Video Signal Controller for Use With a Multi-Sync Monitor for Displaying a Plurality of Different Types of Video Signals

The present invention relates to a video signal controller having a tuner for generating a broadcast video signal and more particularly to a controller which can be used with a digital computer and a display device to display the video signal generated by the digital computer and the broadcast video signal generated by the tuner.

Apparatuses to receive and display raster scan video signals as well as digital video signals are well known in the art. See, for example, U.S. Pat. Nos. 4,899,139; 4,954,819; 4,961,071; 5,027,212; 5,065,143; and 5,179,639. Micro-processor controlled monitors are also well known in the art. See for example, U.S. Pat. Nos. 4,746,983; 4,774,582; 4,855,813; and 4,991,023. In addition, prior art devices have taught the use of an add-on card for a PC computer with a tuner on the card. The tuner on the add-on card would receive "off the air" broadcast video signal and convert them into a raster scan-type signal. In addition, the card would then convert the analog raster scan signal into digital format and through the computer, the signals would then be displayed on the display monitor of the computer. The software executed by the computer permitted alternating the display of the video signal from the tuner as well as the video signal generated by the computer.

One of the drawbacks of the aforementioned prior art add-on card is that with the video signals supplied through the computer, much of the computing resources is consumed. In addition, because the scanning rate and the sizing for a raster scan video signal (such as that broadcast over the air) differs for a video signal which is the output of a digital computer, the display of both types of signals on a computer monitor has resulted in compromise in picture quality.

In accordance with the present invention, a video signal controller is used with a digital computer to control the display of the video signal which is the output of the digital computer and a raster scan-type video signal with optimal display for both types of signals, on a monitor. The video signal controller has a tuner for producing a raster scan video signal. A first multiplexer receives a first input video signal and a second input video signal and produces an output video signal which is supplied to the monitor. The output video signal is either the first or the second input video signal in response to a first control signal controlling the first multiplexer. The controller also comprises a first means for supplying a first video signal to the first multiplexer means as the first input video signal thereof. A second means supplies a second video signal to the first multiplexer means as the second input video signal thereof. Finally, a control means generates the first control signal supplied to the first multiplexer such that the monitor receives either the first video signal which is generated from the tuner or the monitor displays the second input video signal which is the output of the digital computer.

FIG. 1 is a schematic block level diagram of the apparatus of the present invention.

FIG. 2 is a block level diagram showing another aspect of the present invention wherein the digital computer is optimally controlled to respond to the video signals supplied thereto.

Referring to FIG. 1, there is shown a video signal controller 10 of the present invention. The signal controller 10 is particularly suitable for use with a digital computer such as an IBM PC compatible computer 12. In a preferred embodiment, the computer 12 generates a first video signal 14 having a well-known conventional format such as EGA, VGA, or Super VGA. The first video signal 14 is displayed on a dual sync or multi-sync monitor 16 also of conventional design, such as that from Sanyo Corporation. The dual sync monitor 16 is so named because its ability to display video signals having different sync rates.

The controller 10 comprises a conventional tuner 18 having an associated antenna 20 for receiving "off the air" broadcast video signals. The tuner 18 generates a second audio/video signal 22 which is supplied to a first multiplexer 24 along one input thereof. The second audio/video signal 22 received from the "off the air" broadcast is also of well-known standard, such as NTSC in the United States. In addition, the second audio/video signal 22 is supplied to a liquid crystal display 15, which can display the video signal portion of the second audio/video signal 22. The LCD display 15 is controlled by a control signal 17.

The first multiplexer 24 also receives as another input thereof a third audio/video signal 26. The third audio/video signal 26, has the same standard, e.g. NTSC, as the second audio/video signal 22, and can be from any other type of source, such as VCR, video disk etc. The output of the first multiplexer 24 is a fourth audio/video signal 28. The first multiplexer 24 receives a control signal 25. The control signal 25 causes either the second audio/video signal 22 or the third audio/video signal 26 to be supplied from the first multiplexer 24 as the fourth audio/video signal 28. The fourth audio/video signal 28 has its audio portion supplied to a mixer 30. The video portion of the fourth audio/video signal 28 is supplied to a decoder 32.

