Transmission apparatus of video information, transmission system of video information and transmission method of video information Number:7,082,612 from the United States Patent and Trademark Office (PTO) owispatent

Title: Transmission apparatus of video information, transmission system of video information and transmission method of video information

Abstract: A transmission apparatus for video information is disclosed. The apparatus has an input part for inputting video; a level information generation part for generating level information of each pixel on a screen; a memory part for storing the level information of each pixel in the entire region of the screen; a region extraction part for extracting a changed region which is a region on the screen including pixels related to the video information; an update region level information generation part for generating level information of each pixel in the changed region; a compression part for compressing the information amount of level information of each pixel in the changed region; and a communication part for transmitting position information of the changed region and the compressed level information.

Patent Number: 7,082,612 Issued on 07/25/2006 to Okamoto,   et al.

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Inventors:	Okamoto; Kazuo (Hirakata, JP); Masuno; Takashi (Hirakata, JP)
Assignee:	Matsushita Electric Industrial Co., Ltd. (Osaka, JP)
Appl. No.:	09/844,565
Filed:	April 27, 2001

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Foreign Application Priority Data

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Apr 25, 2001 [JP]			2001-128286

Current U.S. Class:	725/39
Current International Class:	G06F 3/00 (20060101)
Field of Search:	375/240.01,240.15,240.13,240.16,240.18,240.26 725/39

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References Cited [Referenced By]

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U.S. Patent Documents

	5448656		September 1995		Tanaka
	6333948		December 2001		Kurobe et al.
	6389073		May 2002		Kurobe et al.

Primary Examiner: Vo; Tung
Attorney, Agent or Firm: Akin Gump Strauss Hauer & Feld, LLP

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Claims

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We claim:

1. A transmission apparatus for video information characterized by having: an input part for inputting video information transmitted by a central processing unit; a level information generation part for generating level information of each pixel on a screen based on at least said video information; a memory part for storing the level information of each pixel in the entire region of the screen; a region extraction part for extracting a changed region which is a region on the screen including pixels related to said video information; an update region level information generation part for generating level information of each pixel in said changed region based on, at least, either the level information of each pixel generated by said level information generation part or the level information of each pixel stored in said memory part; a compression part for compressing the information amount of level information of each pixel in said changed region; and a communication part for transmitting position information of said changed region and said compressed level information.

2. The transmission apparatus for video information according to claim 1 characterized in that said update region level information generation part generates differential information of the level information of each pixel in said changed region extracted based on, at least, the level information of each pixel generated by said level information generation part and the level information of each pixel stored in said memory part and said compression part compresses the differential information.

3. The transmission apparatus for video information according to claim 1, characterized in that said changed region is a region in a rectangular form including pixels of m rows and n columns (in, n are positive integers of 1 or more, respectively).

4. The transmission apparatus for video information according to claim 3, characterized in that said changed region is a set of pixels wherein the upper i bits of the row address (in the case that the row address is assumed to be data of h bits, i is a positive integer satisfying 1<i<(h-1)) and the upper j bits of the column address (in the case that the column address is assumed to be data of k bits, j is a positive integer satisfying 1<j<(k-1)) of each pixel on the screen are the same.

5. The transmission apparatus for video information according to claim 1, characterized in that said communication part is a wireless communication part.

6. The transmission apparatus for video information according to claim 1, characterized, in addition, in that: said memory part outputs level information of each pixel in the entire region of the screen to said update region level information generation part at least once or more, for every constant period of time; said compression part compresses the information amount of the level information of each pixel in said entire region of the screen; and said communication part transmits identification information for identifying said compressed level information of the entire region of the screen from said compressed level information of the changed region or from compressed differential information of the changed region as well as said compressed level information of the entire region of the screen.

7. A transmission system for video information characterized by having: a first terminal apparatus said first terminal apparatus comprising: an input part for inputting video information transmitted by a central processing unit; a level information generation part for generating level information of each pixel on a screen based on at least said video information; a memory part for storing the level information of each pixel in the entire region of the screen; a region extraction part for extracting a changed region which is a region on the screen including pixels related to said video information; an update region level information generation part for generating level information of each pixel in said changed region based on, at least, either the level information of each pixel generated by said level information generation part or the level information of each pixel stored in said memory part; a compression part for compressing the information amount of level information of each pixel in said changed region; a communication part for transmitting position information of said changed region and said compressed level information; and a second terminal apparatus, comprising: a communication part for receiving position information of a changed region and compressed level information of each pixel in said changed region; an expansion part for expanding said compressed level information and outputting level information of each pixel in said changed region; a memory part for storing level information of each pixel in the entire region of the screen and for storing the level information of each pixel outputted by said expansion part in accordance with the position information of said changed region; and a display part for displaying a screen in accordance with the level information of each pixel stored in said memory part.

