JP2002229544A - Circuit failure prevention system in display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the failure of a display device due to excessive signal amount beyond the allowable range of the input signal by employing software for judging, on the basis of the image size and frequency of the input signal, whether an input signal is in the allowable range of the design capacity of a signal- receiving circuit part. SOLUTION: A graphics engine 16 judges whether the image size of received image data falls within the limit of the allowable value by judging the number of horizontal lines of the image every 100 ms on the basis of the counted value of the pixel data received in a period from HSYNC until the following HSYNC, and judging the number of vertical lines of the image on the basis of the counted value of HSYNC received in a period from VSYNC until the following VSYNC. When it is judged that the image size of the transmitted image data is on the outside of the range of the allowable value, the power switch 21 is controlled to turn off the power source of a digital signal receiver 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device used by connecting to information equipment such as a personal computer.
More specifically, the present invention relates to a circuit breakage prevention system in a display device.

[0002]

2. Description of the Related Art In a display device for displaying image data from a personal computer or the like, if the image data from an image output source such as a personal computer exceeds the design capability of a signal receiving circuit unit on the display device side (that is, the image size or image size). If the frequency exceeds the design capability), not only the image cannot be displayed on the display, but also the excessive input heats up the signal receiving circuit, adversely affecting the signal receiving circuit, or possibly damaging the circuit. Such a situation occurs.

In order to prevent such a situation, the conventional display device has a built-in temperature detecting means such as a thermostat, and when the signal receiving circuit section exceeds a certain temperature, the power is turned off or the operating speed is reduced. It is common practice to take workarounds such as dropping

[0004]

However, in the above-mentioned workaround, it is necessary to add hardware such as a thermostat, and there is a problem that the cost is increased.

By the way, in a general display device, in order to display an input signal (image data) from a personal computer or the like, it is already performed to detect a screen size and a frequency of the input signal.

The present invention has been made in view of such a point, and an object of the present invention is to determine whether or not an input signal is within an allowable range of the design capability of a signal receiving circuit unit by determining the screen size and frequency of the input signal. By making a software decision based on, without adding hardware such as a thermostat,
It is an object of the present invention to provide a circuit breakage prevention system in a display device which can reliably avoid a problem caused by an input signal exceeding an allowable range.

[0007]

In order to solve the above-mentioned problems, a circuit breakage prevention system in a display device according to the present invention comprises a timer means for measuring an arbitrary time, an input signal detection means for detecting an input signal, and An input signal determination unit that determines whether the input signal detected by the input signal detection unit is within a range of an allowable value at every first fixed time measured by the timer unit, Power supply control means for turning on and off only the power supply, wherein the power supply control means turns off the power supply of the signal reception circuit unit when the input signal determination means determines that the input signal is out of the allowable range. It is characterized in that it is turned off. In addition, after the power supply of the signal receiving circuit unit is turned off, the power supply of the signal receiving circuit unit is turned on again when a second predetermined time measured by the timer unit elapses.

According to the present invention having such features,
When an excessive input signal exceeding the allowable value range is detected, the power of the signal receiving circuit is turned off, and the power of the signal receiving circuit is turned on again after a lapse of the second fixed time. Accordingly, it is possible to avoid a state in which the signal receiving circuit unit is heated by an excessive input signal, and to prevent the circuit unit from being damaged.

Further, according to the circuit breakage prevention system in the display device of the present invention, the input signal detecting means is capable of stabilizing an input signal after the power of the signal receiving circuit section is turned on by the power control means. The detection of the input signal is prohibited until the fixed time of 3 elapses.

Immediately after the power of the signal receiving circuit is turned on, the input signal is not stable, so that it is determined that there is no input signal, or the type (image size or frequency) of the input signal may be erroneously recognized. is there. Therefore, in the above invention, after the power of the signal receiving circuit unit is turned on, the detection of the input signal is not performed for the third fixed time until the input signal is stabilized, so that the error of the input signal is prevented. Avoiding detection.

Further, according to the circuit breakage prevention system in the display device of the present invention, an input signal presence / absence detecting means for detecting the absence of the input signal for the first predetermined time, and a power supply for the signal receiving circuit unit Power supply monitoring means for monitoring the state of the input signal, and display control means for displaying the state of the input signal on a display unit, wherein the display control means turns on the power of the signal receiving circuit unit by the power supply monitoring means. And when the absence of an input signal is detected by the input signal presence / absence detection means for a first fixed time, information indicating that there is no input signal is displayed on a display unit, and the input signal determination means When the input signal is determined to be out of the range of the allowable value, it is confirmed by the power supply monitoring unit that the power of the signal receiving circuit unit is off. In this case, information indicating that the allowable value of the input signal is out of the range is displayed on the display unit until the power of the signal receiving circuit unit is turned on after the lapse of the second fixed time. Features.

