JP2003167545A - Method for detecting abnormality of image display signal, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device capable of detecting abnormality of an image display signal such as a synchronizing signal without causing any malfunction. <P>SOLUTION: The image display device for displaying an image by receiving the image display signals such as vertical synchronizing signals, horizontal synchronizing signals, and image data signals is provided with a signal monitoring part 20 for detecting abnormality of the image display signals, and the signal monitoring part 20 is provided with a counter part 30 and a judging part 31. The counter part 30 counts the number of inputs of the horizontal synchronizing signals for a period from an input of the vertical synchronizing signal until the next input thereof. The judging part 31 judges the vertical synchronizing signals or the horizontal synchronizing signals as abnormal when the number of the signal inputs counted by the counter part 30 is outside of the predetermined range. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device for displaying an image on an image display section by inputting an image display signal including an image signal and a sync signal. More specifically, the present invention relates to an image display signal abnormality detection method and an image display device for detecting an abnormality in an image display signal due to the inclusion of noise.

[0002]

2. Description of the Related Art In recent years, image display devices typified by liquid crystal display devices are used in office automation equipment such as personal computers and
Widely used as a display device for home electric appliances.

Generally, as a synchronizing signal input to an image display device, as shown in FIG. 7, a vertical synchronizing signal indicating the timing for starting the scanning in the vertical direction and a timing for starting the scanning in the horizontal direction are shown. Horizontal sync signal, and
There is a data enable signal indicating the timing of inputting a valid image data signal to the image display unit.

In the illustrated case, it is assumed that the vertical synchronizing signal and the horizontal synchronizing signal detect the timing at the falling edge of the signal, and the data enable signal is H (high).
Valid data shall be entered during the period of level status.

As shown in the figure, after a vertical blanking period Tvb has passed from the falling of the vertical synchronizing signal and a horizontal blanking period (horizontal retrace period) Thb has passed from the falling of the horizontal synchronizing signal, Data enable signal is H
As a level, the image of the first horizontal line is displayed. Then, after the horizontal blanking period Thb has elapsed from the fall of the next horizontal synchronizing signal, the data enable signal becomes H level, and the image of the next horizontal line is displayed. By repeating the same process thereafter, one screen image is displayed.

After the image of one screen is displayed, the vertical synchronizing signal falls, and after the vertical blanking period (vertical blanking period) Tvb has passed, the data enable signal is input again and the next one screen is displayed. The image is displayed.

[0007]

The above image display device is
Noise waveforms other than the signal waveforms shown in FIG. 7 may be mixed in various situations such as display resolution change, display color change, resume, power saving mode, etc. in addition to power-on and reset. . In this case, there is a problem in that an unsightly image is displayed on the screen for a moment, such as the previous image continues to be displayed or a noise-like image is displayed.

For example, as shown in FIG. 8, when noise is mixed in the vertical synchronizing signal, the next 1
Since the image on the screen is displayed, the remaining image is displayed from the first display line, and the display of the image is displaced.
Similarly, if noise is mixed in the horizontal synchronizing signal or the data enable signal, the display position in pixel units will shift.

As an invention to solve the above problem, Japanese Patent Laid-Open No. 20
There is a flat display device described in Japanese Patent Application No. 01-134244. The flat display device detects an abnormality of the synchronization signal by comparing the synchronization signal input from the outside with a standard signal, and when detecting the abnormality of the synchronization signal, at least the data signal and the synchronization signal are kept constant for a predetermined period. It is fixed at the level.

According to the above configuration, when an abnormality is detected due to noise mixed in the synchronizing signal, the data signal and the synchronizing signal are fixed at a constant level for a predetermined period, so that a time different from the original time of the signal is detected. Therefore, the start timing due to the synchronization signal is not detected, and as a result, malfunctions such as flickering of the screen display can be prevented.

However, in the flat panel display device, the standard signal is used as a means for detecting the abnormality of the synchronization signal. However, if noise is mixed in the standard signal, the detection is performed even if the synchronization signal is normal. If the means for doing so detects an abnormality, it may malfunction.

It is an object of the present invention to provide an image display signal abnormality detecting method and an image display device capable of detecting an abnormality in an image display signal such as a synchronizing signal without causing a malfunction.

[0013]

In order to solve the above-mentioned problems, an abnormality detecting method for an image display signal according to the present invention includes a plurality of image display signals used for displaying an image on an image display device. , With respect to the first signal and the second signal having a shorter period than the first signal, the second signal is input in the period from the input of the first signal to the input of the next first signal. A counting step of counting the number of inputs to which the signal is input, and an abnormality detection step of determining that the first signal or the second signal is abnormal when the counted number of inputs is out of a predetermined range. Is characterized by.

Here, the "image" refers to information displayed on an image display device, and examples of the information include video, characters, text, graphics and the like. Also,
The “image signal” is a signal obtained by converting information to be displayed on the image display device into an electric signal, and may be a digital signal or an analog signal.

As the image display signal, in addition to the image signal, a vertical synchronizing signal, a horizontal synchronizing signal, a data enable signal indicating the timing at which the image signal can be transferred to the image display unit, and other signals. A clock signal or the like serving as a reference for the operation timing of the image display signal may be used.

In the image display signal, the length of one cycle is substantially constant when the signal is normal. Therefore,
Of the plurality of image display signals, a first signal and a first signal
If the second signal having a shorter period than the signal of 1 is normal, one period of the first signal, that is, from the input of the first signal to the input of the next first signal During the period
The number of inputs of the second signal is within a predetermined range.

By the way, when noise is mixed in a normal signal, noise is mixed between the signal input of the normal signal and it is considered that the signal is input, and when noise is mixed in the normal signal. When noise is mixed in at the time of inputting a signal, it may be considered that the signal has not been input.

From this, when it is considered that the first signal is input due to the mixing of noise, the period for counting the number of signal inputs of the second signal becomes short, so that the number of signal inputs is within a predetermined range. Also less. On the other hand, when it is considered that the first signal has not been input due to the mixing of noise, the period for counting the number of signal inputs of the second signal becomes long, so the number of signal inputs becomes larger than the predetermined range.

When it is considered that the second signal has been input due to the mixing of noise, the number of signal inputs of the second signal becomes larger than the predetermined range. On the other hand, when it is considered that the second signal has not been input due to the inclusion of noise, the number of signal inputs of the second signal becomes smaller than the predetermined range.

Therefore, as in the above method, when the number of inputs of the second signal during the period of the first signal is outside the predetermined range, the first signal or the second signal is abnormal. Can be determined.

Thus, the abnormality detecting method for the image display signal of the present invention can detect the abnormality in the image display signal by counting the number of signal inputs of the image display signal. Further, the abnormality detection method of the image display signal of the present invention,
As compared with the conventional display device that detects an abnormality of the synchronization signal using the standard signal, it is possible to prevent malfunction due to noise mixed in the standard signal.

