JPH07271334A - Wrongful-access prevention display device and computer system - Google Patents

Abstract

PURPOSE: To provide a display device containing a lockable display screen. CONSTITUTION: A driving circuit 200 generates an image on a display screen 210 in response to input video signals (R, G, and B). Standby means 270 and SL invalid the driving circuit 200, in response to a standby signal. Resetting means 270 and RL reset the driving circuit 200 to operate upon receiving a prescribed security code.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having means for locking a display screen to prevent unauthorized access to data.

[0002]

2. Description of the Related Art Some information processing systems such as personal computer systems use a power saving mechanism or "power management" mechanism to reduce power consumption when operation is restricted. Typically, such systems have display devices that have their own power management mechanism. An example of such a display device is a display screen of a display panel such as a CRT or liquid crystal. A drive circuit that receives an input video signal is connected to the display screen, and an image is generated on the display screen in response to the input video signal. In order to have a power management function on the display screen, a count is generated by the timer in response to the clock signal, a change in the image content between consecutive frames of the input video signal is detected, and the timer is detected by the detector. Will be reset. A control means is connected to the timer and the drive circuit and at least partially disables the drive circuit in response to the count stored in the timer exceeding a predetermined threshold. Normally, the control means results in the display operating in a standby mode and gradually shuts down the drive circuit with increasing inactivity until the detector, timer and control means remain operational. Is set to do. The display returns from standby mode to normal operation only in response to the detector detecting a change in image content. Generally, the timer, detector and control means are implemented, at least in part, by a microprocessor. With this configuration, a power management function can be obtained in the display device independently of any host computer system. Power management is therefore enabled on the display device independent of the system unit to which the display device is connected.

Another one with power management function
In the example of one display, the return from standby mode to normal operation is by detection of the proximity of the user.
Another example of a display device that has a power management function, when a keyboard or mouse entry is detected,
Normal operation returns from standby mode.

The above display device allows the operator to immediately access the data stored in the system unit when returning from the standby mode to normal operation. Because such displays automatically enter standby mode, the former operator may immediately forget to restart the display and log off from the computer system to which it was connected. This can cause safety issues.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent unauthorized access to data accessible by a computer system via a display device.

[0006]

A display device provided in accordance with the present invention comprises a display screen, an input video signal (R, G,
B) includes a drive circuit that generates an image on the display screen in response to B), and standby means that disables the drive circuit in response to a standby signal, and receives a predetermined security code to restore the operation of the drive circuit. It is characterized by including reset means.

According to the present invention, the drive circuit returns to normal operation only by providing the display device with the appropriate security code, so that the data stored in the host computer system has the appropriate code. It is displayed on the display screen only to users who know it. The present invention thus solves the problem of preventing unauthorized access to data otherwise accessible through a display device from a host computer system to which the display device is connected.

The display device preferably includes entry means for entering a security code. In the preferred embodiment of the present invention, the entry means comprises a keypad having a plurality of pushbuttons. The reset means preferably comprises a processor having a plurality of interrupt inputs for receiving interrupts from the keypad push buttons. The security code is programmed and reprogrammed by the user through this processor.

The processor is preferably configured to control the drive circuitry to change one or more image parameters of the image displayed on the display screen in response to an interrupt from the one or more push buttons. It Therefore, the processor can be configured to provide the keypad with two functions. First, during normal operation of the display device, the keypad can be used to adjust the parameters of the image displayed on the display screen according to the user's preference. Second, when the display is in standby mode, the keypad can be used to enter a security code into the display to restore normal operation.

A preferred embodiment of the present invention includes a lock circuit for setting the standby means to disable the drive circuit, so that the operation of the drive circuit is restored upon receipt of the security code. Are invalidated by the reset means. The waiting means preferably comprises an output port of the processor, and the lock circuit comprises a memory element connected to the input port of the processor for storing the state of the output port. The reset means preferably resets the contents of the memory element upon receipt of the security code. The memory element preferably comprises a capacitor.