"No input signal" when input signal is interrupted
In a general display device that displays a screen, even if there is no input signal due to intentionally turning off the power of the signal receiving circuit unit, the display simply indicates “no input signal”. Therefore, in the above invention, when there is no input signal from the personal computer side, "no input signal" is displayed, and there is an input signal from the personal computer side, but the input signal is within the allowable value range of the processing capability of the signal receiving circuit section. If it exceeds, "Out of range error" is displayed. This allows
The user can clearly know the reason why the image data is not displayed on the display device.

Further, according to the circuit breakage prevention system in the display device of the present invention, a flag for storing on / off of the power of the signal receiving circuit unit as software is used as the power monitoring means. I do. As described above, the on / off of the power of the signal receiving circuit unit is determined by software, so that it is not necessary to add an input terminal for detecting the on / off of the power, and the cost of the graphic engine 16 is reduced. be able to.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a circuit configuration of a display device equipped with a circuit breakage prevention system according to the present invention.

Referring to FIG. 1, the display device of the present embodiment includes a digital video interface connector 11 and an analog video interface connector 12 for capturing image data, which is an input signal from a personal computer 30, into an internal circuit. The video interface connector 11 is connected to a digital signal receiver (signal receiving circuit unit) 13.
The analog interface connector 12 is connected to a digital signal receiver 13 via an A / D converter (A / DC) 14 for converting an analog signal into a digital signal and a data bus 15.

The digital signal receiver 13 is bidirectionally connected to a graphic engine 16, and an output of the graphic engine 16 is connected to a display unit 17 such as an LCD.

Also, the graphic engine 16 has P
The output (clock signal) of the clock circuit 19 controlled by the LL circuit 18 is led. ROM 20
Stores a program for controlling the graphic engine 16.

Further, the output of the graphic engine 16 is guided to a power switch 21, and the output of the power switch 21 is guided to a digital signal receiver 13. That is, the power of the digital signal receiver 13 can be turned on and off by controlling the power switch 21 from the graphic engine 16.

Next, an image display processing operation in the display device having the above configuration will be briefly described.

From the personal computer 30, a horizontal synchronization signal (HS) is synchronized with one data transmission clock.
YNC), a vertical synchronization signal (VSYNC) or pixel data is transmitted. For example, when displaying a screen of 1024 (horizontal) and 768 (vertical) (that is, a screen having a resolution of 1024 × 768), the transmitted signal is as follows.

(H = 0, V = 1) (pixels 0, 0), (pixels 1, 0) (pixels 1023, 0) (H = 1, V = 0) (pixels 0, 1), (pixels 0, 1) (Pixels 1,1) (pixels 1023,1) (H = 1, V = 0) (pixels 0, 2), (pixels 1, 2) (pixels 1023, 2) (H = 1, V = (0,767), (pixel 1,767), (pixel 1023,767) (H = 1, V = 0) In other words, for one screen transmission, VSYNC once, HS
YNC is required 768 times.

The digital signal receiver 13 converts the image data transmitted from the personal computer 30 into the digital video interface connector 11.
Receiving the data through the cable, corrects the data error or the like occurring while passing through the cable, and
Perform the process of passing to.

Upon receiving image data from the digital signal receiver 13, the graphic engine 16 analyzes the image data, calculates a resolution and a refresh rate, and executes image generation and image processing. That is,
The number of horizontal lines on the screen is calculated by counting the number of pixel data received between HSYNC and the next HSYNC. Further, the number of vertical lines on the screen is calculated by counting the number of HSYNCs received from VSYNC to the next VSYNC. Further, the clock circuit 19
The clock signal from the clock is changed to VS for one second.
The number of times the YNC has been received is counted, and the refresh rate (the number of screen receptions per second) is calculated.

The display unit (hereinafter referred to as LCD) 17 converts the pixel data received from the graphic engine 16 into
Write to each coordinate of LCD. That is, the calculated HS
The coordinates of the received pixel data can be calculated from the numbers of YNC and VSYNC, and the received image data is displayed on the screen by sequentially sending data of one pixel to the calculated coordinates.

