JPH075861A - Display device - Google Patents

Abstract

PURPOSE:To prevent burning of a display and reduce power consumption by detecting brightness around the display with a sensor and using its value for controlling a luminance signal. CONSTITUTION:This device is constituted with a sensor section 10 which detects brightness around a display, a detecting section 30 which detects variation of the condition of the display, a time measuring section 40 which measures nonvariation time of the display condition, and a luminance signal control section 20 which controls a luminance signal by a value from the sensor section and a value from the time measuring section, the luminance signal control section reduces the maximum luminance level at every constant interval of time as far as the display condition is not varied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a display device using a screen saver system.

[0002]

2. Description of the Related Art Conventionally, in a display device, the brightness level of the display is set to zero (black level) when the display content of the display does not change for a fixed time (for example, 10 minutes). As a result, when the operator leaves the terminal while leaving the terminal, burn-in of the display is prevented, and power is prevented from being consumed wastefully while leaving the seat (conventional example 1).

Further, Japanese Patent Laid-Open No. 59-33492 discloses that
The operator's chair is equipped with a detector that detects whether the operator is seated or not, and when the operator leaves the desk for a certain period of time, the screen display is fixed at a black level, and when the operator is seated, the display is resumed to achieve the same purpose. (Conventional example 2).

[0004]

In order to further reduce the power consumption in the first conventional example, it is necessary to shorten the time from when the display content of the display does not change until the screen falls to the black level. However, in reality, since the operator may be thinking while looking at the display, it is not possible to make this time too short, and there is a limit in reducing power consumption.

In the second conventional example, not only a special chair is required, but the operator continues to sit down for another job in this chair while causing the computer connected to the display to execute a time-consuming job. Since the display does not automatically go to black level, the operator has to operate the switch of the display to reduce the maximum brightness level on the screen to black level before doing another work in the chair. It is annoying.

It is an object of the present invention to solve the above-mentioned problems, and to provide a display device which is preferable to a man-machine interface and which can further reduce power consumption.

[0007]

A display device according to the present invention includes a display section for displaying an image signal, a state detection section for detecting a change in the display state of the display section, and an output of the state detection section indicating that the display state has not changed. A time length measuring means for continuously measuring the time and detecting whether or not the measurement result exceeds a predetermined value,
When the time length measuring means resets the measurement result every time a predetermined value is exceeded and reduces the maximum luminance level of the display section, and the state detection section output indicates that there is a change, the maximum value of the display section is changed. And a brightness signal control unit for returning the brightness level to the initial value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a flow chart for explaining the operation of this brightness signal control section.

As shown in FIG. 1, the embodiment of the present invention includes a sensor 10 for detecting the brightness around the display, a display section 50 for displaying on the screen based on display data supplied from the external terminal 1. A state detection unit 30 that detects whether or not the display content of the screen has changed based on the display data;
When the output of the state detection unit transits to the display contents unchanged, the time measurement is started, and the measured value is reset when the reset signal 24 is supplied from the brightness signal control unit, and when the measured value reaches the predetermined value T, Based on the time length measuring unit 40 that outputs a signal 42 indicating that, the sensor output 12, the state detecting unit output 34, and the time length measuring unit output 42, a control signal 25 that controls the brightness level of the display unit, and a reset signal. And a luminance signal control unit for outputting 24.

The state detecting section 30 may have various configurations according to the configuration of the display section 50 and the display section input signal from the terminal 1. First, when the display has a built-in backup memory for the display and only the rewriting information of the backup memory is supplied from the terminal 1, the state detecting section 30 includes a circuit for detecting only the presence or absence of the rewriting information. You can use it. Further, when the digital video signal is constantly supplied from the terminal 1, the state detection unit is composed of a frame memory for writing the digital video signal and a comparator for comparing the input and output of the frame memory and detecting a change in display content. Can be configured. Further, when a CPU (not shown) outputs change information indicating a change in display content, the function itself of this CPU also functions as the state detection unit, so that a special circuit from the state detection unit is used. Is unnecessary. In addition, it is appropriate to consider that the display content is changed when the information such as the password is not displayed on the display even if the key is input.

The time length measuring section can be composed of a counter and a comparator. That is, the reset signal 24 is connected to the reset terminal of the built-in counter, the state detector output 34 is connected to the enable terminal, and the clock source (not shown) is connected to the clock input terminal. Also, the counting result is
It is supplied to one of the built-in comparators. The comparator compares the count result with a predetermined value input to the other input and outputs a signal 42.

The display section controls the maximum brightness level on the screen based on the control signal from the brightness signal control section 20.
This control can be realized, for example, by changing the gain of the video amplifier incorporated in the display unit 50.

Next, with reference to FIG. 2, the operation of one embodiment of the present technology, particularly the operation of the luminance signal control section 20, will be described.

The operation of FIG. 2 is step S1 when the power is turned on.
Start with.