If any one of the plurality of image display signals is a combination of a plurality of signals having different periods, any one of the combined plurality of signals is selected. The first signal as the signal of
A signal having a shorter cycle than the signal of can be used as the second signal.

Examples of such image display signals include the data enable signal. As shown in FIG. 7, the data enable signal can be considered to be a signal that is a combination of a signal indicating a vertical blanking period and a signal indicating a horizontal data valid period. Therefore, the abnormality of the data enable signal can be detected by using the signal indicating the vertical blanking period as the first signal and the signal indicating the horizontal data valid period as the second signal.

Therefore, in this case, it is possible to detect a signal abnormality with one image display signal without combining a plurality of image display signals.

Also, in the abnormality detecting method of the image display signal of the present invention, in the above method, the counting step inputs the first signal for each different combination of the first signal and the second signal. The step of counting the number of inputs of the second signal during the period from the start of the input of the next first signal, wherein the abnormality detection step is performed for any one of the combinations. When the number of inputs is out of a predetermined range, it is a step of determining that any one of the first signals or the second signals is abnormal.

According to the above method, it is determined whether or not any one of the first signal and the second signal, which are variously combined from the plurality of image display signals, is abnormal. be able to. Therefore, the abnormality detection method for the image display signal of the present invention can determine whether or not there is an abnormality in three or more signals from the plurality of image display signals.

Further, the image display signal abnormality detecting method of the present invention is the above method, wherein when the first signal or the second signal is determined to be abnormal in the abnormality detecting step, the image display is performed. It is characterized by including an image generation step of generating the image display signal for displaying a predetermined image on the device.

According to the above method, when the abnormality detecting step determines that the first signal or the second signal is abnormal, the image generating step generates the image display signal to generate the image. A predetermined image is displayed on the image display device by transmitting the image to the display device.

Therefore, when the image display signal abnormality detecting method of the present invention is used, a predetermined image is displayed on the image display device when the image display signal abnormality is detected. It is possible to prevent an unsightly image from being displayed on the image display device due to a signal abnormality.

Further, in the abnormality detecting method of the image display signal of the present invention, in the above method, the abnormality detecting step is counted after the first signal or the second signal is determined to be abnormal. When the number of inputs is within a predetermined range, it is determined that the first signal and the second signal have become normal, and the image generation step includes the first signal and the second signal in the abnormality detection step. Is determined to be normal, the generation of the image display signal is stopped.

In the above method, if the first signal or the second signal is free from noise after the first signal or the second signal is determined to be abnormal in the abnormality detecting step, The counted number of inputs is within a predetermined range. At this time, it is determined in the abnormality detection step that the first signal and the second signal are normal, and the generation of the image display signal is stopped in the image generation step. As a result, the normal image display operation is resumed on the image display device.

Therefore, the abnormality detecting method for the image display signal according to the present invention automatically and automatically returns to the normal image when the first signal or the second signal returns to the normal state due to the elimination of noise and the like. Since the display operation is restarted, even if noise is mixed in the first signal or the second signal, it is possible to return to the normal image display operation without bothering the user.

Further, the image display device of the present invention is an image display device which displays an image on an image display section by inputting a plurality of image display signals, wherein the first of the plurality of image display signals is selected. And the second signal having a shorter cycle than the first signal, the second signal is input during the period from the input of the first signal to the input of the next first signal. Counting means for counting the number of inputs to be input, determination means for determining whether the number of inputs counted by the counting means is within a predetermined range, and the determination means for determining that the input number is outside the predetermined range. When it does, it is characterized by comprising an abnormality detecting means for determining that the first signal or the second signal is abnormal.

With the above arrangement, the counting means counts the number of inputs of the second signal in the period of the first signal, and the judging means determines whether the number of inputs is within a predetermined range. If it is determined that the number of inputs is out of the predetermined range, the abnormality detecting unit determines that the first signal or the second signal is abnormal, as described above. .

As a result, the image display device of the present invention counts the number of signal inputs of the image display signal,
An abnormality in the image display signal can be detected. Further, the image display device of the present invention can prevent malfunction due to noise mixed in the standard signal, as compared with the conventional display device which detects an abnormality of the synchronization signal using the standard signal.

As described above, if any of the plurality of image display signals is a combination of a plurality of signals having different periods, the plurality of combined signals are combined. Of these signals, any one of the signals can be the first signal, and the signal having a shorter period than the first signal can be the second signal. In this case, it is possible to detect a signal abnormality with one image display signal without combining a plurality of image display signals.

Further, the image display device of the present invention has, in the above-mentioned configuration, the counting means and the determination means for each different combination of the first signal and the second signal, and the abnormality detection means. Determines that any one of the first signals or the second signals is abnormal when the corresponding determination means determines that the number of inputs counted by any one of the counting means is out of a predetermined range. It is characterized by doing.

According to the above configuration, it is determined whether or not any one of the first signal and the second signal, which are variously combined from the plurality of image display signals, is abnormal. be able to. Therefore, the image display device of the present invention can determine whether or not there is an abnormality in three or more signals of the plurality of image display signals.

Further, the image display device of the present invention further comprises display control means for controlling to display an image on the basis of the image display signal in the above configuration,
The display control means is characterized by controlling to display a predetermined image when the abnormality detecting means determines that the first signal or the second signal is abnormal.

According to the above arrangement, in the normal case, an image is displayed on the image display section based on the image display signal under the control of the display control means. At this time, the first
When the abnormality detecting means determines that the signal of 1 or the second signal is abnormal, a predetermined image is displayed on the image display section by the control of the control means.

Therefore, in the image display device of the present invention, when the abnormality detection means detects an abnormality in the image display signal, the display control means controls to display a predetermined image. It can be prevented from being displayed.

Further, in the image display device of the present invention, in the above structure, after the abnormality detecting means determines that the first signal or the second signal is abnormal, all the input means counted by the counting means. When the corresponding judging means judges that the number is within the predetermined range, the first signal and the second signal
The abnormality detection means determines that the signal of is normal, and at this time, the display control means controls to display an image based on the image display signal.

According to the above arrangement, after the abnormality detecting means detects an abnormality in the image display signal, any one of the first
When noise or the like is eliminated from the signal of No. 2 or the second signal, the number of signal inputs of the second signal counted by the counting means falls within a predetermined range. At this time, the abnormality detection means determines that the first signal or the second signal has returned to normal, and the image based on the image display signal is displayed by the control of the display control means.

Therefore, the image display device of the present invention automatically displays an image based on the image display signal when the first signal or the second signal returns to a normal state due to the elimination of noise and the like. Is displayed, it is possible to return to the normal image display operation without disturbing the user even if noise is mixed in the first signal or the second signal.

Further, the image display device of the present invention is characterized in that, in the above-mentioned constitution, it further comprises setting changing means for changing the predetermined range used by the judging means.