The decoder 32 is a single chip of conventional design, available from, for example Phillips TDA 3566A, to convert the received baseband video signal 28 to its component video signals, such as RGB. It is controlled by a control signal 31, which serves to control the chroma portion of the output RGB signal 34. The output of the decoder 32 is a fifth video signal 34. The fifth video signal 34, as a result of being operated upon by the decoder 32, would be a monitor signal such as RGB or YUV format.

The fifth video signal 34 is supplied to a second multiplexer 36. The first video signal 14 which is the output of the computer 12, and is in video monitor format, such as RGB, is also supplied to the second multiplexer 36. The output of the second multiplexer 36 is an output video signal 38 which is supplied to the dual sync monitor 16. The second multiplexer 36 is controlled by a control signal 35. The control signal 35 causes either the fifth video signal 34 or the first video signal 14 to be supplied from the second multiplexer 36 as the output video signal 38.

The tuner 18, the first multiplexer 24, the decoder 32, the LCD display 15, and the second multiplexer 36 are all under the control of a control 40. In the preferred embodiment, the control 40 is an Intel 8052 microcontroller, operating its associated software 42. A listing of the functional specifications for the software 42 is set forth hereinafter. The control 40 generates a control signal 19 to control the tuner 18 such as, to change channels, increase/decrease volume, adjust tint, etc. The control 40 also generates the control signal 17 to activate the LCD display 15 to display the signal 22. In addition, the control 40 also generates the control signal 25 that controls the first multiplexer 24 to output the fourth audio/video signal 28 as from either the second audio/video signal 22 or the third audio/video signal 26. The control 40 also controls the decoder 32 by adjusting the chroma signal portion of the output. Finally, the control 40 generates a control signal 35 which is supplied to the second multiplexer 36 and causes the output video signal 38 to be either the first video signal 14 or the fifth video signal 34.

The control 40 also communicates with the digital computer 12. In the case where the digital computer 12 is an IBM PC compatible computer, the control 40 communicates with the RS-232 serial port of the digital computer 12.

The second audio/video signal 22, which is the output of the tuner 18, is also supplied to the digital computer 12. In the preferred embodiment, an expansion card is added to the digital computer 12 in one of its expansion slots. The expansion card comprises a first analog-to-digital converter 50 which receives the audio signal portion of the second audio/video signal 22. The expansion card also has a second analog-to-digital converter 52 which receives the video signal portion of the second audio/video signal 22. The output of the first and second analog-to-digital converters 50 and 52 respectively are digital signals which are supplied to a buffer 54. The microprocessor 56 within the digital computer 12 accesses the buffer 54 (as will be explained in greater detail hereinafter). Finally, the digital computer 12, as previously stated, generates a first video signal 14 which is supplied to the second multiplexer 36 along one input thereof. In addition, the digital computer 12 generates an audio signal 60 which is also supplied to the mixer 30. The output of the mixer 30 is a composite audio signal 62 which is supplied to an amplifier 64. The output of the amplifier 64 is supplied to a plurality of speakers 66. In addition, the digital computer 12 executes its associated software 70. A copy of the functional specifications for the software 70 is set forth hereinafter.

Finally, the control 40 has an infrared (IR) decoder 72 which is responsive to a hand held, portable, remote unit 80, generating appropriate infrared signals.

There are three modes of operation for the system controller 10 of the present invention.

In the first mode, the tuner 18 generates the second audio/video signal 22 which is a broadcast video signal in a standard, such as NTSC. The control 40 controls the first multiplexer 24 such that the fourth audio/video signal 28 is the second audio/video signal 22. The video signal portion of the fourth audio/video signal 28 is then supplied to the decoder 32. The control 40 causes the decoder 32 to generate the fifth video signal 34. The fifth video signal 34 supplied to the second multiplexer 36 and the control 40 causes the fifth video signal 34 to be supplied as the output video signal 38. The output video signal 38 is then supplied to the dual sync monitor 16 for display.

In this mode, the dual sync monitor 16 displays the broadcast television signal from the tuner 18. The 15.75 kHz interlaced, overscanned, raster NTSC signal generated by the tuner 18, is received by the monitor 16 and is displayed on the monitor. Thus, the dual sync monitor 16 is perfectly sized to display the NTSC signal from the tuner 18. In addition, in this mode of operation, the control 40 through the IR decoder 72 is responsive to the infrared signals generated by the remote unit 80. The remote unit 80 has a plurality of key buttons 81 for entering data or commands. The control 40 is responsive to the infrared signal generated by the remote unit 80, as decoded by the IR decoder 72 to cause changes in the tuner 18. In this manner, the remote 80 functions as a conventional hand-held remote unit for a television device.

