JP3101466B2 - Display panel backlight adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device in an information processing device such as a notebook personal computer, and more particularly to a display panel backlight adjusting device for automatically dimming a backlight for illuminating a display panel.

[0002]

2. Description of the Related Art In accordance with the recent trend of energy saving, various electronic devices are also required to reduce power consumption. In particular, there is a strong demand for a portable information processing apparatus driven by a battery such as a notebook personal computer (hereinafter referred to as a notebook personal computer), and various improvements for reducing power consumption have been made conventionally. Was.

Many of such notebook personal computers include a liquid crystal display device (hereinafter, referred to as an LCD) as a display device. Among them, a so-called transmissive or semi-transmissive LCD is used in view of the visibility of the display panel. . In this transmissive or transflective LCD, a backlight for illumination is provided on the back side of the display panel, and clear display is possible even in a relatively dark place.

However, in such a type of notebook personal computer, a considerable part of its power consumption (for example, 3
(About 0%) is due to the backlight, and how to save the power consumption of this backlight well is the key to reducing the power consumption of the entire apparatus.

[0005]

However, simply reducing the power supplied to the backlight to reduce the power consumption impairs the visibility of the LCD panel due to the surrounding brightness (for example, the brightness of the room light). Will be. That is, when the surroundings are not very bright, there is no problem in visual sense even if the backlight is not so bright, but when the surroundings are bright, it is difficult to see unless the backlight is considerably brightened. Therefore, if the device is used for a long time in a bright atmosphere without any visual problem, the power consumption by the backlight increases, and the continuous use time in the case of using a battery is shortened.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a display panel backlight adjusting device capable of effectively reducing the power consumption of the backlight without impairing the visual perception during use. The purpose is to gain.

[0007]

According to a first aspect of the present invention, there is provided a display panel backlight adjusting device having a backlight for illuminating a display panel.
(i) an illuminance detection sensor for detecting illuminance on the display panel surface; (ii) a pulse detection means for detecting a pulse component from an output of the illuminance detection sensor; and (iii) an output of the illuminance detection sensor.
The backlight according to the average received light level obtained from
Controlling the dimming voltage supplied to the
The pulse component according to the pulse component detected by the means.
And a dimming means for controlling the dimming voltage to increase or decrease so as to increase the amplitude of the dimming voltage at the H level .

According to a second aspect of the present invention, there is provided a display panel backlight adjusting device, comprising: (i) an illuminance detection sensor for detecting illuminance on a display panel surface; (Ii) pulse detection means for detecting a pulse component from the output of the illuminance detection sensor, and (iii) an oscillator for outputting a pulse of a predetermined frequency,
(iv) When a pulse component is detected from the output of the illuminance detection sensor by the pulse detection means, the detected pulse is selected, and when the pulse component is not detected, a pulse output from the oscillator is selected. Means for selecting,
(v) Average light receiving level obtained from the output of the illuminance detection sensor
Control the dimming voltage supplied to the backlight according to
And the H level of the pulse selected by the selection means.
It is characterized in that it has a, and light control means for increasing or decreasing control the dimming voltage so that the amplitude is enlarged in the dimming voltage at the bell.

According to a third aspect of the present invention, in the display panel backlight adjusting device according to the first aspect, the level of the dimming voltage supplied to the backlight can be manually increased or decreased. It is characterized by having manual light control means.

[0010]

In the display panel backlight adjusting device according to the first aspect of the present invention, the ambient light detected on the display panel surface is adjusted .
According to the average received light level and the flickering change of the ambient light ,
The dimming voltage of the backlight is controlled to increase or decrease. In particular,
Dimming voltage control in response to flickering ambient light
The dimming voltage of the backlight can be expanded selectively during "bright"
Control.

In the display panel backlight adjusting device according to the second aspect of the present invention, when the ambient light does not blink and no pulse component is detected from the sensor on the display panel surface,
Using the pulse from the oscillator, this pulse becomes H level
The amplitude of the dimming voltage of the backlight is expanded at
So that the said dimming voltage is increased or decreased control.

In the display panel backlight adjusting apparatus according to the third aspect of the invention, the dimming voltage level of the backlight is controlled to increase or decrease not only automatically but also manually.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a liquid crystal display device to which a display panel backlight adjusting device according to an embodiment of the present invention is applied. This device is provided with an automatic brightness adjustment signal output circuit 10, the output side of which is connected to the adder 30. The adder 30 also receives a brightness adjustment signal 38 from a manual brightness adjustment unit (not shown) and a contrast adjustment signal 39 from a contrast adjustment circuit (not shown), and adds these to the output of the automatic brightness adjustment signal output circuit 10. Input to the amplifier 32. The output side of the amplifier 30 is connected to a backlight device 34 for illuminating the LCD panel 36 from behind.