As described above, in the image display processing operation of the display device, the H
The number of pixel data received from SYNC to the next HSYNC and the number of HSYNC received from VSYNC to the next VSYNC are counted. Also,
It counts how many times VSYNC is received in one second. As a result, the screen size and the refresh rate (frequency) of the image data transmitted from the personal computer 30 can be known. In the present embodiment, a system for preventing the circuit breakage of the digital signal receiver 13 using these data is used. Is building.

That is, the graphic engine 16
Every first fixed time (for example, 100 ms, etc.), the HS
The number of horizontal lines on the screen is determined based on the count value of the pixel data received from YNC to the next HSYNC,
HS received between VSYNC and the next VSYNC
By determining the number of vertical lines on the screen based on the YNC count value, it is determined whether or not the screen size of the received image data is within the range of the allowable value (that is, the screen size is within the maximum displayable resolution of the LCD 17). Or not).
Also, by counting how many times VSYNC is received during 100 ms, how many times VSYNC is received in one second is calculated, and a refresh rate (frequency) is calculated. It is determined whether or not it is within the range (that is, whether or not it is within the range of the vertical synchronization frequency of the displayable resolution of the LCD 17). If it is determined that the screen size of the image data transmitted from the personal computer 30 is out of the allowable range, or if the refresh rate is determined to be out of the allowable range, the graphic engine 16 , The power switch 21 is controlled to turn off the power of the digital signal receiver 13. Then, when a second fixed time (for example, one second or the like) elapses after the power is turned off, the power of the digital signal receiver 13 is turned on again.

Further, the graphic engine 16 starts the power supply of the digital signal receiver 13 for a third fixed time (for example, 500 ms) when the input signal is stabilized.
Until the time elapses, the image data is invalidated even if image data is sent from the digital signal receiver 13. Thereby, it is possible to prevent the digital signal receiver 13 from erroneously detecting the input signal.

Further, the graphic engine 16 internally has a power flag that sets "1" when the power switch 21 is turned on and "0" when turned off, and confirms the state of this power flag. The state of the power switch 21 can be determined.
Then, the graphic engine 16 confirms from the state of the power flag that the power of the digital signal receiver 13 is in the ON state, and performs the first fixed time (100 m).
If no image data is input from the digital signal receiver 13 during s), “no input signal” is displayed on the LCD 17.
To be displayed. Also, it is confirmed from the state of the power flag that the power of the digital signal receiver 13 is on,
In addition, when it is determined that the screen size or the refresh rate of the received image data is out of the range of the allowable value, or from the state of the power flag, the digital signal receiver 1
When the power of the digital signal receiver 13 is in the off state, the "out of range error" is displayed on the LCD 17 until the power of the digital signal receiver 13 is turned on after the second fixed time (eg, one second) elapses.
To be displayed.

That is, each means described in the claims of the present invention is mainly realized by the graphic engine 16 in this embodiment.

Next, the processing operation of the circuit breakage prevention system in the display device having the above configuration will be described more specifically with reference to an operation flowchart shown in FIG. 2 and a timing chart shown in FIG.

When the display device is started (time t1),
The graphic engine 16 first sets a power flag to 1 (step S1). As a result, the image data transmitted from the personal computer 30 is transmitted to the graphic engine 1 via the digital video interface connector 11 and the digital signal receiver 13.
Handed over to 6.

In the graphic engine 16, the HSYN signal is output every first predetermined time T1 (for example, 100 ms).
The number of horizontal lines on the screen is determined based on the count value of the pixel data received from C to the next HSYNC.
HSYNC received from YNC to the next VSYNC
By determining the number of vertical lines on the screen based on the count value of C, it is determined whether the screen size of the received image data is within the range of the allowable value (that is, within the maximum displayable resolution of the LCD 17). Is determined (step S2). Also, by counting how many times VSYNC is received during 100 ms, VSYNC can be obtained in one second.
Is calculated, the refresh rate (frequency) is calculated, and whether the refresh rate is within the range of the allowable value (that is, within the range of the vertical synchronization frequency of the displayable resolution of the LCD 17). Is determined (step S2).

Here, a method for determining whether or not the received image data is within the range of the allowable value will be specifically described.

