JP7246138B2 - Video processing device, video processing method, television receiver, control program, and recording medium - Google Patents

Description

One aspect of the present invention relates to a video processing device, a video processing method, a television receiver, a control program, and a recording medium.

In recent years, there has been known a G-SYNC (registered trademark) compatible liquid crystal display device capable of scanning with variable timing. Also, HDMI 2.1 (registered trademark) is known as a communication interface standard capable of transmitting video with a variable frame rate.

Japanese Unexamined Patent Application Publication No. 2002-200001 discloses a display device that performs appropriate voltage setting for an input video signal having a variable frame rate. Further, Patent Document 2 below discloses a display control device capable of suppressing the occurrence of transfer.

Japanese Patent Application No. 2015-552882 (published on January 14, 2013) International Publication No. 2016/171069 (published on October 27, 2016)

However, the prior art as described above, when conventional fixed frame rate video techniques such as overdrive, dithering, or shadow correction are applied to variable frame rate video as before, temporarily There is a problem that a part of the screen becomes too bright, and the quality of the image may be degraded.

One aspect of the present invention has been made in view of the above problems, and aims to suppress degradation in video quality when using conventional fixed frame rate video technology for variable frame rate video. aim.

In order to solve the above problems, a video processing device according to an aspect of the present invention is a video processing device including an acquisition unit and a correction unit, wherein the acquisition unit acquires a video signal, and corrects the video signal. The unit determines whether or not the video signal acquired by the acquisition unit includes a video signal whose frame interval can vary, and if it is determined that the video signal whose frame interval can vary is included. or weakens the degree of correction of the video signal acquired by the acquisition unit, or turns off the correction of the video signal acquired by the acquisition unit.

ADVANTAGE OF THE INVENTION According to one aspect of the present invention, it is possible to suppress degradation in video quality when a conventional fixed frame rate video technology is used for a variable frame rate video.

1 is a functional block diagram of a television receiver according to this embodiment; FIG. FIG. 10 is a diagram showing the operation of overdrive correction; 4 is a flowchart showing the flow of processing according to the first embodiment; FIG. 4 is a diagram showing the brightness of each partial area of the display screen of the liquid crystal display device; 9 is a flowchart showing the flow of processing according to the second embodiment; FIG. 11 is a block diagram schematically showing an image signal processing circuit in a correction unit according to Embodiment 3; 1 is a diagram schematically showing first and second columns of pixels in a liquid crystal display device and two source lines arranged on both sides of the first column of pixels; FIG. FIG. 4 is a diagram schematically showing variations in source potential of a target pixel of a liquid crystal display device during one frame; (a) is a diagram showing an example of the source potential of a pixel when correction is not performed by a correction unit in the liquid crystal display device of Embodiment 1 of the present invention, and (b) is a liquid crystal display of Embodiment 1. FIG. FIG. 10C is a diagram showing an example of a correction value calculated by a correction unit in the device, and (c) shows an example of the source potential of a pixel when the source voltage is corrected by the correction unit in the liquid crystal display device of Embodiment 1; It is a diagram. (a) is a diagram schematically showing a change in the source potential in a liquid crystal display device in which a source voltage is applied by one-frame inversion from the previous frame to the next frame; FIG. 12A is a diagram schematically showing fluctuations in the source potential during the period from the current point to the next one frame in (a). FIG. 10 is a diagram showing an example of a case where a blanking period occurs in fluctuation of the source potential; FIG. 3 is a diagram showing input and output of video signals with varying frame rates;

An embodiment of the present invention will be described below with reference to FIGS. 1 to 12. FIG.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. In this embodiment, a configuration for controlling the degree of overdrive processing according to the frame rate of the video signal will be described.

(Configuration of television receiver 1)
FIG. 1 is a functional block diagram of a television receiver 1 according to this embodiment. As shown in FIG. 1 , the television receiver 1 includes a video processing device 10 , a television control section 14 and a display section 16 . The television receiver 1 is a device that displays video input from an external device such as the video output device 100 or television broadcasting via a tuner (not shown in FIG. 1).

The video processing device 10 is a device that corrects an acquired video signal to improve video quality, and includes a device control unit 11 . The device control unit 11 is a control device that controls the entire video processing device 10 and also functions as an acquisition unit 12 and a correction unit 13 . Acquisition unit 12 acquires a video signal from an external device such as video output device 100 . The correction unit 13 performs overdrive correction processing on the video signal acquired by the acquisition unit 12 . Note that the overdrive correction processing is realized by the correction unit 13 interfering with the screen display processing by the display unit 16 . Details of the overdrive correction will be described later.

The television control unit 14 is a control device that controls the entire television receiver 1 and also functions as a display control unit 15 . The display control unit 15 performs processing related to screen display processing of the display unit 16 . The display unit 16 is a display panel that displays moving images.

The video output device 100 is a device that supplies a video signal. The video signal may be generated by the video output device 100 . An example of the video output device 100 is a game machine.

It should be noted that each member included in the television receiver 1 is not limited to a single member, and may be configured to include a plurality of such members.

(Overdrive correction processing)
An example of the overdrive correction (overdrive driving) process, which is the premise of the present embodiment, will be described below with reference to FIG. 2, taking a liquid crystal display device having an overdrive correction function as an example.

Each diagram in FIG. 2 is a diagram showing the operation of overdrive correction. Overdrive correction is a technique for temporarily increasing the voltage applied to a liquid crystal element to shorten the time required for the liquid crystal element to reach a desired pixel voltage, that is, the time required for the color to develop a desired lightness.

Here, in each diagram of FIG. 2, the horizontal axis of the graph represents time (seconds). Further, the liquid crystal display device refreshes the screen every 1/60th of a second. In other words, the refresh rate of the liquid crystal display device is 60 Hz. A waveform composed of straight lines represents the output gradation, which is the voltage applied to the liquid crystal element, and a waveform including curved lines represents the liquid crystal response over time, that is, the degree of color development or luminance of the liquid crystal element.

