JPH06339087A - Luminance adjusting device of image display device - Google Patents

Abstract

PURPOSE:To obtain a luminance adjusting device of a picture receiving tube where the character part of an image displayed on a screen can be easily recognized even if external light illuminance becomes high. CONSTITUTION:Luminance adjusting voltage VAC is added to each of color signals R, G and B by drive circuits 3R, 3G and 3B and the signals are supplied to a picture tube 1. The voltage VAC becomes VUP in the character part of an image, VDW in the rim part and VA in other parts. VA is luminance adjusting voltage to be adjusted by a user and VUP is VA+VC, VDW is VA-VC. VC is corrected voltage formed based on the detection output of a light quantity sensor 4 and become large along with external light illuminance. Because the contrasts of the character part increases as the external light illuminance becomes higher, the recognition of characters becomes easy without being affected by the reflection light even if the external light illuminance becomes high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brightness adjusting device for an image display such as a picture tube for displaying an image including a character.

[0002]

2. Description of the Related Art FIG. 9 shows a relationship between image light output from a display image on a screen of a picture tube and reflected light of external light incident on the screen. In the figure, 1 is a picture tube, L
E is image light output from the display image, LI is external light incident on the screen of the picture tube 1, and LR is reflected light of external light LI reflected on the screen of the picture tube 1.

[0003]

As described above, when the external light LI enters the screen of the picture tube 1, the influence of the reflected light LR on the image light LE increases as the illuminance of the external light LI increases. It becomes difficult to recognize the image.

Therefore, according to the present invention, even if the illuminance of the external light incident on the screen of the image display increases, it is possible to easily recognize the character portion of the image displayed on the screen. The purpose is to provide.

[0005]

A brightness adjusting device for an image display according to the present invention includes an illuminance detecting means for detecting the illuminance of external light, a character portion of an image displayed on the screen of the image display, and a part thereof. A brightness adjusting unit is provided for adjusting the brightness of one or both of the border portions based on the detection output of the illuminance detecting unit.

[0006]

According to the present invention, the brightness of one or both of the character portion and the border portion of the image displayed on the screen of the image display is adjusted according to the illuminance of external light.
For example, the higher the illuminance of the external light, the higher the brightness of the character portion, and the lower the brightness of the border portion. Therefore, as the illuminance of external light increases, the contrast of the character portion increases, and even if the illuminance of external light increases, the character portion of the image displayed on the screen can be easily recognized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In this example, the image display is a picture tube.

In the figure, 2R, 2G and 2B are input terminals, and these input terminals 2R, 2G and 2B are color signals R, red, green and blue for displaying an image including a character.
G and B are supplied. The color signals R, G, B are output from a CD-G decoder of a CD reproducing device (not shown) for reproducing CD-G software for karaoke, for example.

The color signals R, G, B supplied to the input terminals 2R, 2G, 2B are the drive circuits 3R, 3G, respectively.
It is supplied to the picture tube 1 via 3B. As a result, an image including a character is displayed on the screen of the picture tube 1 by the color signals R, G, B.

Reference numeral 4 denotes a light amount sensor as an illuminance detecting means, and an output signal S _D according to the illuminance of external light is obtained from the light amount sensor 4 (shown by a solid line in FIG. 2). When the illuminance of external light becomes higher than a certain illuminance L _ST , the light amount sensor 4 becomes saturated, and thus the output signal S _D corresponding to the illuminance of external light cannot be obtained.

The output signal S _D of the light quantity sensor 4 is supplied to the illuminance correction circuit 5. The illuminance correction circuit 5 is supplied with the clip voltage V _B from the voltage regulator 6. Illuminance correction circuit 5
Then, the portion of the output signal S _D that is equal to or lower than the clipping voltage V _B is set to the voltage V _B regardless of the illuminance (shown by a chain line in FIG. 2). The illuminance corresponding to the voltage V _B is L _B.

