JP4474848B2 - Video display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to display burn-in prevention of a video display device that displays a video signal.
[0002]
[Prior art]
In the conventional display burn-in prevention method, if the difference between fields is zero, it is detected as a still image, and when the still image state continues for a predetermined time, the image contrast circuit is controlled to reduce the image contrast (for example, Patent Document 1).
[0003]
[Patent Document 1]
JP 05-344371 A
[0004]
[Problems to be solved by the invention]
However, with simple field difference information, a subtle change in brightness due to the influence of the previous circuit or transmission system is detected as a difference, so a still image when the brightness changes subtly even though it is a still image. Cannot be detected. If the reference data to be compared when discriminating a still image from the difference information is set to be large and the subtle luminance change of the still image is also changed to be discriminated as a still image, the analog terrestrial signal in the weak electric field state is changed. It is difficult to discriminate between white noise that occurs uniformly on the screen when received and a moving image with a small range of change, and it is impossible to correctly discriminate still images.
[0005]
In addition, since the judgment material is only the still image detection information, the image contrast of the still image video signal having no luminance difference that is unlikely to cause image sticking is lowered. In this case, there is a problem that a video signal having a small luminance difference is set to a video state having a smaller luminance difference and viewed on the display.
[0006]
The present invention has been made in order to solve the above-described problems. By performing weak electric field detection, stationary state detection, and burn-in danger signal detection, an image that avoids display burn-in by a method other than contrast reduction is provided. An object is to provide a display device.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a video display device of the present invention is a video display device that displays a video signal, and includes a weak electric field detection circuit that detects a degree of white noise superimposed on the video signal, A still image detection determination circuit that detects a still image level of a video signal and determines that the image is a still image from the still image level, and detects a sharpness and a luminance difference of the video signal, and displays on a display of the video display device. A seizure risk signal detection circuit that detects that the video signal is a risky image signal that causes a deterioration of the luminous efficiency of a specific part and burns any fixed image on the display, and a seizure risk from the detection result of the seizure risk signal detection circuit. A seizure risk signal judgment circuit for judging that the signal is a signal, and the still image detection judgment circuit judges that it is a still image, and the seizure risk signal judgment circuit judges that it is a seizure risk signal. A timer that measures the duration of a still image that is determined to be a burn-in danger signal, a duration determination circuit that determines that the measurement time of the timer has exceeded an arbitrary value, and is not normally operating A display burn-in prevention circuit that starts an operation for preventing the burn-in of the display unit by special control, and the display when the duration determination circuit determines that the measurement time of the timer exceeds an arbitrary value. And a seizure prevention circuit control device that performs control for operating the seizure prevention circuit.
[0008]
This detects weak electric fields and still images, changes the still image criteria according to the weak electric field detection data, and prevents false detection of still image detection due to weak electric fields. It can be detected as a still image. In addition, by operating the display burn-in prevention circuit when the state that is determined to be a burn-in danger signal for a predetermined time continues for a still image, the possibility of burn-in is low. The image contrast is not lowered.
[0009]
The video display device of the present invention converts still image data stored in a recording medium into a video signal, displays one image data selected from a plurality of still image data, and also displays a plurality of images. A video display device having a function of automatically displaying data sequentially, wherein when the still image data is converted into a video signal, the selected one image is displayed or a plurality of image data are displayed. Still image image data conversion state selection circuit that automatically selects a state to be displayed in sequence, and a still image detection determination circuit that detects a still image degree of the video signal and determines that the image is a still image from the still image degree A timer that measures the duration of the state in which the still image detection determination circuit determines that it is a still image, and a duration determination circuit that determines that the measurement time of the timer has exceeded an arbitrary value. Have However, when the display burn-in prevention circuit that starts the operation to prevent the burn-in of the display unit by special control and the duration determination circuit determines that the measurement time of the timer exceeds an arbitrary value, And a burn-in prevention circuit control device that performs control for operating the display burn-in prevention circuit.
[0010]
As a result, it is possible to reliably prevent display burn-in without reducing the image contrast.
[0011]
The video display device of the present invention is the above-described video display device, wherein the still image detection determination circuit creates a difference in luminance signal between frames, changes the luminance signal in units of pixels between frames, and It is characterized by performing two-dimensional histogram processing of the number of pixels corresponding to the degree of change, and comparing the pixel number distribution shape on the histogram with the arbitrarily determined distribution shape to determine the still image state. is there.
