Abstract:
A computer system using a universal serial bus (USB) hub is provided with a screen locking function. The computer system includes a computer main unit, information input devices electrically connected to the computer main unit for permitting a user to input information to the computer main unit for data processing operation, a display device electrically connected to the computer main unit for providing a visual display of information processed by the computer main unit, and a universal serial bus (USB) hub arranged to electrically connect the information input devices and the display device to the computer main unit and through which, the screen locking apparatus is set to disable operation of the information input devices such as a keyboard and mouse. This way when the user temporarily leave the computer system, a currently executed program is protected from interference and damage.

Description:
CLAIM FOR PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for LOCKING APPARATUS OF COMPUTER SYSTEM USING USB HUB earlier filed in the Korean Industrial Property Office on the 12 th  of July 1997, and there duly assigned Serial No. P97-32391 by that Office, a copy of which application is annexed hereto. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a computer system using an universal serial bus (USB) hub and, more particularly, to a display monitor of a computer system having a screen locking switch for controlling information signal from an information input device such as a keyboard and a mouse, and for preventing computer programs from unwarranted interference. 
     2. Related Art 
     A general computer system includes a computer main unit (which may have built-in storage devices such as floppy disks, hard disks and CD-ROM), a keyboard and a monitor connected to the main computer unit. Other computer peripheral devices such as an input mouse, a printer, a scanner, a telephone, and an external modem may also be connected to the main computer unit. These peripheral devices are generally supplied with power when the computer main unit is provided with power, or supplied with power by operation of a separate power ON/OFF switch. When power is supplied, each peripheral device must be initialized and pre-heated before use. The power supply is consumed by the peripheral device until manual power termination regardless whether the peripheral device is in use or not. 
     CRT monitor which is widely used as a display device of the computer system processes information signal received from the computer system via a signal transmission cable and provides a visual display of the processed information signal on a screen. When there is no signal from the computer system, the monitor remains idle. For purposes of conserving power, the display of data image on the monitor may be blanked during the period of inactivity and re-displayed when the computer system becomes active, i.e., when an input device such as a keyboard is operated. In addition, a screen saver function may be provided by software to store current image data in a separate memory and provides a visual display of a screen saving image during the period of inactivity. However, the screen saving function is automatic and is carried out after a predetermined time of inactivity. The user cannot lock the screen at a specific time that s/he desires. As a result, error may be generated in the program due to continuous keyboard operation by other users. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is therefore an object of the present invention to provide a computer system having a screen locking function for locking a screen precisely at a desired time in order to prevent programs from unwarranted interference. 
     It is also an object to provide a computer system with a screen locking switch conveniently located on a display monitor for permitting a user to lock a screen of the display monitor and disable operation of input devices such as a keyboard and mouse. 
     It is further an object to provide a computer system using a universal serial bus (USB) hub for power and data distribution to different peripheral devices with a screen locking switch located on a display monitor for controlling operation of input devices such as a keyboard and mouse. 
     It is yet an object to provide a computer system providing an on-screen visual display of a screen locking function to inform a user of the status of computer operation. 
     These and other objects of the present invention can be achieved by a computer system provided with a screen locking function which comprises a computer main unit; information input is devices electrically connected to said computer main unit for permitting a user to input information to the computer main unit for data processing operation; a display device for providing a visual display of information processed by the computer main unit; and a screen locking apparatus positioned on the display device, for permitting the user to manually disable operation of the information input devices temporarily. 
     In accordance with another aspect of the present invention, a computer system provided with a screen locking function may be constructed with a computer main unit, a universal serial bus hub electrical connected to the computer main unit serving as a central connection point for power and data distribution to information input devices and a display device; and a screen locking switch positioned on the display device, for permitting a user to manually lock a screen of the display device and disable operation of the information input devices via the universal serial bus (USB) hub. 
