JP3063490B2 - Light control device for in-vehicle display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle display device, and more particularly to a dimming device capable of adjusting display illumination in accordance with ambient illuminance.

[0002]

2. Description of the Related Art Various display devices are provided on an instrument panel of an automobile. Generally, these display devices are provided with an illumination lamp so that the display screen can be illuminated when the surroundings are dark such as at night. In the case of a transmissive display screen using liquid crystal or the like, there is a display screen in which the light source is turned on day and night and the brightness of the light source can be adjusted. Many of such lamps can change the brightness of the illumination lamp arbitrarily, for example, by operating a light control knob with the lighting switch turned on.

[0003] However, when driving in the daytime, for example, when entering a tunnel, the driver's eyes cannot follow a rapid change in the surrounding brightness, so that even if the lighting switch is turned on to turn on the illumination lamp. The display surface is difficult to see at normal (nighttime) brightness. Therefore, the driver must adjust the dimming knob to increase the brightness once to a brightness level for daytime driving, and then lower the brightness as the eyes become accustomed (dark adaptation). Nara. For this reason, the dimming operation becomes complicated, and there is also a problem in safe driving.

In order to solve this problem, for example,
No. 42738 has an automatic light control switch. When the lighting switch is turned on with the automatic light control switch on, the brightness of the display surface is automatically increased once to a predetermined value, and then at a predetermined rate. There has been proposed an automatic light control device for dimming light.

[0005]

However, in this light control device, even if the automatic light control switch is turned on, unless the lighting switch is turned on when entering a tunnel, the above-described automatic light control is performed. For example, when passing through a tunnel intermittently or under an overpass, the lighting switch must be turned on each time, and the operation is still complicated. In this case, there is a method of keeping the lighting switch on together with the automatic dimming switch, but in this case, the brightness of the screen becomes brighter every time a vehicle passes under a tunnel or overpass.
There was a problem that the color changed rapidly from dark to light to dark and so on, which resulted in a loss of visibility.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. By performing automatic dimming corresponding to a driver's pupil adjusting function, an optimum screen illuminance can be obtained according to a change in ambient brightness. It is an object of the present invention to provide a dimming device for a vehicle-mounted display device that can be provided.

[0007]

According to a first aspect of the present invention, there is provided a dimming device for an in-vehicle display device, comprising: an in-vehicle display device having an illumination device; Means, comparing means for comparing the illuminance value measured by the illuminance measuring means with a preset threshold value,
In a state where the lighting device is maintained at the first luminance level corresponding to the daytime ambient illuminance, as a result of the comparison by the comparing unit, at least a plurality of illuminance values measured at predetermined time intervals by the illuminance measuring unit are at least. And a brightness changing means for lowering the brightness of the lighting device to a second brightness level corresponding to the ambient illuminance at night when the brightness is continuously lower than the threshold value.

According to a second aspect of the present invention, in the dimming device for a vehicle-mounted display device according to the first aspect, the illuminance value measured by the illuminance measuring means is further compared with a preset second threshold value. A second comparing unit configured to store the second illumination level in the illumination device at the second luminance level;
As a result of the comparison by the comparing means, when the illuminance value measured by the illuminance measuring means is larger than the second threshold value, the brightness of the lighting device is immediately increased to the first brightness level. Brightness changing means.

[0009]

According to the first aspect of the present invention, when the lighting device is held at the daytime high brightness level (first brightness level), the current illuminance level around the display device becomes smaller than a certain value. in this case, the past of the plurality of time-series luminance data
Adjustment is performed to lower the brightness of the lighting device to the nighttime brightness level (second brightness level) only at least when the brightness is continuously lower than the certain value.

According to the second aspect of the present invention, in addition to the function of the first aspect, when the illumination device is maintained at a high luminance level for night use, the current illuminance level around the display device is constant. If it becomes larger, an adjustment is immediately made to increase the brightness of the lighting device to a daytime brightness level.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 schematically shows an on-vehicle display device provided with a dimming device according to an embodiment of the present invention. This device is provided with a screen control unit 12 including at least a screen luminance control unit 14 and a display information processing unit 15. The screen brightness control unit 14 controls the screen brightness of the display unit 11, and the display information processing unit 15 converts the display information input from the display information creation unit 13 into the display unit 11.
This is for processing into a form (characters, figures, etc.) that can be displayed on the screen.

The illuminance sensor 16 is for detecting the illuminance around the display section 11 (the external illuminance).
The digital data is converted by the D converter 17 and input to the illuminance data storage unit 18. The illuminance data storage unit 18 is connected to the screen brightness control unit 14 of the screen control unit 12.