The predetermined range used by the judging means is
It depends on the specifications of the image display device such as resolution. Therefore, the image display device of the present invention can be applied to various image display devices by changing the predetermined range by the setting changing means.

The image display signal used as the first signal or the second signal is preferably selected from a vertical synchronizing signal, a horizontal synchronizing signal and a data enable signal.

These signals are used for image synchronization, that is, for matching the image disassembly scanning performed on the image transmitting side with the image assembling scanning performed on the image receiving side ( Hereinafter, it is referred to as a "synchronization signal"). Therefore, if noise is mixed in the sync signal, the assembly scanning of the image is not normally performed, and a very unsightly image is displayed.

Therefore, by using the present invention to detect the abnormality of the synchronizing signal, it is possible to reliably prevent the display of an unsightly image due to the mixing of noise.

The predetermined range used by the judging means may be either one or both of the number of lines in one frame period and the number of data in one line.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] An embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 shows a schematic configuration of an image display device according to this embodiment. In this embodiment, as the image display device, a liquid crystal display device using liquid crystal in the image display unit is used. The liquid crystal display device 10 includes an interface (I / F) unit 11, a control IC 12, a source driver 13, a gate driver 14, and a liquid crystal panel 15.

The I / F section 11 has a data signal (image signal) as an image display signal, and a vertical synchronizing signal, a horizontal synchronizing signal and a data enable signal which are synchronizing signals.
A clock signal and is input from the outside. A method of transmitting these signals as differential signals is adopted in order to reduce the influence of radio interference noise. Therefore, the I / F unit 11 has an LVDS for returning the differential signal to the original signal.
A (Low Voltage Differential Signal) circuit (not shown) is provided. The restored synchronization signal, clock signal and data signal are output to the control IC 12.

The control IC 12 processes an input data signal (input data signal) to generate an output data signal, and at the same time, a source driver control signal and a source driver clock signal for driving the source driver 13, and a gate. A gate driver control signal and a gate driver clock signal for driving the driver 14 are generated.

The control IC 12 outputs the generated output data signal, source driver control signal and source driver clock signal to the source driver 13, and also generates the generated gate driver control signal and gate driver clock signal.
Output to 4.

The source driver 13 is a shift register,
The control IC 1 includes a D / A (digital-analog) converter, a latch circuit, and the like, and uses the output data signal from the control IC 12 as an analog video signal.
Based on the source driver control signal and the source driver clock signal from 2, the signal is output to the source lines 16 ... Of the liquid crystal panel 15.

The gate driver 14 is a shift register,
A buffer or the like is provided, and a signal is supplied to the gate lines 17 of the liquid crystal panel 15 based on the gate driver control signal and the gate driver clock signal from the control IC 12 to drive the liquid crystal panel 15,
Display an image.

Next, a schematic structure of the control IC 12 will be described with reference to FIG. Control I
The C12 includes a signal monitoring unit 20 and a data processing unit (display control means) 21.

In the present embodiment, among the image display signals, the vertical synchronizing signal is selected as the first signal and the horizontal synchronizing signal is selected as the second signal.
That is, in the present embodiment, the signal monitoring unit 20 uses the I / F
It monitors whether the vertical synchronizing signal and the horizontal synchronizing signal input from the unit 11 are normal.

When the vertical synchronizing signal and the horizontal synchronizing signal are normal, the signal monitoring unit 20 outputs the input synchronizing signal to the data processing unit 21 as it is. On the other hand, when the vertical synchronization signal or the horizontal synchronization signal is abnormal, the error flag is turned on and output to the data processing unit 21, and the vertical synchronization signal and the horizontal synchronization signal generated inside the signal monitoring unit 20 are output as data. Output to the processing unit 21.

When the vertical synchronizing signal and the horizontal synchronizing signal are returned to normal, the signal monitoring unit 20 turns off the error flag and outputs it to the data processing unit 21, and also the input from the I / F unit 11. The vertical synchronizing signal and the horizontal synchronizing signal are output to the data processing unit 21 as they are.

The signal monitoring section 20 outputs other image display signals (data enable signal, clock signal and input data signal) to the data processing section 21 as they are.

When the error flag from the signal monitoring unit 20 is off, the data processing unit 21, as described above,
The output data signal obtained by processing the input data signal is output to the source driver 13, and when the error flag is ON, the output data signal of a predetermined value (for example, all bits are 0) is output to the source driver 13. Output to.

Further, the schematic configuration inside the signal monitoring unit 20 will be described with reference to FIG. The signal monitoring unit 20 is
A counter unit (counting unit) 30, a determination unit (determination unit, abnormality detection unit) 31, a synchronization signal generation unit 32, and a selector unit 33 are provided.

The vertical synchronizing signal and the horizontal synchronizing signal are input from the I / F unit 11 to the counter unit 30. Further, the counter unit 30 receives the horizontal synchronizing signal input during the period from the input of the vertical synchronizing signal to the input of the next vertical synchronizing signal, that is, the period from the input pulse of the vertical synchronizing signal to the next input pulse. Count the number of input pulses of.
The counted number of input pulses is output to the determination unit 31.

The judging section 31 judges whether or not the number of input pulses of the horizontal synchronizing signal counted by the counter section 30 is within a predetermined range. The predetermined range here is one cycle Tv of the vertical synchronizing signal (see FIG. 7), that is, the allowable range of the number of input pulses of the horizontal synchronizing signal to be input in the vertical scanning period, and the allowable range is the image display. It is determined by the specifications of the image display device such as the resolution of the device.

It should be noted that one vertical scanning period corresponds to one field (1/2 frame) period in the interlace system and one frame period in the progressive system.

At this time, as shown in FIG. 8, when it is considered that the vertical synchronizing signal is input due to the noise mixed in the vertical synchronizing signal, the period for counting the number of input pulses of the horizontal synchronizing signal becomes short, The number of input pulses is less than the predetermined range. On the other hand, when it is considered that the vertical synchronizing signal has not been input due to the noise mixed in the vertical synchronizing signal, the period for counting the number of input pulses becomes long, and thus the number of input pulses becomes larger than the predetermined range.

When it is considered that the horizontal synchronizing signal is input due to the noise mixed in the horizontal synchronizing signal, the number of input pulses of the horizontal synchronizing signal becomes larger than the predetermined range. On the other hand, when it is considered that the horizontal synchronizing signal has not been input due to the inclusion of noise in the horizontal synchronizing signal, the number of input pulses becomes smaller than the predetermined range.

Therefore, when the number of the input pulses is within the predetermined range, the judging section 31 judges that the vertical synchronizing signal and the horizontal synchronizing signal are normal, turns off the error flag, and outputs the input pulse. If the number is out of the predetermined range, it is determined that the vertical synchronizing signal or the horizontal synchronizing signal is abnormal, and the error flag is turned on. The error flag is output to the synchronization signal generator 32, the selector 33, and the data processor 21.

