JP2818915B2 - Portable information processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laptop or notebook personal computer having a liquid crystal display with a backlight such as a cold-cathode tube (in this specification, including a sidelight) as a display unit. The present invention relates to a portable information processing device such as a computer and a word processor.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing an electrical configuration of a conventional portable information processing apparatus of this kind.

In the figure, 2 is a CPU, 4 is a ROM, 6
Is a RAM, 8 is a keyboard, 10 is a floppy disk drive, 12 is a hard disk drive, 14 is a VRAM, 1
6 is a display control unit, 18 is an AND gate, 20 is a liquid crystal display panel (LCD), 22 is a backlight (BL), 24
Is an inverter circuit for converting DC to AC, and 26 is an inverter circuit for adjusting the brightness of the backlight 22.
4, a manual volume control (variable resistor) to adjust the output
28 is a printer interface, 30 is an RS-232C interface connected to a modem for communication, and 32 is an expansion slot.

Next, the operation of the portable information processing apparatus will be described with reference to flowcharts shown in FIGS. In the drawing, the symbols “BLOFF” and “LCDOFF” indicate the backlight 22 and the liquid crystal display panel 20, respectively.
Means control signal. Further, in this specification, for convenience of notation, "/" is used instead of a bar indicating an active row provided above each symbol BLOFF and LCDOFF, and
It is represented as BLOFF, / LCDOFF.

FIG. 6 is a flow chart of the initial setting. At step n1, the backlight-off signal / BLOFF and the liquid crystal display-off signal / LCDOFF are both set to "H" level.

As a result, the inverter circuit 24 becomes active and the backlight 22 is turned on, and the AND gate 18 becomes conductive so that the liquid crystal display panel 20 becomes a display state.

[0007] The brightness of the backlight 22 can be adjusted by operating a manual volume control 26.

In step n2, the variable OFFTIME is set to 2
Set to minutes. The reason why the variable OFFTIME is set to a relatively short value of 2 minutes is that the portable information processing apparatus is assumed to be battery-driven like a laptop type word processor. That is, if two minutes elapse without any operation, the backlight 22 and the liquid crystal display panel 20 are turned off, and preparations are made to minimize battery consumption. Note that the variable O
The setting of the FFTIME time can be changed.

At step n3, the access flag is reset to "0". Then, in step n4, the above-mentioned OFFTIME (two minutes) is set as a timer setting. This is because a timer interrupt shown in FIG. 8 is generated every time the time (two minutes) set in the variable OFFTIME elapses. This completes the initial setting.

FIG. 7 shows related operations during the access processing. At step n11, an input operation on the keyboard 8 and a read /
When there is a write access, a read / write access to the hard disk device 12, or a read / write access to the VRAM 14, the access flag is set to "1". In step n12, both the backlight off signal / BLOFF and the liquid crystal display / off signal / LCDOFF are set to "H" level. That is, since some access has been made, the lighting state of the backlight 22 and the display state of the liquid crystal display panel 20 are continued.

At step n13, OFFTIME (2
Resets and initializes the timer that counts minutes. Then, the process proceeds to execution of a process corresponding to each access.

When the timer counts up OFFTIME (two minutes), the process proceeds to a timer interrupt processing routine shown in FIG. In step n21, it is determined whether or not the access flag is set to "0". If there is an access within the past two minutes and the access flag is set to "1", the process proceeds to step n22, and the access The flag is reset again to “0”. Then, the interrupt processing ends, and the process returns to the original step of the main routine.

If it is determined in step n21 that no access has been made within the past two minutes, and therefore the access flag is still set to "0", step n2
Proceeding to 3, the backlight / off signal / BLOFF and the liquid crystal display / off signal / LCDOFF are both inverted to "L" level. As a result, the inverter circuit 24 becomes inactive and the backlight 22 is turned off, and the AND gate 18 becomes non-conductive so that the display state of the liquid crystal display panel 20 is released.

As described above, OFFTIME (for example, 2
If there is no access for a certain period of time (minutes), the liquid crystal display panel 20 and the backlight 22 are automatically turned off.

[0015]

However, if the set time (OFFTIME) for automatically turning off the liquid crystal display panel 20 and the backlight 22 is long, power is wasted, and in particular, the power However, when the battery is a battery, the life of the battery is shortened, which is a problem.

Conversely, if the set time is shortened, the user is using the information processing device, but is thinking for a while, or has temporarily left his seat, so that access is performed for the set time or more. If not, the liquid crystal display panel 20 and the backlight 22 will be turned off against the user's intention despite being in use, which is extremely inconvenient.