[0012]
As a result, in simple field difference information, subtle changes in luminance due to the influence of the previous circuit and transmission system have been detected as differences, but the difference data in a range where the luminance difference is small is reduced as the difference information. As a result, it is possible to detect a still image whose luminance is slightly changed as a signal to be an object of image sticking prevention.
[0013]
The video display device of the present invention is the video display device described above, and the burn-in danger signal detection circuit differentiates the video signal and compares the maximum amplitude value of the differential signal with an arbitrarily set value to cause burn-in risk. It is characterized by discriminating signals.
[0014]
Thereby, sharpness and luminance difference information of adjacent pixels can be detected and grasped at the same time.
[0015]
The video display device of the present invention is the video display device described above, and the display burn-in prevention circuit is configured to display the video contrast control circuit and the video when the burn-in prevention circuit control device instructs the start of the display burn-in prevention operation. The signal edge emphasis correction circuit is controlled, and the image contrast and the image signal edge emphasis correction are lowered to a signal level that is not determined to be a burn danger signal by the burn danger signal detection circuit.
[0016]
As a result, the seizure risk signal can be reliably changed to a signal outside the seizure risk signal detection range.
[0017]
In the video display device of the present invention, the display burn-in prevention circuit controls the speed modulation (VM) signal control circuit when the burn-in prevention circuit control device instructs to start the display burn-in prevention operation, and the VM signal amplitude is controlled. It is characterized by lowering the effect by reducing.
[0018]
Thereby, the VM signal, which is a burn-in factor other than the sharpness and luminance difference of the video signal, is also controlled, and a more reliable burn-in prevention operation can be performed.
[0019]
The video display device according to claim 7 of the present invention is the video display device described above, wherein the display burn-in prevention circuit is configured such that when the burn-in prevention circuit control device instructs the start of the display burn-in prevention operation, A video display device characterized by controlling a video synchronization signal control circuit to move a video display position displayed on a display.
[0020]
Thereby, it is possible to prevent the display from being burned in without reducing the sharpness and contrast of the image.
[0021]
The video display device according to claim 8 of the present invention is the video display device described above, wherein the display burn-in prevention circuit is configured such that when the burn-in prevention circuit control device instructs the start of the display burn-in prevention operation, The video resizing circuit is controlled, and the size of the video displayed around the center of the display is arbitrarily changed at arbitrary time intervals.
[0022]
Thereby, since the sharpness and contrast of the image are not lowered and the image position is not moved, it is possible to prevent the display from being burned out without giving the user a sense of incongruity.
[0023]
The video display device according to the present invention is the video display device described above, and the state transition caused by the operation of the display burn-in prevention circuit changes slowly about once every several minutes.
[0024]
Thereby, the discomfort of the operation of the display burn-in prevention circuit for the user can be reduced.
[0025]
The video display device of the present invention is the above-described video display device, wherein the display burn-in prevention circuit converts the still image data when the burn-in prevention circuit control device instructs the start of the display burn-in prevention operation. The state selection circuit is controlled to select a state in which a plurality of pieces of image data are automatically displayed in order.
[0026]
As a result, when still image data stored in a recording medium is converted into a video signal for display, the display can be prevented from being burned with a small number of circuits and control specifications.
[0027]
The video display device of the present invention is the video display device described above, wherein the still image and the state that is determined to be a burn-in danger signal are continued, and the burn-in prevention circuit control device is connected to the display burn-in prevention circuit. After starting the operation, when it is determined that the determination result of the still image detection determination circuit is not a still image, control is performed to return the operation of the display burn-in prevention circuit to the state before the display burn-in prevention operation. It is what.
[0028]
As a result, when the display burn-in prevention circuit operation is shifted to an unnecessary state, an image can be provided to the user without the display burn-in prevention circuit operation.
[0029]
The video display device of the present invention is the video display device described above, wherein the still image and the state that is determined to be a burn-in danger signal are continued, and the burn-in prevention circuit control device is connected to the display burn-in prevention circuit. When the operation is started, RED display or OSD display on the display indicates that the operation of the display burn-in prevention circuit is started.
