JP2002123235A - Power source control method for picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the power source of a picture display device properly in accordance with the operation state of a keyboard and the state of a display picture. SOLUTION: This method is the power source control method of a picture display device which is provided with a liquid crystal panel, a back light irradiating the panel with rays of light, a first power source to be used for driving of the panel and a second power source to be used for the irradiation of the back light and which performs picture display based on picture data to be inputted and the method is provided with a first step which, when the inputting of keyboard data is not performed for a prescribed period, generates a first control signal after the prescribed period and stops the first power source based on the first control signal and a second step which, when input picture data do not change, generates a second control signal and stops the second power source based on the second control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control method for an image display device for saving energy of the image display device.

[0002]

2. Description of the Related Art In recent years, with the increase in energy consumption in office buildings, there has been an increasing demand for energy-saving computer and monitor equipment which are becoming larger. In addition, regulations for the purpose of energy saving have been enacted by several organizations. According to the regulation of the energy-saving monitor, the power consumption of the monitor becomes 3 hours after a certain time has been set since the computer operator last used the keyboard.
It must be possible to set the energy saving monitor so that it becomes 0 W or less.

[0003] Various methods are conceivable in order to satisfy such regulation items. For example, if a change has been made to a part of the computer equipment that supplies the image signal and a certain time has elapsed since the operator stopped using the keyboard,
The information is superimposed on the monitor synchronization signal. Then, the monitor decodes the information and performs control to forcibly reduce the power consumption of the monitor itself based on the information. A part of a computer device for supplying an image signal is changed, and when a certain time has elapsed since the operator stopped using the keyboard, the image data is changed to predetermined data and output to a monitor. The monitor identifies the image data and performs control to forcibly reduce the power consumption of the monitor itself when predetermined image data is continuously transmitted for a certain period of time. It is determined whether or not the image data from the computer device that supplies the image signal has changed on the monitor side, and if the change has not occurred for a certain period of time, control is performed to forcibly reduce the power consumption of the monitor itself.

[0004]

However, in the conventional low power consumption mode, there is only a method of controlling the monitor to the low power consumption mode in response to the power consumption mode request from the computer or the television according to the above method. There is no method for shifting to the low-consumption mode at the discretion of the monitor itself. This means that, even if it is desired to shift to the low power consumption mode at the request of the monitor itself, it is not possible to shift to the low power consumption mode without a low power consumption mode request signal from the computer or the television. Therefore, for example, a function of shifting to the low power consumption mode in as short a cycle as possible to extend the life of the backlight in the monitor cannot be realized.

In the case of a monitor having a memory function, for example, a ferroelectric liquid crystal panel display monitor or a plasma display monitor, if there is no change in image data input, part or all of the power supplied to the monitor is cut off. Since the display data does not disappear, if there is no change in the image data, the power supply to the monitor can be cut off to realize the low power consumption mode. However, in order to enhance this effect, it is necessary not only to wait for a request from a computer or the like, but also to enable the monitor to shift to the low power consumption mode as described above. However, this was not possible with the prior art.

Further, the above-mentioned method requires a new function to be added to a computer or television system, and even if an old computer or television system has a low power consumption mode function on the monitor side. I can not cope.

[0007] Further, in the above-described system alone, even if the user does not press the keyboard, if the cursor blinks or the clock is displayed, the image data always changes, so that the mode cannot be shifted to the low consumption mode. Such a problem arises.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image display apparatus having a plurality of power supplies, which can shift to a low power consumption mode at the discretion of the display apparatus itself in view of the problems of the prior art. It is another object of the present invention to control the on / off of each power supply independently and change the display or non-display state according to the cause of shifting to the low power consumption mode.

[0009]

In order to achieve this object, a power supply control method for an image display device according to the present invention comprises a liquid crystal panel, a backlight for illuminating the liquid crystal panel, and a first power supply used for driving the liquid crystal panel. And a second power supply used to illuminate the backlight, the power supply control method for an image display device performing image display based on input image data, wherein input of keyboard data has not been performed for a predetermined period. Generating a first control signal after the predetermined period;
The first power supply is stopped based on the control signal
And generating a second control signal when the input image data has not changed, and stopping the second power supply based on the second control signal. Features.