The output signal S _DC of the illuminance correction circuit 5 is supplied to the bipolar amplifier 7. The clip voltage V _B is supplied from the voltage regulator 6 to the amplifier 7, and the voltage regulator 8
The brightness adjustment voltage V _A is supplied. In the amplifier 7, the voltage V _B portion of the output signal S _DC of the illuminance correction circuit 5 is taken as the voltage V _A, and is amplified in both polarities with reference to this voltage V _A. The positive signal S _UP and the negative signal S _DW are output from the amplifier 7 as shown by the solid line in FIG.

[0013] positive polarity signal S _UP, the external light illuminance to L _B is fixed to the voltage V _A, the external light illuminance is L _B to L _ST is a signal whose voltage value increases as the ambient light illuminance is high. That is, the signal S _UP is obtained by adding the correction voltage V _C (V _C = 0 when the external light illuminance is L _B ) that increases with the external light illuminance from the external light illuminance L _B to L _ST to the voltage V _A. Become. Also, the negative polarity signal S _DW, external light illuminance to L _B is fixed to the voltage V _A, the external light illuminance is from L _B to L _ST is a signal whose voltage value decreases as the ambient light illuminance is high.
That is, the signal S _DW is a value obtained by subtracting the above-described correction voltage V _C from the voltage V _A when the external light illuminance is from L _B to L _ST .

The output signals S _UP and S _DW of the bipolar amplifier 7 are supplied to the brightness adjustment voltage correction circuit 9. The brightness adjusting voltage V _A is supplied from the voltage adjuster 8 to the correction circuit 9. Also,
The correction circuit 9 receives the character signal S _CA from the input terminal 10.
Is supplied and the border signal S from the input terminal 11 is supplied.
_PO is supplied. The character signal S _CA is, for example, a high level “H” signal corresponding to the character portion of the image displayed on the screen of the picture tube 1, and the border signal S _PO.
Is a signal which becomes a high level "H" corresponding to the border part which borders the character part. The character signal S _CA and the border signal S _PO are, for example, the above-mentioned CD-
It is supplied from the G decoder.

FIG. 4 shows a specific structure of the brightness adjustment voltage correction circuit 9, which is composed of a changeover switch 90. The output signals S _UP and S _DW of the bipolar amplifier 7 are supplied to fixed terminals on the a side and the b side of the changeover switch 90, respectively, and the brightness adjustment voltage V _A from the voltage regulator 8 is fixed on the c side of the changeover switch 90. Supplied to the terminal. The character signal S _CA and the border signal S _PO from the input terminals 10 and 11 are supplied to the changeover switch 90 as a 2-bit changeover control signal.

FIG. 5 shows the character signal S._CA, Borderbird
Issue S_POAnd the brightness adjustment after correction output from the correction circuit 9
Voltage V_ACShows the relationship with. That is, the image
Compatible with both the lacquer part and its border part
No, S_CA= "L", S_PO= "L", the switching switch
The switch 90 is connected to the a side, and V_AC= V_AIt is said that Ki
Corresponding to the character part, S_CA= "H", S_PO= “L”
In some cases, the changeover switch 90 is connected to the c side, and V_AC
= V_UPIt is said that Corresponds to the border part, S_CA=
"L", S_PO= “H”, the changeover switch 90
Is connected to the b side, V _AC= V_DWIt is said that

Returning to FIG. 1, the corrected brightness adjustment voltage V _AC output from the brightness adjustment voltage correction circuit 9 is supplied to the drive circuits 3R, 3G, 3B. Drive circuit 3R, 3
In G and 3B, the brightness adjustment voltage V _CA is added to the color signals R, G and B, respectively. Thus, the brightness of the image displayed on the screen of the picture tube 1 is adjusted.

Here, when the color signals R, G, B supplied to the input terminals 2R, 2G, 2B are as shown in FIG. 6A, the character signal S _CA is high in the character portion as shown in FIG. 6B. The level becomes “H”, and the border signal S _PO becomes high level “H” in the border portion as shown in FIG. The level of the character portion of the color signals R, G, B is Va, the level of the border portion is Vc, and the levels of other portions are Vb.