The present invention also provides a computer system including a display device as described above, a system unit for generating an input video signal to generate an image on the screen of the display device, and data and commands for the system unit. Input means for inputting is assumed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a computer system comprises a random access memory (RAM) 10, a read only memory (ROS) 20, a central processing unit (CP).
U) 30, communication adapter 40, display adapter 70, pointing device adapter 80, keyboard adapter 90, and mass storage device 100 (hard disk drive, tape streamer, etc.) are all interconnected by the bus architecture 60. It includes a connected system unit 5. System unit 5 is an adapter 9
0 to the keyboard 110. The pointing device 120 (touch screen, tablet, mouse, etc.) is connected to the system unit 5 through the adapter 80. The system unit 5 is also an adapter 70
And an interface cable 135 to connect to a display device 130 such as a cathode ray tube (CRT) display device or a liquid crystal display device (LCD). The network 50 of the other system unit is connected to the system unit 5 through the communication adapter 40.

In operation, the CPU 30 transfers the data stored in the device in which the RAM 10 and the mass storage device 100 are combined to the ROS 20, the RAM 10, and the mass storage device 10.
Processes under the control of computer program code stored in a combination of zeros. Communication adapter 40
Controls the transfer of data and computer program code between the system unit 5 and other system units of the network 50 via the communication adapter 40. Data and instructions can be manually entered into the system unit 5 from the keyboard 110 and pointing device 120 by keyboard and mouse adapters 90 and 80, respectively. The display adapter 70 converts the output data from the system unit 5 into video signals R, G, B and into horizontal and vertical image synchronization (SYNC), H and V to generate visual data output. The display device 130 is set. Bus architecture 60 is RA
Coordinate data transfer between M10, ROS 20, CPU 30, storage device 100 and adapters 40, 90, 80, 70.

Referring to FIG. 2, the display device 130 includes a color cathode ray tube (CR) connected to a display driving circuit 200.
It includes a display screen 210 in the form of T). Display drive circuit 20
0 is the EHT (Extra High) connected to the display screen 210.
Tension) generator 230 and video amplifier 250. The line and frame deflection coils 290, 280 are located around the neck of the CRT. Deflection coil 290,
Reference numeral 280 denotes a line and frame scanning circuit 22 respectively.
0,240. Line scanning circuit 220 and EH
Each T generator 230 may be in the form of a flyback circuit. The operation of the flyback circuit is well known. The EHT generator 230 and the line scanning circuit 220 may be integrated into one flyback circuit, as is also well known. A power supply (not shown) is provided with an EHT generator 230, a video amplifier 250 and line / frame scanning circuits 220, 24 through a power supply rail (not shown).
Connected to 0. The power supply, in use, supplies power to the internal mains power supply from a line / neutral connection (not shown) through the power rail. The power supply may be in the form of a switch mode power supply, the operation of which is well known.

The EHT generator 230, video amplifier 250 and line / frame scanning circuits 220, 240 are each connected to a display processor 270. Display processor 270 preferably includes a microprocessor,
It includes processor logic in the form of a microcomputer with memory. The drive circuit 200 includes a user control panel 260 connected to the key pad interrupt line of the display processor 270. The control panel 260 includes a plurality of switches that can be manually operated.

During operation, the EHT generator 230 is C
In the RT 210, an electric field is generated which accelerates the electrons of the beams corresponding to the three primary colors of red, green and blue toward the screen of the CRT.
The line / frame scanning circuits 220 and 240 generate line / frame scanning currents in the deflection coils 290 and 280. Line / frame scan current is a form of ramp signal that produces a magnetic field that changes over time. This magnetic field scans the electron beam on the screen of the CRT 210 in a raster pattern. The line / frame scan signal is
The line / frame scanning circuit is synchronized and the line / frame synchronization (SYNC) signals H and V generated by the video adapter 70 are input. Video amplifier 250 modulates the red, green, and blue electron beams to produce an output display on CRT 210 as a function of the corresponding red, green, and blue input video signals R, G, B produced by adapter 70. The line / frame sync signals H and V and the video signals R, G, B are sent from the adapter 70 to the display device 130 through corresponding signal lines of the interface cable 135. The signal line of the interface cable 135 terminates at a connector (not shown) at the end remote from the display device 130. The connector removably connects the signal line to the adapter 70. From the standpoint of compatibility, this connector is preferably a 15-pin D-type connector, although other connectors can be used.