[0030]
Thereby, the user can easily identify whether or not the operation of the display burn-in prevention circuit is being performed, and appropriate device control becomes extremely easy.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, embodiment shown here is an Example to the last, Comprising: It is not necessarily limited to this embodiment.
[0032]
(Embodiment 1)
FIG. 1 is a diagram illustrating a configuration of a video display apparatus according to the first embodiment.
[0033]
In FIG. 1, 1 is a video display device, 2 is an analog video signal transmission device, and 3 is a digital video signal transmission device.
[0034]
The analog video signal 4 input from the terminal 6 is converted into an 8-bit digital luminance video signal 22 by the A / D converter 7. The digital video signal 5 input from the terminal 21 is converted into an 8-bit digital luminance video signal 23 by the digital signal decoding circuit 8. The 8-bit digital luminance signal is selected by the changeover switch circuit 9 and input to the weak electric field detection circuit 10, the still image detection determination circuit, and the edge enhancement correction circuit 12 in the video signal.
[0035]
The video signal in which the edge of the video signal is emphasized and corrected by the edge enhancement correction circuit 12 in the video signal is input to the video contrast control circuit 13, the video contrast is controlled, the VM signal generation circuit 24, and the burn-in danger signal detection circuit 14. , Input to the D / A converter 18, respectively. The weak electric field detection circuit 10 detects a noise component in the synchronization signal portion of the analog video signal 4, creates a weak electric field detection circuit detection result 26, and supplies the result to the burn-in prevention circuit control device 15.
[0036]
The still image detection determination circuit 11 creates a still image detection determination circuit detection result 27 and supplies it to the image sticking prevention control device 15. The seizure risk signal detection circuit 14 detects the risk of display seizure from the video signal supplied from the video contrast control circuit 13, creates a seizure risk signal circuit detection result 28, and sends it to the seizure control prevention device 15. Supply.
[0037]
The burn-in prevention circuit control device 15 causes display burn-in using the detection results of the weak electric field detection circuit detection result 26, the still image detection determination circuit detection result 27, and the burn-in danger signal circuit detection result 28 as determination criteria. It is determined whether or not the video reception state is highly likely to be performed.
[0038]
When it is determined that the video image receiving state is likely to cause display burn-in, the timer 16 first counts the duration of the current state. When it is determined by the count of the timer 16 that the video image receiving state where there is a high possibility of image sticking has continued for a predetermined time or longer, the image sticking prevention circuit control device 15 uses the control signal 29 to display the image sticking prevention circuit 17. Is started to notify the microcomputer 19 of the control state of the display burn-in prevention circuit.
[0039]
The microcomputer 19 controls the OSD (on-screen) adding circuit 20 to add the OSD signal on the video signal 25 in order to notify the user of the video display device 1 that the burn-in prevention circuit 17 is operating. Then, it is displayed on the display device 30. The same operation is performed when a GUI (Graphical User Interface) signal is input to the terminal 6 or the terminal 21.
[0040]
Here, the configuration of the still image detection determination circuit 11 will be described with reference to FIGS. The digital luminance signal 41 is supplied to the 1-frame delay circuit 43 and the frame difference creation circuit 44. The one-frame delay circuit 43 delays the digital luminance signal 41 by one frame to generate a one-frame delayed digital luminance signal 42 and supplies it to the frame difference generation circuit 44. The frame difference creating circuit 44 creates a luminance difference between frames in units of pixels from the digital luminance signal 41 and the one-frame delayed digital luminance signal 42 and supplies difference information 46 to the histogram forming circuit 45 at intervals of one frame unit. To do. The operation of the histogram forming circuit 45 will be described with reference to FIG.
[0041]
The histogram forming circuit 45 classifies the difference information 46 into eight difference ranges D0, D1, D2, D3, D4, D5, D6, and D7 divided by arbitrary seven threshold values, and forms a histogram. In the histogram of FIG. 3, the X axis indicates the difference range (D0, D1, D2, D3, D4, D5, D6, D7), and the Y axis indicates the number of pixels (H0, H1, H2, H3, H4, H5, H6, H7). The threshold levels T2, T3, T4, T5, T6, and T7 are used to obtain comparison results R2, R3, R4, R5, R6, and R7 with the number of pixels within each difference range.