It is preferable that the first and second control signals are further observed, and the first and second steps are controlled in a priority order according to the detected control signal. For example, the first and second control signals are generated substantially simultaneously, or the first control signal is generated and the first control signal is generated before the control by the second control signal (the stop of the second power supply) is performed. When the control signal is generated, the control based on the first control signal (stop of the second power supply) is executed instead of the control by the second control signal.

[0011]

According to this structure, when no keyboard data has been input for a predetermined period, the first power supply is stopped after the predetermined period. When the input image data has not changed, the second power supply is stopped. That is, the transition to the low power consumption mode having different contents is performed according to the cause of the transition to the low power consumption mode. Therefore, a predetermined low power consumption specification can be satisfied, and further power saving can be achieved.

[0012]

FIG. 1 is a block diagram showing a system having a display device according to an embodiment of the present invention. In the figure, 20 is a monitor, 1 is a computer or a television for supplying image data to the monitor 20, and 2 is a computer or a television 1
A synchronizing signal generating unit for superimposing a signal requesting the monitor 20 to shift to the low power consumption mode on the monitor synchronization signal, from when the user stops performing keyboard input to when the low power consumption mode is executed. , A keyboard as an input device of the user, 5 a decoding unit for detecting a low power consumption mode from a synchronization signal sent from the computer or the television 1, and 7 an image meaning the low power consumption mode An image data setting unit 6 in which data is set in advance is used to compare image data sent from the computer or the television 1 with arbitrary image data from the image data setting unit 7 to detect the low power consumption mode. A rewriting detection unit 8 for detecting a change amount of image data sent from the computer or the television 1 9 rewriting determination unit determines whether the change of the image data by the one or noise image data is rewritten, the condition setting unit 10 that sets the criteria for the rewrite determining unit 9, 11 decoding section 5, detector 6,
And a timer group for receiving three types of low power consumption mode transition signals sent from the rewrite determination unit 9 and setting a time until transition to the low power consumption mode for each mode. A timer setting unit 13 receives each low power consumption mode transition signal from the timer group 11 and sends a low power consumption mode transition signal to the panel controller 15. A control unit 14 cancels the low power consumption mode. The release unit 15 receives each low power consumption mode transition signal from the control unit 13 and
A panel controller for controlling each of the power supplies, 16 is a power supply for driving the panel, 17 is a power supply for the backlight,
18 is a power supply for the panel controller 15, 19 is a panel unit (panel, panel drive circuit, backlight),
Reference numeral 21 denotes a switching unit necessary for changing the control method of the control unit 13. FIG. 2 shows the control unit 13 and the timer setting unit 1
FIG. 2 is a block diagram of a timer group 11 and the like. As shown in the figure, the timer setting unit 12 and the timer group 11 have three timer setting units and three timers connected to them, in response to each low power consumption mode transition signal.

Next, a procedure for shifting to the low power consumption mode will be described in detail. In the monitor 20,
The control unit 13 receives control signals (shift signals) for shifting to the first to third three low power consumption modes, and the panel controller 1 based on the control signals and information in the control unit 13.
5 is transferred to each mode of low power consumption.

First, a procedure for generating a control signal (transition signal) in the first low power consumption mode will be described. The computer or the television 1 measures the time from when the user stops pressing the keyboard 4 with the timer 3, and when a certain time has elapsed, the synchronization signal generation unit 2 superimposes the low power consumption mode on the synchronization signal. As a method thereof, the pulse width of the synchronization signal may be changed according to each low power consumption mode, or the level of the synchronization pulse may be changed. The monitor 20 receives the synchronizing signal, and the power consumption mode decoding unit 5 detects each low power consumption mode from its pulse width and level. The detected information is the timer group 1
1 and the information is sent to the control unit 13 after a time according to the setting of the timer setting unit 12.