Display processor 270 outputs the outputs of EHT generator 230, video amplifier 250, and line / frame scanning circuits 220, 240 to preprogrammed display mode data and user control panel 260.
Is set to control through control link 275 as a function of the input of. The display mode data includes a preset image parameter value set. The image parameter values are 1024 × 768 pixels and 640 × 480, respectively.
It corresponds to a general display mode such as pixels and 1280 × 1024 pixels. Each set of image display parameter values includes a height and centering value for setting the output of the frame scanning circuit 240 and a width and centering value for controlling the line scanning circuit 220. The display mode data also includes preset common image parameter values to control the gain and cutoff of each of the red, green and blue channels of the video amplifier 250, and the EHT generator 2.
Includes preset control values for controlling 40 outputs. Image parameter values are selected by the display processor 270 in response to input mode information from the adapter 70. Mode information is sent from the adapter 70 to the display processor 270 via line / frame sync lines H and V. Display processor 270 processes the selected image parameter values to produce analog control levels on the control link.

The user is the red on the video amplifier 250 side,
The user control panel 26 controls the control levels for controlling the video gain and cutoff of green and blue, and the width, height, and centering of the image on the side of the line / frame scanning circuits 220 and 240.
It can also be adjusted manually through 0. The user control panel 260 displays image height, centering, width, brightness,
It includes a series of up / down control keys corresponding to each of the contrasts.

Referring now to FIG. 3, the control keys are preferably in the form of push buttons connected to the keypad interrupt input 320 to the display processor 270. For example, when the width up key is pressed, the user control panel 26
0 issues an interrupt corresponding to the display processor 270. The source of this interrupt is determined by the display processor 270 through an interrupt polling routine.
The display processor 270 responds to the interrupt from the width key by gradually increasing the corresponding analog control level sent to the line scanning circuit 220. The width of the image gradually increases. The release of the interrupt is detected by the display processor 270 and the digital value that sets the width control level is retained. Height, centering, brightness and contrast settings can be similarly adjusted by the user. User control panel 26
0 preferably further comprises a storage key. An interrupt is generated when the user presses the store key, and the display processor 270 responds by storing the parameter value corresponding to the current setting of the digital output to the D / A converter in memory as the preferred display format. Thus, the user can program the particular display image parameters into the display device 130 as desired.

Continuing to refer to FIG. 3, the display processor 270 maintains a pulse count of the clock signal under the control of the microcode instruction program to provide the display device 130 with a power management function.
Display processor 270 detects changes in image content between successive frames of the input video signal and resets the count. If there is no change in the image content, the display processor 2
70 continues to increment the count with each pulse of the clock signal. The display processor 270 starts disabling the driving circuit 200 in response to the count stored in the timer exceeding the first predetermined threshold value. Display processor 270
First disables only the high power portions of drive circuit 200, such as line scan circuit 220, EHT generator 230, etc. However, when the count continues to exceed another threshold value that gradually increases from the first threshold value, the low power portion of the driving circuit 200 such as the frame scanning circuit 240 and the video amplifier 250 is disabled. It As a result, only the low power part of the power supply remains valid and power is supplied to the display processor 270 on the low voltage supply line Vs (typically 5V). The power supply control port SL of the display processor 270 is connected to the power supply of the display device 130 to selectively disable and enable the high power portion of the power supply. Display processor 270 sets control port SL high to disable the high power portion of the power supply. The display is now operating in standby mode.

Display device 130 includes lock circuit 300 coupled to display processor 270, in accordance with the present invention. Lock circuit 300 includes field effect transistor switches Q1, Q2. The drain of Q2 is the register R1
It is connected to the low voltage power supply line Vs through (usually 1 k ohm). The source of Q2 is connected to circuit ground 0V. The drain of Q2 is also connected to the lock sense input port LO of the display processor 270. The gate of Q2 is connected to the power supply control output port SL of the display processor 270 through the diode D1. Normally 0.5μF
Capacitor C1 is connected to system ground 0V through the gate of Q2. The drain of Q1 is connected to the gate of Q2. Source of Q1 is system ground 0
Connected to V. The gate of Q1 is the display processor 270.
Of the reset output port SR. Transistors Q1 and Q2 are preferably insulated gate field effect transistors (IGFETs) because they typically have large and very low leakage gate capacitances compared to other types of transistors. Is. Similarly, capacitor C1 is preferably a polycarbonate capacitor, because such capacitors typically have much higher insulation resistance than other types of capacitors. For example, if a 1 μF polycarbonate capacitor is used for C1, the hold time may exceed 24 hours.