In this case, the corrected luminance adjustment voltage V _AC output from the correction circuit 9 becomes V _UP in the character portion, V _{DW in} the border portion, and V _{A in the} other portions as shown in FIG. Become. Therefore, the drive circuits 3R, 3
The corrected color signals R _C , G _C , and B _C supplied from G and 3B to the picture tube 1 are added with V _UP in the character portion and V _{DW in} the border portion as shown in FIG. , And in other parts, V _A is added.

Therefore, when the external light illuminance is from L _B to L _ST , the correction voltage V _C increases as the external light illuminance increases as described above, and the contrast of the character portion increases as the external light illuminance increases. , There is an advantage that the character can be easily recognized even when the illuminance of outside light is high. Here, the external light illuminance L _B is the correction start illuminance, and the external light illuminance L _ST is the correction maximum illuminance.

The correction start illuminance L _B can be varied by adjusting the clip voltage V _B with the voltage regulator 6. The correction start illuminance L _B, for example the external light LI is incident on the picture tube 1, so that the character image due to the influence of the reflected light LR is set to the minimum external light illuminance to be difficult to recognize.

FIG. 7 shows a character displayed on the screen of the picture tube 1 in this example, and the brightness adjustment voltage V _CA corrected by the correction circuit 9 corresponding to the I-I line. On the other hand, FIG. 8 shows a character displayed on the screen of the conventional picture tube 1 and the brightness adjustment voltage corresponding to the I-I line, but the brightness adjustment voltage is uniform over the entire screen. Even if it is adjusted, the brightness of the entire screen changes, and it is not easy to recognize the character as in this example.

In the above embodiment, the brightness of both the character portion and the border portion thereof is adjusted according to the illuminance of external light. However, one of the character portion and the border portion is adjusted according to the illuminance of external light. However, since the contrast of the character portion increases as the illuminance of outside light increases, there is an advantage that the character can be easily recognized.

Further, in the above-mentioned embodiment, an example is shown in which the character portion is displayed with high luminance and the border portion is displayed with low luminance, but the present invention can be applied to the case where the luminance relationship is reversed. In that case, the luminance of the character portion is adjusted to be lower as the illuminance of the external light is increased, and the luminance of the border portion is adjusted to be higher.

In the above embodiment, the image display is the picture tube 1.
However, it is needless to say that the same can be applied to other devices such as a liquid crystal display.

[0026]

According to the present invention, the brightness of one or both of the character portion and the border portion of the image displayed on the screen of the image display device is adjusted according to the illuminance of the outside light. The higher the illuminance, the higher the brightness of the character part and the lower the brightness of the border part. Therefore, the higher the illuminance of external light, the higher the contrast of the character part and the illuminance of the external light. Even if the height is increased, it is easy to recognize the character of the image displayed on the screen.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a brightness adjusting device for an image display according to the present invention.

FIG. 2 is a diagram showing output signals of a light amount sensor and an illuminance correction circuit.

FIG. 3 is a diagram showing an output signal of a bipolar amplifier.

FIG. 4 is a diagram showing a configuration of a brightness adjustment voltage correction circuit.

FIG. 5 is a diagram showing a relationship between a character signal, a border signal, and a corrected brightness adjustment voltage.

FIG. 6 is a waveform diagram for explaining the operation of the embodiment.

FIG. 7 is a diagram for explaining a brightness adjustment voltage according to the embodiment.

FIG. 8 is a diagram for explaining a conventional brightness adjustment voltage.

FIG. 9 is a diagram showing a relationship between image light from a display image on a picture tube and reflected light of external light.

[Explanation of symbols]

 1 Picture tube 3R, 3G, 3B drive circuit 4 Light intensity sensor 5 Illuminance correction circuit 6, 8 Voltage regulator 7 Bipolar amplifier 9 Brightness adjustment voltage correction circuit

Claims (1)

[Claims] 1. An illuminance detecting means for detecting an illuminance of external light, and a luminance of one or both of a character portion and an edge portion of an image displayed on a screen of a picture tube of an image display of the illuminance detecting means. A brightness adjusting device for an image display, comprising brightness adjusting means for adjusting based on a detection output.