JPH07294877A - Display back light controller - Google Patents

Abstract

PURPOSE:To automatically enable controlling the lighting and turning off of a back light and also to appropriately maintain the lighting state of the back light even though the exposure state of an external light is changed complicatedly by a surrounding environment by detecting the external light. CONSTITUTION:A threshold value setting part 4 stores a first light quantity level set for lighting a back light 5 and a second light quantity level set for turning off the light. A back light control part 3 compares the external light quantity detected by a photosensor 1 with respective light quantity levels being in the threshold value setting part 4 and controls the lighting and turning off of the back light 5 according to the compared result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display backlight control device for turning on / off a backlight for illuminating a light-receiving display section such as a liquid crystal display panel in electronic equipment such as a handy terminal.

[0002]

2. Description of the Related Art Conventionally, as a display backlight control device, a backlight is turned on / off by a method of turning on the electronic device at the same time as turning on the backlight or by a user operating a specific switch as needed. A method of making it known is known.

[0003]

However, the former has a drawback that the life of the backlight and the power supply battery is shortened because the backlight is kept on while the power is on, and the latter is dark. There were drawbacks such as difficulty in operating switches at locations. Therefore, it is conceivable to install an optical sensor and automatically turn on / off the backlight by detecting the external light, but it is a binary state of dark or bright depending on complicated changes in the surrounding environment and how the light hits. When the backlight is turned on / off, the lighting / extinguishment is remarkably repeated and the backlight blinks in some cases, which causes a problem that the readability is extremely deteriorated. An object of the present invention is to detect the external light and automatically control the turning on / off of the backlight. Even if the external light hits in a complicated manner depending on the surrounding environment, the lighting state of the backlight is appropriately adjusted. It is to be able to maintain.

[0004]

The means of the present invention are as follows. (1) The level setting means includes a first light amount level for illuminating the backlight for illuminating the light-receiving type display portion and the first light amount level.
The second light intensity level for lighting the backlight is set to a value higher than the light intensity level of, and even if the light intensity level is fixed in advance, it may be arbitrarily set by the user. It may be. (2) The detection means is an optical sensor that detects the amount of external light. (3) The comparing means compares the light quantity detected by the detecting means with each light quantity level set in the level setting means. (4) The control means controls the turning on / off of the backlight according to the comparison result of the comparison means.

[0005]

The operation of the means of the present invention is as follows. Now, in a state where the first and second light intensity levels are set, when the light intensity of the external light reaches the first light intensity level (when the surroundings become dark), the backlight is turned on and the second light intensity level is set. When the surroundings become bright enough to reach, the backlight is turned off. Therefore, in addition to being able to detect the external light and control the turning on / off of the backlight automatically,
It is possible to appropriately maintain the lighting state of the backlight even when external light strikes in a complicated manner due to the surrounding environment.

[0006]

[First Embodiment] A first embodiment will be described below with reference to FIGS. FIG. 1 is a block diagram of a display backlight control device. The optical sensor 1 is composed of, for example, a cds photo sensor or the like, and detects the amount of external light. The data conversion unit 2 is an A / D converter, which converts the light amount detection signal from the optical sensor 1 into digital numerical value data and gives it to the backlight control unit 3. The backlight control unit 3 has a configuration including a data comparator, a driver, etc., compares the light amount taken from the data conversion unit 2 with a preset value set in the threshold setting unit 4, and depending on the comparison result. The backlight 5 is turned on / off. The backlight control unit 3 operates according to an operation command signal output from the CPU 6 at regular intervals.