8. A transmission system for video information characterized by having: a first terminal apparatus, comprising: an input part for inputting video information transmitted by a central processing unit; a level information generation part for generating level information of each pixel on a screen based on at least said video information; a memory part for storing the level information of each pixel in the entire region of the screen; a region extraction part for extracting a changed region which is a region on the screen including pixels related to said video information; an update region level information generation part for generating level information of each pixel in said changed region based on, at least, either the level information of each pixel generated by said level information generation part or the level information of each pixel stored in said memory part; a compression part for compressing the information amount of level information of each pixel in said changed region; a communication part for transmitting position information of said changed region and said compressed level information, wherein said update region level information generation part generates differential information of the level information of each pixel in said changed region extracted based on, at least, the level information of each pixel generated by said level information generation part and the level information of each pixel stored in said memory part and said compression part compresses the differential information; and a second terminal apparatus comprising: a communication part for receiving position information of a changed region and compressed level information of each pixel in said changed region; an expansion part for expanding said compressed level information and outputting level information of each pixel in said changed region; a memory part for storing level information of each pixel in the entire region of the screen and for storing the level information of each pixel outputted by said expansion part in accordance with the position information of said changed region; a display part for displaying a screen in accordance with the level information of each pixel stored in said memory part; a level information updating part for updating the level information of each pixel stored in said memory part; characterized in that the communication part receives compressed differential information which is a compressed difference of the level information of each pixel in said changed region; the expansion part expands said compressed differential information and generates differential information of the level information of each pixel in said changed region; and the level information updating part updates the level information of each pixel stored in said memory part based on the position information of the changed region received by said communication part, the differential information of the level information of each pixel generated by said expansion part and the level information of each pixel stored in said memory part, wherein said update region level information generation part generates differential information of the level information of each pixel in said changed region extracted, based on, at least, the level information of each pixel generated by said level information generation part and the level information of each pixel stored in said memory part, and said compression part compresses the differential information.

9. The transmission system for video information according to claim 7, characterized in that said communication parts of said first terminal apparatus and said second terminal apparatus are wireless communication parts, respectively.

10. A transmission method for video information, characterized by the steps of: inputting video information transmitted by a central processing unit; generating level information of each pixel on a screen based on, at least, said video information; storing said level information of each pixel in a memory part; extracting a changed region which is a region of the screen including pixels related to said video information; generating level information of each pixel in said changed region of the screen based on at least, either the level information of each pixel generated in said level information generation step or the level information of each pixel stored in said memory step; compressing the information amount of the level information of each pixel in said changed region; and transmitting position information of said changed region and said compressed level information.

11. The transmission method for video information according to claim 10, characterized in that: the update region level information generation step generates differential information of level information of each pixel in said changed region extracted based on, the level information of each pixel generated in said level information generation step and the level information of each pixel stored in a memory and the compression step compresses the differential information.

12. The transmission method for video information according to claim 10, characterized in that said changed region is a rectangular region including pixels of m rows and n columns (m, n are positive integers of 1 or more, respectively).

13. The transmission method for video information according to claim 12, characterized in that said changed region is a set of pixels wherein the upper i bits of the row address (in the case that the row address is assumed to be data of h bits, i is a positive integer satisfying 1<i<(h-1)) and the upper j bits of the column address (in the case that the column address is assumed to be data of k bits, j is a positive integer satisfying 1<j<(k-1)) of each pixel on the screen are the same.

14. The transmission method for video information according to claim 10, characterized in that information are transmitted by means of a wireless communication in said transmission step.

15. The transmission method for video information according to claim 10, further characterized by: reading out level information of each pixel in the entire region of the screen from said memory part with a frequency of at least once or more for a constant period of time; compressing the information amount of the level information of each pixel in the entire region of the screen; and transmitting identification information for identifying said compressed level information of the entire region of the screen from said compressed level information of the changed region or from compressed differential information of the changed region and said compressed level information of the entire region of the screen.

16. A transmission method for video information inputting video information transmitted by a central processing unit; generating level information of each pixel on a screen based on, at least, said video information; storing said level information of each pixel in a memory part; extracting a changed region which is a region of the screen including pixels related to said video information; generating level information of each pixel in said changed region of the screen based on, at least, either the level information of each pixel generated in said level information generation step or the level information of each pixel stored in said memory step; compressing the information amount of the level information of each pixel in said changed region; and transmitting position information of said changed region and said compressed level information receiving position information of said changed region and compressed level information of each pixel in said changed region; expanding said compressed level information and outputting level information of each pixel in said changed region; storing the level information of each pixel outputted in said expansion step in a memory part in accordance with the position information of said changed region; and displaying a screen in accordance with the level information of each pixel stored in said memory part.