    
    
     The present invention is more specifically described in the following paragraphs by reference to the drawings attached only by way of example. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the present invention, and many of the attendant advantages thereof, will become readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
     FIG. 1 is a block diagram of a typical computer system with a keyboard and a display monitor; 
     FIG. 2 is a block diagram of a computer system using a universal serial bus (USB) hub for power distribution to peripheral devices; 
     FIG. 3 is a detailed circuit diagram of the universal serial bus (USB) hub as shown in FIG. 2; 
     FIG. 4 is a detailed circuit diagram of a display monitor; 
     FIG. 5 is a schematic view of a control panel of a display monitor constructed according to the principles of the present invention as a preferred embodiment; 
     FIG. 6 is a flowchart of a screen locking process according to the principles of the present invention; and 
     FIG. 7 is a schematic view of the display monitor illustrating execution of screen locking according to the principles of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings and particularly to FIG. 1, which illustrates an exemplary computer system comprising a computer main unit  1  and peripheral devices such as a keyboard  2 , a mouse,  3  and a display monitor  4  connected to the computer main unit  1 . Each respective peripheral device has a port available via unoccupied one of slots on the mother board of the computer main unit  1 . Typically, the user has to open the computer main unit  1  and insert an interface card in a corresponding slot on the mother board. On occasions the user must operate a switch, set a jumper or arrange the types of connectors such as serial or parallel appropriate for the peripheral devices. Each peripheral device is generally supplied with power when the computer main unit  1  is provided with power, or supplied with power by operation of a separate power ON/OFF switch. When power is supplied, each peripheral device must be initialized and pre-heated before use. The power supply is consumed by the peripheral device until manual power termination regardless whether the peripheral device is in use or not. For instance, a display monitor of either a cathode-ray tube or a liquid crystal display which is widely used to process information signal received from the computer system via a signal transmission cable and provide a visual display of the processed information signal on a screen, the display monitor generally remains idle, when there is no signal activity from the computer system. A screen blank function may be provided such that display of data image on the monitor is blanked during the period of inactivity and re-displayed when the computer system becomes active, i.e., when an input device such as a keyboard is operated. In addition, a screen saver function may be provided by software such that current image data is stored in a separate memory and a screen saving image is displayed on the screen during the period of inactivity. However, the screen saving function is automatic and is carried out after a predetermined time of inactivity. The user cannot lock the screen at a specific time that s/he desires. As a result, error may be generated in the program due to continuous keyboard operation by other users. 
     This type of error is augmented when the computer system uses a universal serial bus (USB) hub which serves as a central connection point of the computer system for power and data distribution to all peripheral devices in order to conveniently control power distribution over different peripheral devices. The universal serial bus (USB) hub is used to reduce the number of interface cards and slots available on the mother board of the main unit  1  of the computer system. The peripheral devices to be connected to the universal serial bus (USB) hub may include a telephone network, a modem, a printer, a microphone, a mouse, a scanner, a digital camera and so on. Simplicity and convenience are the major advantages of the USB hub. This is because the universal serial bus (USB) hub can sense the addition or removal of peripheral devices from the computer system without rebooting the system even when power is still activated, unlike the conventional built-in slots. In addition, the USB hub supports plug-and-play operations such that information relating to the source, e.g., driver software required for the respective peripheral devices or band width of the bus can be obtained automatically without intervention of the user. 
     The use of a universal serial bus (USB) hub  10  is shown in FIG. 2 for connecting all peripheral devices such as a display monitor  4 , a printer  5 , a scanner  6  and an external modem  7  to the computer main unit  1  of the computer system. The keyboard  2  and display monitor  4  may be connected directly the computer main unit  1 . The USB hub  10  allows the user to install all other peripheral devices or its related cards to the computer system without having to open the computer main unit  1  for interface cards installation. The USB hub  10  provides connections between the computer main unit  1  and up to 127 peripheral devices and supplies an operational voltage of only 5 volts to the respective peripheral devices without consuming a vast DC voltage. In addition, the USB hub  10  has a data transmission rate of 12 Mbit/sec sufficient that most peripheral devices of a large band width can have a tremendous capacity at a little expense relative to the cost for the current connector technique. 
     FIG. 3 illustrates a circuit diagram of the USB hub  10  for power distribution of a designated peripheral device such as a display monitor  4 . The USB hub  10  includes a USB control circuit  11  for controlling information transmission between the computer main unit  1  and peripheral devices using data and clock provided by the display monitor  4 , a DC-DC converter  12  for processing the power supplied from the display monitor  4  to provide operation power to USB control circuit  11  and down stream ports  14 ,  15  and  16  respectively connected to peripheral devices  5 - 7 , and an over-current protection circuit  13  for detecting output current of DC-DC converter  12  to prevent damages due to over-current. The computer main unit  1  is constructed such that it supplies the USB control circuit  11  with an operational power of 5 volts and exchanges information and clocks mutually with the USB control circuit  11 . 
     As shown in FIG. 3, the power (14V) supplied from the display monitor  4  passes through DC-DC converter  12 , to be provided to USB control circuit  11  as its operation voltage (5V). The power (5V) from DC-DC converter  12  is supplied to USB control circuit  11  and to peripheral devices  5 - 7  through down stream ports  14 ,  15  and  16 . The computer system is connected to up stream port of USB control circuit  11 . In this case, USB environment is set in the computer, and the computer main computer  1  automatically supports the USB control environment. When the computer peripheral devices  5 ,  6  and  7  are connected to down stream ports  14 ,  15  and  16  of USB hub  10 , the computer main unit  1  identifies the ID and, if acceptable, installs the peripheral devices  5 - 7  automatically without separate action of the user. 
