possible. That is, since it is not necessary to use all the colors of RGB888 data such as a real image while performing a subtle color expression such as a mixed color, a color that can be specified by an 8-bit color number code PO0 to PO7 is used as a pixel. Just by selecting the data, the display device 45 can provide a sufficiently beautiful image expression.
[0039]
As described above, since a signal having a width of 10 to 20 bits is applied as a signal to be supplied from the video transmission device 41 to the display device 45 through the transmission path 59, a signal having a data width of 24 bits (conventional technology 2) is used. The data width of the serial signal can be reduced, and the resolution and the number of color data are not reduced.
[0040]
Also, as for the frequency of the serial signal, a data amount of 8 bits per pixel is sufficient, so that a resolution of about VGA requires a frequency of 300 MHz as described above. That is, the signal frequency in the transmission path 59 can be reduced to half or less as compared with the related art 2 that transmits a differential signal near 1 GHz. Therefore, even if an inexpensive transmission harness is used, there is little influence from jitter (signal fluctuation) and skew (variation in signal phase), and the transition (screen switching) time is shorter than in the conventional technology 2. Reduce.
[0041]
Next, when a serial signal is provided from the serial differential signal transmitter 53 of the video transmission device 41 through the transmission path 59, the receiver 43 in the display device 45 deserializes the serial signal and generates an 8-bit color number code. PO0 to PO7 are output to the lookup table 55, and the synchronization signal SYNC and the pixel clock signal DOTCLK are output to the liquid crystal display panel 57.
[0042]
The reference table 55 to which the 8-bit color number codes PO0 to PO7 are given indicates that the color number codes PO0 to PO7 are used as reference keys, and the corresponding RGB888 data are converted into parallel signals in which the ports are divided for each of the three RGB color components. Output to the liquid crystal display panel 57.
[0043]
As described above, since the signal output from the reference table 55 to the liquid crystal display panel 57 is a parallel signal, sufficient video quality can be ensured even if the signal frequency is set relatively lower than that of the serial signal.
[0044]
Moreover, since an image can be represented by RGB888 data (pixel data), it is possible to secure the inexpensive and sufficient image quality as described above without lowering the resolution and color data.
[0045]
In the above embodiment, the color number codes PO0 to PO7 having an 8-bit width are applied. However, a color number code having a 4-bit width or a 16-bit width may be applied. Even in this case, a signal having a data width smaller than that of the color component data can be transmitted through the transmission path 59.
[0046]
Further, as described above, in the above embodiment, a total of 24 bits of RGB888 data has been described as an example of the color component data. However, the present invention may be applied to a case where each of the RGB colors is 16 bits of data. Of course.
[0047]
Further, in the above-described embodiment, a serial LVDS signal is described as an example of a balanced serial signal, but a gigabit Ethernet signal may be used.
[0048]
Furthermore, in the above-described embodiment, an example of mounting on an automobile has been described. However, it is needless to say that the present invention can be applied to other fields of image display.
[0049]
【The invention's effect】
According to the first, second, and eighth aspects of the present invention, the video transmitting apparatus includes a color number code for specifying each pixel data of the video data in the serial signal and transmits the serial number to the display apparatus. Then, in the display device, the color number code in the serial signal is referred to as a reference key and the color palette of the reference table is referred to, the color number code is converted into pixel data of a predetermined color component, and the predetermined Since the video is displayed by the video display means based on the pixel data of the color component, the color number code of the color number code is smaller than when the pixel data of the predetermined color component is directly transmitted from the video transmission device to the display device (prior art 1). It is possible to reduce the data width. Then, since the color number code having a small data width is transmitted as a serial signal, a differential signal such as RGB888 data is transmitted (prior art 2), or a serial LVDS method, a serial gigabit Ethernet method, or the like is used as it is. Even when the signal frequency of the serial signal is set lower than in the case of transmitting by the serial differential transmission method (the proposed example), the jitter (signal fluctuation) and the skew (signal skew) are reduced without lowering the resolution and the number of color data. It is possible to reduce the influence of, for example, variations in signal phase) and to reduce the transition (screen change) time.
[0050]
More specifically, as described in claim 3 and claim 9, the pixel data of the color component is a pixel data of a total of 24 bits such as an 8-bit width or a 16-bit width of three color components per color, and has a 4-bit width of 8 bits. It can be represented by a color number code having a bit width or a 16-bit width, and this can be sufficiently included in a balanced serial signal.
[0051]
Further, it is possible to add other data to the balanced serial signal in addition to the 4-bit width, 8-bit width or 16-bit width color number code. For this reason, other signals having a small bit width (for example, 4 bit width) such as a synchronization signal and other control signals having a 2-bit width or a 2-bit width are included in the balanced serial signal in addition to the color number code. Is possible.
[0052]
In this case, specifically, the pixel data of the color component transmitted from the lookup table to the video display means may be a parallel signal.
[0053]
These are particularly effective when mounted on an automobile for which line saving is desired as described in claim 6, and when an image is displayed on a car navigation apparatus as described in claim 7, Since the image of the navigation device is a map, character information, etc., and the number of colors used is smaller than that of the actual photographed image, even if a color number code with a small bit width is used, it is sufficient to use the color in practical use. It is possible to represent pixel data.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a video signal transmission and display system according to one embodiment of the present invention.
FIG. 2 is a block diagram showing a video signal transmission / display system according to Prior Art 1.
FIG. 3 is a block diagram showing a video signal transmission / display system according to a conventional technique 2.
[Explanation of symbols]
41 Video transmitting device 43 Receiver 45 Display device 51 Graphics unit 53 Serial differential signal transmitter 55 Lookup table 57 Liquid crystal display panel 57 Direct liquid crystal display panel 59 Transmission path