17. A transmission method for video information inputting video information transmitted by a central processing unit; generating level information of each pixel on a screen based on, at least, said video information; storing said level information of each pixel in a memory part; extracting a changed region which is a region of the screen including pixels related to said video information; generating level information of each pixel in said changed region of the screen based on, at least, either the level information of each pixel generated in said level information generation step or the level information of each pixel stored in said memory step; compressing the information amount of the level information of each pixel in said changed region; and transmitting position information of said changed region and said compressed level information, wherein the update region level information generation step generates differential information of level information of each pixel in said changed region extracted based on, the level information of each pixel generated in said level information generation step and the level information of each pixel stored in a memory and the compression step compresses the differential information, the method further including; a communication step for receiving position information of a changed region and compressed level information of each pixel in said changed region an expansion step for expanding said compressed level information and outputting level information of each pixel in said changed region; a memory step for storing the level information of each pixel outputted in said expansion step in a memory part in accordance with the position information of said changed region; a display step for displaying a screen in accordance with the level information of each pixel stored in said memory part; a level information updating step for updating level information of each pixel stored in a memory part, characterized in that the a communication step receives compressed differential information which is a compressed difference of the level information of each pixel in said changed region, wherein the expansion step expands said compressed differential information and generating differential information of the level information of each pixel in said changed region, and the level information updating step updates level information of each pixel stored in a memory part based on the position information of the changed region received in said communication step, the differential information of the level information of each pixel generated in said expansion step and the level information of each pixel stored in said memory step wherein the update region level information generation step generates differential information of level information of each pixel in said changed region extracted, based on, the level information of each pixel generated in said level information generation step and the level information of each pixel stored in a memory, and the compression step compresses the differential information.

18. The transmission method for video information according to claim 16, characterized in that said transmission step and said reception step are implemented by means of a wireless communication.

19. A terminal apparatus for video information characterized by having: a communication part for receiving position information of a changed region and compressed level information of each pixel in said changed region which are transmitted by a transmission apparatus for video information according to claim 1; an expansion part for expanding said compressed level information and outputting level information of each pixel in said changed region; a memory part for storing level information of each pixel in the entire region of the screen and for storing the level information of each pixel outputted by said expansion part in accordance with the position information of said changed region ; and a display part for displaying a screen in accordance with the level information of each pixel stored in said memory part.

20. The terminal apparatus for video information according to claim 19 further having: a level information updating part for updating the level information of each pixel stored in said memory part; characterized in that the communication part receives compressed differential information which is a compressed difference of the level information of each pixel in said changed region and transmitted by a transmission apparatus for video information; the expansion part expands said compressed differential information and generates differential information of the level information of each pixel in said changed region; and the level information updating part updates the level information of each pixel stored in said memory part based on the position information of the changed region received by said communication part, the differential information of the level information of each pixel generated by said expansion part and the level information of each pixel stored in said memory part, wherein said update region level information generation part generates differential information of the level information of each pixel in said changed region extracted, based on, at least, the level information of each pixel generated by said level information generation part and the level information of each pixel stored in said memory part, and said compression part compresses the differential information.

21. The terminal apparatus for video information according to claim 19, characterized in that said communication part is a wireless communication part.

22. A transmission method for video information characterized by having: a communication step for receiving position information of a changed region and compressed level information of each pixel in said changed region which are transmitted by a transmission method for video information according to claim 10; an expansion step for expanding said compressed level information and outputting level information of each pixel in said changed region; a memory step for storing the level information of each pixel outputted in said expansion step in a memory part in accordance with the position information of said changed region; and a display step for displaying a screen in accordance with the level information of each pixel stored in said memory part.

23. The transmission method for video information according to claim 22 further having: a level information updating step for updating level information of each pixel stored in a memory part, characterized in that the communication step receives compressed differential information which is a compressed difference of the level information of each pixel in said changed region and transmitted by a transmission method for video information, the expansion step expands said compressed differential information and generating differential information of the level information of each pixel in said changed region, and the level information updating step updates level information of each pixel stored in a memory part based on the position information of the changed region received in said communication step, the differential information of the level information of each pixel generated in said expansion step and the level information of each pixel stored in said memory step wherein the update region level information generation step generates differential information of level information of each pixel in said changed region extracted, based on, the level information of each pixel generated in said level information generation step and the level information of each pixel stored in a memory, and the compression step compresses the differential information.

24. The transmission method for video information according to claim 22, characterized in that said communication step is a wireless communication step.

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Description

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BACKGROUND OF THE INVENTION

The present invention relates to a transmission apparatus of video information, a transmission system of video information and a transmission method of video information.

In recent years the application field of computers has widened. In it a computer wherein a part (referred to as "first terminal apparatus") including a CPU (central processing unit) or the like, and a part (referred to as "second terminal apparatus") including a display part for video (or display part and input part) are separated is in demand by the market.

FIG. 3 is a conceptual diagram of a computer which has a first terminal apparatus and a second terminal apparatus.

In FIG. 3, the first terminal apparatus which includes a CPU is denoted as 301, the second terminal apparatus which includes a display part and a pen input part is denoted as 302, a conventional PC (abbreviation of personal computer which has a CPU and a display part) is denoted as 303, a docking station is denoted as 304, a keyboard is denoted as 305 and a display part is denoted as 306. The first terminal apparatus 301 has a CPU 311 and a wireless communication part 312. The second terminal apparatus 302 has a display and pen input part 321 and a wireless communication part 323. The user can input instructions to the computer by touching a pen 322 to the display and pen input part 321.

Video information generated in the CPU 311 of the first terminal apparatus 301 is transmitted from the wireless communication part 312. The wireless communication part 323 of the second terminal apparatus 302 receives the video information and transmits it to the display and pen input part 321. The display and pen input part 321 displays the inputted video information.