When any key is operated on the keyboard 8 again by the resume function despite such an auto-off function, the process proceeds from step n11 to step n12, where the backlight 22 is turned on and the liquid crystal display panel 20 is turned on. Can be set to the same screen display state as when turned off.

However, if such auto-off and key input in a state where the screen display is turned off are repeated, not only is the usability extremely bad, but also the power consumption is increased.

It is considered that the cause of such inconvenience is that there are only two states of turning on and off the liquid crystal display panel and the backlight, and the system cannot control an intermediate state between them.

The present invention has been made in view of such circumstances, and it is possible to minimize the inconvenience that the liquid crystal display panel and the backlight are turned off against the user's intention, while minimizing the inconvenience. The purpose is to reduce power consumption.

[0021]

SUMMARY OF THE INVENTION A portable information processing apparatus according to the present invention comprises a liquid crystal display panel with a backlight and an inverter circuit for adjusting the brightness of the backlight. A digital potentiometer is provided as adjusting means for the inverter circuit, and when there is no access for more than a predetermined time, the output of the inverter circuit is reduced by one step, and such a state where there is no access for more than the predetermined time. Means for controlling the digital potentiometer so that the output of the inverter circuit is returned to the initial state when access is made within a predetermined time while repeating the stepwise output decrease of the inverter circuit; Turn off the backlight and liquid crystal display panel when the number of times is exceeded It is characterized in that a stage.

[0022]

When there is no access for more than a predetermined time, the digital potentiometer is controlled to reduce the output of the inverter circuit by one step to lower the brightness of the backlight by one rank, thereby suppressing power consumption in the backlight. Further, when there is no access for more than a predetermined time, the same operation is repeated to further lower the brightness of the backlight by one rank, thereby further suppressing power consumption. When the number of times of no access exceeding the predetermined time exceeds the predetermined number of times, that is, when the set time elapses, the backlight and the liquid crystal display panel are automatically turned off and the power consumption is reduced. Sever.

When an access is made within a predetermined time in the above-mentioned stepwise dimming state, the output of the inverter circuit is returned to the initial state by controlling the digital potentiometer, and the brightness of the backlight is returned to the original state. .

Even if the set time is relatively long, low power consumption is achieved by the stepwise dimming of the backlight, and the set time can be increased, so that
It is possible to allow time for shifting from temporary suspension of access to resumption of access for thinking and the like, and it is easy to avoid a situation in which the liquid crystal display panel and the backlight are suddenly turned off against the user's intention.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a portable information processing apparatus according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an electrical configuration of a portable information processing apparatus (notebook type personal computer) according to the embodiment.

In the figure, reference numeral 2 denotes a CPU (central processing unit) for controlling the entire system, 4 denotes a ROM (read only memory) storing a program for the control,
Reference numeral 6 denotes a RAM which assists control and functions as a working memory and a user memory for storing data.
(Random access memory), 8 is a keyboard as an input device, 10 is a floppy disk device (FDD),
12 is a hard disk drive (HDD), 14 is a VRAM
(Video RAM), 16 is a display controller (liquid crystal driver), 18 is an AND gate, 20 is a liquid crystal display panel (L
CD), 22 is a backlight (BL), 24 is an inverter circuit for converting DC to AC, and 26a is a backlight 2
2, a digital potentiometer for adjusting the output of the inverter circuit 24 to adjust the brightness; 28, a printer interface; 30, an RS-232C interface connected to a modem for communication; and 32, an expansion slot.

The difference from the conventional example shown in FIG. 5 is that in the conventional example, the output of the inverter circuit 24 and thus the brightness of the backlight 22 are adjusted by a manual volume control (variable resistor) 26. In contrast, in the embodiment of the present invention,
A digital potentiometer 26 which is an IC capable of setting a resistance value according to a value set in an internal register.
This is the point using a. The input of the set value to the internal register is performed from the CPU 2.

Next, the operation of the portable information processing apparatus (notebook type personal computer) will be described with reference to the flowcharts shown in FIGS.

First, the operation of the initial setting will be described with reference to the flowchart of FIG. In the case of a notebook-type personal computer, the brightness of the backlight 22 and the time (OFFTIME) from the start of no access to the turning off of the liquid crystal display panel 20 and the backlight 22 are first determined (for example, when installing application software). Must be set. This is generally performed using utility software for initial setting of the state of the system, usually called setup.

Here, as an example, the backlight 22
Brightness to 80%, time until display disappears (OFFTI
ME) is set for two minutes. In this case, a data value corresponding to 80% is stored in the internal register of the digital potentiometer 26a. Also,
Regarding the brightness level of the backlight 22, the initial setting value (80%), 75% of the initial setting value, and 50 of the initial setting value
%, 25% of the initial set value, and five steps of turning off the light.