Next, a procedure for generating a control signal in the second low power consumption mode will be described. The computer or the television 1 measures the time from when the user no longer presses the keyboard 4 with the timer 3 and, when a certain time has elapsed, converts the image data between the monitors into predetermined image data. On the other hand, the monitor 20 sets the above-described predetermined image data in the arbitrary image data setting unit 7. The monitor 20 compares the image data sent from the computer or the television 1 with the image data set by the image data setting unit 7 in the arbitrary image data detection unit 6 and, if they are the same, sets the low power consumption mode. Recognizing that, the information is sent to the timer group 11. The timer group 11 sends the information to the control unit 13 after a time according to the timer setting of the timer setting unit 12.

The first and second low power consumption modes are released when the user presses the keyboard 4 again, or when the user accesses the computer or the television 1 connected to the monitor 20 via a network from outside, and obtains the image. This is done when data is changed. When these are detected, the synchronization signal and the image data are changed to the normal mode in the computer or the television 1, respectively. Then, a release signal is thereby generated in the low power consumption mode decoding unit 5 and the arbitrary image data detection unit 6, respectively, and transferred to the control unit 13 via the timer group 11. When the control unit 13 receives the release signal, the information is transmitted to the panel controller 15 and the various turned off power supplies are turned on.

Next, a procedure for generating a control signal in the third low power consumption mode will be described. The monitor 20 monitors the image data from the computer or the television 1 at any time and rewrites the amount of change in the image data by the rewriting detection unit 8 irrespective of the information after the user stops pressing the keyboard 4 from the computer or the television 1. To detect. That is, the level of the image data of the previous frame stored in the frame memory for one frame is compared with the level of the current image data at the same position, and the difference is detected. Alternatively, the difference may be detected by comparing the characteristics of the image, for example, the vertical and horizontal change rates of the image data and the run length of the image data with those of the previous frame. When the above difference is detected, data indicating the size of the difference is sent to the rewrite judging unit 9. The rewrite determination unit 9 determines whether the difference in the transmitted image data is due to extraneous noise,
It is determined whether the data has been rewritten by the user. Normally, the condition for shifting to the low power consumption mode is only when the difference between the image data is zero. However, when the image data sent from the computer or the TV 1 is data having an analog value, Even if the user does not rewrite the image data when the noise is superimposed, a slight change in the image data is detected, so that a control signal for shifting to the low power consumption mode cannot be generated. Therefore, in consideration of the noise, when the difference between the image data is smaller than the value set by the condition setting unit 10, it is determined that there is no change in the image data, and the information indicating the low power consumption mode is sent to the timer group 11. The timer group 11 sends the information to the control unit 13 after a time according to the timer setting unit 12.

The control unit 13 observes the above three low power consumption mode control signals at any time, and transfers an optimal low power consumption control signal for the panel unit 19 to the panel controller 15. That is, as shown in FIG. 2, the control unit 13 has a priority order and simple combination logic means for the three low power consumption mode control signals to be inputted, and thereby, the panel controller 15 Can be changed. For example, by giving a priority order, the panel driving power source 1 is controlled by the third low power consumption mode control signal.
After the control unit 13 receives the first low power consumption mode control signal after transferring the signal for controlling the turning off of the control panel 6 to the panel controller 15 or when the transfer is attempted, the first low power consumption mode control is performed. The low power consumption control signal of the panel specified by the signal is transferred. According to this, since the execution request of the low power consumption mode from the computer or the television 1 can be prioritized, it is effective in satisfying the standard specification of the low power consumption mode determined in the computer or the television 1. Further, the provision of the combinational logic means enables control according to the specification level regarding low power consumption of the computer or the television 1 connected to the monitor 20. For example, if the monitor 20 is connected to a computer or the television 1 that does not satisfy the specification for superimposing the low power consumption mode on the synchronization signal for generating the first low power consumption mode control signal,
By taking the AND of "0" with the low power consumption mode control signal, the control unit 13 does not receive an erroneous control signal. Further, for example, when it is desired to enable all of the first, second, and third low power consumption modes, O
This can be realized by taking R.

