JP2003215533A - Information display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure visibility without regard to an external light incident angle. <P>SOLUTION: This information display device is provided with a display part 16 for displaying information via a liquid crystal display surface, a front light 162 for irradiating the liquid crystal display surface from its back surface and/or side surface with illumination light, a first illumination sensor 24 and a second illumination sensor 26 for obtaining the incident angle of external incident light incident on the liquid crystal display surface, a CPU 11 for operating based on an operation program and controlling the display part 16 and the front light 162. The CPU 11 controls the luminance of the illumination light from the front light 162 on the basis of the incident angle obtained by the first illumination sensor 24 and the second illumination sensor 26. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information display device which forms a liquid crystal display surface by a reflective liquid crystal display element or a hybrid liquid crystal display element, and is particularly suitable for application to a portable information terminal.

[0002]

2. Description of the Related Art In recent years, information terminals suitable for carrying such as so-called mobile computers and PDAs (hereinafter referred to as portable information terminals) have been widely developed. A liquid crystal display is adopted for these portable information terminals from the viewpoint of realizing weight reduction and thickness reduction.

A liquid crystal display uses a reflective liquid crystal display element as a light modulation element or a hybrid liquid crystal display element that uses both reflected light and transmitted light of a backlight. Generally, these liquid crystal display elements have the best visibility when the incident angle of external light is perpendicular to the liquid crystal display surface as shown in FIG. 9 or an angle slightly deviated from the perpendicular. .

[0004]

However, because of the convenience of carrying these portable information terminals, these portable information terminals are used not only in a specific place such as work or home but also in various places. In particular, when the portable information terminal is installed in an automobile, the portable information terminal is often used with an inclination such that the incident angle of external light becomes low with respect to the liquid crystal display surface as shown in FIG. The incident angle of outside light is not always almost vertical.

If the incident angle of external light deviates significantly from the vertical, the amount of reflected light of the liquid crystal display element becomes low, and as a result, there is a problem that the visibility is significantly deteriorated.

Therefore, the present invention has been proposed in view of the above-mentioned circumstances, and in an information display device employing a liquid crystal display, the information display device can ensure the visibility regardless of the incident angle of external light. The purpose is to provide.

[0007]

The present inventor pays attention to the amount of reflected light of a liquid crystal display element which changes according to the incident angle of external light, and can always ensure the visibility regardless of the incident angle of external light. The information display device was invented.

That is, the information display device according to the present invention is
In order to solve the above-mentioned problems, display means for displaying information via a liquid crystal display surface, illuminating means for irradiating illumination light from the back surface and / or side surface of the liquid crystal display surface, and the liquid crystal display surface An incident angle detecting means for detecting an incident angle of light incident from the outside and a control means for operating the display means and the illuminating means by operating based on an operation program are provided, and the control means detects the incident angle. The brightness output of the illumination light emitted from the illumination means is controlled based on the incident angle detected by the means.

This information display device detects the incident angle of light incident from the outside on the liquid crystal display surface, and controls the luminance output of the illumination light emitted from the illumination means based on the detected incident angle.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The present invention is applied to a portable information terminal 1 as shown in FIG. 1, for example. In FIG. 1, a mobile information terminal 1 includes a CPU (Central Processing Unit) 11,
Data bus 12, ROM 13, DRAM 14, graphic controller 15, display unit 16, PWM
Driver 17, display converter 18, power button 19, battery 20, DC / DC converter 2
1, an operation button 22, an LED 23, a first illuminance sensor 24, a first A / D converter 25, a second illuminance sensor 26, a second A / D converter 27, and a regulator 28. And an infrared communication controller 29.

The CPU 11 is a central processing unit that controls the entire portable information terminal 1, and a ROM 13 that stores a control program to be executed via the data bus 12.
Also, it is connected to the DRAM 14 as a work area used for storing and expanding data. Also, this CPU 11
First illuminance sensor 24 and / or second illuminance sensor 26
Based on the external incident light detected by the data bus 12
And the display unit 16 via the graphic controller 15.
To control. Further, the CPU 11 transmits the information disclosed to the user to the display unit 16 via the graphic controller 15 and the like.

In addition to the control program, the ROM 13 stores a database for calculating latitude and longitude based on map data and address. In addition, the DRAM 14
Always stores personal management data regardless of whether the main power supply is ON or OFF.