FIG. 2 shows the appearance of the vehicle-mounted display device shown in FIG. In the display unit 21, the above-described screen control unit 12, display information creation unit 13, A / D converter 17
And the illuminance data storage unit 18 are integrally housed. The display unit 11 is provided on the front of the display unit 21,
The illuminance sensor 16 is provided on a side surface of the display unit 21.

The operation of the dimming device for a vehicle-mounted display device having the above configuration will be described.

When the illuminance sensor 16 outputs a voltage corresponding to the illuminance around the display unit 21, the output voltage is A / A
The digital data is converted by the D converter 17 and sequentially stored in the illuminance data storage unit 18. The sampling at this time is performed, for example, every second, and the illuminance data storage unit 18 stores data for at least the past 30 seconds.

The screen brightness control unit 14 of the screen control unit 12
The display brightness of the entire screen of the display unit 11 is controlled based on the illuminance data input from the illuminance data storage unit 18. The display information processing unit 15 processes the display information input from the display information creation unit 13 and displays it on the display unit 11 as a figure or a character.

Next, the operation of the screen brightness control unit 14 will be described. In the present embodiment, the screen luminance control unit 14 performs automatic dimming basically in accordance with the pupil opening / closing adjustment function of a human. That is, the human pupil opens slowly when the external brightness changes from light to dark, but closes quickly when the light changes from dark to bright. Therefore, in the present embodiment, when the vehicle is running in the daytime, the illuminance around the display unit 11 is checked three times in a time series, and the amount of change in the illuminance data is compared. If it is determined that the vehicle has entered the shadow of the artifact, the change of the screen brightness of the display unit 11 from the high-brightness display for the day to the low-brightness display for the night is delayed while the vehicle When it comes out of the shadow, the display is changed from the low-brightness display for nighttime to the high-brightness display for daytime.

Hereinafter, the operation of the screen brightness control unit 14 will be described in detail with reference to FIG.

The screen luminance control unit 14 firstly outputs the illuminance data X (30) 30 seconds ago, the illuminance data X (1) 30 seconds ago,
After resetting the current illuminance data X (0) (step S101), the latest X
(30), X (1) and X (0) are read (Step S)
102).

Next, the screen brightness control unit 14 determines whether the current screen of the display unit 11 is in the high brightness display state for day or the low brightness display state for night (step S103). ).

Here, when the screen of the display unit 11 is in the low brightness state for night (step S103; N), the current illuminance data X (0) is compared with the reference value a (step S104). ). Here, the reference value a is a threshold value for determining whether to change from low-brightness display for night to high-brightness display for day, and is set to, for example, 200 lux (Lx). As a result of the comparison, when X (0) is larger than the reference value a (step S104; Y), the display is changed from the low-brightness display for night to the high-brightness display for day (step S105), and X (0) becomes the reference value. If the value is equal to or less than a (step S104; N), the low-luminance display for night is maintained (step S106).

On the other hand, in step S103, when the screen of the display section 11 is in the daytime high brightness state (step S103; Y), the three illuminance data X (0), X
(1) and X (30) are compared with the reference value b (steps S107 to S109). Here, the reference value b
Is a threshold value for determining whether or not to change from high-brightness display for day to low-brightness display for night, and has a relationship of b <a, and is set to, for example, 100 lux. As a result of the comparison, X
If all of (0), X (1), and X (30) are less than the reference value b (step S107; Y, S108;
Y and S109; Y), the display is changed from the high-brightness display for day to the low-brightness display for night (step S110), and X (0), X
If any one of (1) and X (30) is greater than or equal to the reference value b (step S107; N, S108; N, or S109; N), the daytime high-brightness display is maintained (step S111).

The processing from step S101 to S111 is performed until the engine is turned off (step S11).
2; Y).

FIG. 4 shows an example of the display brightness control performed by the above steps. In this figure,
(A) shows the temporal change of the external illuminance, and (B) shows the temporal change of the screen luminance. As shown in this figure, the illuminance data X (30) 30 seconds ago, the illuminance data X (1) 1 second ago, and the current illuminance data X (0) are all smaller than the reference value b. A change from the high brightness display to the night low brightness display is performed. The reason why the illuminance data one second before is also taken into account is to fail-safe against accidental illuminance change.