The threshold value setting unit 4 stores a threshold value for turning on / off the backlight 5 according to the amount of external light that strikes the optical sensor 1, and the CPU 6 is a value arbitrarily input by a user or the like. Threshold setting section 4
Write in. Here, a threshold value representing a first light amount level for turning on the backlight 5 and a threshold value indicating a second light amount level for turning off the backlight 5 are set in the threshold value setting unit 4. And each light level is second
Light intensity level> first light intensity level. At this time, the user needs to set each light amount level in consideration of the actual use environment and the like, and also set the second light amount level in consideration of the influence of the lighting of the backlight 5. The backlight 5 is a small fluorescent tube that illuminates the liquid crystal display unit 7, and illuminates the entire display screen of the liquid crystal display unit 7 that outputs display data from the CPU 6.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 2 is a diagram showing a control timing for turning on / off the backlight 5 according to the external light amount. In the figure, the light amount is a first light amount level for turning on the backlight 5, and the light amount is a second light amount for turning off the backlight 5. The light intensity level is set in the threshold value setting unit 4 in advance by a user or the like. Now, the CPU 6 operates the backlight control unit 3 at regular intervals. Then, the backlight control unit 3 compares the external light amount from the data conversion unit 2 with each set value in the threshold value setting unit 4, and determines whether the external light amount is equal to or lower than the first light amount level or the second light amount. Detects whether the level is above the level. As a result, when the surroundings become dark and the external light amount becomes equal to or lower than the first light amount level, the backlight control unit 3 turns on the backlight 5. In this case, the backlight control unit 3 determines that the external light amount is the first
The backlight 5 is turned on while the light intensity level is 1 or less, and if the external light amount is less than the second light amount level even if the surroundings become bright, the backlight 5 is continuously turned on as it is and the second light amount level or more. When it becomes, the backlight 5 is turned off. Therefore, even if the amount of external light fluctuates drastically due to the surrounding environment or the like, the backlight lighting period is not affected by the fluctuation and is as illustrated.

[0009]

[Second Embodiment] A second embodiment will be described below with reference to FIGS. In this embodiment, the CPU 6 controls the turning on / off of the backlight 5 by software, and the other points are substantially the same as those in the first embodiment. In this case, the CPU 6 operates the optical sensor 1, the data conversion unit 2, and the backlight drive unit 8 at regular intervals, and sets the external light amount from the data conversion unit 2 and the threshold value setting unit 4. The respective threshold values corresponding to the first and second light amount levels are compared with each other, and a backlight ON / OFF signal is given to the backlight drive unit 8 in accordance with the comparison result.
FIG. 4 is a flowchart showing the backlight control process, in which the optical sensor 1 and the data conversion unit 2 are operated at regular intervals to capture the external light amount (step S1), and the contents of the threshold value setting unit 4 are referred to. It is checked whether the external light quantity is below the first light quantity level (step S2) or above the second light quantity level (step S3). As a result, a backlight ON signal is given to the backlight drive unit 8 when the first light amount level or less is detected (step S4), and a backlight OFF signal is sent when the second light amount level or more is detected. (Step S5).
In this way, the turning on / off of the backlight 5 is controlled under the control of the CPU 6.

In the above embodiment, only the case where the control of the backlight 5 is controlled according to the amount of external light is shown. Of course, the function of turning on / off the backlight 5 by operating an external switch is also used. You may do it. In this case, if the switch operation is prioritized over the control according to the external light amount, the backlight 5 can be turned on at any time as needed, and the backlight 5 is turned on according to the external light amount. In this state, even if the external light amount is less than the second light amount level, the backlight 5 can be turned off immediately after confirming the display content.

If the backlight 5 is turned on in accordance with the amount of external light, the timer starts the time counting operation, and the backlight 5 is automatically turned off after the time set by the timer elapses. Even when the state of less than the light amount level of 2 continues for a long time, the backlight 5 can be automatically turned off after a certain time has elapsed from its lighting. Further, the present invention is not limited to the liquid crystal display unit, and can of course be applied to those that illuminate other light receiving display units.

[0012]

According to the present invention, in addition to being able to detect the external light and automatically control the turning on / off of the backlight, even if the contact condition of the external light changes in a complicated manner due to the surrounding environment, etc. The lighting state can be appropriately maintained, which is effective for a portable electronic device such as a handy terminal and is highly practical.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a display backlight control device according to an embodiment.

FIG. 2 is a diagram showing a lighting / extinguishing timing of a backlight according to an external light amount.

FIG. 3 is a block configuration diagram of a display backlight control device according to a second embodiment.

FIG. 4 is a flowchart showing the operation of the second embodiment.

[Explanation of symbols]

 1 Optical Sensor 2 Data Conversion Section 3 Backlight Control Section 4 Threshold Setting Section 5 Backlight 6 CPU 7 Liquid Crystal Display Section 8 Backlight Driving Section

Claims (1)

[Claims] 1. A level setting for setting a first light amount level for lighting a backlight for illuminating a light-receiving type display unit and a second light amount level for lighting a backlight higher than the first light amount level. Means, detecting means for detecting the light quantity of the external light, comparing means for respectively comparing the light quantity detected by this detecting means with each light quantity level set in the level setting means, and the comparison result of this comparing means Lighting of the backlight according to
A display backlight control device comprising: a control unit that controls turning off.