FIG. 2A is a diagram showing the operation of overdrive correction when the frame rate of the video signal input to the liquid crystal display device does not fluctuate.

In the example shown in FIG. 2(a), the voltage applied to the liquid crystal element reaches the desired brightness after one frame, that is, 1/60 second after the start of voltage application. Applied voltages set to reach the desired pixel voltage of 100000000000000000000000000000000000000000. Note that the waveform including the dotted curve represents the liquid crystal response when no overdrive correction is used. When overdrive correction is not performed, a voltage corresponding to the value of B is applied to the liquid crystal element from the beginning.

FIG. 2B is a diagram showing the operation of overdrive correction when the video signal frame interval input to the liquid crystal display device is changed. In the example shown in FIG. 2(b), the time for applying the voltage corresponding to the value of C to the liquid crystal element is longer than in the case of FIG. 2(a). Therefore, the pixel voltage of the liquid crystal element temporarily becomes higher than the desired pixel voltage corresponding to the B value. That is, there is a possibility that the brightness of the liquid crystal element temporarily becomes higher than the desired value, and the image quality deteriorates.

FIG. 2(c) is a diagram showing the operation of the liquid crystal display device when the degree of overdrive correction processing in FIG. 2(b) is weakened. When the liquid crystal display device judges that the input video signal includes a video signal whose frame interval can fluctuate, the voltage applied to the liquid crystal element is changed to B, as shown in FIG. 2(c). In the range above the voltage corresponding to the value, it is controlled to be lowered by a preset amount. In other words, the liquid crystal display device weakens the degree of overdrive correction for the video signal. Alternatively, in the case described above, the liquid crystal display device may turn off the overdrive correction for the video signal.

According to the configuration shown in FIG. 2C, it is possible to suppress deterioration in image quality due to excessive brightness of some liquid crystals.

(Processing flow)
The flow of processing in this embodiment using the configuration of FIG. 1 will be described step by step with reference to FIGS. 1 to 3. FIG. FIG. 3 is a flow chart showing the flow of processing in this embodiment.

(S101)
In step S<b>101 , the acquisition unit 12 acquires a video signal from the video output device 100 .

(S102)
Subsequently, in step S102, the correction unit 13 determines whether the frame rate of the video signal acquired by the acquisition unit 12 in step S101 has changed from the previous determination in step S102. If the frame rate has changed, then the process of step S103 is executed, and if the frame rate has not changed, then the process of S104 is executed. It should be noted that when the process first transitions to this step, the process of step S104 is subsequently executed.

(S103)
In step S103, the correction unit 13 determines to weaken the degree of overdrive correction for the video signal, as described above with reference to FIG. 2(c). Alternatively, in this step, the correction unit 13 may determine to turn off the overdrive correction for the video signal.

(S104)
In step S104, the correction unit 13 determines to perform normal overdrive correction processing on the video signal.

(S105)
In step S105, the display control unit 15 displays an image indicated by the video signal acquired by the acquisition unit 12 in step S101. In displaying the image, the correction unit 13 performs overdrive correction according to the degree determined in step S103 or step S104.

The television receiver 1 repeats the processing from step S101 to step S105 described above until the user performs a predetermined end operation. The above is the flow of processing based on the flowchart of FIG.

[Embodiment 2]
A second embodiment of the present invention will be described below. In this embodiment, a configuration for controlling on/off of the dithering process according to the frame rate of the video signal will be described. For the sake of convenience, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and descriptions thereof are omitted.

(Configuration of television receiver 1)
The configuration shown in FIG. 1 is also used in this embodiment. However, the correction unit 13 according to the present embodiment has a function of performing dithering correction processing.

(Dithering correction processing)
Hereinafter, with reference to FIG. 4, a liquid crystal display device having a dithering correction function will be described as an example of dithering correction processing, which is a premise of the present embodiment, and uneven brightness that may occur on the display screen. .

Dithering is a technique for expressing intermediate colors by randomly mixing and arranging pixels of different colors. By performing dithering, for example, gradation can be expressed using only pixels of two colors.

However, in the dithered area, pixels with a small number of colors are arranged in a specific pattern. may stand out.

On the other hand, when the frame rate of the video signal input to the display device fluctuates, part of the screen may appear bright temporarily. An example of the above case will be described below using a simplified model.

FIG. 4 is a diagram showing the brightness of each partial area of the display screen of the liquid crystal display device. Each graph in FIGS. 4A and 4B corresponds to display areas I to IV in order from the top, and the horizontal axis of the graph represents time (seconds). Further, although the refresh rate of the liquid crystal display device is usually 60 Hz, scanning can be performed at timing according to the frame rate of the input video signal. Further, predetermined corrections are sequentially applied to the partial areas I to IV of the display screen. Here, it is assumed that the luminance value of the partial area increases from 512 to 513 while the correction is being performed.

FIG. 4A is a diagram showing the brightness of each partial area of the display screen when the frame rate does not fluctuate. For example, the display area I has a luminance value of 513 in the first frame and a luminance value of 512 in the other three frames. As a result, the cumulative value of luminance values for four frames is 2,049. In the other partial regions II to IV, the luminance value is 513 for any one frame, and the luminance value is 512 for the other three frames. becomes.

Further, in the first frame, the luminance value of the partial area I is 513, and the luminance values of the other partial areas II to IV are 512, so the total luminance value of the entire screen is 2,049. In the 2nd to 4th frames, the luminance value of one of the partial areas is 513 and the luminance value of the other partial area is 512, so the cumulative luminance value of the entire screen is 2,049. Since the screen switching of each frame is performed at high speed, it seems that there is usually no bias in brightness between the partial regions in the four frames described above.

FIG. 4B is a diagram showing the brightness of each partial area of the display screen when the frame rate fluctuates. In the example shown in FIG. 4B as well, in each frame, the luminance value of one of the partial regions is 513 and the luminance value of the other partial region is 512, so the cumulative luminance value of the entire screen is , 2049.