After the display is switched to the low-brightness display for night, the display is not changed to the high-brightness display for daytime even if there is an illuminance change (peaks P1 and P2) that does not reach the reference value a. Is exceeded (peak P3), the display is changed to daytime high-brightness display. Further, in the case where the external illuminance equal to or less than the reference value b continues in the daytime high brightness display state, even if there is an instantaneous illuminance change (peak P4) during that time, the illuminance data X '(30) 30 seconds ago Illuminance data X 'one second before
As long as (1) and the current illuminance data X '(0) are all smaller than the reference value b, the change from the daytime high luminance display to the night low luminance display is performed. Therefore, as shown in FIG. 7B, even when the external illuminance changes in a short cycle after intermittently passing through a short tunnel or under an overpass, the external illuminance changes from light to dark. Since the change of the screen brightness is delayed, the brightness of the screen does not rapidly change to bright / dark / bright. Further, as shown in FIG. 7A, when the vehicle enters a relatively long tunnel, the display screen does not become dark before the driver's eyes darkly adapt, and the driver's pupil adjustment function is not provided. Automatic dimming is possible.

In the above embodiment, the reference value a for changing from the low-luminance display for night to the low-luminance display for night has been described as 200 lux. However, the present invention is not limited to this. It is of course possible to employ.

Next, another embodiment of the present invention will be described.

FIG. 5 shows the operation of the light control device according to the second embodiment of the present invention. In the present embodiment, in consideration of the sunshine condition, the brightness is changed in two stages at the change speed from the high-brightness display for day to the low-brightness display for night.

The screen luminance control unit 14 firstly outputs the illuminance data X (30) 30 seconds ago, the illuminance data X (1) 30 seconds ago,
After resetting the current illuminance data X (0) (step S201), the latest X
(30), X (1) and X (0) are read (Step S)
202).

Next, the screen brightness control unit 14 determines whether the current screen of the display unit 11 is in the high brightness display state for day or the low brightness display state for night (step S203). ).

Here, when the screen of the display unit 11 is in the low brightness state for night use (step S203; N), it is determined whether or not the current illuminance data X (0) exceeds the reference value a. (Step S204). Here, the reference value a is a threshold value for determining whether or not to change from low-luminance display for night to high-luminance display for day, and is set to, for example, 200 lux. As a result of this determination, when X (0) is larger than the reference value a (step S204; Y), the display is quickly changed from the low-brightness display for night to the high-brightness display for day (step S20).
5) If X (0) is equal to or smaller than the reference value a (step S)
204; N), the low-luminance display for night is maintained (step S).
206).

On the other hand, in step S203, when the screen of the display unit 11 is in the daytime high luminance state (step S203; Y), the illuminance data X (0) is compared with the reference value b1, and X (1 ) And the reference value b2, and X (3
0) and the reference values b1 and b2 (step S2).
07 to S210). Here, the reference values b1 and b2 are thresholds for determining whether or not to change from high-brightness display for day to low-brightness display for night, and have a relationship of b1 <b2 <a. a = 200 lux, b2 = 150 lux, b
1 = 100 lux is set. As a result of the comparison, X (0)
≦ b1, X (1) ≦ b2 and X (30) ≦ b1 (Steps S207; Y, S208; Y, S20)
9; Y and S210; Y), the display is slowly changed from the high-brightness display for day to the low-brightness display for night (step S211).
(0) ≦ b1, X (1) ≦ b2, and b1 <X (30)
≤ b2 (Step S207; Y, S208;
Y, S209; Y, and S210; N), and quickly change from high-brightness display for day to low-brightness display for night (step S2).
12). If X (0)> b1, X (1)> b2, and X (30)> b2 (step S207; N,
S208; N or S209; N), the daytime high-luminance display is maintained (step S213).

The processing in steps S201 to S213 is performed until the engine is turned off (step S21).
4; Y), repeated.

FIG. 6 shows an example of display brightness control performed by the steps according to the second embodiment. In this figure, (A) shows the time change of the external illuminance, and (B) shows the time change of the screen luminance. As shown in this figure, when the illuminance data X (30) 30 seconds ago, the illuminance data X (1) one second ago, and the current illuminance data X (0) are all smaller than the reference value b1, the daytime The change from the high-brightness display to the low-brightness display for night is the same as in the first embodiment (FIGS. 3 and 4), but in this embodiment, the brightness change in that case is performed slowly. This is X (30) ≦
When b1 holds, it is considered that the outside world has been darkened instantaneously by entering a tunnel or the like, and the pupil of the driver is not yet sufficiently opened.
This is because it is preferable to lower the screen brightness slowly. When b1 <X ′ (30) ≦ b2 is satisfied, the screen brightness is changed from the daytime high brightness display to the nighttime low brightness display slightly faster. In this case, as shown in FIG.
This is because it is considered that the external illuminance is slowly changing due to the change in the sunshine, and the pupil of the driver is already considered to be quite open. Therefore, it is preferable to change the luminance relatively quickly.