[0042]
For example, when an ideal still digital image is received, the pixels on the histogram are concentrated in the difference range D0, and there are no pixels in the other difference ranges. Therefore, even if the threshold levels T2, T3, T4, T5, T6, and T7 are set to values that are as close to zero as possible, each comparison result R * (* represents an arbitrary number) is R * = H. * <T *. That is, if R * = H * <T *, it is possible to detect and determine that the image is a still image. Actually, since white noise is superimposed, the value of the threshold level T7 of D7, which is the largest difference range, is set to a larger value.
[0043]
Further, by setting each threshold level to a predetermined value based on the detection result 26 of the weak electric field detection circuit 10, still image detection determination according to the weak electric field level becomes possible, and the still image determination is erroneous due to the weak electric field. Can be avoided. Specifically, if the electric field level is strong, the threshold value T7 is set to be small, and if the electric field level is weak, the threshold level is set to be large.
[0044]
Next, the configuration of the seizing danger signal detection circuit 14 will be described with reference to FIGS. The digital luminance signal 51 is supplied to the differentiation circuit 52. The differentiation circuit 52 supplies the differentiation signal 53 to the amplitude level detection circuit 54. The amplitude level detection circuit 54 compares the differential signal 53 with a predetermined threshold 55, counts the number of pixels in which the differential signal 53 is larger than the threshold 55 in units of one frame, and detects the burn-in danger signal circuit in FIG. The result 28 is supplied to the burn-in prevention circuit controller 15. In this embodiment, a signal with a high risk of display burn-in is considered to be a video signal containing a high-frequency component and having a large luminance difference between adjacent pixels. When a signal including a high frequency component and having a large luminance difference between adjacent pixels is differentiated, the differential waveform of the signal has a large amplitude value. Therefore, by counting the number of pixels having an amplitude equal to or greater than a predetermined threshold in units of frames, it is possible to determine the risk of image burn-in in the display.
[0045]
Next, the operation of the display burn-in prevention circuit 17 will be described with reference to FIG. When the still image detection determination circuit detection result 27 in FIG. 1 determines that the image is a still image and the burn-in danger signal circuit detection result 28 determines that the image is a burn-in danger signal, the timer 16 adds 1 to the state duration time. Count. Thereafter, when the timer counts the duration of the state for a predetermined time or more, the correction amount of the edge enhancement correction circuit 12 in the video signal is reduced by a predetermined level, and the contrast of the video contrast control circuit 13 is set to a predetermined level. It is reduced by the amount, and based on the seizure danger signal circuit detection result 28, it is determined again whether or not it is a danger signal. At this time, if it is determined as a still image and a danger signal, the correction amount of the edge enhancement correction circuit 12 in the video signal and the contrast of the video contrast control circuit 13 are gradually reduced to a level where it is not judged as a danger signal. To do.
[0046]
When the correction amount of the edge enhancement correction circuit 12 in the video signal and the contrast of the video contrast control circuit 13 are reduced to a level that is not determined as a danger signal in the still image, the still image is checked again and the still image state If so, the video signal state at a level that is not determined as a danger signal is held. In this holding state, when the still image determination is determined to be a moving image, the reduced video signal edge enhancement correction amount and the video contrast amount are returned to the original values, and the initial state is restored. By a series of these control operations, it is possible to prevent image sticking.
[0047]
(Embodiment 2)
FIG. 7 is a diagram showing a configuration of the display burn-in prevention circuit 17 in the second embodiment. The digital video signal 61 that is the output of the digital switch 9 in FIG. 1 is compressed and expanded at an arbitrary magnification by the video resizing circuit 62, the video size is resized, and the resized digital video signal 63 is supplied to the display 64. To do. FIG. 8 is a diagram for explaining a video image displayed on the display 64.
[0048]
When the display burn-in circuit is activated, the video compression rate changes stepwise from A to B, then from B to C, and then from C to A at predetermined time intervals counted by the timer 16 in FIG. Let By this compression rate change operation, the video on the video display becomes a pseudo video, preventing partial burn-in deterioration on the display and fixing the video center, It is possible to reduce the uncomfortable feeling of change in the video compression rate. In addition, by setting the time interval for changing the compression rate to a slow change of about once every few minutes, it is possible to reduce the user's uncomfortable feeling of the change in the video compression rate during viewing.