The synchronizing signal generator 32 generates a normal vertical synchronizing signal and a horizontal synchronizing signal when the error flag input from the determiner 31 is on, and the selector 3
Output to 3.

The selector section 33 includes a vertical synchronizing signal and a horizontal synchronizing signal from the I / F section 11, and a synchronizing signal generating section 3.
The vertical synchronizing signal and the horizontal synchronizing signal from 2 are input, and one of the vertical synchronizing signal and the horizontal synchronizing signal is selected based on the error flag and output to the data processing unit 21. That is, if the error flag is off, I
If the vertical sync signal and the horizontal sync signal from the / F unit 11 are selected and the error flag is on, the vertical sync signal and the horizontal sync signal from the sync signal generation unit 32 are selected, and the data processing unit 21 is selected. Output to. As a result, the normal vertical synchronizing signal and the normal horizontal synchronizing signal are always input to the data processing unit 21.

In the liquid crystal display device 10 of this embodiment,
Of the image display signals input from the outside, the vertical synchronizing signal and the horizontal synchronizing signal are input to the signal monitoring unit 20 in the control IC 12 via the I / F unit 11, and the data signal, the data enable signal, and the clock are supplied. The signal is
It is input to the data processing unit 21 in the control IC 12 via the I / F unit 11.

Counter section 30 in signal monitoring section 20
Counts the number of input pulses of the horizontal synchronizing signal input during the period from the input pulse of the vertical synchronizing signal to the next input pulse based on the input vertical synchronizing signal and horizontal synchronizing signal.

The judging section 31 judges whether or not the number of input pulses is within a predetermined range, and if it is within the predetermined range, it is judged that the vertical synchronizing signal and the horizontal synchronizing signal are normal and the error flag is determined. Is turned off, and when it is outside the predetermined range, it is determined that either the vertical synchronizing signal or the horizontal synchronizing signal is abnormal, and the error flag is turned on. When the number of input pulses is again within the predetermined range after the error flag is turned on, the error flag is turned off.

When the error flag is off, the selector section 33 selects the vertical synchronizing signal and the horizontal synchronizing signal from the I / F section 11 and outputs them to the data processing section 21.
Then, the data processing unit 21 generates the source driver control signal, the source driver clock signal, and the output data signal based on the synchronization signal, the clock signal, and the input data signal, and outputs them to the source driver 13 as in the normal case. At the same time as outputting, a gate driver control signal and a gate driver clock signal are generated and output to the gate driver 14. As a result, a normal image display operation is performed on the liquid crystal panel 15.

On the other hand, when the error flag is ON, the selector section 33 selects the vertical synchronizing signal and the horizontal synchronizing signal from the synchronizing signal generating section 32 and selects them from the data processing section 2.
Output to 1. As a result, even if noise is mixed in the vertical sync signal or the horizontal sync signal from the outside, normal image display operation can be performed by using the normal vertical sync signal and horizontal sync signal from the sync signal generation circuit 32. Can be done.

When the error flag is on, the data processing section 21 generates an output data signal having a predetermined value and outputs it to the source driver 13. This allows
A predetermined image can be displayed on the liquid crystal panel 15.
For example, all the data bits are 0 as the predetermined value.
When the output data signal is output to the source driver 13, a black image on the entire screen is displayed on the liquid crystal panel 15.

Therefore, in the liquid crystal display device 10 of the present embodiment, the counter section 30 counts the number of signal inputs of the horizontal synchronizing signal in the period from the pulse input of the vertical synchronizing signal to the next pulse input, whereby the vertical synchronizing signal is obtained. Since the abnormality of the signal or the horizontal synchronizing signal is detected, the abnormality of the synchronizing signal is detected by using the standard signal.
Compared with the display device described in Japanese Patent Laid-Open No. 44, it is possible to prevent malfunction due to noise mixed in the standard signal.

Further, the liquid crystal display device 10 of this embodiment is
When the signal monitoring unit 20 detects an abnormality in the vertical synchronization signal or the horizontal synchronization signal, a predetermined image is displayed on the liquid crystal panel 15 under the control of the data processing unit 21, so that noise is generated in the vertical synchronization signal or the horizontal synchronization signal. It is possible to prevent the unsightly image from being displayed on the liquid crystal panel 15 due to the mixture.

Further, the liquid crystal display device 10 of this embodiment is
When the vertical sync signal and the horizontal sync signal are no longer mixed with noise and returned to a normal state, the error flag is turned off and an image based on the image display signal is automatically displayed on the liquid crystal panel 15. Even if noise is mixed in the vertical synchronizing signal or the horizontal synchronizing signal, it is possible to return to the normal image display operation without bothering the user.

Further, the liquid crystal display device 10 of this embodiment is
Since the abnormality of the vertical synchronizing signal or the horizontal synchronizing signal is detected for each scanning in the vertical direction, the data processing unit 21 switches the data signal processed based on the input data signal to a predetermined data signal, or a predetermined data signal. Can be switched to the processed data signal and output as an output data signal for each vertical scanning. Therefore, when the vertical synchronization signal and the horizontal synchronization signal return from the abnormal state to the normal state, An image can be displayed on the liquid crystal panel 15 from the first line.

Further, the detection of the abnormality of the vertical synchronizing signal or the horizontal synchronizing signal can be realized by a simple circuit configuration of the counter section 30 and the judging section 31.

[Second Embodiment] Next, another embodiment of the present invention will be described with reference to FIG. Note that configurations having the same functions as the configurations described in the above-described embodiments are given the same reference numerals, and description thereof will be omitted.

The liquid crystal display device of the present embodiment has a signal monitoring section having a configuration different from that of the signal monitoring section 20 in the control IC 12 as compared with the display apparatus shown in FIG. 1, and the other configurations are the same. is there. FIG. 4 shows a schematic configuration of the signal monitoring unit 40 in this embodiment.

The signal monitoring section 40 includes a judging section 41 having a configuration different from that of the judging section 31 shown in FIG. 3 as compared with the signal monitoring section 20 shown in FIG. 3, and a new counter section and a judging section. The second counter unit (counting unit) 42 and the second determination unit (determination unit) 43 are different, and the other configurations are the same.

The determination unit 41 of this embodiment is different from the determination unit 31 shown in FIG. 3 only in the condition for returning the error flag from ON to OFF. The conditions will be described later.

The second counter section 42 of this embodiment selects the horizontal synchronizing signal as the first signal for detecting the abnormality and the clock signal as the second signal. That is, the second determination unit 43 of this embodiment determines whether or not the horizontal synchronization signal and the clock signal input from the I / F unit 11 are normal.

The horizontal synchronizing signal and the clock signal are input from the I / F unit 11 to the second counter unit 42, and the clock signal input in the period from the input pulse of the horizontal synchronizing signal to the next input pulse is input. Count the number of clocks. The counted number of clocks is determined by the second determination unit 43.
Is output to.