Claims (9)

A video signal transmission and display system for transmitting and displaying predetermined video data through a predetermined transmission path,
A video transmission device that outputs video data as a serial signal,
A display device that performs video display based on the serial signal provided from the video transmission device through the transmission path,
The video transmission device,
The serial signal includes a color number code for specifying each pixel data of the video data,
The display device,
As a reference key, the color number code in the serial signal provided from the video transmission device through the transmission path, a reference table that converts the pixel data of a predetermined color component with reference to a previously held color palette,
A video signal transmission / display system comprising: video display means for displaying a video based on the pixel data of the color component converted by the lookup table. The video signal transmission and display system according to claim 1,
The video transmission device,
A graphics unit that outputs at least the color number code as each pixel data of video data,
A transmitter for transmitting the serial signal to the display device via the transmission path based on the color number code from the graphics unit. The video signal transmission / display system according to claim 1 or 2, wherein:
The pixel data of the color component is pixel data of a three-color component having a width of 8 bits or 16 bits per color,
The color number code is 4-bit, 8-bit or 16-bit data,
A video signal transmission / display system in which the serial signal is a balanced serial signal. The video signal transmission and display system according to claim 3,
The video transmitting apparatus transmits the serial signal to the display device by including other signals in the serial signal in addition to the color number code of 4 bits, 8 bits or 16 bits in width. Signal transmission display system. The video signal transmission / display system according to any one of claims 1 to 4, wherein
A video signal transmission display system in which the pixel data of the color component transmitted from the lookup table to the video display means is a parallel signal. The video signal transmission / display system according to claim 1, wherein:
A video signal transmission and display system in which the video signal transmission and display system is mounted on an automobile. The video signal transmission and display system according to claim 6, wherein
A video signal transmission and display system in which the video transmission device is a car navigation device. A display device that performs video display based on a serial signal of video data provided through a transmission path from a predetermined video transmission device,
The serial signal includes a color number code for specifying each pixel data of the video data,
A reference table for converting the color number code into pixel data of a predetermined color component with reference to a color palette held in advance as a reference key,
A display device for displaying an image based on the pixel data of the color component converted by the reference table. The display device according to claim 8, wherein:
The pixel data of the color component is pixel data of a three-color component having a width of 8 bits or 16 bits per color,
The color number code is 4-bit, 8-bit or 16-bit data,
A display device, wherein the serial signal is a balanced serial signal.

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