[0049]
(Embodiment 3)
FIG. 9 is a diagram showing a configuration of the display burn-in prevention circuit 17 according to the third embodiment. The VM signal generation circuit 24 in FIG. 1 generates a VM signal 72 from the digital video luminance signal 71 that is the output of the video contrast control circuit 13 and supplies the VM signal 72 to the VM signal amplitude control circuit 73. The VM signal amplitude control circuit 73 is controlled by the microcomputer 74, determines the amplitude value of the VM signal to be output, and supplies the VM signal to the VM coil 75.
[0050]
The burn-in prevention circuit control device 15 in FIG. 1 detects the risk of burn-in, and the microcomputer 74 controls the VM signal amplitude control circuit 73 to reduce the VM signal amplitude, so that the luminance of the video signal is different. It is possible to reduce the difference in the beam current density to the CRT display phosphor screen generated in step 1 without reducing the image contrast. However, the third embodiment is effective only for a display in which a speed modulation coil (VM coil) is used for the display.
[0051]
(Embodiment 4)
FIG. 10 is a diagram illustrating a configuration of the video display device according to the fourth embodiment.
[0052]
In FIG. 10, 81 is a video display device, and 82 is a still image data recording medium such as an SD card. The data 83 stored in the still image data recording medium passes through the still image data recording medium connection terminal 96 and is switched by the changeover switch 84, and the video data decoding circuit 85 for one-screen playback or the video data decoding circuit automatic continuous playback. Supplied to 86. The video data decoding circuit for one-screen playback 85 decodes only one still image data of a recording medium on which a plurality of still image images are recorded into a video data format, and the D / A converter 91 and the still image detection determination This is supplied to the circuit 88 and seizure risk signal detection circuit 97. The video data decoding circuit 86 for automatic continuous reproduction decodes the first still image data of a recording medium on which a plurality of still image images are recorded into a video data format, and a D / A converter 91 and a still image detection determination circuit. Then, the second still picture data is automatically decoded, and thereafter, the still picture recorded automatically is sequentially decoded in order.
[0053]
The difference between the video data decoding circuit for one-screen playback 85 and the video data decoding circuit for automatic continuous playback 86 is that the still image data is sequentially or automatically decoded sequentially or only one selected still image data is decoded. It is a difference of what to do. The still image detection determination circuit 88 creates a still image detection determination circuit detection result 89 and supplies it to the image sticking prevention control device 89. The seizure risk signal detection circuit 97 creates a seizure risk signal circuit detection result 98 and supplies it to the seizure prevention circuit controller 89. The burn-in prevention circuit control device 89 determines whether or not the display is in a video image receiving state where there is a high possibility that the burn-in of the display will occur, based on the switching information of the changeover switch 84 and the detection results 89 and 98 as judgment criteria.
[0054]
When it is determined that the video image receiving state is likely to cause display burn-in, the timer 90 first counts the duration of the current state. If it is determined by the count of the timer 90 that the image receiving state where the display burn-in is likely to occur has continued for a predetermined time or longer, the burn-in prevention circuit control device 89 uses the changeover switch 84 to display a still image of one screen. The video data decoding circuit that continuously decodes the video data decoding circuit that automatically decodes the video in sequential order 85 from the one-screen playback 85, and the control state of the display burn-in prevention circuit is notified to the microcomputer 92 To do. The microcomputer 92 controls the OSD (on-screen) additional circuit 83 to notify the user of the video display device 81 that the burn-in prevention circuit control device 89 has started the burn-in prevention operation, and the video signal An OSD signal is added on 94 and displayed on the display device 95.
[0055]
【The invention's effect】
As described above, according to the embodiment of the present invention, weak electric field detection by white noise level detection, video still image level detection, video signal display burn-in risk detection, display burn-in danger state continuation By detecting the time, it is possible to provide a video display device that accurately discriminates a display burn-in danger state, starts a display burn-in prevention circuit operation, and avoids display burn-in. .
[0056]
As a first effect, it is possible to accurately determine a display burn-in dangerous state based on information of weak electric field detection by white noise level detection and discrimination by histogram processing of a still image level of a video. Even if a subtle change in luminance due to the influence of the image or some white noise is superimposed, it is possible to accurately determine that the image is a still image.