     Display monitor  4  processes information signal received from the computer main unit  1  via a signal transmission cable and provides a visual display of the processed information signal on a screen. An internal circuit of the display monitor  4  is shown in FIG.  4 . 
     Referring to FIG. 4, the computer main unit  100  includes a central processing unit (CPU)  110  for receiving an input keyboard signal, processing the input signal, and generating image data, and a video card  120  for receiving the image data from CPU  110 , processing the same as a video signal (R,G,B), and generating horizontal and vertical synchronous H-SYNC and V-SYNC signals for synchronizing the video signal. The video signal (R,G,B) and horizontal and vertical synchronous H-SYNC and V-SYNC signals are sent from video card  120  of the computer main unit  100  to the monitor  200  through a video signal cable (not shown). 
     Display monitor  200  receives the video signal and the horizontal and vertical synchronous H-SYNC and V-SYNC signals from the video card  120  of the computer main unit  100 . The display monitor  200  is composed of a microcomputer  210  which receives the horizontal and vertical synchronous signals, a control button section  220  for generating a screen control signal, a horizontal and vertical output circuit  230  for formulating an image, a video circuit section  240  for processing the video signal received from the video card  120  through amplification, and a power supply circuit  250  for supplying a driving power to the microcomputer  210 , the horizontal and vertical output circuit  230 , and the video circuit section  240 . 
     Microcomputer  210  which stores all sorts of screen control data is receptive to the horizontal and vertical synchronous H-SYNC and V-SYNC signals from the video card  120 , and generates an image adjusting signal and a reference oscillating signal in response to the screen control signal applied from the control button section  220 . A horizontal/vertical oscillation signal processor  231  receives the image adjusting signal and the reference oscillating signal from the microcomputer  210 , and supplies a vertical pulse to a vertical drive circuit  232 . The vertical pulse is used to control the switching rate, of a sawtooth wave generating circuit in response to the horizontal and vertical synchronous H-SYNC and V-SYNC signals. 
     The video drive circuit  232  can be either a one-stage vertical amplification type or an emitter follower type. The emitter follower type vertical drive circuit has the base of transistor used as an input with the emitter as an output. Hence the vertical drive circuit  232  normally has improved linear characteristic but not gain. The vertical drive circuit  232 , after amplification, supplies a drive current to a vertical output circuit  233 , which will apply a sawtooth current corresponding to a vertical synchronous V-SYNC pulse flowing through a V-DY, determining a vertical scanning period depending on the sawtooth current. In addition, a horizontal drive circuit  234  receives a horizontal oscillating signal from the horizontal and vertical oscillating processor  231 , and accordingly, supplies a drive current high enough to switch the horizontal output circuit  235 . 
     Upon receipt of the drive current from the horizontal drive circuit  234 , the horizontal output circuit  235  will generate a sawtooth current to the H-DY, determining a horizontal scanning period depending on the sawtooth current. Such a horizontal drive circuit  234  is divided into two classes; in-phase type whose output is ON with the drive terminal ON, and out-of-phase type wherein the output is OFF with the drive terminal ON. 
     High-voltage circuit  236  and FBT (flyback Transformer)  237  generate a high voltage in order to supply a stable DC voltage to the anode terminal  244   a  of a cathode-ray tube (CRT)  244 . Even when a collector pulse is very weak, high-voltage circuit  235  and FBT  237  can generate a high voltage by use of a harmonic wave due to inductance and distribution capacity. This high voltage is applied to the anode terminal  244   a  of the CRT  244 , forming a high voltage across the anodic surface of the CRT  244 . Simultaneously, the video circuit section  240  has an on-screen display (OSD) IC  241  which receives OSD data generated during the screen control of the microcomputer  210  to generate an OSD gain signal. This OSD gain signal from the OSD IC  241  is sent to a video pre-amplifier  242 . 
     Upon receipt of the OSD gain signal from the OSD IC  241  and the RGB video signal from the video card  120 , the video pre-amplifier  242  amplifies the RGB picture signals to a limited voltage level via a low-voltage amplifier. For example, a video signal less than 1 V pp  is converted to the voltage of 4 to 6 V pp  through an amplification in the video pre-amplifier  242 . This video signal is further amplified to 40 and 60 V pp  in a video output amplifier  243  and then sent to the cathode of the CRT  244  for a visual display of a variable video image. The image which has been produced through the CRT  244  in response to the RGB video signal and the OSD signal has its scanning period determined by the H-DY and V-DY and is visually displayed on the screen of CRT  244 . The RGB video signal or the OSD signal which are amplified by the vide output amplifier  243  will be displayed as a variable video image with the luminance regulated by the high voltage formed across the anode surface of CRT  244 . 