In addition to the above embodiment, the screen brightness can be adjusted by the following method. That is, the illuminance data X (30) 30 seconds ago, the illuminance data X (15) 15 seconds ago, and the current illuminance data X (0) are compared, and the chronological decrease in illuminance is equal to or less than a certain amount (change If the inclination is equal to or more than a certain value), it is determined that the pupil of the driver is already open due to the decrease in illuminance due to the sunset, and the screen luminance is reduced somewhat quickly, while X (0) and X (1) are reduced. ,
If X (30) is uniformly low and there is almost no difference, it is determined that the pupil has not yet opened sufficiently due to a rapid decrease in illuminance caused by entering a tunnel or the like before 30 seconds, and the screen brightness is determined. Adjust to lower slowly.

In the second embodiment, the screen brightness change from the high brightness display for the day to the low brightness display for the night is performed by two values b1,
Although b2 is set as the reference value, the present invention is not limited to this. The screen brightness may be changed from daytime high brightness display to nighttime low brightness display using three or more reference values.

The reference values b1 and b2 are set to 100
Lux, 150 lux, but it is not limited to this, and it is of course possible to set it to another value. Further, in the above two embodiments, the illuminance data acquired in time series is described as three pieces. However, the present invention is not limited to this, and two or four or more pieces may be used.

[0039]

As described above, according to the first aspect of the present invention, when the illuminating device is maintained at the high luminance level for daytime, the current illuminance level around the display device becomes smaller than a certain value. Even if it becomes small, the screen brightness is not immediately lowered, but only when the past multiple illuminance data measured in time series has become smaller than a certain value at least continuously. Even if the external illuminance changes in a short cycle due to intermittent passing through a short tunnel or underpass, etc., the screen will be displayed when the external illuminance changes from light to dark. The change in brightness is delayed. For this reason, the brightness of the screen does not rapidly change to bright / dark / bright in accordance with the change in the external illuminance, and the visibility of the screen of the display device can be kept good.

Further, even when the vehicle enters a relatively long tunnel, the display screen does not become dark before the driver's eyes darkly adapt as in the prior art, and the pupil adjustment characteristics (darkness) of the driver do not change. This makes it possible to perform automatic dimming in accordance with poor adaptation responsiveness), and in this regard, there is also an effect that it can contribute to ensuring the visibility of the screen of the display device.

According to the second aspect of the present invention, when the illuminating device is maintained at the high brightness level for night use, and when the current illuminance level around the display device becomes larger than a certain value, Since the adjustment for immediately increasing the luminance of the lighting device to the daylight luminance level is performed, in addition to the effect of the invention according to claim 1, the driver's pupil with respect to the change of the external illuminance from dark to bright is adjusted. It is possible to change the screen brightness corresponding to the good responsiveness of adaptation (light adaptation).

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a vehicle-mounted display device provided with a dimming device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of the vehicle-mounted display device of FIG.

FIG. 3 is a flowchart showing a first embodiment of the operation of the screen brightness control unit 14 of FIG. 1;

FIG. 4 is a timing chart showing an example of display luminance control in the first embodiment.

FIG. 5 is a flowchart showing a second example of the operation of the screen brightness control unit 14 of FIG. 1;

FIG. 6 is a timing chart showing an example of display luminance control in the second embodiment.

FIG. 7 is an explanatory diagram showing various change patterns of the external illuminance of the display unit.

[Explanation of symbols]

 Reference Signs List 11 display unit 12 screen control unit 13 display information creation unit 14 screen brightness control unit 15 display information processing unit 16 illuminance sensor 18 illuminance data storage unit 21 display unit

Claims (2)

(57) [Claims] 1. An in-vehicle display device provided with an illumination device, wherein: an illuminance measurement unit that measures illuminance around the display device; and an illuminance value measured by the illuminance measurement unit is compared with a preset threshold value. Comparing means, in a state in which the lighting device is held at a first luminance level corresponding to ambient illuminance in daytime, as a result of comparison by the comparing means, a plurality of light sources measured at predetermined time intervals by the illuminance measuring means. Brightness changing means for lowering the brightness of the lighting device to a second brightness level corresponding to nighttime ambient illuminance when the illuminance value is at least continuously lower than the threshold value. Light control device for in-vehicle display device. 2. The illuminating device according to claim 1, further comprising: a second comparing unit that compares an illuminance value measured by the illuminance measuring unit with a second threshold value set in advance. When the illuminance value measured by the illuminance measurement unit is larger than the second threshold value as a result of the comparison by the second comparison unit in a state where the illuminating device is held at the level, the luminance of the illumination device is immediately increased. And a second brightness changing unit for increasing the brightness to a first brightness level.