On the other hand, the display area I has a luminance value of 513 for a longer period of time than in the case shown in FIG. 4(a). Therefore, the accumulated luminance value of the display area I in the four frames exceeds 2049, which is higher than the accumulated luminance values of the other display areas II to IV. In the display area II, the time during which the luminance value is 513 is shorter than in the case shown in FIG. 4(a). Therefore, the accumulated luminance value of the display area II in the four frames is less than 2049, which is lower than the accumulated luminance values of the other display areas I, III, and IV.

As a result, in the four frames described above, only the display area I appears to have a higher brightness than the other display areas II to IV, and the dithering pattern may stand out.

When the liquid crystal display device determines that an input video signal includes a video signal whose frame interval may fluctuate, the liquid crystal display device suppresses deterioration in video quality by turning off dithering correction for the video signal. be able to.

(Processing flow)
The flow of processing in this embodiment using the configuration of FIG. 1 will be described step by step with reference to FIGS. 1 and 5. FIG. FIG. 5 is a flow chart showing the flow of processing in this embodiment.

(S101, S102)
In steps S101 and S102, the same processing as in the first embodiment is performed. If the frame rate of the video signal acquired by the acquisition unit 12 in step S101 has changed from the previous determination in step S102, then the process of step S203 is executed. Processing is performed. It should be noted that when the process first transitions to this step, the process of step S204 is subsequently executed.

(S203)
Subsequently, in step S203, the correction unit 13 turns off the dithering correction for the input video signal.

(S204)
In step S204, the correction unit 13 applies dithering correction to the video signal.

(S205)
In step S205, the display control unit 15 displays an image indicated by the video signal acquired by the acquisition unit 12 in step S101.

The television receiver 1 repeats the processing from step S101 to step S205 described above until the user performs a predetermined end operation. The above is the flow of processing based on the flowchart of FIG.

[Embodiment 3]
A third embodiment of the present invention will be described below. In this embodiment, a configuration for controlling ON/OFF of shadow correction according to the frame rate of the video signal will be described. For the sake of convenience, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and descriptions thereof are omitted.

(Configuration of television receiver 1)
The configuration shown in FIG. 1 is also used in this embodiment. However, the correction unit 13 according to the present embodiment has the configuration shown in FIG. 6 and the function of performing shadow correction processing.

FIG. 6 is a block diagram schematically showing an image signal processing circuit in the correction section 13 according to this embodiment. The correction unit 13 includes an input unit 31, a gradation voltage conversion unit 32, a vertical voltage integration unit 33, a reference voltage integration unit 34, an addition/subtraction unit 35, a coefficient multiplication unit 36, a correction value calculation unit 37, a correction value addition unit 38, and an output Including part 39 .

Further, the television receiver 1 according to the present embodiment performs screen display by a frame inversion driving method in which the polarity of the voltage applied to the liquid crystal element is inverted for each frame.

(Outline of display control)
Hereinafter, with reference to FIGS. 6 to 10, the processing of shadow correction that is the premise of the present embodiment and the method of calculating parameters used for shadow correction will be described for each item, taking a liquid crystal display device having a shadow correction function as an example. to explain. The liquid crystal device includes a correction section 13, like the television receiver 1 according to the present embodiment.

The correction unit 13 calculates the correction value of the source potential of the target pixel 20 using the amount of displacement of the source potential of the target pixel 20 in the next one frame (the amount of displacement for the next one frame). Except for the calculation of the displacement amount of the source voltage of the target pixel, calculation of the correction value of the source voltage applied to the target pixel by the correction unit 13 is performed by a known method such as that described in Patent Document 2, for example. can be done by

First, image data of an image to be displayed on the liquid crystal display device is input to the input unit 31 . The input unit 31 outputs the image data to the subsequent gradation voltage conversion unit 32 .

The gradation voltage conversion section 32 converts image data (input gradation) input from the input section 31 into a source voltage. For example, the gradation voltage conversion unit 32 converts the input gradation by using a LUT (lookup table) in which voltages lower than the common electrode potential (Vcom) are used as a reference and voltages higher than the Vcom are set as negative values and positive voltages higher than the common electrode potential. Convert to source voltage. The gradation voltage conversion section 32 outputs the source voltage to the vertical voltage integration section 33 and the reference voltage integration section 34 in the latter stage.

Operations of the vertical voltage integrator 33, the reference voltage integrator 34, and the addition/subtraction unit 35 subsequent thereto will be described later. From these, the amount of displacement of the source potential of the target pixel 20 in the next one frame is obtained. The addition/subtraction unit 35 outputs the displacement amount to the subsequent coefficient multiplication unit 36 .

The coefficient multiplication unit 36 multiplies the displacement amount by a coefficient, and outputs the displacement amount multiplied by the coefficient to the correction value calculation unit 37 in the subsequent stage. The coefficient is, for example, the ratio (Csou1/ΣC) of the parasitic capacitance (Csou1) due to the source line S1 in the pixel 20 to the total capacitance (ΣC) of the pixel 20 .

The correction value calculation unit 37 calculates a correction value (correction gradation) from the displacement amount obtained by the coefficient multiplication unit 36 and the gradation of the pixel 20, and outputs the correction value to the correction value addition unit 38 in the subsequent stage.

The correction value addition unit 38 adds the correction value (correction gradation) from the correction value calculation unit 37 to the gradation of the display image. In this way, the correction value adding section 38 calculates the corrected output gradation and outputs it to the output section 39 .

The correction value calculated by the correction value calculator 37 can be either a positive number or a negative number. For example, when the source potential of the pixel 20 deviates in the direction of making the pixel 20 brighter, the correction value becomes a negative number. be a number.

The output unit 39 sends the corrected output gradation from the correction value adding unit 38 to the source driver.

(Calculation method of displacement amount)
Next, a method of calculating the displacement amount of the source potential of the target pixel, which is performed by the correction unit 13, will be described. The displacement amount is calculated by the vertical voltage integrating section 33, the reference voltage integrating section 34, and the addition/subtraction section 35 in the latter stage thereof.