When the user inputs instruction for the computer to the display and pen input part 321 of the second terminal apparatus with the pen 322, this instruction information is transmitted from the wireless communication part 323. The wireless communication part 312 of the first terminal apparatus 301 inputs this instruction information, and transmits it to the CPU 311. The CPU 311 inputs instruction information and processes information in accordance with the instruction information.

Generally the user only utilizes the first terminal apparatus 301 and the second terminal apparatus 302. The user can move freely by carrying around the second terminal apparatus 302 which is light and which does not have a connection cord.

The user connects the docking station 304 to the first terminal apparatus 301 and connects the keyboard 305 and the display part 306 to the docking station 304 and, thereby, can construct and utilize a computer system comprising the first terminal apparatus 301, the docking station 304, the keyboard 305 and the display part 306.

An optional wireless communication part 331 can be incorporated into the conventional PC 303. The video information generated by the CPU of the PC 303 is transmitted from the wireless communication part 331. The wireless communication part 323 of the second terminal apparatus 302 receives the video information and transmits it to the display and pen input part 321. The display and pen input part 321 displays the inputted video information.

When the user inputs instruction for the computer to the display and pen input part 321 of the second terminal apparatus with the pen 322, this instruction information is transmitted from the wireless communication part 323. The wireless communication part 331, which is incorporated into the conventional PC 303, inputs this instruction information and transmits it to the CPU. The CPU of the conventional PC 303 inputs the instruction information and processes information in accordance with the instruction information.

In this manner, the user can utilize a conventional PC as the first terminal apparatus 301.

FIG. 15 is a block diagram, (mainly showing a transmission apparatus for video information and a transmission system for video information included in the computer) of a conventional computer which has a first terminal apparatus and a second terminal apparatus. The conventional computer of FIG. 15 includes an video information transmission apparatus which transmits video information from the first terminal apparatus to the second terminal apparatus.

In FIG. 15, the first terminal apparatus is denoted as 1501, the second terminal apparatus is denoted as 1502, a display (display part) is denoted as 1503 and a wire connecting the first terminal apparatus 1501 with the second terminal apparatus 1502 is denoted as 1504.

The first terminal apparatus 1501 has a CPU 1511, a video graphics control part 1513, an LCD driving part 1515 (liquid crystal display driving part), a liquid crystal display 1516 and a communication board 1514. Though indispensable for a computer, a ROM, a RAM and the like, which do not relate directly to the present invention, are omitted in the description.

The CPU 1511, the video graphics control part 1513 and the communication board 1514 are connected to each other via a PCI bus 1512.

The video graphics control part 1513 has a CPU 1521, an input/output part 1522, a RAM 1523, a VRAM 1524, a write in/read out address register 1525, a read out address register 1526, a clock generator 1527 and a parallel/serial conversion part 1528.

The CPU 1521, the input/output part 1522, the RAM 1523, the VRAM 1524, the write in/read out address register 1525 and the like are connected to each other via an internal bus 1529.

The CPU 1511 transmits video change instructions which are described in a software language (such as DirectX (registered trademark of Microsoft Corporation)) to the video graphics control part 1513 and the communication board 1514 via the PCI bus 1512.

The input/output part 1522 of the video graphics control part 1513 transmits the inputted video change instructions which are described in a software language to the CPU 1521 via the internal bus 1529.

The CPU 1521 converts the video change instructions which are described in a software language (program arranged on the Application Programming Interface of the OS of this computer) into the level information (for example, information concerning the value to which the value of any address of the VRAM is changed) of each pixel at the hardware level by utilizing an video information decoder 1541. The RAM 1523 is a scratch region at the time when the level information of each pixel is generated, by utilizing the video information decoder 1541. The VRAM 1524 is a dual port RAM for video display which has a port that can randomly access an arbitrary address so as to carry out write in and read out (address is designated by a write in/read out address register 1525) and a port that can read out data of each address at high speed and in a constant order (address is designated by a read out address register 1526). The level information (level information of each of the sub-pixels, RGB), attribute data and the like are stored in the VRAM 1524.

The CPU 1521 and the like set an address in the write in/read out address register 1525. Information is written into this address through the internal bus 1529 and information is read out from this address through the internal bus 1529.

The clock generator 1527 sets a read out address register 1526. The set value of the address register 1526 is generally incremented at an extremely high rate. The information of the address designated by the address register 1526 is read out and is forwarded to the parallel/serial conversion part 1528. The parallel/serial conversion part 1528 converts the inputted information of each address (level information of each pixel) into serial data, which are then outputted.

An output signal from the parallel/serial conversion part 1528 is transmitted to an LCD driving part 1515 and is converted to a signal for driving an LCD (liquid crystal display). The LCD driving part 1515 drives the liquid crystal display 1516. The liquid crystal display 1516 displays video.

In addition, the output signal from the parallel/serial conversion part 1528 is transmitted to the external display 1503. The display 1503 displays video.

The communication board 1514 receives the video change instructions which are described in a software language and which are transmitted through the PCI bus 1512 (outputted by the CPU 1511). The communication board 1514 transmits the video change instructions which are described in a software language to the second terminal apparatus 1502 through the connecting wire 1504.