For example, if the maximum resolution of the mounted LCD 17 is 1280 × 1024 (SXGA), HSYNC is 64 kHz, and VSYNC is 60 Hz, VSY
HSYNC received from NC to next VSYNC
If the count value (i.e., the number of vertical lines on the screen) is, for example, 1200, it is determined that 1200> 1024, which is outside the range of the allowable value. That is, when the count value is 1024 or less, it is determined that the count value is within the range of the allowable value. If the VSYNC count value (refresh rate) for one second is, for example, 75, then 75> 6
It becomes 0 and is determined to be outside the range of the allowable value. That is, VS
If the YNC count value is 60 or less, it is determined that the YNC count value is within the allowable value range. In this example, the maximum resolution is 1280 × 1024 (SXGA) and the HSYNC is 6
This is a case in which the display device is applied to a display device of 4 kHz and VSYNC of 60 Hz.
Of course, the tolerances will also be different.

As a result of this determination, if the screen size and the refresh rate are within the allowable range (time t2), the graphic engine 16 displays the received image data on the LCD 17 as it is (step S2).
3).

On the other hand, as a result of the determination in step S2, when the screen size or the refresh rate of the image data transmitted from the personal computer 30 is out of the allowable range (time t3), the graphic engine 16
Controls the power switch 21 to turn off the power of the digital signal receiver 13 (step S4). The graphic engine 16 displays "out of range error" on the LCD 17 (step S5), and sets the power flag to 0 (indicated by reference numeral 51 in FIG. 3) (step S6).

Thereafter, the graphic engine 16 uses the clock signal from the clock circuit 19 to execute step S
When the second fixed time T2, for example, one second, elapses after the power is turned off at time 3 (time t4), the power of the digital signal receiver 13 is turned on again (time t5) (step S7).

The graphic engine 16 turns on the power of the digital signal receiver 13 (at time t).
From 5), until the third fixed time T3 at which the input signal is stabilized, e.g., 500 ms, elapses (time t6), the power flag remains 0 and the digital signal receiver 13
Is invalidated even if image data is sent from the server. When 500 ms elapses after the power is turned on, the power flag is set to 1 (indicated by reference numeral 52 in FIG. 3) (step S8), and the process of receiving the image data transmitted from the personal computer 30 is started again. Then, the process returns to step S2.

The above is the processing when it is determined in step S2 that there is an input signal.

Next, when there is no input signal from the personal computer 30, and when the power of the digital signal receiver 13 is turned off in step S4, there is no input signal to the graphic engine 16, the process proceeds from step S2 to step S9. Advance the operation to. That is, the graphic engine 16 determines whether the state of no input signal is no input signal due to no input signal from the personal computer 30 or the digital signal receiver 1
It is determined whether there is no input signal due to turning off the power supply of No. 3. Specifically, when the power of the digital signal receiver 13 is turned on, the power flag is 1, and when the power is off, the power flag is 0. Therefore, the graphic engine 16 determines the state of the power flag.

As a result, when the power flag is 1,
That is, when the power of the digital signal receiver 13 is on (the state indicated by reference numeral 61 in FIG. 3),
“No input signal” is displayed on the LCD 17 (step S
10). If the power flag is 0, that is, if the power of the digital signal receiver 13 is off (indicated by reference numeral 62 in FIG. 3), an "out of range error" is displayed on the LCD 17 (step S11). ).

In the above embodiment, the case where the image data transmitted from the personal computer 30 is a digital signal is described. However, if the image data is an analog signal, the analog video interface connector 12 and the A / D The image data is transferred to the graphic engine 16 via the converter 14 and the digital signal receiver 13. Also in this case, the only difference is that the range of the allowable value serving as the criterion in the graphic engine 16 is set to a value corresponding to the analog signal, and the other processing is substantially the same as that described in the digital signal. It is.

[0044]

According to the circuit breakage prevention system in the display device of the present invention, when an excessive input signal exceeding the allowable value range is detected, the power of the signal receiving circuit section is turned off, and the second constant level is set. Since the power of the signal receiving circuit unit is turned on again after a lapse of time, a state in which the signal receiving circuit unit is heated by an excessive input signal can be avoided, and the circuit unit can be prevented from being damaged.

Further, according to the circuit damage prevention system in the display device of the present invention, the input signal detecting means includes:
The configuration is such that the detection of the input signal is inhibited until the third fixed time period during which the input signal is stabilized after the power of the signal receiving circuit unit is turned on by the power control unit.
That is, immediately after the power of the signal receiving circuit unit is turned on, since the input signal is not stable, it is determined that there is no input signal, or the type of the input signal (image size or frequency)
However, according to the present invention, after the power of the signal receiving circuit unit is turned on, the input signal is not detected only for the third fixed time until the input signal is stabilized. Therefore, erroneous detection of an input signal when the power is turned on can be reliably avoided.