In operation, when control port SL goes high and the high voltage portion of the power supply is disabled, C1 charges to a voltage that is one diode drop below D1 below Vs (eg, 5V-0.7V). Therefore Q
2 turns on. When control port SL goes low, D1 is reverse biased. Therefore, the voltage of the gate of Q2 is
It remains so even if the display processor 270 is powered off. When Q2 turns on, the drain of Q2 becomes LO
W. Therefore, the lockout input LO to the display processor 270 will be low. The display processor 270 polls the lockout input port LO in response to an operation attempting to bring the display device 130 out of standby mode.
If the polling indicates that the input port LO is low, the display processor 270 continues to disable the drive circuit 200. Since the preferred embodiment of Q2, Q2, and C1 has a low charge leakage characteristic, the “hold time” in which the lock circuit 300 holds the input port LO at LOW after the power of the display device 130 is cut off becomes long. Since there is C1, the rise time of the output port SL may be long. As a result, the delay in switching the operation of the display device 130 to the standby mode may fall below the allowable level. This problem is solved in the embodiment of the present invention by using a buffer on the output port SL side. The buffer also serves to increase the voltage applied to C1 to lengthen the hold time or, alternatively, allow the use of lower value capacitors as an example of C1.

In accordance with the present invention, the user must enter a security code into the display processor 270 to exit the standby mode of the display device 130. When the display processor 270 recognizes the correct security code, it pulses the reset output port RL high. Q1 turns on in response to a pulse on output port RL. Therefore C1 is discharged through Q1. Therefore Q
The voltage at the gate of 2 drops and Q2 turns off. The lockout input LO will therefore go high. Display device 130
Is thus unlocked. The display processor enables the drive circuit 200 to display the data on the display screen 210 through the control link 275.

The security code is preferably entered by pressing buttons on the user control panel 260 in a predetermined sequence. In other words, the display processor 270 pulls the reset output port RL high only when it detects a predetermined sequence of interrupts on the keypad interrupt input 320. The user control panel 260 preferably includes another push button 310 to allow a new security code to be programmed into the display processor 270. The security code is entered first by push button 310 and then by entering a new desired sequence before releasing button 310. The display processor 270 has a button 310.
, And record the sequence of interrupts received from other buttons while the interrupt from button 310 is present as the new security code.

When the display device 130 is locked in the standby mode by the lock circuit 300, a user who does not have permission to access the display device 130 has to unlock the new display device (which itself is unlocked in the standby mode). ) Can only access the visual information from the computer system. This makes such access attempts visible to the observer. Reference is now made to the lower half of FIG. In order to eliminate this possibility, especially in the embodiment of the present invention, a mechanical security function 400 is provided in the display device 130.
The security feature 400, in use, prevents the interface cable 135 from being removed from the system unit 5 without the use of a key. Refer to the upper half of FIG. Interface cable 13 of display device 130
5 is fitted with a multi-pin connector for releasably connecting the display device 130 to the display adapter 70 of the system unit 5. Connector 410 includes a pair of knurled screws 420. When using the screw 420,
Engage the threaded receptacle on the unit housing,
Tightened to lock connector 410 in place. Refer to the lower half of FIG. The mechanical security feature 400 preferably comprises a shroud with two portions 430, 450 adapted to fit in a clamshell.
Portions 430 and 450 are preferably molded from plastic material. The key operation locking mechanism 450 is for fixing the two parts 440, 430. In use, with the connector 410 fixed to the system unit 5, the two parts 440, 430 are fixed with the interface cable 135 centered and the connector 41
0 (broken line in the lower half of FIG. 4) is stored. The locking mechanism is biased by the two parts 440, 430 sticking together. Thereafter, the two parts 440, 430 cannot be separated without releasing the locking mechanism with the corresponding key. Screw 4
The access to 20 is disabled by the shroud so that connector 410 cannot be removed from system unit 5.

In the preferred embodiment of the invention described above, the lock circuit 300 includes memory means in the form of a capacitor C1 to maintain a constant hold time.
In another embodiment of the present invention, the hold time can be arbitrarily extended by adding memory means such as a non-volatile memory to the lock circuit 300.

Although the preferred embodiment of the present invention has been described with reference to a CRT display device, it will be apparent that the present invention is equally applicable to other types of display devices, such as flat panel displays including liquid crystal displays. Will.

In summary, the following matters will be disclosed regarding the configuration of the present invention.