The communication board 1531 of the second terminal apparatus 1502 transmits the received video change instructions which are described in a software language to the video graphics control part 1532. The video graphics control parts 1532 and 1513 have the same configuration. The video graphics control part 1532 generates and outputs the display data of each pixel based on the video change instructions which are described in a software language. The display 1533 displays video by driving each pixel in accordance with the display data.

In a conventional computer which has a first terminal apparatus and a second terminal apparatus, however, information flow between the first terminal apparatus and the second terminal apparatus is carried out with video change instructions which are described in a software language. Therefore, data cannot be transmitted or received between the first terminal apparatus and the second terminal apparatus in which different OSs are installed. In particular, the user who has a plurality of first terminal apparatus in which plural and different OSs are installed must utilize, through precise differentiation, a first terminal apparatus and a second terminal apparatus in which a first OS is installed as well as a first terminal apparatus and a second terminal apparatus in which a second OS is installed, and, in this regard, mistakes may easily occur. For example, the case wherein the user brings the first terminal apparatus in which the first OS is installed and the second terminal apparatus in which the second OS is installed on a distant trip, results in the apparatus being unusable. Therefore, a data transmission system between a first terminal apparatus and a second terminal apparatus that does not depend on an OS is requested by users who have a plurality of first terminal apparatus in which plural and different OSs are installed.

There is also the idea of transmitting the output signal from the parallel/serial conversion part 1528 to the second terminal apparatus 1502 without change. However, in the case that a full color display with RGB consisting, respectively, of 8 bits is implemented on a UXGA screen (1600.times.1200 pixels), the output signal of the parallel/serial conversion part exceeds 46 Mbps. It is extremely difficult to transmit data at such a high rate in a wireless manner.

The present invention has the purpose of providing a transmission apparatus for video information, a transmission system for video information and a transmission method for video information which enable wireless transmission of video information at a low rate regardless of OS.

SUMMARY OF THE INVENTION

The present invention solves the above-described problem by means of the below-described configurations.

The present invention according to claim 1 provides a transmission apparatus for video information characterized by having:

an input part for inputting video information transmitted by a central processing unit;

a level information generation part for generating level information of each pixel on a screen based on at least said video information;

a memory part for storing level information of each pixel in the entire region of the screen;

a region extraction part for extracting a region on the screen including pixels related to said video information;

an update region level information generation part for generating level information of each pixel in said region of the screen based on, at least, either the level information of each pixel generated by said level information generation part or the level information of each pixel stored in said memory part;

a compression part for compressing the information amount of level information of each pixel in said region of the screen; and

a communication part for transmitting position information of said region of the screen and said compressed level information.

The present invention according to claim 2 provides

a transmission apparatus for video information characterized by having:

an input part for inputting video information transmitted by a central processing unit;

a level information generation part for generating level information of each pixel on a screen based on at least said video information;

a memory part for storing level information of each pixel in the entire region of the screen;

a region extraction part for extracting a region on the screen including pixels related to said video information;

an update region level information generation part for generating differential information of the level information of each pixel in said extracted region of the screen based on, at least, the level information of each pixel generated by said level information generation part and the level information of each pixel stored in said memory part;

a compression part for compressing the information amount of the differential information of the level information of each pixel in said extracted region of the screen; and

a communication part for transmitting position information of said region of the screen and said compressed differential information.

The present invention according to claim 3 provides a transmission apparatus for video information according to claim 1 or 2, characterized in that said extracted region of the screen is a region in a rectangular form including pixels of m rows and n columns (m, n are positive integers of 1 or more, respectively).

The present invention according to claim 4 provides a transmission apparatus for video information according to claim 3, characterized in that said extracted region of the screen is a set of pixels wherein the upper i bits of the row address (in the case that the row address is assumed to be data of h bits, i is a positive integer satisfying 1.ltoreq.i.ltoreq.(h-1)) and the upper j bits of the column address (in the case that the column address is assumed to be data of k bits, j is a positive integer satisfying 1.ltoreq.j.ltoreq.(k-1)) of each pixel on the screen are the same.

The present invention according to claim 5 provides a transmission apparatus for video information according to claim 1 or 2, characterized in that said communication part is a wireless communication part.

The present invention according to claim 6 provides

a transmission apparatus for video information according to claim 1 or 2, characterized, in addition, in that:

said memory part outputs level information of each pixel in the entire region of the screen to said update region level information generation part at least once or more for every constant period of time;

said compression part compresses the information amount of the level information of each pixel in said entire region of the screen; and

said communication part transmits identification information for identifying said compressed level information of the entire region of the screen from said compressed level information of the region of the screen or from said compressed differential information as well as said compressed level information of the entire region of the screen.