Further, according to the circuit damage prevention system in the display device of the present invention, there is provided an input signal presence / absence detecting means for detecting that there is no input signal for the first predetermined time,
Power supply monitoring means for monitoring the state of the power supply of the signal receiving circuit unit, and display control means for displaying the state of the input signal on the display unit, wherein the display control means controls the power supply of the signal receiving circuit unit by the power supply monitoring means. Is turned on,
When the absence of an input signal is detected by the input signal presence / absence detection means for the first fixed time, information indicating that there is no input signal is displayed on the display unit, and the input signal is determined by the input signal determination means to be out of the allowable range. When it is determined that the power supply of the signal receiving circuit unit is in the off state by the power supply monitoring unit, the power supply of the signal receiving circuit unit is Until the switch is turned on, information indicating that the allowable value of the input signal is out of the range is displayed on the display unit. In other words, if there is no input signal from the personal computer, "No input signal" is displayed, and there is an input signal from the personal computer, but the input signal exceeds the allowable value of the processing capability of the signal receiving circuit unit. In this case, by displaying "out of range error", the user can clearly know the reason why the display device is not displayed.

According to the system for preventing circuit breakage in a display device of the present invention,
A configuration is used in which a flag for storing the on / off state of the power supply of the signal receiving circuit unit by software is used. That is, by determining the power on / off of the signal receiving circuit unit by software, it is not necessary to add an input terminal for detecting power on / off, thereby reducing the cost of the signal receiving circuit unit. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a display device equipped with a circuit breakage prevention system according to the present invention.

FIG. 2 is a flowchart showing a processing operation of a circuit damage prevention system in the display device of the present invention.

FIG. 3 is a timing chart showing the processing operation of the circuit breakage prevention system in the display device of the present invention.

[Explanation of symbols]

 Reference Signs List 11 digital video interface connector 12 analog video interface connector 13 digital signal receiver (signal receiving circuit unit) 14 A / D converter 15 data bus 16 graphic engine 17 display unit (LCD) 18 PLL circuit 19 clock circuit 20 ROM 21 power switch

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 5/12 G09G 5/12 H04N 17/00 H04N 17/00 CF term (Reference) 5C061 BB03 BB13 CC05 5C080 AA10 BB05 DD14 DD19 DD20 JJ02 JJ04 JJ07 5C082 AA01 BB02 BC03 CA85 CB01 CB10 DA76 MM03

Claims (6)

[Claims] A timer for measuring an arbitrary time; an input signal detecting means for detecting an input signal; and determining whether an input signal detected by the input signal detecting means is within an allowable value range. An input signal determining unit that determines at every first fixed time measured by the timer unit; and a power control unit that turns on and off only the power of the signal receiving circuit unit. The power control unit includes the input signal. A circuit breakage prevention system in a display device, wherein when a determination unit determines that an input signal is out of a range of an allowable value, a power supply of the signal receiving circuit unit is turned off. 2. The power supply control unit turns on the power of the signal receiving circuit unit again when a second predetermined time measured by the timer unit elapses after the power supply of the signal receiving circuit unit is turned off. The system according to claim 1, wherein the circuit breakage prevention system is provided. 3. The apparatus according to claim 1, wherein the input signal detecting unit is configured to detect the input signal from a time when the power of the signal receiving circuit unit is turned on by the power control unit until a third fixed time period when the input signal is stabilized. 3. The system according to claim 2, wherein the detection is prohibited. 4. An input signal presence / absence detection means for detecting the absence of the input signal for the first predetermined time; a power supply monitoring means for monitoring a power supply state of the signal reception circuit unit; Display control means for displaying a state on a display unit, wherein the display control means confirms that the power of the signal receiving circuit unit is on by the power supply monitoring means, and the input signal presence / absence detection means When no input signal is detected for the first fixed time, information indicating that there is no input signal is displayed on the display unit, and the input signal determination means determines that the input signal is out of the allowable range. And when the power supply monitoring means has confirmed that the power of the signal receiving circuit unit is in the off state, the second predetermined time has elapsed and the power of the signal receiving circuit unit is turned on. 4. The system according to claim 2, wherein information indicating that the allowable value of the input signal is out of the range is displayed on the display unit until the input signal is out of range. 5. The system according to claim 4, wherein the power supply monitoring means is a flag for storing on / off of the power supply of the signal receiving circuit unit as software. . 6. The system according to claim 1, wherein the input signal is an image signal from a personal computer.