[0057]
Furthermore, the display signal burn-in risk of the video signal is detected by counting the number of pixels of the differential signal amplitude level of the video signal in units of frames, and only in the case of a still image and a signal with a high burn-in risk By operating the display burn-in prevention circuit, it is possible to provide an image display device that can avoid unnecessary operation of the display burn-in prevention circuit and suppress a sense of discomfort given to the user.
[0058]
As a second effect, the still image detection / judgment circuit creates a difference between luminance signals between frames, and a two-dimensional distribution of the degree of change in luminance signal in units of pixels and the number of pixels corresponding to each degree of change. By comparing the pixel shape distribution shape on the histogram with the arbitrarily determined distribution shape and determining the still image state, the subtle still image determination is performed rather than the simple field difference information determination. Therefore, it is possible to provide a video display device that can accurately detect a signal that is subject to image sticking prevention.
[0059]
As a third effect, the seizure risk signal detection circuit differentiates the video signal, compares the maximum amplitude value of the differential signal with an arbitrarily set value, and discriminates the seizure risk signal. It is possible to simultaneously detect and grasp the luminance difference information of the pixels to be performed, and to provide a video display device capable of detecting the burn-in risk of the video signal. .
[0060]
As a fourth effect, when the burn-in prevention circuit control device instructs the start of the display burn-in prevention operation, the image contrast control circuit and the edge enhancement correction circuit in the video signal are controlled, and the burn-in danger signal detection circuit detects the burn-in danger signal. It is possible to provide a video display device that can reliably change the burn-in danger signal to a signal outside the burn-in danger signal detection range by lowering the video contrast and the edge enhancement correction in the video signal to a signal level that is not judged to be It becomes.
[0061]
As a fifth effect, when the image sticking prevention circuit control device instructs the start of the display image sticking prevention operation, the speed modulation (VM) signal control circuit is controlled, and the effect is reduced by reducing the VM signal amplitude. It is possible to provide a video display apparatus that controls the VM signal, which is a burn-in factor other than the sharpness and luminance difference of the video signal, and performs a more reliable burn-in prevention operation.
[0062]
As a sixth effect, as an operation of the display burn-in prevention circuit, by controlling the video resizing circuit and performing an operation of changing a predetermined video compression rate every predetermined time in a state where the center position on the display is secured. Since the image sharpness and contrast are not lowered and the position of the image is not moved, it is possible to provide an image display device that prevents the display from being burned in without causing the user to feel uncomfortable.
[0063]
As a seventh effect, by setting the state transition due to the operation of the display burn-in prevention circuit to a slow change of about once every several minutes as the operation of the display burn-in prevention circuit, the display burn-in prevention to the user is achieved. It is possible to provide a video display device capable of reducing the uncomfortable feeling of circuit operation.
[0064]
As an eighth effect, when still image data stored in a recording medium is converted into a video signal and displayed, a plurality of image data are automatically displayed in order as an operation of the display burn-in prevention circuit. By selecting the state to be performed, it is possible to provide a video display device capable of preventing display burn-in with a small number of circuits and control specifications.
[0065]
As a ninth effect, the operation of the display burn-in prevention circuit continues to be a still image and a state determined as a burn-in danger signal, and the burn-in prevention circuit control device starts the operation of the display burn-in prevention circuit. Later, when the determination result of the still image detection determination circuit is not a still image, the display burn-in prevention circuit is controlled by returning the operation of the display burn-in prevention circuit to the state before the display burn-in prevention operation. When a transition is made to an operation unnecessary state, it is possible to provide a video display device that provides video to the user without the operation of the display burn-in prevention circuit.
[0066]
As a tenth effect, when the state determined to be a still image and a burn-in danger signal continues and the burn-in prevention circuit control device starts the operation of the display burn-in prevention circuit, the operation of the display burn-in prevention circuit By displaying the RED display and the OSD display on the display, the user can easily identify whether or not the operation of the display burn-in prevention circuit is being performed, and appropriate device control is extremely possible. It becomes possible to provide a video display device that is easy.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a video display device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a still image detection determination circuit of the video display device
FIG. 3 is a diagram showing an operation content of a still image detection determination circuit of the video display device.
FIG. 4 is a diagram showing a configuration of a burn-in danger signal detection circuit of the video display device.
