JP2017111288A - Display control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which a luminance switch timing of a backlight and a video image switch timing do not always match, and an amount of luminance change upon switching cannot be followed by a human eye, and is visually recognized as a flicker.SOLUTION: A display control device comprises: a color brightness calculation unit that calculates color brightness of video image data on a video image source; a color brightness prediction unit that predicts video image data on a post-switched second video image source, and calculates color brightness of video image data after switched; an offset time calculation unit that calculates a first offset time prior to a switch timing, and a second offset time after the switch timing on the basis of backlight luminance, switch timing, color brightness of video image data on a first video image source, and color brightness of second video image data; and a backlight luminance change unit that starts a change of the backlight luminance before the first offset time further than the switch timing, and changes the backlight luminance after the second offset time further than the switch timing.SELECTED DRAWING: Figure 1

Description

The present invention relates to a display control apparatus capable of switching a plurality of video sources by car navigation or the like.

Some conventional display control devices change the backlight luminance when switching video sources (for example, Patent Document 1).

JP 2007-143122 A

A conventional display control apparatus has a backlight luminance setting value corresponding to each of a plurality of video sources, and the value can be freely set by an end user. However, when switching the video source, the luminance switching timing of the backlight and the video source switching timing do not always match, and if there is a sudden and large luminance change, the luminance change amount cannot follow the human eye, and the source switching There was a problem that it sometimes flickers.

A display control apparatus according to the present invention includes a backlight luminance setting unit that sets a backlight luminance according to each of a plurality of video sources, and a first video source to a second video source among the plurality of video sources. A switching timing setting unit for setting a switching timing for switching;
Based on the color brightness calculator that calculates the color brightness of the video data of the video source and the video data of the second video source before switching from the first video source to the second video source, The color brightness prediction unit that predicts the video data after switching the source and calculates the color brightness of the video data after switching the second video source, and the backlight brightness and switching timing set by the backlight brightness setting unit Based on the switching timing set by the setting unit, the color brightness of the video data of the first video source calculated by the color brightness calculation unit, and the color brightness of the second video data calculated by the color brightness prediction unit , The offset time calculation unit that calculates the first offset time before the switching timing and the second offset time after the switching timing, and the switching timing when switching the video source To initiate a change in backlight luminance before one offset time includes a backlight luminance changing unit for changing the backlight luminance from the switching timing after a second offset time, the.

According to the present invention, the amount of change in luminance per unit time before and after switching the video source is reduced (the luminance gradually changes) to reduce flicker, and the brightness of the screen color is taken into consideration, thereby bringing the screen situation By calculating the combined luminance change amount, it is possible to reduce the flicker that occurs when the video source is switched.

The figure which shows the relationship between the display control apparatus of this invention, and a display part. The block diagram which shows each function in CPU5 of FIG. Reference diagram for understanding the relationship between backlight brightness and time change The figure which shows the relationship between the backlight brightness | luminance of this invention, and a time change. The figure which shows the flowchart of the process of this invention.

Embodiment 1

FIG. 1 is a diagram showing the relationship between the display control device 3 and the display unit 4 of the present invention. A video source 1 (first video source) and a video source 2 (second video source) are video sources connected through an external input (AUX, HDMI (registered trademark), etc.), and are a TV, iPod (registered trademark). ), DVD, navigation screen or the like. The video processing circuit 6 processes the video data 1 and the video data 2 captured from the video source 1 and the video source 2, and the display unit 2 displays the processing result. The video processing circuit 6 also outputs to the CPU 5 video data information 1 and video data information 2 for acquiring screen brightness information. The CPU 5 outputs a PWM control signal based on the luminance value set by the user to the dimming circuit 7, and the dimming circuit 7 controls the current value or voltage value flowing through the LED of the backlight control unit 9. The display drive control unit 8 drives the liquid crystal screen based on the signal received from the video processing circuit 6. In the first embodiment of the present invention, the display screen is switched from the video source 1 to the video source 2 while monitoring the video data 2 of the video source 2 output before switching the display screen. A backlight luminance is input to the input unit 10 by the user. Although two video sources are shown for convenience, the video processing circuit 6 monitors all video data of a plurality of connected video sources.

FIG. 2 is a block diagram showing each function in the CPU 5 of FIG. In the backlight luminance setting unit 51, the backlight luminance is set by the user through the input unit 10 according to each of a plurality of video sources. The switching timing setting unit 52 sets the timing for switching from the video source 1 to the video source 2. The color brightness calculation unit 53 calculates the color brightness of the video data 1 from the color information (hue, brightness, saturation) included in the video data 1 of the video source 1. The color brightness prediction unit 54 predicts the video data after switching for the video data 2 of the video source 2 at the timing before switching, and calculates the color brightness of the video data after switching from the predicted video data. The offset time calculation unit 55 determines transition times before and after switching. The backlight luminance changing unit 56 switches the video source and luminance.