When the error flag is on, the second judging section 43 judges whether or not the number of clocks of the clock signal counted by the second counter section 42 is within a predetermined range, If the error flag is off, the determination process is stopped. The predetermined range here is one cycle Th (see FIG. 7) of the horizontal synchronizing signal, that is, the allowable range of the number of clock signals of the clock signal to be input in the horizontal scanning period, and the allowable range is the range of the image display device. It is determined by the specifications of the image display device such as resolution.

At this time, similarly to the case of the vertical synchronizing signal shown in FIG. 8, when it is considered that the horizontal synchronizing signal is input due to the noise mixed in the horizontal synchronizing signal, the period for counting the number of clocks of the clock signal is Since it becomes shorter, the number of clocks becomes smaller than the predetermined range. On the other hand, when it is considered that the horizontal synchronizing signal has not been input due to noise mixed in the horizontal synchronizing signal, the period for counting the number of clocks becomes long, so the number of clocks becomes larger than the predetermined range.

When it is considered that the clock signal is input due to the noise mixed in the clock signal, the number of clocks of the clock signal becomes larger than the predetermined range. On the other hand, when it is considered that the clock signal has not been input due to noise mixed in the clock signal, the number of clocks becomes smaller than the predetermined range.

Therefore, when the number of clocks is within the predetermined range, the second judging section 43 judges that the horizontal synchronizing signal and the clock signal are normal, and turns off the second error flag, When the number of clocks is out of the predetermined range, it is determined that the horizontal synchronizing signal or the clock signal is abnormal, and the second error flag is turned on. The second error flag is output to the determination unit 41.

The judging section 41 receives the number of input pulses of the horizontal synchronizing signal from the counter section 30 until the next input pulse number is input. 2 The status of the error flag is monitored.

If the second error flag is turned on even once in the period, the judging section 41 determines that an error occurs even if the number of input pulses of the horizontal synchronizing signal from the counter section 30 is within a predetermined range. The flag is kept on, and the error flag is turned off only when the second error flag is always off during the period and the number of input pulses of the horizontal synchronizing signal is within a predetermined range.

In the liquid crystal display device 10 having the above structure, the error flag is turned off and the normal image display operation is resumed only when the vertical synchronizing signal and the horizontal synchronizing signal are normal and the clock signal is normal. . So, for example,
When the image display signal is extremely unstable and does not meet the specifications, such as when the power of the external device that generates the image display signal is turned on, the vertical sync signal and the horizontal sync signal are both Even if the number of input pulses of the horizontal synchronizing signal counted by the counter unit 30 happens to fall within a predetermined range due to the inclusion of noise in the horizontal synchronizing signal or clock by the second determining unit 43. When the signal is determined to be abnormal, the normal image display operation is not returned, so that it is possible to prevent the display of an image whose display is disturbed on the liquid crystal panel 15.

Further, even if the vertical synchronizing signal and the horizontal synchronizing signal are returned to normal, if the clock signal is abnormal, the normal image display operation is not returned, so that the image based on the abnormal clock signal is not returned. Can be prevented from being displayed on the liquid crystal panel 15.

In the above embodiment, the counter unit 30
The error flag is turned on when the number of input pulses of the horizontal synchronizing signal counted in step 3 is out of the predetermined range, but the error flag is turned on when the second error flag is turned on. The operation of the determination unit 41 may be changed. In this case, even if noise is mixed only in the clock signal, the error flag is turned on,
Since the predetermined image is displayed, it is possible to prevent the image based on the abnormal input data signal from being displayed on the liquid crystal panel 15.

Similarly, the error flag is turned on when the number of input pulses of the horizontal synchronizing signal counted by the counter section 30 is out of a predetermined range and / or when the second error flag is turned on. As described above, the operation of the determination unit 41 may be changed. In this case, if noise is mixed in at least one of the vertical synchronizing signal, the horizontal synchronizing signal, and the clock signal, the error flag is turned on,
Since the predetermined image is displayed, it is possible to further reduce the probability that the image is disturbed by the mixing of noise.

Further, the number of clocks of the clock signal counted by the second counter section 42 is changed so as to be inputted to the judging section 41, and the number of input pulses of the horizontal synchronizing signal counted by the counter section 30 is within a predetermined range. When outside
And / or, when the number of clocks of the clock signal counted by the second counter unit 42 is out of a predetermined range, an error flag is turned on, the number of input pulses is within a predetermined range, and the number of clocks is It is also possible to change the error flag to be turned off when it is within a predetermined range. In this case, the second determination unit 43 is unnecessary.

It should be noted that, in the above-mentioned embodiment, the second judgment unit 4
In No. 3, the second error flag is turned on when the number of clocks counted by the second counter unit 42 is out of the predetermined range even once, but this is set to a predetermined number of times (for example, five times) in one vertical scanning period. As described above, the second error flag may be turned on when it is out of the predetermined range.

In the above embodiment, the image display device in which the data enable signal and the clock signal are input as the image display signal in addition to the vertical synchronizing signal, the horizontal synchronizing signal and the input data signal has been described. ,
The present invention can be applied to an image display device in which only a vertical synchronizing signal, a horizontal synchronizing signal, and an input data signal are input as image display signals such as a television signal. In this case, the PL provided in the image display device 10
The above operation can be performed by using the clock signal generated by the L (Phase Locked Loop) circuit.

When a data enable signal is used as the synchronizing signal in addition to the vertical synchronizing signal and the horizontal synchronizing signal, it is necessary to match the input timings of the data enable signal and the horizontal synchronizing signal. The signal generator 32 preferably also generates a data enable signal when generating the vertical synchronizing signal and the horizontal synchronizing signal.

In this case, the selector unit 33 has the I / F unit 1
The vertical sync signal, the horizontal sync signal and the data enable signal from 1 and the vertical sync signal, the horizontal sync signal and the data enable signal from the sync signal generation unit 32 are input, and the I / F unit 11 is based on the error flag. It is desirable that the vertical synchronizing signal, the horizontal synchronizing signal, and the data enable signal from any one of the synchronizing signal generating section 32 are selected and output to the data processing section 21.

[Third Embodiment] Next, still another embodiment of the present invention will be described. In the present embodiment, of the image display signals, the data enable signal is used as the above-mentioned first signal and second signal to detect an abnormality in the data enable signal.

Therefore, in the present embodiment and the embodiments described later, since the abnormality of the data enable signal is detected, the image display device which drives the source driver 13 and the gate driver 14 based on the data enable signal is used. It is suitable.

On the other hand, in the above-described embodiment, since the abnormality of the vertical synchronizing signal or the horizontal synchronizing signal is detected, the image display for driving the source driver 13 and the gate driver 14 based on the vertical synchronizing signal and the horizontal synchronizing signal. Suitable for equipment.