The automatic brightness adjustment signal output circuit 10 has an LC
A light receiving sensor 11 for detecting the brightness (illuminance) in the vicinity of the D panel 36 is provided, and converts a photocurrent corresponding to the amount of received light into a voltage and outputs it. As the light receiving sensor 11,
For example, a phototransistor or CdS is used. The output of the light receiving sensor 11 is input to a smoothing circuit 12 and a pulse detecting circuit 13, and the former detects an average amount of received light, while the latter detects a pulse component. The output side of the smoothing circuit 12 is directly connected to the adder 30, and the output side of the pulse detection circuit 13 is connected to the selector 14 and the oscillator 15 that oscillates a pulse of a predetermined frequency (for example, 50 Hz). The selector 14 selects a pulse signal when it is input from the pulse detection circuit 13,
When a pulse signal is not input, a pulse oscillation output from the oscillator 15 is selected and output to the amplifier 16. The output of the amplifier 16 is input to the adder 30.

The operation of the display panel backlight adjusting device having the above configuration will be described.

Now, assuming that the lighting of a room using a notebook computer equipped with the present apparatus is a fluorescent lamp, the fluorescent lamp blinks at a commercial power frequency (for example, 50 Hz).
The LCD panel 36 is illuminated. As is well known, the human eye perceives continuous illumination under flickering at such a frequency. The light receiving sensor 11 receives such flickering illumination and outputs a light receiving voltage 17 having a waveform as shown in FIG. The smoothing circuit 12 smoothes the received light voltage,
The average received light voltage 18 shown in FIG. In this figure, the symbol A indicates the average light receiving voltage level.

On the other hand, the pulse detection circuit 13 detects the light receiving voltage 1
A pulse component is extracted from the pulse No. 7 and a pulse 19 having the waveform shown in FIG. If the pulse 19 is detected, the selector 14 outputs this to the amplifier 16. When the room light is a light source that does not blink, such as an incandescent lamp, the pulse 19 is not detected, and the oscillator 15 detects this and detects the same frequency (5) as that of the fluorescent lamp.
(0 Hz) pulse oscillation (similar to FIG. 2C) is started. In this case, the selector 14 selects an output pulse of the oscillator 15 and inputs the output pulse to the amplifier 16. And the amplifier 16
From this, an amplified pulse 20 as shown in FIG. 2D is output and input to the adder 30.

The adder 30 adds the average received light voltage 18, the amplified pulse 20, the manual brightness adjustment signal 38, and the contrast adjustment signal 39, and outputs an addition signal 31 shown in FIG. input. In this figure, the symbol B indicates the sum of the manual brightness adjustment signal 38 and the contrast adjustment signal 39. The addition signal 31 is amplified by an amplifier 32 and input to a backlight device 34 as a luminance adjustment voltage 33.

FIG. 3 shows the backlight device 34. As shown in this figure, the luminance adjustment voltage 33 is input to the inverter 41. This inverter 41 has 3
An oscillator 42 that oscillates at a frequency of 5 kHz is built in, and controls the lighting of the fluorescent tube 43 with an amplitude waveform of 35 KHz having the waveform of the luminance adjustment voltage 33 as an envelope.

FIG. 4A shows a blinking waveform of the indoor fluorescent lamp, and FIG. 4B shows a high-frequency voltage waveform applied between the two electrodes of the fluorescent tube 43 from the inverter 41. As shown in this figure, the “bright”
The amplitude of the luminance adjustment voltage 33 is large in a portion synchronized with the “.”, And small in a portion synchronized with “dark”. This
If the amplitude is reduced in the “dark” part,
And turn on the fluorescent tube at the peak level of the brightness adjustment voltage 33
Compared to the case where control is performed, the amplitude of the “dark”
The actual brightness of the backlight decreases in accordance with the decrease. I
However, during the “dark” corresponding period of the luminance adjustment voltage 33,
Is the same cycle as the flickering of
Is the backlight (fluorescent
The decrease in the brightness of the tube is not recognized. Therefore, the user
The peak level of the brightness adjustment voltage 33 for all periods in terms of quality
The same visual feeling as controlling the lighting of fluorescent tubes with a bell
On the other hand, the energy supplied to the fluorescent tube 43 is smaller than that in the case where the lighting control is performed at the peak level of the luminance adjustment voltage 33 for all periods only in the shaded portions in the figure. As a result, power consumption can be reduced. Moreover, in this case, since the blinking of the indoor fluorescent lamp and the pulse timing of the luminance adjusting voltage 33 are completely synchronized, there is no decrease in the visual sense due to flickering of the display screen.

On the other hand, even when the interior light does not flicker like an incandescent lamp, as described above, the oscillation output of the oscillator 15 is selected and the pulse-like adjustment voltage waveform is supplied to the inverter 41. Therefore, the backlight device 34, the interior light is similarly control the lighting system in the case of fluorescent lamps. As a result, power consumption is saved as in the case described above. Of course, also in this case, the power supply to the backlight is thinned out at a frequency of about 50 Hz.
The user does not recognize the brightness drop during the thinning
Quality is not compromised.

In this embodiment, the commercial power frequency is 5
Although the case of 0 Hz has been described, the present invention is not limited to this, and it can be used for any other frequency (for example, 60 Hz) without any circuit change or the like. This is because a pulse component is extracted from the ambient light and amplitude control synchronized with this is performed.