The graphic controller 15 is a CPU
Under the control of 11, the painting processing on the display unit 16 is executed. This graphic controller 15 is a PWM
Through the driver 17, the contrast and brightness of the display unit 16 are adjusted.

The display unit 16 comprises a liquid crystal display element 161, a front light 162, and a touch panel 163, and is an interface for the user to interact with the portable information terminal 1.

The liquid crystal display element 161 is, for example, a reflective liquid crystal display element or a light modulation element including a hybrid liquid crystal display element that uses both reflected light and transmitted light of a backlight, and a liquid crystal that displays information to the user. Configure the display surface. When this liquid crystal display element 161 is used with an inclination such that the incident angle of external light becomes low with respect to the liquid crystal display surface, the amount of reflected light becomes low, resulting in poor visibility. Therefore, the visibility of the liquid crystal display is secured by illuminating the liquid crystal display surface with the front light 162.

The touch panel 163 is a resistance film type panel that changes the output voltage according to the pressed area. The touch panel 163 is pressed by the user in accordance with areas such as menus and operation icons displayed on the liquid crystal display device 161, and is used as an input tablet when handwritten character recognition is performed.

The display converter 18 is connected to the CPU 11 and the touch panel 163, and the touch panel 163 is connected.
The output voltage from is detected and converted into digital data,
It is transmitted to the CPU 11.

The power button 19 is arranged outside the portable information terminal 1, and when pressed by the user, the CPU 11
Is notified to the power input.

The battery 20 is a built-in unit for supplying driving power to the entire portable information terminal 1.
The battery 20 may be composed of, for example, a lithium secondary battery. Power is supplied from the battery 20 to the CPU that detects the pressing input of the power button 19 described above.
It is controlled based on 11.

The DC / DC converter 21 includes the CPU 11
Based on the control by, the power supplied from the battery 20 is converted into a power supply voltage required for each device constituting the mobile information terminal 1. In addition, this DC / DC converter 2
1 supplies power to the front light 162 for illumination.

The operation button 22 is a button for pressing and inputting when changing the display contents on the display unit 16. That is, by depressing the operation button 22, it is possible to change to a predetermined display content, for example, from a state of displaying a schedule table to a state of displaying a map.

The LED 23 is a light emitting element for notifying the user of the state of the portable information terminal 1, and is turned on when the power is input and turned off when the power is turned off.

The first illuminance sensor 24 is the portable information terminal 1
Is a light receiving element for detecting the illuminance of light incident from the outside. The first illuminance sensor 24 transmits the detection result to the CPU 11 via the first converter 25.

The second illuminance sensor 26 is arranged so that the direction different from that of the first illuminance sensor 24 described above is set as the detection direction, and detects the illuminance of light incident on the portable information terminal 1 from the outside. Is a light receiving element. The second illuminance sensor 26 outputs the detection result to the C converter via the second converter 27.
It transmits to PU11.

The regilator 28 supplies power to devices such as the CPU 11 and the DRAM 14 that require backup in the power-off state.

The infrared communication controller 29 is a controller for transmitting and receiving data by optical communication with an external device. The infrared communication controller 29 inputs / outputs data to / from the external device to / from the CPU 11 and the like via the connected data bus 12. The portable information terminal 1
May have an interface for transmitting and receiving data to and from an external device via USB.

Next, the outer shape of the portable information terminal 1 will be described with reference to FIG.

The external dimensions of the portable information terminal 1 are, for example, width 7
1.0mm, height 118.5mm, depth 16.8mm
The size is set so that it can be easily carried. As shown in FIG. 2, the user touches the touch panel 163, the power button 19, and the operation button 22 from outside the mobile information terminal 1.
And the like.

Further, in the example shown in FIG. 2, the first illuminance sensor 24 is provided at a position capable of detecting external light incident from the front of the liquid crystal display surface, and the second illuminance sensor 26 is provided on the liquid crystal display surface. It is provided at a position where external light incident from the vertical direction can be detected. That is, the first illuminance sensor 24 and the second illuminance sensor 26 are arranged so that the direction angle difference is 90 °.

Next, a specific processing procedure of the portable information terminal 1 to which the present invention is applied will be described.