As shown in FIG. 7, the data enable signal is maintained at the L (low) level in the vertical blanking period Tvb, and after the vertical blanking period Tvb elapses, 1
A pulse signal having the same period as the horizontal scanning period Th is input. While the pulse signal is at the H level (horizontal data valid period), the data signal for one horizontal line is supplied to the liquid crystal panel 1.
5 is input and an image for one horizontal line is displayed.
By repeating this, when one screen of image is displayed,
The vertical scanning period Tvb ends. After that, for each screen,
This operation is repeated.

Therefore, when the data enable signal is maintained at the L level for a predetermined period, the vertical blanking period T
It can be determined to be vb. The period from the determination of the vertical blanking period Tvb to the determination of the next vertical blanking period Tvb is one vertical scanning period Tvb.
Is the same as. Therefore, from the data enable signal,
The vertical scanning period Tvb can be detected.

That is, from the data enable signal,
It is possible to detect a signal having a cycle of one vertical scanning period Tv and a signal having a cycle of one horizontal scanning period Th, and by using each of them as the above-described first signal and second signal, the data enable is performed. Signal anomalies can be detected.

The configuration of this embodiment will be described below with reference to FIG. Note that configurations having the same functions as the configurations described in the above-described embodiments are given the same reference numerals, and description thereof will be omitted.

The liquid crystal display device of the present embodiment has a signal monitoring section having a configuration different from that of the signal monitoring section 20 in the control IC 12 as compared with the display apparatus shown in FIG. 1, and the other configurations are the same. is there. FIG. 5 shows a schematic configuration of the signal monitoring unit 50 in this embodiment.

In the present embodiment, the signal monitoring section 50 uses the I / O
It is monitored whether the data enable signal input from the F section 11 is normal. The signal monitoring unit 50 includes a counter unit 51, a determination unit 52, a synchronization signal generation unit 53, and a selector unit 54.

A data enable signal is input from the I / F unit 11 to the counter unit 51. The counter section 51 is
Based on the data enable signal, the number of input pulses input during the vertical blanking period Tvb to the next vertical blanking period Tvb, that is, the vertical data valid period (see FIG. 7) is counted. The counted number of input pulses is output to the determination unit 52.

The judging section 52 judges whether or not the number of input pulses counted by the counter section 51 is within a predetermined range. The predetermined range here is 1 in one vertical scanning period.
It is an allowable range of the number of horizontal lines required to display the image on the screen, and the allowable range is determined by the specifications of the image display device such as the resolution of the image display device.

At this time, when noise is mixed into the pulse signal input during the vertical data valid period, the pulse signal is maintained at the L level for a predetermined period and the vertical blanking period Tvb is reached. Since the period for counting the number becomes short, the number of input pulses becomes smaller than the predetermined range. On the other hand, the vertical blanking period Tvb
When noise is mixed in and becomes H level, the number of input pulses becomes larger than a predetermined range.

Therefore, when the number of input pulses is within the predetermined range, the determination section 52 determines that the data enable signal is normal, turns off the error flag, and sets the number of input pulses to the predetermined value. If it is out of the range, it is determined that the data enable signal is abnormal, and the error flag is turned on. The error flag is used by the synchronization signal generator 5
3, output to the selector unit 54 and the data processing unit 21.

When the error flag input from the determination unit 52 is on, the synchronization signal generation unit 53 generates a normal data enable signal and outputs it to the selector unit 54.

The data enable signal from the I / F unit 11 and the data enable signal from the synchronization signal generating unit 53 are input to the selector unit 54, and one of the data enable signals is selected based on the error flag. And outputs it to the data processing unit 21. That is, when the error flag is off, the data enable signal from the I / F unit 11 is selected, and when the error flag is on, the data enable signal from the synchronization signal generation unit 32 is selected. , To the data processing unit 21. As a result, a normal data enable signal is always input to the data processing unit 21.

Therefore, in the liquid crystal display device 10 of the present embodiment, in addition to the effect of the embodiment shown in FIG. 3, it is possible to detect a signal abnormality only with the data enable signal.

Further, even in the image display device in which only the data enable signal is inputted as the synchronizing signal instead of the vertical synchronizing signal and the horizontal synchronizing signal, the abnormality of the synchronizing signal can be detected.

[Fourth Embodiment] Next, still another embodiment of the present invention will be described with reference to FIG. Note that configurations having the same functions as the configurations described in the above-described embodiments are given the same reference numerals, and description thereof will be omitted.

The liquid crystal display device of the present embodiment is different from the display device shown in FIG. 1 in that it has a signal monitoring section having a configuration different from that of the signal monitoring section 20 in the control IC 12, and other configurations are the same. is there. FIG. 6 shows a schematic configuration of the signal monitoring unit 60 in this embodiment.

The signal monitoring unit 60 includes a judging unit 61 having a configuration different from that of the judging unit 52 shown in FIG. 5 as compared with the signal monitoring unit 50 shown in FIG. 5, and as a new counter unit and judging unit. 3, except that a data counter section (counting means) 62 and a data determination section (determination means) 43 are provided, and the other configurations are the same.

The determination unit 61 of the present embodiment is different from the determination unit 52 shown in FIG. 5 only in the condition for returning the error flag from ON to OFF, which is different from the determination unit 41 shown in FIG. The description is omitted because it is the same.

The data counter section 62 of this embodiment selects the pulse signal of the data enable signal in the vertical data valid period as the first signal for detecting an abnormality and the clock signal as the second signal. That is, the data determination unit 63 of this embodiment determines whether the data enable signal and the clock signal input from the I / F unit 11 are normal.

The data counter section 62 includes an I / F section 11
The data enable signal and the clock signal are input from. Further, the data counter unit 62 detects the pulse signal in the vertical data valid period from the data enable signal and counts the number of clocks of the clock signal input during the period in which the pulse signal is at the H level. The counted number of clocks is output to the data determination unit 63.

The data judging section 63 is the data counter section 6
It is determined whether or not the number of clocks of the clock signal counted in 2 is within a predetermined range. The predetermined range here is the number of clocks of the clock signal to be input during the period in which the pulse signal is at the H level, that is, during the period in which image data for one horizontal line is input based on the clock signal, that is, 1 This is an allowable range of the number of data for horizontal lines, and the allowable range is determined by the specifications of the image display device such as the resolution of the image display device.

At this time, if the period in which the pulse signal is at the H level is shortened due to the mixing of noise in the data enable signal, the number of clocks becomes smaller than a predetermined range and becomes the H level of the pulse signal. If the period becomes longer, the number of clocks becomes larger than the predetermined range.

When it is considered that the clock signal is input due to the noise mixed in the clock signal, the number of clocks of the clock signal becomes larger than the predetermined range. On the other hand, when it is considered that the clock signal has not been input due to noise mixed in the clock signal, the number of clocks becomes smaller than the predetermined range.