Moreover, the control 40 with its software, can cause the keys 81 on the remote unit 80 to be redefinable by the user, initially, or dynamically. Thus, each user of the system 10 can have his or her own favorite set of keys 81, defined in his or her own particular definition, such as particular buttons 81 to denote favorite pre-selected channels.

Through a single key on the remote unit 80, the video signal controller 10 of the present invention can enter into its second mode of operation. In the second mode of operation, the control 40 activates the control signal 35 to switch the second multiplexer 36. The output video signal 38 of the second multiplexer 36 is then from the first video signal 14 which is generated by the computer 12. Thus, in this second mode of operation, the video signal controller 10 permits the digital computer 12 to display its video signal, such as EGA, VGA or Super VGA, on the dual sync monitor 16 as if the digital computer 12 were operating in a stand alone mode of operation.

In addition, however, because the remote unit 80 transmits infrared signals to the IR decoder 72 which is received by the control 40, the signals from the remote unit 80 can be mapped by the control 40 to supply command to the digital computer 12 along its RS-232 serial input port. Thus, data or command can be supplied from the remote unit 80 to the digital computer 12 as if the remote unit 80 were a portable input device such as a portable keyboard.

Moreover, because the control 40 can interpret the IR signals generated by the remote 80 as decoded by the IR decoder 72, the control 40 can cause the keys 81 on the remote unit 80 to be redefinable by the user, initially, or dynamically. Thus, each user of the system 10 can have his or her own favorite set of keys 81, defined in his or her own particular definition as command or data keys for the digital computer 12.

Finally, in a third mode of operation, the controller 10 can display two video signals simultaneously in a number of different possible ways. In the first way, the tuner 18 can receive video signals from one channel and display that on the monitor 16, while simultaneously a video signal from another channel on the LCD display 15. This, of course, would require two tuners 16.

In another way, the computer 12 can be displaying its video signals on the monitor 16, while the video signals from the tuner 18 is displayed on the LCD display 15.

Finally, the second audio/video signal 22 can be supplied to the digital computer 12. The control signal 35 to the second multiplexer 36 is switched such that the output video signal 38 to the dual sync monitor 16 is supplied from the first video signal 14 from the digital computer 12. However, because the second audio/video signal 22 is also supplied to the digital computer 12, the second audio/video signal 22 is digitized and is placed in the buffer 54. Thereafter, the CPU 56 of the digital computer 12 can retrieve the data from the buffer 54 and place it as a "window" in a location within its display, thereby accomplishing a "picture-in-picture" (P-I-P) display. However, unlike conventional, prior art P-I-P displays, wherein two signals having the same format, e.g. two NTSC signals are displayed on the same screen, or two digital signals forming windows for a digital computer display, in this mode of operation, two video signals having different standards are displayed in a P-I-P format.

In yet another variation, one channel of the second audio/video signal 22 can be supplied to the digital computer 12. The control signal 35 to the second multiplexer 36 is switched such that the output video signal 38 to the dual sync monitor 16 is supplied from another channel of video signal from the tuner 18. The one channel of video signals from the audio/video signal 22 is digitized and is placed in the buffer 54. Thereafter, the CPU 56 of the digital computer 12 can retrieve the data from the buffer 54 and place it as a "window" The mux 36 can be continually switched back and forth to accomplish the prior art technique of displaying a broadcast picture-in-broadcast picture.

Another aspect of the present invention is the particular manner in which the P-I-P display is accomplished. In the preferred embodiment, the CPU 56 is an Intel or Intel-compatible X86 processor, where X86 is preferably of the type 386 or 486. These processors 56 have four modes of operation: real, virtual, protect, and system management. Referring to FIG. 2, there is shown a block level diagram of the typical components of the digital computer 12. The CPU 56 and the buffer 54 are connected to and communicate with an internal bus 90 of the computer 12. In addition, a memory control unit 92 communicates with the bus 90. The memory control 92 controls a main memory 96 comprises an access memory portion 96a and a system management memory portion 96b. In addition, the memory control 92 communicates with a cache memory 94. Finally, a video memory 98 communicates with a bus 90 and supplies the necessary video signals to the video monitor 16.