The present invention according to claim 7 provides

a transmission system for video information characterized by having:

a first terminal apparatus including a central processing unit and a transmission apparatus for video information according to claim 1; and

a second terminal apparatus, wherein

said second terminal apparatus has:

a communication part for receiving position information of said region of the screen and said compressed level information;

an expansion part for expanding said compressed level information and outputs level information of each pixel in the extracted region of the screen;

a memory part which stores the level information of each pixel in the entire region of the screen and which stores the level information of each pixel outputted by said expansion part in accordance with the position information of said region of the screen; and

a display part for displaying a screen in accordance with the level information of each pixel stored in said memory part.

The present invention according to claim 8 provides

a transmission system for video information characterized by having:

a first terminal apparatus including a central processing unit and a transmission apparatus for video information according to claim 2; and

a second terminal apparatus, wherein

said second terminal apparatus has:

a communication part for receiving position information of said region of the screen and said compressed differential information;

an expansion part for expanding said compressed differential information and generates differential information of each pixel in the extracted region of the screen;

a memory part which stores the level information of each pixel in the entire region of the screen and which stores the level information of each pixel generated by the level information generation part in accordance with the position information of said region of the screen;

said level information generation part for generating level information of each pixel based on the differential information of each pixel generated by said expansion part and the level information of each pixel stored in said memory part; and

a display part for displaying a screen in accordance with the level information of each pixel stored in said memory part.

The present invention according to claim 9 provides

a transmission system for video information according to claim 7 or 8, characterize in that said communication parts of said first terminal apparatus and said second terminal apparatus are wireless communication parts, respectively.

The present invention according to claim 10 provides

a transmission method for video information, characterized by having:

the input step of inputting video information transmitted by a central processing unit;

the level information generation step of generating level information of each pixel on a screen based on, at least, said video information;

the memory step of storing said level information of each pixel in a memory part;

the region extraction step of extracting a region of the screen which includes pixels related to said video information;

the update region level information generation step of generating level information of each pixel in said region of the screen based on, at least, either the level information of each pixel generated in said level information generation step or the level information of each pixel stored in said memory part;

the compression step of compressing the information amount of the level information of each pixel in said region of the screen; and

the transmission step of transmitting position information of said region of the screen and said compressed level information.

The present invention according to claim 11 provides

a transmission method for video information, characterized by having:

the input step of inputting video information transmitted by a central processing unit;

the level information generation step of generating level information of each pixel on a screen based on, at least, said video information;

the region extraction step of extracting a region of the screen which includes pixels related to said video information;

the update region level information generation step of generating differential information of level information of each pixel in said extracted region of the screen based on, at least, the level information of each pixel generated in said level information generation step and the level information of each pixel stored in a memory part;

the memory step of storing said level information of each pixel in said memory part;

the compression step of compressing the information amount of the differential information of the level information of each pixel in said extracted region of the screen; and

the transmission step of transmitting position information of said region of the screen and said compressed differential information.

The present invention according to claim 12 provides a transmission method for video information according to claim 10 or 11, characterized in that said extracted region of the screen is a rectangular region including pixels of m rows and n columns (m, n are positive integers of 1 or more, respectively).

The present invention according to claim 13 provides

a transmission method for video information according to claim 12, characterized in that said extracted region of the screen is a set of pixels wherein the upper i bits of the row address (in the case that the row address is assumed to be data of h bits, i is a positive integer satisfying 1.ltoreq.i.ltoreq.(h-1)) and the upper j bits of the column address (in the case that the column address is assumed to be data of k bits, j is a positive integer satisfying 1.ltoreq.j.ltoreq.(k-1)) of each pixel on the screen are the same.

The present invention according to claim 14 provides

a transmission method for video information according to claim 10 or 11, characterized in that information are transmitted by means of a wireless communication in said transmission step.

The present invention according to claim 15 provides

a transmission method for video information according to claim 10 or 11, characterized by further having:

the entire region level information generation step of reading out level information of each pixel in the entire region of the screen from said memory part with a frequency of at least once or more for a constant period of time;

the entire region level information compression step of compressing the information amount of the level information of each pixel in the entire region of the screen; and

the entire region level information transmission step of transmitting identification information for identifying said compressed level information of the entire region of the screen from said compressed level information of the region of the screen or from said compressed differential information and said compressed level information of the entire region of the screen.

The present invention according to claim 16 provides

a transmission method for video information characterized by having:

each step of the transmission method for video information according to claim 10;

the communication step of receiving said position information of the region of the screen and said compressed level information of the region of the screen;

the expansion step of expanding said compressed level information of the region of the screen and of outputting level information of each pixel of the region of the screen;

the memory step of storing the level information of each pixel outputted in said expansion step in a memory part in accordance with said position information of the region of the screen; and

the display step of displaying a screen in accordance with the level information of each pixel stored in said memory part.

The present invention according to claim 17 provides

a transmission method for video information characterized by having:

each step of the transmission method for video information according to claim 11;

the reception step of receiving said position information of the region of the screen and said compressed differential information;

the expansion step of expanding said compressed differential information and of generating differential information of level information of each pixel of the extracted region of the screen;

the level information generation step of generating level information of each pixel based on the differential information of the level information of each pixel generated in said expansion step and the level information of each pixel stored in the memory part

the memory step of storing the level information of each pixel generated in said level information generation step in said memory part in accordance with said position information of the region of the screen; and

the display step of displaying a screen in accordance with the level information of each pixel stored in said memory part.