Therefore, when the number of clocks is within the predetermined range, the data determination unit 63 determines that the data enable signal and the clock signal are normal, turns off the data error flag, and sets the number of clocks. Is outside the predetermined range, it is determined that the data enable signal or the clock signal is abnormal, and the data error flag is turned on. The data error flag is output to the determination unit 61.

Therefore, in the liquid crystal display device 10 of the present embodiment, in addition to the effect of the embodiment shown in FIG. 4, an image display in which only the data enable signal is input as the synchronizing signal instead of the vertical synchronizing signal and the horizontal synchronizing signal. The device can also detect an abnormality in the synchronization signal.

In the liquid crystal display device 10 of this embodiment, the number of horizontal lines input in one vertical scanning period, that is, one frame period or one field period and the number of data input in one horizontal scanning period. By comparing with, it is possible to detect the abnormality of the signal.

In the above embodiment, the abnormality of the synchronizing signal and the clock signal is detected.
0.51, the condition that the second counter unit 42 and the data counter unit 52 can count, that is, the condition that the first signal has a longer cycle than the second signal, other image display The use signal can be used as the first signal and the second signal.

Further, in the above embodiment, the judging section 3
The control IC 12 may be provided with a setting terminal (setting changing means) so that the setting of the predetermined range judged by the 1, 41, 52, 61, the second judging section 43, and the data judging section 63 can be changed. In this case, by changing the setting of the predetermined range, it is possible to easily cope with the liquid crystal panels 15 having different resolutions.

In the above embodiment, when the error flag is on, the data processing unit 21 fixes the output data signal to a predetermined value and outputs it to the source driver 13. The monitoring unit 20 may change the input data signal so that it is fixed to a predetermined value and output to the data processing unit 21.

In this case, the data processing section 21 can have an existing structure, and the signal monitoring section 20 can realize the operation and effect of the present invention. Therefore, the effect of the present invention can be realized only by adding the signal monitoring unit 20 without changing the internal logic of the existing control IC 12, so that the risk accompanying the design change can be avoided and the design period can be shortened. You can

In the above embodiment, the liquid crystal display device 10 using the liquid crystal panel 15 is used as the image display device. However, since the invention of the present application is intended to detect an abnormality of an image display signal, the invention of the present application is a CRT (cathode ray tube), a PDP (plasma display panel), an EL (electroluminescence) element, an FED (field emission). (Element) etc., and is applicable to an image display device using other image display elements.

[0138]

As described above, the method of detecting an abnormality of the image display signal according to the present invention is the first signal among the plurality of image display signals used for displaying the image on the image display device. , A second signal having a shorter period than the first signal, an input to which the second signal is input during a period from the input of the first signal to the input of the next first signal The method includes a counting step of counting the number and an abnormality detecting step of determining that the first signal or the second signal is abnormal when the counted number of inputs is out of a predetermined range.

Thus, by counting the number of signal inputs of the image display signal, it is possible to detect an abnormality in the image display signal. Further, as compared with the conventional display device that detects the abnormality of the synchronization signal using the standard signal, it is possible to prevent the malfunction due to the noise mixed in the standard signal.

If any one of the plurality of image display signals is a combination of a plurality of signals having different periods, any one of the combined plurality of signals is selected. The first signal as the signal of
A signal having a shorter cycle than the signal of can be used as the second signal. In this case, there is an effect that it is possible to detect a signal abnormality with one image display signal without combining a plurality of image display signals.

As described above, the method of detecting an abnormality in the image display signal according to the present invention is such that, in the above method, the counting step is performed for each of different combinations of the first signal and the second signal. After the signal of
Is a step of counting the number of inputs to which the second signal is input during the period until the signal of is input, and the abnormality detection step is such that the number of inputs counted for any one of the combinations is within a predetermined range. When outside, either first
This is a step of determining that the signal or the second signal is abnormal.

Thus, it is possible to determine whether or not there is an abnormality in three or more signals from the plurality of image display signals.

As described above, the image display signal abnormality detecting method of the present invention determines that the first signal or the second signal is abnormal in the abnormality detecting step in the above method. Sometimes, the method includes an image generating step of generating the image display signal for displaying a predetermined image on the image display device.

Thus, when an abnormality in the image display signal is detected, a predetermined image is displayed on the image display device, so that an unsightly image is displayed on the image display device due to the abnormality in the image display signal. This has the effect of preventing this.

As described above, in the method of detecting an abnormality of the image display signal of the present invention, in the above method, the abnormality detecting step determines that the first signal or the second signal is abnormal. After that, when the counted number of inputs falls within a predetermined range, it is determined that the first signal and the second signal have become normal, and the image generation step causes the first signal in the abnormality detection step. When it is determined that the second signal is normal, the generation of the image display signal is stopped.

As a result, when the first signal or the second signal is no longer mixed with noise and returns to the normal state, the normal image display operation is automatically restarted.
Even if noise is mixed in the first signal or the second signal, it is possible to return to the normal image display operation without bothering the user.

Further, as described above, the image display device of the present invention is an image display device which displays an image on the image display section by inputting a plurality of image display signals. Of the first signal and the second signal having a shorter period than the first signal, the first signal and the second signal are input in the period from the input of the first signal to the input of the next first signal. The counting means for counting the number of inputs to which the signal No. 2 is input, the judging means for judging whether or not the number of inputs counted by the counting means is within a predetermined range, and the number of inputs is outside the predetermined range. When the judgment means makes a judgment, the abnormality detection means judges that the first signal or the second signal is abnormal.

With this, by counting the number of signal inputs of the image display signal, it is possible to detect the abnormality of the image display signal. Further, as compared with the conventional display device that detects the abnormality of the synchronization signal using the standard signal, it is possible to prevent the malfunction due to the noise mixed in the standard signal.

As described above, if any of the plurality of image display signals is a combination of a plurality of signals having different periods, the plurality of combined signals are combined. Of these signals, any one of the signals can be the first signal, and the signal having a shorter period than the first signal can be the second signal. In this case, there is an effect that it is possible to detect a signal abnormality with one image display signal without combining a plurality of image display signals.

Further, as described above, the image display device of the present invention is provided with the counting means and the determination means for each different combination of the first signal and the second signal in the above configuration. When the corresponding judging means judges that the number of inputs counted by any one of the counting means is out of a predetermined range, the abnormality detecting means outputs any one of the first signal and the second signal. The configuration is such that it is determined to be abnormal.

Thus, it is possible to determine whether or not there is an abnormality in three or more of the plurality of image display signals.

As described above, the image display device of the present invention further comprises display control means for controlling the display of an image based on the image display signal in the above-mentioned configuration. The control means is configured to control to display a predetermined image when the abnormality detecting means determines that the first signal or the second signal is abnormal.