(1) A display screen, a drive circuit for generating an image on the display screen in response to an input video signal, and a standby means for disabling the drive circuit in response to a standby signal. A display device comprising reset means for receiving and restoring the operation of the drive circuit. (2) The display device according to (1), further including an entry unit for inputting the security code. (3) The display device according to (2), wherein the entry means includes a key pad having a plurality of push buttons. (4) The display device according to (3), wherein the reset means includes a processor having a plurality of interrupt inputs for receiving interrupts from the push buttons of the key pad. (5) The processor controls a drive circuit to change one or more image parameters of the image displayed on the display screen in response to an interrupt from one or more of the push buttons. Set to (4) above
Display device described. (6) A lock circuit for setting the standby means to disable the drive circuit is included, and the lock circuit is disabled so that the operation of the drive circuit is restored when the reset means receives the security code. Yes, above (5)
Display device described. (7) The standby means includes an output port of the processor, and the lock circuit includes a memory element connected to an input port of the processor for storing a state of the output port. Display device described. (8) The display device according to (7), wherein the reset means resets the contents of the memory element when the security code is received. (9) In the above (8), the memory element includes a capacitor.
Display device described. (10) The above (1), (2), (3), (4), (5), including key operable means for preventing disconnection of the display device from the computer system unit.
The display device according to any one of (6), (7), (8), and (9). (11) The above (1), (2), (3), (4),
(5), (6), (7), (8), (9) or (1
0) A display device according to any one of 0), a system unit for generating an input video signal for generating an image on the screen of the display device, and a data input means for inputting data and commands to the system unit. Computer system, including. (12) The display device according to (1) above, and security.
A display device including entry means for entering a code.

[0030]

According to the present invention, it is possible to prevent unauthorized access to data that can be accessed from a computer system via a display device.

[Brief description of drawings]

FIG. 1 is a block diagram of a computer system.

FIG. 2 is a block diagram of a display device of a computer system.

FIG. 3 is a block diagram of a user control panel and display processor of a display device.

FIG. 4 is a diagram of a mechanical security function of a display device.

[Explanation of symbols]

 5 system unit 10 random access memory (RAM) 20 read only memory (ROS) 30 central processing unit (CPU) 40 communication adapter 50 network 60 bus architecture 70 display adapter 80 pointing device adapter 90 keyboard adapter 100 Mass Storage Device 110 Keyboard 120 Pointing Device 130 Display Device 135 Interface Cable 200 Display Driving Circuit 210 Display Screen 230 EHT Generator 250 Video Amplifier 220 Line Scan Circuit 240 Frame Scan Circuit 260 User Control Panel 270 Display Processor 275 Control Panel, Control link 280 Deflection coil 290 Deflection coil 300 Lock circuit 310 Push button 320 Keypad De interrupt input 400 security features 410 connector 420 threaded 430, 450 member 450 locking mechanism

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Claims (12)

[Claims] 1. A display screen, a drive circuit for generating an image on the display screen in response to an input video signal, and standby means for disabling the drive circuit in response to a standby signal, and receiving a predetermined security code. A display device including reset means for restoring the operation of the drive circuit. 2. The display device according to claim 1, further comprising entry means for inputting the security code. 3. The display device of claim 2, wherein said entry means includes a keypad having a plurality of push buttons. 4. The display device of claim 3 wherein said reset means includes a processor having a plurality of interrupt inputs for receiving interrupts from said pushbuttons of said keypad. 5. One of the images displayed on the display screen in response to an interrupt from one or more of the push buttons.
The display device of claim 4, wherein the processor is configured to control a drive circuit to change one or more image parameters. 6. A lock circuit for setting the standby means to disable the drive circuit, wherein the reset means resets the operation of the drive circuit when the security code is received. The display device according to claim 5, wherein the display device is invalidated. 7. The standby means includes an output port of the processor, and the lock circuit includes a memory element connected to an input port of the processor for storing a state of the output port. 6. The display device according to 6. 8. The reset means is the security
The display device according to claim 7, wherein the content of the memory element is reset when a code is received. 9. The display device according to claim 8, wherein the memory element includes a capacitor. 10. Any of claims 1, 2, 3, 4, 5, 6, 7, 8 or 9 including key operable means to prevent disconnection of said display device from the computer system unit. The display device according to claim 1. 11. Claims 1, 2, 3, 4, 5, 6, 7,
Display device according to any one of 8, 9 or 10, a system unit for generating an input video signal for generating an image on the screen of the display device, and for inputting data and commands to the system unit A computer system including data input means. 12. A display device comprising the display device according to claim 1 and an entry means for inputting a security code.