     Power supplying circuit section  250 , which is to provide a driving voltage for displaying the RGB video signal on the screen of the display monitor, receives an AC (Alternative Current) through an AC input  251 . The AC is applied to a degaussing coil  252 , which resumes the color blotted due to the influence of the earth magnetic field or external environment to the original distinct one. For this, degaussing coil  252  disperses the magnetic field of a DC component formed across the shadow mask in CRT  244  while an AC is applied to the degaussing coil  252  momentarily for 2-8 seconds, and prevents the electron beams from being deflected unstably due to the magnetic field. The AC is normally rectified into a DC through a rectifier  251  and transmitted to a switching transformer  254 . The switching transformer  254  supplies all sorts of driving voltage required in the monitor  200  via a voltage regulator  255 . At this stage, PWM (Pulse Width Modulation) IC  256  controls the switching operation of the switching transformer  254 , stabilizing the output voltage of the transformer. 
     Microcomputer  210  which is in a DPMS (Display Power Management Signaling) mode to economize power consumed in the display monitor  200 , sets up a power-off mode and a suspend mode depending on the presence of horizontal and vertical synchronous H-SYNC and V-SYNC signals, and accordingly saves the power in the display monitor  200 . If the user adjusts a screen or wants to have information about the display mode of the display monitor which is in a current use, s/he has to choose the OSD function through the control button section  220  as programmed in the microcomputer  210 . Upon the user&#39;s pressing a button for the OSD function, the microcomputer  210  serves the OSD function in response to a key signal through the OSD IC  241 . In this case, the microcomputer  210  sends OSD data already stored therein to the OSD IC  241 , which processes the OSD data to generate an OSD gain signal to the video pre-amplifier  242  and the video output amplifier  243 . The OSD gain signal is then displayed on the screen of the CRT  244  after amplification via those amplifiers  242  and  243 . Under the OSD signal, the CRT  244  provides an on-screen display of menus relating to the OSD function. The user may choose one menu containing information ofthe display monitor  200 , such as screen locking, screen adjustment, display mode, horizontal and vertical frequencies, and the like. 
     Control button section  220 , as shown in FIG. 5, includes a variety of picture control buttons which are left/right position control key  221 , top/bottom position control key  222 , left/right size control key  223 , top/bottom size control key  224  and side pincushion control key  225 . While a certain control key is pushed, a minus control key and plus control key  226  are used to realize a picture in a required form. In addition those keys, the control button section of the display monitor according to the present invention also includes a screen locking switch  227  which operates in a toggle manner and maintains its setting state by repeating ON/OFF states. The screen locking switch  227  is configured to permit the user to manually lock the screen of the display monitor anytime, anywhere at any situation without having to wait for the screen saving function or the like in order to protect the programs which is currently executed, from potential interference or damage. 
     Now the operation of screen locking function provided by the screen locking switch  229  will be described in detail with reference to FIGS. 1,  4  and  6  as follows. 
     First of all, the user pushes the screen locking switch  227  on the control panel of the display monitor  200  at step S 10 . Here, the microcomputer  210  of the display monitor  200  confirms if a screen locking flag is set or not at step S 20 . When the screen locking switch is pushed while the screen locking flag is set, the microcomputer  210  of the display monitor  200  enables operation of information input devices such as a keyboard  2  and mouse  3  through the universal serial bus (USB) hub  10  at step S 31 . Then, the screen locking flag is reset at step S 41 . When the screen locking switch is pushed while the screen locking flag is not set, the microcomputer  210  of the display monitor  260  disables operation of the information input devices such as the keyboard  2  and mouse  3  at step S 32 . When the screen locking flag is set at step S 42 , OSD characters are displayed on the display monitor at step S 50 , as shown in FIG. 7, to inform the user that the screen locking has been carried out. Meantime, during execution of screen locking, the microcomputer  210  of the display monitor  200  outputs a control signal to realize the DPMS mode immediately. After setting of screen locking switch; transition from stand-by mode to suspend mode to power-off mode is performed with the lapse of time. Here, the operations of the information input devices such as the keyboard and mouse are controlled depending on whether the screen locking switch is set or not. 
     As described above, the present invention allows the user to control the keyboard and mouse in the computer system which can exchange information with them using the USB hub. Furthermore, when the user has to leave the system during execution of important program, the program can be prevented from being damaged by others. 
     While there have been illustrated and described what are considered to be preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the screen locking function of a computer system using USB hub of the present invention. In addition, many modifications may be made to adapt a particular situation to the teaching of the present invention without departing from the central scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the present invention, but that the present invention includes all embodiments falling within the scope of the appended claims.