Accordingly, when the abnormality detecting means detects an abnormality in the image display signal, the display control means controls to display a predetermined image, so that an unsightly image can be prevented from being displayed. Has the effect.

As described above, in the image display device of the present invention, in the above configuration, after the abnormality detecting means determines that the first signal or the second signal is abnormal, all the counts are counted. When the corresponding determining means determines that the number of inputs counted by the means is within a predetermined range, the abnormality detecting means determines that the first signal and the second signal are normal. The display control means controls the display of an image based on the image display signal.

As a result, when the first signal or the second signal returns to a normal state due to the elimination of noise and the like, the image based on the image display signal is automatically displayed. Even if noise or the like is mixed in the second signal or the second signal, it is possible to return to the normal image display operation without bothering the user.

As described above, the image display device of the present invention has the configuration described above, further including setting changing means for changing the predetermined range used by the determining means.

As a result, it is possible to deal with various image display devices by changing the predetermined range by the setting changing means.

The image display signal used as the first signal or the second signal is preferably selected from a vertical synchronizing signal, a horizontal synchronizing signal and a data enable signal. In this case, it is possible to reliably prevent the display of an unsightly image due to the mixing of noise.

The predetermined range used by the judging means may be either one or both of the number of lines in one frame period and the number of data in one line.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a control IC in FIG.

3 is a block diagram showing a schematic configuration of a signal monitoring unit in FIG.

FIG. 4 is a block diagram showing a schematic configuration of a signal monitoring unit in a liquid crystal display device according to another embodiment of the present invention.

FIG. 5 is a block diagram showing a schematic configuration of a signal monitoring unit in a liquid crystal display device according to still another embodiment of the present invention.

FIG. 6 is a block diagram showing a schematic configuration of a signal monitoring unit in a liquid crystal display device according to still another embodiment of the present invention.

FIG. 7 is a timing chart showing input waveforms of a vertical synchronizing signal, a horizontal synchronizing signal, and a data enable signal which are input as image display signals.

FIG. 8 is a timing chart showing a state in which noise is mixed in the vertical synchronizing signal in FIG.

[Explanation of symbols]

10 Liquid crystal display device (image display device) 12 Control IC 20 Signal monitoring unit 21 data processing unit (display control means) 30 counter section (counting means) 31 Judgment unit (judgment means, abnormality detection means) 40 Signal monitoring unit 41 Judgment unit (judgment means, abnormality detection means) 42 Second Counter Unit (Counting Unit) 43 Second determination unit (determination means) 50 Signal monitoring unit 51 Counter Unit (Counting Unit) 52 Judgment unit (judgment means, abnormality detection means) 60 signal monitoring unit 61 Judgment unit (judgment means, abnormality detection means) 62 data counter section (counting means) 63 Data determination unit (determination means)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H093 NA79 NC27 NC52 NC59 ND40                 5C006 AA01 AF51 AF53 AF65 AF67                       BF14 BF22 BF24                 5C025 AA30 BA09 BA18 CA03 DA06                 5C080 AA10 BB05 DD09 DD14 GG07                       GG08 JJ02 JJ04

Claims (13)

[Claims] 1. A first signal among a plurality of image display signals used for displaying an image on an image display device, and a second signal having a shorter period than the first signal. 1
Counting step for counting the number of inputs of the second signal during the period from the input of the signal of 1 to the input of the next first signal, and the counted number of inputs is out of the predetermined range. Sometimes, an abnormality detecting step of determining that the first signal or the second signal is abnormal is included. 2. An image display signal of any of the plurality of image display signals is a combination of a plurality of signals having different periods, and any one of the combined plurality of signals is used. Is used as a first signal, and a signal having a shorter period than the first signal is used as a second signal. The method for detecting an abnormality of an image display signal according to claim 1, wherein 3. The counting step, for each different combination of the first signal and the second signal, during the period from the input of the first signal to the input of the next first signal, 2 is a step of counting the number of inputs to be input, the abnormality detection step, when the number of inputs counted for any one of the combinations is out of a predetermined range, any one of the first signals The method for detecting an abnormality in an image display signal according to claim 1 or 2, which is a step of determining that the second signal is abnormal. 4. When the abnormality detecting step determines that the first signal or the second signal is abnormal, the image display signal for displaying a predetermined image on the image display device is generated. The method for detecting an abnormality of an image display signal according to claim 1, further comprising an image generation step. 5. The abnormality detecting step, when the counted number of inputs falls within a predetermined range after it is determined that the first signal or the second signal is abnormal, the first signal and the second signal are detected. When it is determined that the first signal and the second signal are normal in the abnormality detection step, the generation of the image display signal is stopped. The method for detecting an abnormality in an image display signal according to claim 4, wherein 6. An image display device for displaying an image on an image display unit by inputting a plurality of image display signals, wherein a first signal and a first signal among the plurality of image display signals are provided.
With respect to the second signal having a shorter period than the signal of, the number of inputs of the second signal is counted in the period from the input of the first signal to the input of the next first signal. Counting means, a judging means for judging whether or not the number of inputs counted by the counting means is within a predetermined range, and when the judging means judges that the input number is outside the predetermined range, the first An image display device, comprising: an abnormality detection unit that determines that the signal or the second signal is abnormal. 7. An image display signal of any of the plurality of image display signals is a combination of a plurality of signals having different periods, and one of the combined plurality of signals is included. The image display device according to claim 6, wherein the signal is a first signal, and the signal having a shorter period than the first signal is a second signal. 8. The counting means and the determining means are provided for each different combination of the first signal and the second signal, and the abnormality detecting means is an input counted by any one of the counting means. When the corresponding judging means judges that the number is out of the predetermined range, either the first signal or the second signal
The image display device according to claim 6 or 7, wherein the signal is determined to be abnormal. 9. A display control means for controlling to display an image on the basis of the image display signal is further provided, wherein the display control means determines that the first signal or the second signal is abnormal. 9. The image display device according to claim 6, wherein when the abnormality detection unit makes a determination, the image display device is controlled to display a predetermined image. 10. The abnormality detecting means, when the number of inputs counted by all the counting means is within a predetermined range after determining that the first signal or the second signal is abnormal, the corresponding means is provided. When the determination means determines, the first signal and the second signal are determined to be normal, and the display control means is determined by the abnormality detection means to be the first signal and the second signal are normal. The image display device according to any one of claims 6 to 9, characterized in that when it does, control is performed so as to display an image based on the image display signal. 11. The image display device according to claim 6, further comprising setting changing means for changing a predetermined range used by the judging means. 12. The image display signal used as the first signal or the second signal is selected from a vertical synchronizing signal, a horizontal synchronizing signal and a data enable signal. 12. The image display device according to any one of 1 to 11. 13. The predetermined range used by the judging means is either one or both of the number of lines in one frame period and the number of data in one line. 13. The image display device according to any one of 12.