When the user uses the portable information terminal 1,
First, the illuminance of the incident external light is detected by the first illuminance sensor 24 and the second illuminance sensor 26. Since the illuminance detected by the first illuminance sensor 24 and the illuminance detected by the second illuminance sensor 26 differs depending on the inclination of the liquid crystal display surface with respect to external light,
When the detected illuminance of the illuminance sensor 24 is Xf and the detected illuminance of the second illuminance sensor 26 is Xu, the detected illuminance ratio Xu / X
f can be expressed as a function of the incident angle of external light on the liquid crystal display surface.

That is, by always detecting the illuminance ratio Xu / Xf, the incident angle of external light can be detected in real time. Further, by presetting the optimum brightness output Br of the front light 162 with respect to this incident angle of external light, the brightness output of the front light 162 can be controlled in real time.

FIG. 3 shows the luminance output Br of the front light 162 preset with respect to the illuminance ratio Xu / Xf. In FIG. 3, the first illuminance sensor 24 and the second illuminance sensor 24
The difference in direction angle with the illuminance sensor 26 is 90 °, but the luminance output Br has a linear relationship with the illuminance ratio Xu / Xf.

For example, as the detected illuminance of the first illuminance sensor 24 becomes higher and the detected illuminance of the second sensor 26 becomes lower, in other words, as the illuminance ratio Xu / Xf becomes smaller, the incident angle of external light becomes It approaches vertical as shown in FIG.
In such a case, since the visibility of the liquid crystal display element 161 is sufficiently secured, the luminance output Br of the front light 162 can be low. Therefore, as shown in FIG. 3, when the value of the illuminance ratio Xu / Xf is small, the front light 162 is
If the brightness output Br is set to be low, the liquid crystal display element 161 can be controlled so that the visibility is always ensured.

On the other hand, as the illuminance detected by the first illuminance sensor 24 is low and the illuminance detected by the second illuminance sensor 26 is high, in other words, as the illuminance ratio Xu / Xf is increased, the incident angle of external light becomes. , As shown in FIG. In such a case, the visibility of the liquid crystal display element 161 is not ensured, the illumination by the front light 162 is essential, and it is necessary to increase the luminance output Br. That is, as shown in FIG. 3, if the luminance output Br of the front light 162 is set to be high when the value of the illuminance ratio Xu / Xf is large, the visibility of the liquid crystal display element 161 can be always ensured. Can be controlled.

The luminance output Br shown in FIG. 3 is Xu / X.
Although linear with respect to f, for example, the first illuminance sensor 2
4 and the second illuminance sensor 26 can be freely changed according to the direction angle difference, the mounting position, the usage environment, etc., and may be non-linear.

As described above, the portable information terminal 1 to which the present invention is applied detects the incident angle of light incident on the liquid crystal display surface from the outside, and illuminates light emitted from the illuminating means based on the detected incident angle. Control the brightness output of. As a result, the information display device 1 to which the present invention is applied can ensure the visibility regardless of the incident angle of external light. Further, when the reflection of external light on the liquid crystal display element 161 is sufficient, the brightness output of the front light and the backlight can be reduced, and the power consumption of the portable information terminal 1 as a whole can be reduced.

The present invention is not limited to the above embodiment. For example, as an alternative to the first illuminance sensor 24 and the second illuminance sensor 26, the mobile information terminal 1
It is also possible to use an acceleration sensor (not shown) mounted on the. The portable information terminal 1 including the acceleration sensor (not shown) detects the acceleration of the liquid crystal display surface and calculates the tilt of the liquid crystal display surface according to the detected acceleration. Then, it is possible to predict the incident angle of external light according to the calculated inclination and control the luminance output Br of the front light 162 to always ensure the visibility.

Further, there is a case where the minimum output in the brightness of the front light 162 cannot be secured only by the acceleration sensor (not shown).
It is also possible to use the illuminance sensor 24 and / or the second illuminance sensor 26 together. As a result, the actual illuminance becomes clear, and it is also possible to guarantee the minimum value Br0 of the brightness of the front light 162 as shown in FIG.

Further, not only when controlling the luminance output of the front light 162, but also by controlling the luminance output of the backlight which illuminates from the back surface of the liquid crystal display element, it is possible to always ensure visibility.