The control unit 13 transfers a necessary low power consumption control signal to the panel controller 15 according to the above-described priority and combination logic. The priority and the combination logic are controlled by a microcomputer constituting the control unit 13, and can be externally changed by the user by the switching unit 21.

Further, the control section 13 has a function of releasing the low power consumption mode by the monitor 20 itself. This is because the mode shifts to the low power consumption mode by the third low power consumption control signal, and when the backlight power supply 17 is off, the user can check the display contents even when the image data does not change. Required if you want to. The user forcibly releases the low power consumption mode by the release unit 14 having a device such as a switch attached to the monitor 20,
The backlight can be turned on. Of course, when any change in the image data is determined by the rewrite determination unit 9, the determination signal is sent to the control unit 13,
The control is transferred to the panel controller 15 via the control line in FIG. 1C to turn on the backlight power supply 17. Therefore, the panel controller 1 required for release
The power supply 18 for 5 is kept on at any time irrespective of the control of the control unit 13.

The contents of the low-power-consumption control signal include a panel power supply off, a backlight power off, and both power supplies off. This transfer may be performed via the dedicated control signal line c, or may be superimposed on a part of the image data bus d for transferring the image data to the panel controller 15. In FIG. 1, the image data to the panel controller 15 is transferred from the rewrite detection unit 8. This is only necessary if a monitor having a memory function such as a ferroelectric liquid crystal panel receives only the image data of the rewritten portion. For good,
The monitor having no memory may receive the image data directly from the computer or the television 1. The panel controller 15 can receive a control signal at any time, but has a control unit for controlling the timing when the panel drive power supply 16 is turned off. This is effective for a device such as a liquid crystal panel that causes deterioration of the panel when a DC voltage is applied. The panel controller 15 does not immediately turn off the power when it receives the control signal for turning off the panel driving power, but performs the writing when one line has been written and the writing voltage has disappeared between the panels. This prevents DC voltage from being applied to the panel.

[0022]

As described above, according to the present invention, when input of keyboard data has not been performed for a predetermined period,
After the predetermined period, the first power supply is stopped. When the input image data has not changed, the second power supply is stopped. That is, the transition to the low power consumption mode having different contents is performed according to the cause of the transition to the low power consumption mode. Therefore, a predetermined low power consumption specification can be satisfied, and further power saving can be achieved, and the life of the display device, particularly, the backlight can be extended.

[Brief description of the drawings]

FIG. 1 is a block diagram of a monitor system (display device) according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control unit for controlling low power consumption of the monitor system of FIG. 1 and a peripheral part thereof;

[Explanation of symbols]

1: computer or television, 2: synchronization signal generation unit, 3: timer, 4: keyboard, 5: decoding unit,
7: image data setting unit, 6: detection unit, 8: rewrite detection unit, 9: rewrite determination unit, 10: condition setting unit, 11: timer group, 12: timer setting unit, 13: control unit, 14: release unit , 15: panel controller, 16: power supply for panel drive, 17: power supply for backlight, 18:
Power supply for panel controller 15, 19: panel unit, 20: monitor, 21: switching unit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/34 G09G 3/34 J

Claims (2)

[Claims] An image data comprising a liquid crystal panel, a backlight for illuminating the liquid crystal panel, a first power supply for driving the liquid crystal panel, and a second power supply for illuminating the backlight. A power supply control method for an image display device that performs image display based on the following, when input of keyboard data has not been performed for a predetermined period,
A first step of generating a first control signal after the predetermined period and stopping the first power supply based on the first control signal; and a second step of, when input image data has not changed, A power control method for an image display device, comprising: a second step of generating a control signal and stopping the second power supply based on the second control signal. 2. The method according to claim 1, further comprising observing the first and second control signals and controlling the first and second steps in a priority order according to the detected control signal. A power supply control method for an image display device as described in the above.