The correction unit 13 calculates the amount of displacement of the source potential of the target pixel 20 in the next one frame (the amount of displacement for the next one frame) in the target pixel 20 when the write timing of the target pixel 20 is set as the starting point. is calculated by referring to the integrated value of the source potential of the previous frame.

The time required for vertical scanning for one frame is, for example, a very short time of 1/60 second when the frame rate is 60 frames per second. Therefore, in both moving images and still images, the source potential in a certain frame is a good approximation of the source potential in the previous frame. Therefore, in obtaining the displacement amount, for example, it is practically possible to replace the integrated value for the next one frame with respect to the current time with the integrated value for the previous one frame. In this way, by referring to the most recent actual integrated amount of the source potential for one frame, the integrated value for the next one frame can be obtained without a large amount of processing for actually calculating it. It can be obtained by simple processing.

The method of using the integral value for obtaining the displacement amount can be appropriately determined within the range in which the displacement amount can be obtained. For example, the correction unit 13 calculates the amount of displacement of the source potential of the target pixel 20 for the next one frame from the difference between the two integrated values. The first integrated value is the integrated value of the actual source potential of the target pixel 20 in the past one-frame period starting from the writing timing of the target pixel 20 . The second integrated value is a value obtained by integrating the source potential for a period of one frame when the writing timing of the target pixel 20 is set as a starting point.

Next, how to obtain the first and second integrated values will be described. FIG. 7 is a diagram schematically showing first and second columns of pixels in a liquid crystal display device and two source lines arranged on both sides of the first column of pixels. FIG. 7 shows, as an example, pixels 20 on the first column in a liquid crystal display device having 4320 rows of pixels, and two source lines S1 and S2 to be connected to gate lines in the pixels 20 . Also, FIG. 8 is a diagram schematically showing fluctuations of the source potential of the target pixel of the liquid crystal display device during one frame. In FIG. 8, Vs represents the source potential and Vcom represents the potential of the common electrode. In FIG. 8, the polarity (sign) of the source potential Vs above Vcom is + (plus), and the polarity (sign) of the source potential Vs below Vcom is − (minus).

In the column of pixels 20, the source voltage is sequentially applied from the source driver to the pixels 20 on the first row, which is the first row, to the pixels 20 on the last row, which is the 4320th row, within one vertical scanning period. A period required for applying the source voltage once to all the pixels 20 belonging to a certain column is called one frame or one vertical scanning period. Assume that the source potential is currently written to the pixel 20 in the n-th row (1≦n≦4320) of the f frame.

The first integrated value is, as described above, the integrated value of the source potential in the pixel 20 to which the source voltage was actually applied during the past one frame period. The first integrated value is the integrated value of the source potential Vs1 in the pixel 20 from the n-th row to the 4320th row in the f−1 frame, and the integrated value from the 1st row to the n-th row in the f frame. is the sum of

The second integrated value is, as described above, a value obtained by integrating the source potential with the writing timing of the target pixel 20 as a starting point for a period of one frame. The second integrated value is the integrated value of the source potential Vs1(f, n) in the n-th row pixel 20 in the f-frame from the n-th row to the 4320th row in the f-frame, and the one row in the f+1 frame. It is the sum of the integrated values from the th row to the nth row.

Then, the amount of displacement of the source potential of the target pixel 20, that is, the amount of displacement of the source potential of the pixel 20 in the n-th row in the f+1 frame is, as described above, the first integral value and the second integral value calculated by the difference between The amount of displacement in the n-th pixel 20 in the f frame is represented by the following formula (1), and is represented by the area of the hatched portion Δc in FIG. The amount of displacement in the n-th row pixel 20 in the f+1 frame is represented by the following formula (2), and is represented by the area of the hatched portion Δd in FIG. Therefore, the displacement amount (ΔVs1(f+1, n)) of the potential of the target pixel 20 is obtained by Equation (3).

Typically, the vertical voltage integrator 33 obtains the integrated value of the source potential in the pixels to which the source voltage is actually applied for the desired period of one frame. Further, the reference voltage accumulator 34 obtains the integrated value of the reference source potential for the above period. Then, the addition/subtraction unit 35 performs calculation processing on these integrated values as necessary, and obtains the difference between the integrated values.

The amount of displacement of the source potential of the target pixel 20 is obtained by obtaining the difference in the integral value for each frame and then adding the difference in each frame, as shown in the above formulas (1) to (3). may be calculated by Alternatively, the amount of displacement may be calculated by calculating respective integrated values in a period of one frame and then adjusting them.

Further, the displacement amount of the source potential of the target pixel 20 is the difference obtained by subtracting the reference source potential (Vs1(f, n) in the above formula) from the actual source potential (Vs1(k) in the above formula). It may be calculated by calculating for each pixel 20 and integrating the difference for one frame. In this case, the correction unit 13 may have an appropriate configuration for calculating the integrated value of the difference instead of the vertical voltage integration unit 33, the reference voltage integration unit 34, and the addition/subtraction unit 35. FIG. For example, in the above case, the correction unit 13 may have a subtraction unit that obtains the difference for each pixel 20 and an integration unit that integrates the obtained difference for one frame.

(Effect of correction)
(a) of FIG. 9 is a diagram showing an example of the source potential of a pixel when correction is not performed by the correction unit 13 in the liquid crystal display device. (b) of FIG. 9 is a diagram showing an example of correction values calculated by the correction unit 13 in the liquid crystal display device. (c) of FIG. 9 is a diagram showing an example of the source potential of a pixel when the source voltage is corrected by the correction unit 13 in the liquid crystal display device.

In the case where the correcting unit 13 does not correct the applied value of the source voltage, the amount of change in the source voltage applied to the pixel 20 due to polarity reversal may increase. Therefore, as shown in FIG. 9(a), the source potential of the pixel 20 without correction may gradually decrease toward the end of one frame.