FIG. 3 shows a reference diagram for understanding the relationship between backlight luminance and temporal change. The change in backlight luminance when the video source is switched from video source 1 to video source 2 at a certain timing t0 is shown. L1 represents the luminance setting value of the video source 1, and L2 represents the luminance setting value of the video source 2, which is a fixed value. These luminance values may be preset by the user.

Here, the flicker occurs at the timing of switching the backlight luminance shown in FIG. 3, and the flicker occurrence condition is when all of the following conditions are satisfied.
Occurrence condition 1: When the backlight luminance switching timing does not match the video source switching timing Occurrence condition 2: When the luminance change is abrupt Occurrence condition 3: When the luminance difference (L2-L1) is large

In order to suppress flickering, control should be performed so that the occurrence condition 1 is not satisfied. However, considering variations in each circuit, the backlight luminance switching timing and the video source switching timing are adjusted for every device in order to completely match. Is necessary and difficult. Therefore, in the present invention, paying attention to the generation condition 2, a method of reducing flicker by gradual change in luminance is used.

FIG. 4 shows the relationship between the backlight luminance and the time change of the present invention. Time T is provided for the change in luminance from the luminance L1 before switching to the luminance L2 after switching. here,
T = T1 + T2 (Formula 1)
It is. This time T is a backlight luminance switching time. At this time, the video source 1 side is set as T1 (first offset time), and the video source 2 side is set as T2 (second offset time). T1 and T2 are values that can be set by the user or automatically. By increasing the times T1 and T2, the amount of change in luminance per unit time is reduced, and flicker can be reduced.

Flickering can be reduced simply by appropriately setting T1 and T2, but other parameters exist in the screen luminance and affect flickering. Therefore, in the present invention, another luminance value L0 is provided. L0 is the intermediate luminance value between L1 and L2
L0 = (L1 + L2) / 2 (Formula 2)
And the luminance value at t0 which is the video source switching timing.

The calculation formula of each luminance change in the video source 1 and the video source 2 is as follows.
■ Video source 1 (t1 = 0 to T1)
f (t1) = (L2−L1) × t1 / (2 × T1) + L1 (Equation 3)
Here, t1 is a variable having (t0-T1) as the origin and having a range up to the origin + T1 as a domain.
■ Video source 2 (t2 = 0 to T2)
f (t2) = (L2−L1) × t2 / (2 × T2) + L0 (Formula 4)
Here, t2 is a variable with t0 as the origin, and the range up to the origin + T2 is defined.

Next, a process of switching from the video source 1 (first video source) to the video source 2 (second video source) will be described with reference to FIGS. 1 and 2 based on the flowchart of FIG. The video processing circuit 6 switches the display screen from the video source 1 (for example, TV) to the video source 2 (for example, navigation screen) while monitoring the video data 2 of the video source 2 output before switching the display screen. Shall. The user turns on the video source switching signal (step S41). The switching timing setting unit 52 determines a switching timing t0 for switching from the video source 1 to the video source 2 (step S42). The backlight brightness setting unit 51 sets the backlight brightness L1 and L2 of each video source (step S43).

Hereinafter, the value calculated by the CPU 5 for the color brightness for one frame of the video data from the RGB color information (hue, lightness, saturation) included in the video data information is RGB-L. RGB-L indicates the color brightness (color brightness) for one frame of video data, and is a parameter independent of the backlight luminance. The color brightness calculator 53 obtains the color brightness RGB-L1 of the video data 1 from the RGB color information (hue, brightness, saturation) included in the video data 1 of the video source 1 (step S44).

In general, since various colors are included in one frame, the color brightness for one frame is calculated by integrating and calculating the color information (hue, brightness, saturation) of all the colors included in one frame. The calculated value is defined as RGB-L (color brightness) of the frame. For example, if all frames are white, RGB-L is the maximum value, and if all frames are black, RGB-L is the minimum value.

The video processing circuit 6 monitors both the video data 1 and the video data 2 before switching the video source. Here, based on the video data of the video source 2 before switching from the video source 1 to the video source 2, the color brightness prediction unit 54 uses the “frame” which is a general technique for the video data after switching the video source 2. The color brightness of the video data after switching is calculated (step S45). The color brightness for one frame of the (predicted) video data 2 after the switching is RGB-L2. As an example of the inter-frame prediction technique, there is a patent document such as JP-A-7-193819.

