JPH04291227A - Power supply controller for display - Google Patents

Abstract

PURPOSE:To prevent damage to liquid crystal even when power failure is momentarily generated in a liquid crystal display device and to enable normal display by validating power supply after the lapse of prescribed time when the liquid crystal driving power supply is made invalid by the momentary power failure. CONSTITUTION:When the momentary power failure is generated, a power failure detection signal S2 outputted from a power supply part 21 is made valid and made invalid again later. At such a time, a clear signal S1 similarly outputted from the power supply part 21 is not made valid. Further, both a power source V0 for control and a power source V1 for driving the liquid crystal are not made invalid as well. In this case, when it is detected that the power failure detection signal S2 is made valid, a control part 22 instructs a timer monitor part 24 to start counting. The timer monitor part 24 counts time set in advance and after the counting is completed, it is informed of the control part 22. At that time, the control part 22 validates a liquid crystal driving power source V2. Therefore, even when the momentary power failure is generated, the normal display is enabled as long as a system is under an active state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display power control device used in information processing apparatuses such as word processors and personal computers having a liquid crystal display device as a display device.

0002

2. Description of the Related Art Conventionally, many information processing apparatuses such as word processors and personal computers use liquid crystal display devices as display devices. Figure 3
4 is a block diagram showing the configuration of a power supply control device for a liquid crystal display device, and FIG. 4 is a timing chart for explaining the operation of the power supply control device.

In FIG. 3, 11 is a power supply section, 12 is a control section, and 13 is a display section. The power supply section 11 supplies a system-common control power supply V0 to the control section 12 and the display section 13, and also supplies a clear signal S1, a power failure detection signal S2, and a liquid crystal drive power supply V1 to the control section 12. The clear signal S1 is a signal for initializing the entire system. The power outage detection signal S2 is a signal indicating a power outage state. The liquid crystal driving power supply V1 is a power supply for the display section 13 necessary for the control section 12. The control unit 12 receives a control signal S3
and a liquid crystal drive power supply V2 are supplied to the display section 13. The control signal S3 is a signal for controlling the display section 13. The liquid crystal drive power supply V2 is a power supply necessary for the display section 13. The display unit 13 is composed of a liquid crystal display device and performs liquid crystal display.

In such a configuration, when the power is turned on, the power supply unit 11 first enables the control power supply V0 and the liquid crystal driving power supply V1, and after a predetermined time has elapsed, disables the clear signal S1. The control unit 12 sends a clear signal S1
When it is detected that the control signal S3 and the liquid crystal drive power supply V2 are disabled, the control signal S3 and the liquid crystal drive power supply V2 are enabled to prevent damage to the liquid crystal. Further, when the power is cut off, the power failure detection signal S2 is valid, so the control unit 12 detects the power failure detection signal S2 and outputs the control signal S3 and the liquid crystal drive power supply V.
2 to prevent damage to the LCD screen. Control signal S3
becomes invalid when the clear signal S1 becomes valid.

[0005]

By the way, in the conventional power supply control described above, when a momentary power outage occurs, the timing is as shown by the dotted line in FIG. 4. That is, when a momentary power outage occurs, there is a problem in that the control signal S3 and the liquid crystal drive power supply V2 become invalid even though the system is operating, and the display stops.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a display power supply control device that can prevent damage to the liquid crystal and provide normal display even in the event of a momentary power outage. purpose.

[0007]

[Means for Solving the Problems] The present invention detects a momentary power outage state in a display power supply control device that controls power supply to a display unit, disables the power supply to the display unit, and at this time, a timer means is used to A set time is counted, and after the count ends, power supply to the display section is enabled.

[0008]

[Operation] According to the above structure, even if a momentary power outage occurs, display power can be supplied to the display section, and thereby normal display can be performed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A display power control device according to an embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing the configuration of a power supply control device for a liquid crystal display device, and Figure 2
is a timing chart for explaining the operation of the power supply control device.

In FIG. 1, 21 is a power supply section, 22 is a control section, and 23 is a display section. The power supply section 21 supplies a system-common control power supply V0 to the control section 22 and the display section 23, and also supplies a clear signal S1, a power failure detection signal S2, and a liquid crystal drive power supply V1 to the control section 22. The clear signal S1 is a signal for initializing the entire system. The power outage detection signal S2 is a signal indicating a power outage state. The liquid crystal driving power supply V1 is a power supply for the display section 23 necessary for the control section 22. The control unit 22 receives a control signal S3
and a liquid crystal drive power supply V2 are supplied to the display section 23. The control signal S3 is a signal for controlling the display section 23. The liquid crystal drive power supply V2 is a power supply necessary for the display section 23. The display unit 23 is composed of a liquid crystal display device and performs liquid crystal display. Further, in the same embodiment, a timer monitoring section 24 is provided. The timer monitoring section 24 counts a preset time T based on instructions from the control section 22.

Next, the operation of this embodiment will be explained. In addition,
Since the operations at power-on and power-off are the same as conventional ones, the operation when a momentary power outage occurs will be described here.

When a momentary power outage occurs, as shown by the dotted line in FIG.
becomes valid and then invalidated again. At this time, the clear signal S1 output from the power supply section 21 does not become valid. Further, both the control power supply V0 and the liquid crystal driving power supply V1 are not disabled.

Here, the control section 22 outputs a power outage detection signal S2.
When the timer monitoring unit 24 detects that the
instructs to start counting. The timer monitoring unit 24 counts a preset time T according to this instruction, and
After the count ends, the controller 22 is notified of this fact. When the control unit 22 receives this count end notification, it enables the liquid crystal drive power supply V2. As a result, even if a momentary power outage occurs, if the system is in the startup state, the display section 2
The liquid crystal drive power supply V2 is supplied to the display panel 3, and normal display is performed.

[0014]

As described above, according to the present invention, even if a momentary power outage occurs when a liquid crystal display device is used as a display device, damage to the liquid crystal can be prevented and power for display can be supplied. normal display.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a display power control device according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the embodiment.

FIG. 3 is a block diagram showing the configuration of a conventional display power control device.

FIG. 4 is a timing chart for explaining conventional operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 21... Power supply part, 22... Control part, 23... Display part, 24... Timer monitoring part, S1... Clear signal, S2... Power failure detection signal, S3... Control signal, V0... Control power supply, V1...
Liquid crystal drive power supply, V2...Liquid crystal drive power supply.

Claims (1)

[Claims] 1. A display power supply control device that controls power supply to a display section, comprising a power outage state detection means for detecting a momentary power outage state and disabling the power supply to the display section; It is characterized by comprising a timer means for counting a preset time when a power outage condition is detected, and a control means for enabling power supply to the display unit after the timer means finishes counting. Display power control device.