As described above, the correction unit 13 uses the difference between the integrated value of the source potential of the target pixel 20 for the past one frame and the integrated value of the source potential of the target pixel 20 for one frame to can be calculated. More specifically, the correcting unit 13 calculates the actual amount of displacement of the source potential of the pixel 20 from the reference potential (Vs(f, n)) over the past one frame from the difference between the integrated values, and calculates the amount of displacement. The correction value is calculated based on the amount. For example, when the source potential gradually decreases during one frame as described above, the correction unit 13 corrects the applied value of the source voltage that gradually increases during one frame as shown in FIG. Calculate as a value.

By applying the source voltage corrected in this way to the pixels 20 from the source line S1, the gradual decrease in the source potential due to polarity reversal during one frame is canceled. As a result, the desired source potential substantially the same as the reference potential is achieved, as shown in FIG. 9(c).

As described above, the correction unit 13 calculates the displacement amount of the source potential of the target pixel 20 for calculating the correction value of the source voltage applied to the target pixel 20 from the difference of the integrated values. The difference between the integrated values is the integrated value of the source potential of the target pixel 20 for the past one frame and the source potential of the target pixel 20 for one frame when the writing timing of the target pixel 20 is taken as a starting point. is the difference from the integrated value of Therefore, the source potential, which unintentionally fluctuates between frames, can be maintained at a desired potential, as in the case where the source potential drops during one frame.

(Supplementary information on source potential)
Hereinafter, the displacement amount of the pixels 20 in a predetermined column (eg, the first column) is calculated by summing this displacement amount and the displacement amount of the pixels 20 connected to the adjacent source line (eg, the second column). I will explain the case where it is requested.

For example, the amount of displacement of the source potential of the source line S1 shown in FIG. 7 in the next frame is obtained by the method described above. The amount of displacement of the source potential of the source line S2 is, for example, the amount of displacement of the source potential of the pixels 20 on the n-th row next to the pixels 20 on the first column, that is, the pixels 20 on the second column in the next frame. is. This displacement amount is obtained in the same manner as for the source line S1 except that the target pixel 20 and the source line are different. That is, the displacement amount of the source voltage in the source line S2 is expressed by an equation obtained by replacing "s1" in the above equations (1) to (3) with "s2".

In this way, the amount of displacement of the source potential of the target pixel 20 (row n, column m) in the next one frame is the amount of displacement of the source potential of the pixel 20 of row n, column m due to the source line Sm, , and the amount of displacement of the source potential due to the source line Sm+1 of the pixel 20 of the m+1 column. Here, both m and n are positive integers. Therefore, assuming that the amount of displacement to be obtained is "ΔV1(n)", the amount of displacement can be obtained by the following equation (4).

Typically, the vertical voltage integrator 33 obtains the integrated value of the source potential for each of the two adjacent pixels 20 during the desired period of one frame. Further, the reference voltage integrating section 34 obtains an integrated value of the reference source potential in each of the two adjacent pixels 20 during the above period. Then, the addition/subtraction unit 35 obtains the difference between the integrated values. The addition/subtraction unit 35 appropriately applies calculation processing to the integrated value as necessary.

Thus, the potential displacement amount of the target pixel 20 is the sum of the first displacement amount and the second displacement amount. The first displacement amount is the difference between the integrated values when the source line S1 arranged on one side of the pixel 20 is used as the source line of the target pixel 20 (for example, m-th column). The second amount of displacement is the difference between integrated values when the source line S2 arranged on the other side of the target pixel 20 is used as the source line for the target pixel 20 (for example, column m+1).

According to the above configuration, the amount of displacement of the source potential of the target pixel due to the influence of the source line that is adjacent to the pixel in the single source line structure but is not electrically connected, such as parasitic capacitance, is further reduced. precision is required. Therefore, the correction unit 13 can calculate a more precise correction value. Therefore, it is more effective from the viewpoint of displaying the desired high-definition image even in the latter half of one frame (lower part of the screen).

(Frame inversion drive)
Hereinafter, the above system will be described assuming that the liquid crystal display device operates according to the frame inversion driving system.

(a) of FIG. 10 is a diagram schematically showing the fluctuation of the source potential in the liquid crystal display device in which the source voltage is applied by one-frame inversion during the period from the previous frame to the next frame. (b) of FIG. 10 is a diagram schematically showing fluctuations in the source potential during the period from the current point to the next one frame in (a) of FIG. 10 . The currently written pixel 20 is the n-th pixel in the f frame. Here, the time required for vertical scanning for one frame is, for example, a very short time of 1/60 seconds when the frame rate is 60 frames per second. Therefore, in both a moving image and a still image, the source potential in the frame (f) one frame before is a good approximation of the source potential in the previous frame (f-1).

The integrated value σa of the source potential in the previous frame (f−1 frame) is expressed by Equation (5). Further, the integrated value σb of the source potential up to the current pixel in the current frame (f frame) is expressed by Equation (6). Then, the integrated value σ0 for one frame of the current source potential Vn in the pixel 20 of the n-th column is expressed by Equation (7).

Δc shown in (b) of FIG. 10 is an integrated value of the amount of displacement with respect to the current source potential Vn of the n-th pixel in the source potential after the current time in the current frame. .DELTA.c is obtained by subtracting the integrated value of Vn of the pixels in the n and subsequent columns from .sigma.c. Since the source potential of the previous frame (f-1 frame) is a good approximation of the source potential of the current frame (f frame), from (a) of FIG. is subtracted. Therefore, Δc is represented by Equation (8).

The absolute value of Δd can be obtained from (b) of FIG. 10 by subtracting the integrated value σb of the actually applied source potential from the integrated value of the source potential Vn of the n-th pixel in the f+1 frame.

Here, the sign of the integrated value is appropriately adjusted according to the difference in the polarity of the source potential between frames. For example, σa is the value of f−1 frames and the polarity of the source potential is opposite to the polarity of the source potential in f frames. Therefore, in Equation (8), the sign of σa is inverted. As for Δd, the polarity is reversed in the f+1 frame with respect to the f frame. Therefore, for Δd, the sign of the integrated value of the actual source potential is reversed. Therefore, Δd is represented by Equation (9).