There are four parameters that define brightness, L1, L2, RGB-L1, and RGB-L2. However, if you feel bright, that is, reducing the luminance difference per unit time on the video source side where this parameter is high, Flicker can be further suppressed. This is expressed by a ratio (Expression 5).
L1 / RGB-L2: L2 / RGB-L1 = T1: T2 (Formula 5)

When (Expression 5) is modified, T1 and T2 are obtained as (Expression 6) and (Expression 7).
T1 = L1 / L2 × RGB−L1 / RGB−L2 (Expression 6)
T2 = L2 / L1 × RGB−L2 / RGB−L1 (Expression 7)

(Expression 6) and (Expression 7) indicate that T1 is proportional to L1 and RGB-L1, and T2 is proportional to L2 and RGB-L2.

(Expression 8) and (Expression 9) are obtained from (Expression 1) and (Expression 5).
T1 = L1 / (L1 + RGB−L2 / RGB−L1 × L2) × T (Expression 8)
T2 = L2 / (L2 + RGB−L1 / RGB−L2 × L1) × T (Equation 9)

The offset time calculation unit 55 calculates T1 (first offset time) and T2 (second offset time) based on (Expression 8) and (Expression 9) (step S46). Next, the backlight luminance changing unit 56 switches the backlight luminance according to L (t1) and L (t2) calculated based on (Equation 3) and (Equation 4) (step S47), and the video processing circuit 6 Are switched at the timing of t0 (step S48).

In FIG. 3A, when L1 = 500, L2 = 600, and T = 1, for example, when RGB-L1 = 100 and RGB-L2 = 120, T1 = 0.4 and T2 = 0.6. Thus, the time T2 on the video source 2 side is longer than the time T1 on the video source 1 side. On the other hand, when L1 = 500, L2 = 600, and T = 1, for example, when RGB-L1 = 120 and RGB-L2 = 100, T1 = T2 = 0.5, and the time T1 on the video source 1 side Is the same as the time T2 on the video source 2 side. The video source and the luminance are switched based on T1 and T2 calculated in this way.

  Note that the offset time calculation unit 55 may determine the first offset time and the second offset time by using a table instead of the calculation by the CPU 5.

Further, the offset time calculation unit 55 may adjust the first offset time and the second offset time by providing a correction coefficient for each apparatus.

Further, in FIG. 4, the backlight luminance changing unit 56 shows a case where the backlight luminance is changed linearly, but the backlight luminance may be changed nonlinearly.

As described above, according to the first embodiment, flicker is reduced by reducing the amount of change in luminance per unit time before and after video source switching (the luminance gradually changes), and the brightness of the screen color is also taken into consideration. By calculating the amount of change in brightness according to the screen conditions, flickering caused by switching the video source can be reduced.

  In addition to the above, within the scope of the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted.

1 video source 1 (first video source), 2 video source 2 (second video source),
3 display control device, 4 display unit, 5 CPU, 6 video processing circuit, 7 dimming circuit,
8 display drive control unit, 9 backlight control unit, 10 input unit,
51 backlight luminance setting unit, 52 switching timing setting unit,
53 color brightness calculator, 54 color brightness predictor,
55 offset time calculation unit, 56 backlight luminance change unit,

Claims (6)

A backlight luminance setting unit for setting the backlight luminance according to each of a plurality of video sources;
A switching timing setting unit for setting a switching timing for switching from the first video source to the second video source among the plurality of video sources;
A color brightness calculator for calculating the color brightness of the video data of the video source;
Based on the video data of the second video source before switching from the first video source to the second video source, predicting the video data after switching the second video source, A color brightness prediction unit for calculating the color brightness of the video data after switching the video source;
The backlight luminance set by the backlight luminance setting unit, the switching timing set by the switching timing setting unit, the color brightness of the video data of the first video source calculated by the color brightness calculation unit, and the color An offset time calculation unit that calculates a first offset time before the switching timing and a second offset time after the switching timing based on the color brightness of the second video data calculated by the brightness prediction unit;
When the video source is switched, the backlight luminance starts to change the backlight luminance before the first offset time from the switching timing, and changes the backlight luminance after the second offset time from the switching timing. Change part,
A display control device. The display control apparatus according to claim 1, wherein the backlight luminance changing unit linearly changes the backlight luminance when the video source is switched. The display control apparatus according to claim 1, wherein the color brightness calculation unit calculates color brightness from all colors included in one frame of video data of the video source. The color brightness prediction unit predicts video data after switching the second video source by inter-frame prediction, and from all colors included in one frame of the video data after switching the second video source. The display control apparatus according to claim 1, wherein color brightness is calculated. The display control apparatus according to claim 1, further comprising an input unit that inputs backlight luminance, wherein the backlight luminance is set in the backlight luminance setting unit from the input unit according to a video source. The display control apparatus according to claim 1, wherein the offset time calculation unit adjusts the first offset time or the second offset time based on a correction coefficient included in each video source.

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