The present invention according to claim 18 provides

a transmission method for video information according to claim 16 or 17, characterized in that said transmission step and said reception step are implemented by means of a wireless communication.

According to the present invention, all the video information is not transmitted but, rather, only the information of the changed part is transmitted. In addition, by utilizing the differential information of the data (difference between previous data and current data), information amount to be transmitted can be further reduced.

The present invention has the effect that a transmission apparatus for video information, a transmission system for video information and a transmission method for video information which allow the transmission of video information (in particular, the transmission by means of a wireless communication) at a low bit rate regardless of OS can be implemented.

The novel features of the invention will be hereinafter fully described and particularly pointed out in the appended claims, and the construction and details of the invention, together with other objects and features thereof, will become better understood and appreciated by reference to the following detailed description when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a first terminal apparatus in a computer according to Embodiment 1;

FIG. 2 is a block diagram of a second terminal apparatus in a computer according to Embodiment 1;

FIG. 3 is a conceptual diagram of a computer which has a first terminal apparatus and a second terminal apparatus;

FIG. 4 is a flow chart at the transmission end of a transmission method for video information using a transmission apparatus or a transmission system of Embodiment 1;

FIG. 5 is a flow chart at the reception end of a transmission method for video information using a transmission apparatus or a transmission system of Embodiment 1;

FIG. 6 is a block diagram of a first terminal apparatus in a computer according to Embodiment 2;

FIG. 7 is a block diagram of a second terminal apparatus in a computer according to Embodiment 2;

FIG. 8 is a flow chart at the transmission end of a transmission method for video information using a transmission apparatus or a transmission system of Embodiment 2;

FIG. 9 is a flow chart at the reception end of a transmission method for video information using a transmission apparatus or a transmission system of Embodiment 2;

FIG. 10 is a diagram for describing a compression pattern control signal;

FIG. 11 is a diagram showing groups of changed regions formed in the case that a method for grouping regions continuing only in the lateral direction is used;

FIG. 12 is a diagram showing a variety of groups of changed regions formed in the case that a method for grouping regions continuing in the longitudinal direction and the lateral direction is used;

FIG. 13 is a diagram showing data written into the write in upper address memory part in the case that a method for grouping regions continuing only in the lateral direction is used;

FIG. 14 is a diagram showing two dimensional data written in the write in upper address memory part in the case that a method for grouping regions continuing in the longitudinal direction and in the lateral direction is used; and

FIG. 15 is a block diagram of a conventional computer which has a first terminal apparatus and a second terminal apparatus.

It will be appreciated that all or part of the drawings are purely diagrammatic for illustrative purposes and do not necessarily present faithful depictions of the actual relative sizes and positions of the illustrated elements.

DETAILED DESCRIPTION OF THE INVENTION

In the following, embodiments which concretely show the best mode for carrying out the present invention are described in conjunction with the drawings.

EMBODIMENT 1

In reference to FIGS. 1 to 5, a transmission apparatus for video information, a transmission system for video information and a transmission method for video information are described according to Embodiment 1.

FIG. 3 is a conceptual diagram of a computer which has a first terminal apparatus and a second terminal apparatus. FIG. 3 is already described in the prior art. FIG. 3 shows an example of a conceptual diagram of a computer which has a first terminal apparatus and a second terminal apparatus in order to facilitate the understanding of the present invention while the objectives of applications of the present invention are not limited to a computer which has the configuration of FIG. 3.

<Description of the Configurations of the Transmission Apparatus for Video Information and the Transmission System for Video Information>

In reference to FIGS. 1 and 2, the configurations of a transmission apparatus for video information and transmission system for video information included in a computer according to Embodiment 1 of the present invention which has a first terminal apparatus and a second terminal apparatus are described.

FIG. 1 is a block diagram (mainly showing a transmission apparatus for video information and a transmission system for video information included in the computer) of a first terminal apparatus 101 in a computer according to Embodiment 1 of the present invention which has a first terminal apparatus and a second terminal apparatus.

In FIG. 1, the first terminal apparatus 101 has a CPU 111, a video graphics control part 113, a wireless communication part 114 and an input/output part 115. An external display 116 can be connected to the first terminal apparatus 101.

In FIG. 1, though indispensable for a computer, a ROM, a RAM and the like which do not directly relate to the present invention are omitted in description.

The CPU 111, the video graphics control part 113 and the input/output part 115 are connected to each other via a PCI bus 112.

The video graphics control part 113 has a CPU 121, an input/output part 122, a RAM 123, a VRAM 124, a write in/read out address register 125, a read out address register 126, a clock generator 127, a parallel/serial conversion part 128, a change region extraction part 130, a compression part 131, a RAM 132, a multiplexer 133 and a parallel/serial conversion part 134.

The CPU 121, the input/output part 122, the RAM 123, the VRAM 124, the write in/read out address register 125, the change region extraction part 130, the compression part 131 and the like are connected to each other via an internal bus 129.

The change region extraction part 130 has a write in upper address memory part 141, an upper address comparison part 142 and a gate 143.