The displacement amount of the source potential in the n-th row pixel 20 in the current frame (f+1 frame) is obtained from the sum of Δc and Δd. Therefore, the displacement amount of the source potential in the pixel 20 of the n-th row in the current frame can be obtained from equation (10).

The amount of displacement of the integrated value of the source potential can be calculated by the vertical voltage integrating section 33, the reference voltage integrating section 34, and the addition/subtraction section 35 described above. For example, the vertical voltage integrator 33 calculates σa, σb and their difference based on the past actual integrated value of the source potential. The reference voltage integrator 34 calculates an integrated value ((4320−n)×Vn) in the f frame of the source potential Vn in the n-th pixel of the f frame. Then, the addition/subtraction unit 35 performs sign reversal processing by inverting the polarity of the values calculated by the two integrating units as necessary, calculates Δc and Δd of the equations (8) and (9), and calculates their values. Calculate the sum.

Alternatively, the calculation of the displacement amount can be performed by the correction unit 13 including other components as necessary. For example, the calculation of the displacement amount can be performed by the correction section 13 further including a sign inverting section that changes the sign of the source potential by reversing the polarity of the source potential. The sign inverting section is provided, for example, between the vertical voltage accumulating section 33 and the reference voltage accumulating section 34 and the addition/subtraction section 35, and changes the positive and negative signs of the calculated values of both accumulating sections as necessary.

In this manner, when the polarity of the source potential is reversed between consecutive frames, the correction unit 13 reverses the sign of the integrated value according to the polarity reversal. Therefore, the liquid crystal display device is configured to apply a source voltage whose polarity is reversed for each frame to the source line. Then, the correction unit 13 calculates the amount of displacement of the source potential of the target pixel 20 by replacing the integrated value of the source potential of the previous frame with the integrated value of the source potential of the current frame. This is much more effective from the viewpoint of obtaining the displacement amount more easily.

(Blanking period)
With reference to FIG. 11, it will be described that an error occurs in the parameter Δ described above when the frame rate of the video signal input to the liquid crystal display device fluctuates.

FIG. 11 is a diagram showing an example in which a blanking period occurs in the variation of the source potential shown in FIG. 10(b).

In the example shown in FIG. 11, there is a blanking period during which no voltage is applied to the liquid crystal element for updating the display screen due to the difference between the refresh rate of the liquid crystal display device and the frame rate of the input video signal. . An error occurs in the value of the parameter Δ due to the voltage Vcom during the blanking period being included in the calculation of Δc. Therefore, the shadow correction performed using the parameter Δ containing the error may further deteriorate the image quality of the display screen.

When the liquid crystal display device determines that an input video signal includes a video signal whose frame interval may fluctuate, the liquid crystal display device suppresses degradation in video quality by turning off shadow correction for the video signal. can be done.

(Processing flow)
The process flow described with reference to FIG. 5 in the second embodiment can also be applied to this embodiment by replacing the dithering process with shadow correction.

As described above in Embodiments 1 to 3, the video processing device 10 includes the acquiring unit 12 and the correcting unit 13. The acquiring unit 12 acquires a video signal, and the correcting unit 13 determines whether or not the video signal acquired by the acquisition unit 12 includes a video signal whose frame interval can vary, and if it is determined that the video signal whose frame interval can vary is included, The degree of correction for the video signal acquired by the acquisition unit 12 is weakened, or the correction for the video signal acquired by the acquisition unit 12 is turned off.

According to the above configuration, it is possible to suppress deterioration in image quality when a conventional image technique for a fixed frame rate is used for an image of a variable frame rate.

Further, the correction processing applied by the correction unit 13 may include at least one of overdrive, dithering, and shadow correction.

According to the above configuration, in the case where each of the correction processes described above is applied to the input video signal, deterioration in video quality when the frame rate of the video signal fluctuates can be suppressed.

[Embodiment 4]
A fourth embodiment of the present invention will be described below. In this embodiment, a configuration that can be applied to the above-described first to third embodiments and in which the video processing apparatus 10 detects variations in the frame rate of an input video signal will be described. For the sake of convenience, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and descriptions thereof are omitted.

(Configuration of television receiver 1)
The configuration shown in FIG. 1 is also used in this embodiment. However, when using the first output method described later, the video processing device 10 further includes a frame memory for storing moving images.

(Processing flow)
The flow of processing in this embodiment will be described with reference to FIG. FIG. 12 is a diagram showing input and output of a video signal whose frame rate fluctuates. 12(a) is a diagram showing a video signal input to the video processing device 10. FIG. As shown in FIG. 12(a), the video signal fluctuates from 60 Hz to 30 Hz, and further fluctuates to 60 Hz after three frames. FIG. 12(b) is a diagram showing a first output method of the input video signal. FIG. 12(c) is a diagram showing a second output method of the input video signal. In the examples shown in FIGS. 12(b) and 12(c), it is assumed that the initially output video signal with a frame rate of 60 Hz is subjected to any correction process by the correction unit 13 as needed.

First, the above-described first output method will be described with reference to FIG. 12(b). In the first output method, the video signal output from the video processing device 10 is delayed by one frame using a frame memory that stores moving images. Specifically, the acquisition unit 12 stores the acquired video signal in a frame memory, and then the correction unit 13 determines whether the frame rate has changed for each frame of the video signal. When detecting that the frame rate of the video signal has changed to 30 Hz, the correction unit 13 turns off the degree of correction processing described above in the first to third embodiments, or weakens it if possible.

Note that the correcting unit 13 detects a signal for synchronizing with the refresh rate of the display screen in the input video signal, for example, in the cycle in which the frame of the video signal of 60 Hz is input. It may be determined that there has been a change. Further, when detecting that the frame rate of the video signal has changed again to 60 Hz, the correction unit 13 may perform the original correction processing again.

According to the first output method, as indicated by the arrow in FIG. 12(b), it is possible to accurately apply changes in correction processing to frames having a frame rate different from the refresh rate of the video processing device 10. FIG.