In the prior art, when the computer 12 is operational, it executes an operating system program such as MS DOS (available from Microsoft Corporation) and Windows (also available from Microsoft Corporation). These operating system programs are stored in the access memory 96a portion of the main memory 96. Typically, the Windows program causes the video memory 98 to contain a display to be displayed on the monitor 16 showing various "windows" or application programs that are operational. The application programs operating under the Windows environment are also stored in the access memory portion 96a of the main memory 96.

In the prior art, as the buffer 54 is filled with video data generated by the tuner 18, periodically, an interrupt signal is generated and is transmitted to the CPU 56. The interrupt signal typically, can be generated after one raster scan full of data and is based upon the sync signal. Since the CPU 56 is executing an application program under the Windows environment, the CPU 56, would seek an instruction from the application program that is designed to handle the interrupt by sending a signal to the bus 90, through the memory control 92 and into the access memory 96a. The instruction from the application program in 96a is then retrieved back through the memory control 92 through the bus 90 and into the CPU 56. The instruction is then processed. However, since the application program is running under the Windows environment, the particular instruction, for example, if it is to service the data in the buffer 54 by moving it into the video memory 98, must again be passed into the Windows operating instruction environment. The CPU 56 would then send a signal, to the bus 90, through the memory control 92 and into the access memory portion 96a into the portion of the Windows program residing in the access memory 96a and retrieve an instruction therefrom. The instruction retrieved from the Window program must be passed back through the memory control 92 through the bus 90 and into the CPU 56 for execution. Each byte of data in the buffer 54 must be operated upon in this manner, i.e. by going entirely through the application program into the Windows operating system program before the data is operated upon.

In the present invention, the CPU 56 again receives an interrupt signal from the buffer 54. Upon receiving the interrupt signal from the buffer 54, the CPU 56 enters into the system management mode of operation. In the system management mode of operation, the CPU 56 accesses a system management program located in the system management memory portion 96b of the main memory. The system management mode of operation, as designed by the manufacturer of the microprocessor 56 is intended solely to "power down" the processor 56 and the entire digital computer 12. However, in the present invention, a software program 70 is written and is stored in the system management memory portion 96b of the main memory 96. Upon receiving the interrupt from the buffer 54, the program from the system management memory 96b is then retrieved by the CPU 56. The program from the system management memory 96b then executes on the data in the buffer 54 by moving them from the buffer 54 into the video memory 98. By bypassing the need to go through the application program, and its associated operating system program under which the application program executes, using the system management mode of operation, greater throughput is achieved.

Unlike the Terminate and Stay Resident (TSR) programs of the prior art, in which a program reside in the same memory as the operating system and application programs, the program residing in the system management memory portion 96b of the main memory 96 is not accessible and cannot be altered by any of the programs (application or operating system) from the access memory 96a.

In another aspect of the present invention, in the prior art, raster scan television devices are able to provide only one channel of audio although it is common to display two or more channels of video, such as in P-I-P. In this mode of operation, the audio signal portion of the audio/video signal 22 from the tuner 18, can be mixed in a mixer 30 with the audio signal portion of another audio/video signal, which is passed through the digital computer 12 by the mixer 30. The output of the mixer 30 is then supplied to an amplifier 64 which is then produced at the speakers 66. In this manner, if for example, the speakers 66 comprise a plurality of stereo sound system, one sound for one of the channels can be directed to, e.g. the left speaker, and another audio signal for a different channel can be directed to, e.g. the right speaker. If the speakers are sufficiently spatially separated, the two channels of sound can be active simultaneously with the display of the two video signals from the two different channels on the display 16. Furthermore, the user can mentally distinguish between these two channels. The following is a listing of the functional specifications for the software 42. ##SPC1##

From the foregoing, it can be seen that a video signal controller, operating with a computer monitor and a computer, can display conventional television signals without interrupting or taking away the processing capabilities of the digital computer 12 as in the prior art. Furthermore, the computer 12 can display P-I-P type images with substantially reduced overhead.