FIG. 5 is a diagram showing an operation content of a burn-in danger signal detection circuit of the video display device.
FIG. 6 is a diagram showing an operation content of a display burn-in prevention circuit in the video display device.
FIG. 7 is a diagram showing a configuration of a display burn-in prevention circuit of a video display device according to a second embodiment of the present invention.
FIG. 8 is a diagram for explaining a video image displayed on a display displayed by the operation of the display burn-in prevention circuit;
FIG. 9 is a diagram showing a configuration of a display burn-in prevention circuit of a video display device according to a third embodiment of the present invention.
FIG. 10 is a diagram showing a configuration of a video display device according to a fourth embodiment of the present invention.
[Explanation of symbols]
1 Video display device
2 Analog video signal transmitter
3 Digital video signal transmitter
4 Analog video signal
5 Digital video signal
6 terminals
7 A / D converter
8 Digital signal decoding circuit
9 Changeover switch circuit
10 Weak electric field detection circuit
11 Still image detection judgment circuit
12 Edge enhancement correction circuit in video signal
13 Image contrast control circuit
14 Seizing danger signal detection circuit
15 Seizure prevention circuit control device
16 timer
17 Display burn-in prevention circuit
18 D / A converter
19 Microcomputer
20 OSD additional circuit
21 terminals
22 Digital luminance video signal
23 Digital luminance video signal
24 VM signal generation circuit
25 Video signal
26 Weak electric field detection circuit detection results
27 Still image detection judgment circuit detection result
28 Seizing hazard signal circuit detection result
29 Control signal
30 Display device
41 Digital luminance signal
42 1 frame delayed digital luminance signal
43 1-frame delay circuit
44 Frame difference creation circuit
45 Histogram forming circuit
46 Difference information
51 Digital luminance signal
52 Differentiation circuit
53 Differential signal
54 Amplitude level detection circuit
55 Predetermined threshold
61 Digital video signal
62 Video resizing circuit
63 Digital video signal after resizing
64 display
71 Digital video luminance signal
72 VM signal
73 VM signal amplitude control circuit
74 Microcomputer
75 VM coil
81 Video display device
82 Still image data recording media
83 Data stored in still image data recording media
84 changeover switch
85 Video data decoding circuit for single screen playback
86 Video data decoding circuit for automatic continuous playback
88 Still image detection judgment circuit
89 Still image detection judgment circuit detection result
90 timer
91 D / A converter
92 Microcomputer
94 Video signal
95 Display device
96 Still image data recording media connection terminal
97 Seizing danger signal detection circuit
98 seizure hazard signal circuit detection results

Claims (3)

A weak electric field detection circuit for detecting the degree of white noise superimposed on the analog video signal;
A 1-frame delay unit that creates a 1-frame delayed digital brightness signal by delaying the digital brightness signal by 1 frame, and a frame difference creation that creates difference information between frames in units of pixels from the digital brightness signal and the 1-frame delayed digital brightness signal And a histogram forming unit that calculates the number of pixels for each difference range based on the difference information, and a threshold value level of the largest difference range based on the detection output of the weak electric field detection circuit is reduced if the electric field level is strong A still image detection determination circuit that determines that the image is a still image only when the number of pixels that is the output of the histogram forming unit is smaller than the threshold level.
A differential unit for differentiating a digital luminance signal and a differential signal that is an output of the differential unit are compared with a predetermined threshold, and based on a value obtained by counting the number of pixels in which the differential signal has an amplitude equal to or greater than the predetermined threshold in units of frames. A seizure risk signal judgment circuit for judging that it is a seizure risk signal;
When the still image detection determination circuit determines that it is a still image and the burn-in danger signal determination circuit determines that it is a burn-in danger signal, it measures the duration of the still image as a burn-in danger signal. A timer to
A display burn-in prevention circuit that operates when the measurement time of the timer exceeds a predetermined value;
A video display device.   2. The video display apparatus according to claim 1, wherein the display burn-in prevention circuit controls the video contrast control circuit and the edge enhancement correction circuit in the video signal to reduce the video contrast and the edge enhancement correction amount in the video signal.   2. The video display device according to claim 1, wherein the display burn-in prevention circuit controls the speed modulation signal control circuit to reduce the speed modulation signal amplitude.

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