Next, the above-described second output method will be described with reference to FIG. 12(c). In the second output method, when outputting a frame, it is determined whether or not the frame rate has changed from the previous frame. When detecting a change in the frame rate, the correction unit 13 turns off the degree of correction processing described above in the first to third embodiments, or weakens it if possible, for the next and subsequent frames. Further, when detecting that the frame rate of the video signal has changed again to 60 Hz, the correction unit 13 may perform the original correction processing again.

Since the second output method does not use a frame memory, as shown in FIG. 12(c), the timing of detecting a change in frame rate is delayed by half a frame compared to the first output method. However, there is an advantage that no frame memory is required and the delay of the output video signal is less than at least the first output method.

As described above, the correction unit 13 may refer to the video signal acquired by the acquisition unit 12 and detect a change in frame interval in the video signal acquired by the acquisition unit 12 . According to the above configuration, it is possible to realize the video processing device 10 that can detect variations in the frame interval by referring to the video signal.

[Modification 1]
When determining whether or not the video signal acquired by the acquisition unit 12 includes a video signal whose frame interval may vary, the correction unit 13 corrects the metadata included in the video signal, or the video signal may be configured to refer to a video signal acquired along with .

For example, when the video signal is transmitted in compliance with the HDMI standard, an identifier indicating whether or not the frame interval can vary is included in InfoFrame in the metadata, and the correction unit 13 refers to the identifier. , it is possible to determine whether or not a video signal whose frame interval can fluctuate is included.

In this way, the correction unit 13 refers to the metadata included in the video signal acquired by the acquisition unit 12 or the control signal acquired accompanying the video signal, and corrects the video signal acquired by the acquisition unit 12. Alternatively, it may be determined whether or not a video signal whose frame interval may vary is included.

This modification may or may not be used in combination with the determination processing described in the fourth embodiment. When combined with the determination processing described in Embodiment 4, for example, by referring to the metadata or control signal, when it is determined that a video signal whose frame interval may vary is included, the degree of correction processing is weakened, and furthermore, when a change in the frame interval is detected by the determination processing described in the fourth embodiment, the degree of correction processing can be further weakened or set to 0.

According to the above configuration, it is possible to realize the video processing device 10 that can detect variations in the frame interval by referring to the metadata or the control signal.

[Modification 2]
The video processing device 10 according to Modification 2 additionally includes a user operation reception unit that receives a user operation for setting the degree of correction processing by the correction unit 13 . In the above configuration, the degree of correction processing by the correction unit 13 can be arbitrarily set by the user, for example, by switching to strong, medium, weak, or off via the user operation reception unit. good.

As described above, the image processing apparatus 10 includes the acquisition unit 12, the correction unit 13, and the user operation reception unit. receives a user operation regarding the degree of correction by the correcting unit 13, the correcting unit 13 performs correction processing on the video signal acquired by the acquiring unit 12 with the degree of correction indicated by the user operation, and the correcting unit 13 correction processing includes at least one of overdrive, dithering, and shadow correction.

According to the above configuration, it is possible to realize the video processing device 10 that performs each of the correction processes described above in accordance with the degree of correction indicated by the user's operation.

[Modification 3]
The video processing device 10 may control the degree of correction processing according to the type of content indicated by the input video signal. For example, in the case of content with a lot of movement on the display screen, such as an action game or a shooting game, it is determined that the image processing load such as GPU calculation in the image output device 100 is large, and the frame rate drops. Correction processing may be turned off or attenuated if possible. In other words, the video processing device 10 may determine whether or not the video signal includes a video signal whose frame interval may vary depending on the type of content.

Note that the content type determination method is not limited to a specific method. For example, the video processing device 10 may separately acquire information indicating the type of content from the video output device 100, or may estimate the type of content from the amount of color change in the video indicated by the input video signal. good too.

As described above, the correction unit 13 determines whether or not the video signal acquired by the acquisition unit 12 includes a video signal whose frame interval may vary, depending on the type of content indicated by the video signal. may According to the above configuration, it is possible to realize the video processing device 10 that determines a change in the frame interval according to the type of content.

This modification may or may not be used in combination with the determination processing described in the fourth embodiment. When combined with the determination processing described in Embodiment 4, for example, the content indicated by the input video signal is content with a lot of movement on the display screen, and the video signal includes a video signal whose frame interval may vary. When it is determined, the degree of correction processing is weakened, and further, when a change in the frame interval is detected by the determination processing described in Embodiment 4, the degree of correction processing is further weakened or set to 0. control can also be performed.

Note that the above-described embodiments and modifications may be implemented in combination with other embodiments or modifications.

[Example of realization by software]
The control blocks (especially the acquisition unit 12 and the correction unit 13) of the video processing device 10 may be implemented by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be implemented by software. good.

In the latter case, the video processing device has a computer that executes instructions of a program, which is software that implements each function. This computer includes, for example, at least one processor (control device) and at least one computer-readable recording medium storing the program. In the computer, the processor reads the program from the recording medium and executes it, thereby achieving the object of the present invention. As the processor, for example, a CPU (Central Processing Unit) can be used. As the recording medium, a "non-temporary tangible medium" such as a ROM (Read Only Memory), a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. In addition, a RAM (Random Access Memory) for developing the above program may be further provided. Also, the program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. Note that one aspect of the present invention can also be implemented in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

〔summary〕
A video processing device according to aspect 1 of the present invention is a video processing device comprising an acquiring unit and a correcting unit, wherein the acquiring unit acquires the video signal, and the correcting unit acquires the video signal obtained by the acquiring unit. Determining whether the video signal includes a video signal whose frame interval can vary, and determining that the video signal includes a video signal whose frame interval can vary, the video signal obtained by the obtaining unit is weakened, or the correction for the video signal acquired by the acquisition unit is turned off. According to the above configuration, it is possible to suppress deterioration in image quality when a conventional image technique for a fixed frame rate is used for an image of a variable frame rate.

In the video processing device according to aspect 2 of the present invention, in aspect 1 above, the correcting unit refers to the video signal acquired by the acquiring unit, and adjusts the frame interval fluctuation in the video signal acquired by the acquiring unit. It is good also as a structure which detects. According to the above configuration, it is possible to realize the video processing device 10 that can detect variations in the frame interval by referring to the video signal.