The CPU 111 transmits change instructions of video described in a software language (for example, DirectX) to the video graphics control part 113 through the PCI bus 112.

The input/output part 122 of the video graphics control part 113 transmits the inputted change instructions of video described in a software language to the CPU 121 via the internal bus 129.

The CPU 121 converts the change instructions of video described in a software language (program arranged on the Application Programming Interface of the OS of this computer) to level information of each pixel at a hardware level (for example, information indicating a change of data of any address in the VRAM into a certain value) by utilizing an video information decoder 151. The RAM 123 is a scratch region at the time of generating level information (referred to as "video data") of each pixel by utilizing the video information decoder 151.

The VRAM 124 is a dual port RAM for video display which has a port that can randomly access an arbitrary address so as to carry out write in or read out (address is designated by the write in/read out address register 125) and a port that can read out data of each address at a high rate and in a constant order (address is designated by the read out address register 126). The level information of each pixel (level information of each of sub-pixels of RGB), attribute data and the like are stored in the VRAM 124.

The RAM 123 forms, in many cases, a part of the VRAM 124 in the video graphics control part. In this case the VRAM has a display area and a non-display area, wherein the display area corresponds to the VRAM 124 of FIG. 1 while the non-display area corresponds to the RAM 123 of FIG. 1.

The CPU 121 or the like sets an address in the write in/read out address register 125. Video data (level information of each pixel) are written into this address through the internal bus 129 and video data are read out from this address through the internal bus 129.

The write in upper address memory part 141 of the change region extraction part 130 stores the upper bits of the write in address set in the write in/read out address resistor 125. In the case that the write in address is assumed to be formed of row address data of h bits and column address data of k bits (h, k are arbitrary positive integers of 2 or more), the write in upper address memory part 141 stores the upper i bits (i is an arbitrary integer satisfying 1.ltoreq.i.ltoreq.h-1) of the row address data and the upper j bits (j is an arbitrary integer satisfying 1.ltoreq.j.ltoreq.k-1) of the column address data.

Thereby, the upper address of the address of the VRAM 124 (display area of a VRAM in the case that the VRAM includes the RAM 123 and the VRAM 124) to which new data have been written in is stored.

The clock generator 127 sets the read out address register 126. The set value of the address register 126 is generally incremented at an extremely high rate. The video data (video data stored in the VRAM 124) of the address designated by the address register 126 are read out and forwarded to the parallel/serial conversion part 128. The parallel/serial conversion part 128 converts the inputted video data of each address into serial data, which are outputted.

The output signal of the parallel/serial conversion part 128 is transmitted to the external display 116. The display 116 displays video based on the serial data (level information of each pixel).

When the information of the address (information stored in the VRAM i24) designated by the read out address register 126 are read out, the upper address comparison part 142 compares the upper address of the read out address register 126 and the upper address stored in the write in upper address memory part 141. When both agree, the upper address comparison part 142 converts the gate 143 to the conductive condition. When both do not agree, the upper address comparison part 142 converts the gate 143 to the cut off condition.

When the gate 143 is in the conductive condition, the video data outputted by the VRAM 124 are inputted into the compression part 131. The compression part 131 inputs only the video data of the upper address which includes the address to which new video data have been written in. As for the upper address wherein the video data are not rewritten at all, those video data are not inputted into the compression part 131.

The compression part 131 compresses the inputted video data. The compression method is arbitrary. For example, after carrying out an encoding conversion such as a DCT (discrete cosine transform), compression of the information amount is carried out by means of a run length method. In addition, an entropy coding such as Huffman coding may be carried out. The RAM 132 is a memory for the compression part 131 to store the inputted video data temporarily and to write in the video data after compression. The compression part 131 outputs the video data of which the information amount is compressed.

The multiplexer 133 inputs the video data (output signal of the compression part 131), of which the information amount is compressed, and the upper address information outputted by the upper address comparison part 142 (upper row address and upper column address), and multiplexes and outputs these pieces of information.

The multiplexer 133 erases the outputted upper address from the write in upper address memory part 141.

The information outputted by the compression part 131 is the information which has the unit of a rectangular region specified by the upper row address and the upper column address. Accordingly, the multiplexer 133 multiplexes and outputs the upper row address and the upper column address as well as the compressed video data and, thereby, the second terminal apparatus can identify the compressed video data as information of some definite address.

The parallel/serial conversion part 134 inputs the output signal of the multiplexer 133 and converts it to a serial signal so as to be outputted.

The wireless communication part 114 inputs the output signal of the parallel/serial conversion part 134 so as to transmit it in a wireless manner.

In comparison with the case where all data of each pixel stored in the VRAM 124 are transmitted without change, the information amount transmitted in a wireless manner is much smaller in the transmission system for video information of Embodiment 1. Accordingly, wireless transmission of video information becomes possible.

The wireless communication part 114 receives information transmitted from the second terminal apparatus (instructions or the like through a pen input) and transmits it to the input/output part 115. The input/output part 115 transmits the information transmitted from the second terminal apparatus to the CPU 111 through the PCI bus 112.

FIG. 2 is a block di