In step S1, the brightness signal controller 2
0 receives the brightness around the display device detected by the sensor 1, and sets the initial value of the brightness level that is the most visible according to the brightness.

In step S2, the presence or absence of a change in the display content of the screen is detected based on the output 34 of the state detection unit. If there is a change, the process returns to step S1. If there is no change, the process proceeds to step S3, the time length measuring unit 40 starts time measurement, and the process proceeds to step S4.

In step S4, it is determined based on the output 34 of the state detection unit whether or not the screen display contents have changed. If there is no change in the display, the process proceeds to step S5, and if there is a change, the process proceeds to step S11. When the process proceeds to step S11, the measurement result of the time length measuring unit is reset, and then the process returns to step S1.

In step S5, the luminance signal control section (hereinafter, "control section") 20 determines from the time length measurement section output 42 whether or not the measurement result has passed the predetermined value T.
If the predetermined value T has not elapsed, the operation of the control unit returns to step S4. If the predetermined value T has passed, step S
Go to 6.

In step S6, in order to lower the maximum brightness level by, for example, a fixed value, a control signal indicating a new maximum brightness level is sent to the video amplifier built in the display unit 50 to lower its gain. As a result, each time the time T elapses, the maximum brightness level is lowered by a constant value. next,
The operation of the control unit 20 proceeds to step S7.

In step S7, the control section 20 determines whether or not the maximum brightness level set in step S6 is below a predetermined value. If it exceeds the predetermined value, the control unit 20 sends a reset signal 24 to the time length measuring unit to reset the measurement result in step S10, and returns to step S3. In this way, steps S3, S4, S
As a result of the loop processing of 5, S6, S7, and S10, the maximum brightness level on the screen becomes lower every fixed time T unless the screen content changes.

When it is determined in step S7 that the maximum brightness level is lower than the predetermined value, the operation of the controller 20 proceeds to step S8. In step S8, the gain of the video amplifier in the display unit 50 is set to the minimum so that the maximum brightness level substantially matches the black level. After this, the control unit 2
The operation of 0 proceeds to step S9.

In step S9, the control unit 20 determines based on the state detection unit output 34 whether or not the display content of the screen has changed. If there is no change in the determination result, the operation of the control unit is in the standby state in step S9. If there is a change in the determination result, the control unit 20 supplies the reset signal 24 to the time length measuring unit 40 in step S11, and then returns to step S1.

FIG. 3 schematically shows the effect of reducing power consumption according to the present invention. In FIG. 3, the vertical axis represents the maximum brightness level, and the horizontal axis represents the elapsed time after there is no change in the display content on the screen. The maximum brightness level on the vertical axis is a relative value with respect to the value set in step S1 of FIG. In FIG. 3, for example, assuming that T = 2 minutes, the broken line in the drawing shows the control result of the maximum brightness level in Conventional Example 1, and the broken line shows the control result in the present invention. It will be easily understood that in the present invention, the power consumption is reduced as compared with the conventional example 1 by the amount corresponding to the area of the hatched portion in FIG.

Further, in step S1 of FIG. 2, the initial value is determined according to the output of the sensor 10, so that the initial value can be set to the brightness that is the most visible on the display screen according to the brightness around the display.

In the above description, the maximum brightness level is reduced by a constant value each time the time T elapses. However, in the present invention, the maximum brightness level may be reduced by a constant ratio instead. Good.

[0026]

As described above, the present invention has a control function of monitoring the time when the display state of the display does not change and gradually lowering the brightness level according to the elapsed time, so that it is superior to the conventional operator. In addition to providing a man-machine interface, it is possible to prevent display burn-in and further reduce power consumption.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of one embodiment of the present invention, in particular, the operation of the luminance signal control unit.

FIG. 3 is a diagram for explaining the effect of the present invention.

[Explanation of symbols]

 10 sensor section 20 luminance signal control section 30 state detecting section 40 time measuring section 50 display section

Claims (4)

[Claims] 1. A display unit for displaying an image signal, a state detection unit for detecting a change in the display state of the display unit, and a time period during which the output of the state detection unit continuously indicates that the display state has not changed, and the measured time. Time length measuring means for detecting whether or not the result exceeds a predetermined value, and resetting the measurement result each time the measurement result of the time length measuring means reaches a predetermined value, and reducing the maximum brightness level of the display section. And a brightness signal control unit for returning the maximum brightness level of the display unit to the initial value when the output of the state detection unit indicates a change. 2. The display device according to claim 1, further comprising a sensor for detecting brightness around the display, wherein the brightness signal control unit determines the initial value according to the sensor output. 3. The display device according to claim 1, wherein the brightness signal control unit reduces the maximum brightness level by a constant value when the measurement result reaches a predetermined value. 4. The display device according to claim 1, wherein the brightness signal control unit reduces the maximum brightness level by a constant ratio each time the measurement result reaches a predetermined value.