In the video processing device according to aspect 3 of the present invention, in aspect 1 or 2 above, the correcting unit acquires metadata included in the video signal acquired by the acquiring unit or accompanying the video signal. The control signal may be referenced to determine whether or not the video signal acquired by the acquisition unit includes a video signal whose frame interval may vary. According to the above configuration, it is possible to realize the video processing device 10 that can detect variations in the frame interval by referring to the metadata or the control signal.

In the video processing device according to aspect 4 of the present invention, in any one of aspects 1 to 3, the correcting unit, in accordance with the type of content indicated by the video signal, adds to the video signal acquired by the acquiring unit: A configuration may be adopted in which it is determined whether or not a video signal whose frame interval is variable is included. According to the above configuration, it is possible to realize the video processing device 10 that determines a change in the frame interval according to the type of content.

In the video processing device according to aspect 5 of the present invention, in any one of aspects 1 to 4, the correction processing applied by the correction unit includes at least one of overdrive, dithering, and shadow correction. It may be configured to be According to the above configuration, in the case where each of the correction processes described above is applied to the input video signal, deterioration in video quality when the frame rate of the video signal fluctuates can be suppressed.

A video processing device according to aspect 6 of the present invention is a video processing device comprising an acquisition unit, a correction unit, and a user operation reception unit, wherein the acquisition unit acquires a video signal, and the user operation reception unit receives a user operation regarding the degree of correction by the correction unit, the correction unit performs correction processing on the video signal acquired by the acquisition unit, with the degree of correction indicated by the user operation, and the correction unit performs The correction processing includes at least one of overdrive, dithering, and shadow correction. According to the above configuration, it is possible to realize the video processing device 10 that performs each of the correction processes described above in accordance with the degree of correction indicated by the user's operation.

A video processing method according to aspect 7 of the present invention is a video processing method by an apparatus, comprising: an acquiring step of acquiring a video signal; If it is determined that a video signal whose frame interval can fluctuate is included, weaken the degree of correction for the video signal acquired in the acquisition step, or in the acquisition step and a correction step of turning off the correction to the acquired video signal. According to the above method, it is possible to suppress deterioration in image quality when a conventional image technology for a fixed frame rate is used for an image of a variable frame rate.

A television receiver characterized by comprising the video processing device according to aspect 8 of the present invention may be configured to comprise the video processing device according to any one of aspects 1 to 6 above. According to the above configuration, the television receiver 1 having the same effect as the video processing device 10 can be realized.

A control program according to aspect 9 of the present invention is a control program for causing a computer to function as the video processing device 10 according to any one of aspects 1 to 6 above, wherein the computer includes an acquisition unit 12 and a correction unit. 13 may be used.

A recording medium according to the tenth aspect of the present invention may be a computer-readable recording medium recording the control program according to the ninth aspect.

The video processing device according to each aspect of the present invention may be realized by a computer. In this case, the computer is operated as each part (software element) included in the video processing device, thereby converting the video processing device to the computer. A control program for a video processing device realized by a computer and a computer-readable recording medium recording it are also included in the scope of the present invention.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

1 TV receiver 10 Video processing device 11 Device control unit 12 Acquisition unit 13 Correction unit 14 TV control unit 15 Display control unit 16 Display unit 20 Pixel 31 Input unit 32 Gradation voltage conversion unit 33 Vertical voltage integration unit 34 Reference voltage integration Unit 35 Adder/subtracter 36 Coefficient multiplier 37 Correction value calculator 38 Correction value adder 39 Output unit 100 Video output device

Claims (9)

A video processing device comprising an acquisition unit and a correction unit,
The acquisition unit acquires a video signal,
The corrector is
determining whether the video signal obtained by the obtaining unit is a video signal with a variable frame rate;
When it is determined that the above variable frame rate video signal has been acquired,
For overdrive correction, which temporarily increases the applied voltage when starting to apply the voltage and shortens the time until the desired pixel voltage is reached,
When the frame interval of the variable frame rate is longer than the frame interval of the fixed frame, the video processing is characterized in that the applied voltage is controlled to be lower than the applied voltage applied when the video signal of the fixed frame rate is acquired. Device. The corrector is
The applied voltage at the start of voltage application is set to be lower than the applied voltage set so that the desired brightness is reached one frame after the start of voltage application when a video signal at a fixed frame rate is acquired. 2. The video processing apparatus according to claim 1, wherein the control is performed so as to The corrector is
2. The method according to claim 1, wherein, when a signal for synchronizing with a refresh rate of a display screen cannot be detected in the video signal input from the acquisition unit, it is determined that the video signal of the variable frame rate has been received. 1. The video processing device according to 1. The corrector is
4. The video processing apparatus according to claim 1, wherein dithering correction for expressing intermediate colors by mixing and arranging pixels of different colors is turned off. The corrector is
The source voltage is corrected with a correction value calculated by referring to the integrated value of the source potential of the target pixel for the past one frame, and the source potential that fluctuates unintentionally between one frame is maintained at the desired potential. 4. The video processing apparatus according to claim 1, wherein shard correction is turned off. A video processing method by a device,
an acquisition step of acquiring a video signal;
determining whether the video signal obtained in the obtaining step is a variable frame rate video signal;
When it is determined that the above variable frame rate video signal has been acquired,
For overdrive correction, which temporarily increases the applied voltage when starting to apply the voltage and shortens the time until the desired pixel voltage is reached,
and a correction step of controlling the applied voltage to be lower than the applied voltage applied when the fixed frame rate video signal is acquired when the frame interval of the variable frame rate is longer than the frame interval of the fixed frame. An image processing method characterized by: A television receiver comprising the video processing device according to any one of claims 1 to 5 . A control program for causing a computer to function as the image processing apparatus according to any one of claims 1 to 5 , the control program for causing the computer to function as the acquisition section and the correction section. A computer-readable recording medium recording the control program according to claim 8 .

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