In this embodiment, since the adder 30 adds the contrast adjustment signal 39 in addition to the automatic brightness adjustment signal, the brightness adjustment related to the state of the contrast can be performed. In this case, for example, when the surroundings are bright, slightly lower the contrast and increase the brightness,
Controls such as slightly increasing the contrast and lowering the brightness when dark are conceivable. Of course, the contrast at this time can also be automatically adjusted by the same method as described above.

In the present embodiment, the adder 30 also adds the manual brightness adjustment signal 38, so that fine adjustment according to the user's preference is possible.

It is to be noted that the present apparatus can be constituted by using a microcomputer instead of the automatic brightness adjustment signal output circuit 10, the adder 30, and the amplifier 32 in FIG. 1. In this case, the same effect as above can be obtained. Of course you can get it.

[0027]

According to the first aspect of the present invention, the dimming voltage of the backlight is controlled to increase or decrease according to the average level of ambient light detected on the display panel surface and the flicker of the ambient light. As a result, the power supplied to the backlight can be saved, and the power consumption of the entire apparatus can be effectively reduced. Moreover, since the thinning of the supply power is performed in synchronization with the flickering of the ambient light, there is no problem that the visual perception of the user is lost. Further, since the backlight adjustment is performed automatically in synchronization with the blinking frequency of the ambient light regardless of the blinking frequency of the ambient light, there is an effect that the backlight adjustment can be directly applied to various commercial power supplies.

According to the second aspect of the present invention, when the ambient light does not flicker and no pulse component is detected from the sensor on the display panel surface, a pulse from the oscillator is used to synchronize the backlight with the pulse. Since the dimming voltage is controlled to increase or decrease, even in the case of an incandescent lamp or the like in which ambient light does not flicker, power consumption can be reduced in the same manner as in claim 1 without impairing visual perception. This has the effect. In other words, when the surroundings are bright under incandescent or natural light,
Also, the dimming voltage only when the pulse obtained from the oscillator is at the H level
Control to increase the amplitude of the
In addition, the power consumption can be reduced.

According to the third aspect of the invention, in addition to the automatic adjustment, the dimming voltage level of the backlight can be controlled to be increased or decreased manually, so that it is possible to delicately respond to the user's preference. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a display panel backlight adjusting device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing signal waveforms at various parts of the display panel backlight adjusting device of FIG. 1;

FIG. 3 is a block diagram showing the backlight device in FIG. 1;

FIG. 4 is an explanatory diagram showing a relationship between flickering timing of ambient light and a high-frequency voltage waveform applied to a fluorescent tube from an inverter in FIG. 3;

[Explanation of symbols]

 Reference Signs List 10 automatic brightness adjustment signal output circuit 11 light receiving sensor 12 smoothing circuit 13 pulse detection circuit 14 selector 15 oscillator 16, 32 amplifier 30 adder 34 backlight device 36 LCD panel 41 inverter 43 fluorescent tube

Continuation of the front page (72) Inventor Toshiaki Miyake 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-2-309316 (JP, A) JP-A-63-94228 (JP, A) JP-A-62-125329 (JP, A) JP-A-4-352128 (JP, A) JP-A-4-254820 (JP, A) JP-A-3-92820 (JP, A) Kaihei 2-102523 (JP, U) (58) Fields studied (Int. Cl. ⁷ , DB name) G09F 9/00 G09G 3/18 G02F 1/133

Claims (3)

(57) [Claims] 1. A display device having a backlight for illuminating a display panel, comprising: an illuminance detection sensor that detects illuminance on the display panel surface; and a pulse detection unit that detects a pulse component from an output of the illuminance detection sensor. And the average received light level obtained from the output of the illuminance detection sensor
Control the dimming voltage supplied to the backlight according to
And a pulse detected by the pulse detecting means.
The dimming voltage when the pulse component is at the H level according to the component
Display panel backlight adjustment apparatus characterized by comprising a light control means for increasing or decreasing control the dimming voltage, the so amplitude expanding. 2. A display device having a backlight for illuminating a display panel, comprising: an illuminance detection sensor for detecting illuminance on the display panel surface; and a pulse detection means for detecting a pulse component from an output of the illuminance detection sensor. An oscillator that outputs a pulse of a predetermined frequency; and when a pulse component is detected from the output of the illuminance detection sensor by the pulse detection unit, the detected pulse is selected, and when the pulse component is not detected. Means for selecting a pulse output from the oscillator, and an average light receiving level obtained from the output of the illuminance detection sensor.
Control the dimming voltage supplied to the backlight according to
And the H level of the pulse selected by the selection means.
Display panel backlight adjustment apparatus characterized by comprising a light control means for increasing or decreasing control the dimming voltage, the so amplitude expansion of the dimming voltage at the bell. 3. The display panel backlight adjusting device according to claim 1, further comprising a manual dimming unit capable of controlling a level of the dimming voltage supplied to the backlight manually.