Further, in the present invention, as an alternative to the first sensor and the second sensor, for example, as shown in FIG. 7, a first sensor arranged on the bottom surface of a concave portion formed in the vertical direction with respect to the liquid crystal display surface. It is also possible to use the illuminance sensor of No. 3. The third illuminance sensor obtains a high detected illuminance because the light emitted from the external light source goes straight to the third illuminance sensor arranged on the bottom surface of the recess only when the incident angle of the external light is 90 °. be able to. On the other hand, if the incident angle of outside light deviates from 90 ° even a little, as shown in FIG. 8, outside light does not go straight to the third illuminance sensor, and the detected illuminance extremely decreases.

That is, by using one third illuminance sensor in which the detected illuminance changes remarkably with respect to the incident angle of outside light, it is possible to achieve the same level as in the case where both the first illuminance sensor 24 and the second illuminance sensor 26 are used. The incident angle of outside light can be obtained with high accuracy. As a result, the number of sensors used can be reduced, and the efficiency can be further improved. The relationship between the detected illuminance of the third illuminance sensor and the incident angle of external light to be obtained depends on the depth of the recess and the diameter of the recess.
It is controllable.

[0044]

As described above in detail, the information display device according to the present invention detects the incident angle of light incident on the liquid crystal display surface from the outside, and detects the incident angle based on the detected incident angle. It controls the brightness output of the illumination light that is emitted.

As a result, according to the present invention, the visibility can be ensured regardless of the incident angle of external light, and when the reflection of external light on the liquid crystal display element is sufficient, the brightness of the front light or the like can be improved. By suppressing the output, power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a mobile information terminal to which the present invention is applied.

FIG. 2 is a diagram for explaining the outer shape of a portable information terminal to which the present invention has been applied.

FIG. 3 is a diagram showing a luminance output Br of a front light which is preset with respect to an illuminance ratio Xu / Xf.

FIG. 4 is a diagram for explaining an incident angle of external light when the illuminance ratio Xu / Xf is small.

FIG. 5 is a diagram for explaining an incident angle of external light when the illuminance ratio Xu / Xf is large.

FIG. 6 shows an acceleration sensor detection value and a preset brightness output B when an acceleration sensor and an illuminance sensor are used together.
It is the figure which showed r.

FIG. 7 is a diagram showing a case where a third illuminance sensor arranged on the bottom surface of a recess formed in the direction perpendicular to the liquid crystal display surface is arranged.

FIG. 8 is a diagram for explaining a case where external light having an incident angle deviated from 90 ° is detected by a third illuminance sensor.

FIG. 9 is a diagram showing a case where external light enters the liquid crystal display surface vertically or at an angle slightly deviated from vertical.

FIG. 10 is a diagram for explaining a case where the portable information terminal is used with an inclination such that an incident angle of external light becomes low with respect to a liquid crystal display surface.

[Explanation of symbols]

1 portable information terminal, 11 CPU, 12 data bus,
13 ROM, 14 DRAM, 15 graphic controller, 16 display section, 17 PWM driver, 18
Display unit converter, 19 power button, 20 battery, 21 DC / DC converter, 22 operation button, 23 LED, 24 first illuminance sensor, 25 first A / D converter, 26 second illuminance sensor, 27
Second A / D converter, 28 Regulator, 29
Infrared communication controller, 161 Liquid crystal display device, 16
2 front light, 163 touch panel

Claims (4)

[Claims] 1. A display means for displaying information via a liquid crystal display surface, an illuminating means for irradiating illumination light from the back surface and / or side surface of the liquid crystal display surface, and external incident light incident on the liquid crystal display surface. An incident angle detecting means for obtaining an incident angle and a control means for operating the display means and the illuminating means by operating based on an operation program are provided, and the control means controls the incident angle obtained by the incident angle detecting means. An information display device, characterized in that the brightness of illumination light emitted from the illumination means is controlled based on the above. 2. The information display device according to claim 1, wherein the incident angle detecting means obtains the incident angle based on illuminances detected from two directions with respect to the external incident light. 3. The incident angle detecting means detects an acceleration of the liquid crystal display surface, calculates an inclination of the liquid crystal display surface according to the detected acceleration, and obtains the incident angle according to the calculated inclination. The information display device according to claim 1, wherein: 4. The incident angle detecting means is a sensor for detecting the illuminance of the external incident light, which is arranged on the bottom surface of a recess formed in the normal direction of the liquid crystal display surface. Item 1. The information display device according to item 1.