In the flowchart of FIG. 2, in step S1, both the backlight off signal / BLOFF and the liquid crystal display / off signal / LCDOFF are set to "H" level.

As a result, the inverter circuit 24 becomes active, the backlight 22 is turned on, and the AND gate 18 becomes conductive, so that the liquid crystal display panel 20 enters the display state.

In step S2, 80% is set as an initial setting value BLo of the brightness of the backlight 22, and a variable B for setting the brightness of the backlight 22 is set.
A variable OFFT that sets the initial setting value BLo to L and sets the time from the start of no access to the disappearance of display.
Set IME to 2 minutes. The setting is made as short as two minutes because the notebook computer is driven by a battery. The value of the initial setting value BLo and the value of the variable OFFTIME can be freely changed.

In step S3, "4", which is obtained by subtracting one step of turning off light from five steps, is set as a variable N indicating the number of steps of stepwise light reduction. Next, in step S4, the access flag is reset to "0". Then, in step S5, the above-mentioned OFFTIME (2
For example, 30 seconds which is 1/4 of the minute) is set. This is because a timer interrupt shown in FIG. 4 is issued every time the timer set time (30 seconds) elapses. This completes the initial setting.

When the initial setting is completed, the application software is started. The user gives various commands by input operation of the keyboard 8. The CPU 2 executes an access relating to a predetermined control operation in accordance with the command and the program in the ROM 4, and an operation at an initial stage during the access processing will be described with reference to a flowchart of FIG.

In step S11, the CPU 2 performs an input operation on the keyboard 8, a read / write access to the floppy disk device 10, a read / write access to the hard disk device 12, or a VR.
When there is a read / write access to the AM 14, the access flag is set to "1".

Next, at step S12, the backlight
Off signal / BLOFF and liquid crystal display / off signal / LCDO
Both the FFs are set to the “H” level, and the variable BL for setting the brightness of the backlight 22 is set to the initial setting value BLo (= 80%). That is, since there has been any access, the lighting state of the backlight 22 at the initial setting value BLo and the display state of the liquid crystal display panel 20 are continued.

Further, in step S13, a variable N indicating the number of steps of the dimming of the backlight 22 is set to "4", and in step S14, a timer which counts OFFTIME (two minutes) is reset. To initialize. Then, the process proceeds to execution of a process corresponding to each access.

When the timer is set to the timer (30 seconds = OFFTI)
When ME / 4) is counted up, the process proceeds to the timer interrupt processing routine of FIG.

In step S21, it is determined whether or not the access flag is set to "0".
If there is an access within seconds and the access flag is set to "1", the process proceeds to step S22, where the access flag is reset again to "0". And
The interrupt processing ends, and the process returns to the original step of the main routine.

In the judgment of step S21, the past 30
If there is no access within seconds, and therefore the access flag remains set to "0", step S
At 23, the variable N indicating the number of steps of the stepwise dimming of the backlight 22 is decremented (N ← N−1). As a result, N = 3 in the first decrement. In step S24, it is determined whether or not the variable N has become "0". If yes, the process proceeds to step S26; otherwise, the process proceeds to step S25. If N = 3, 2, 1, the process proceeds to step S25.

In step S25, the CPU 2 sets an initial set value B as a variable BL indicating the brightness of the backlight 22.
The result obtained by multiplying Lo by N / 4 is substituted (BL ← BL
oxN / 4). BLo = 80%, and at the first time, N
= 3, the resulting variable BL has an initial set value BLo
(= 80%), that is, BL = 80 × 3/4
= 60%. The CPU 2 transfers the variable BL indicating the brightness of the backlight 22 after the resetting to the internal register of the digital potentiometer 26a and stores it.
As a result, the frequency of the inverter circuit 24 is reduced, and the brightness of the backlight 22 is reduced by 25% compared to the original brightness. This exits the timer interrupt processing routine and returns to the original step of the main routine.

Hereinafter, it is assumed that the state of no access continues.

Subsequently, the timer counts up 30 seconds (the state of no access continues for 60 seconds).
The process proceeds to the timer interrupt processing routine from step S21, N = 2 is set by decrement in step S23, and the process proceeds to step S25 from step S24, where the initial setting value BLo ( = 80%) is multiplied by 2/4, that is, BL = 80 × 2/4 = 40% is set, transferred to the internal register of the digital potentiometer 26a, and stored. As a result, the frequency of the inverter circuit 24 is further reduced, and the brightness of the backlight 22 is reduced by 50% compared to the original brightness.

When the timer continuously counts up 30 seconds (the state of no access continues for 1 minute and 30 seconds), N = 1 is set in the decrement of step S23, and in step S25, the variable BL is set as a variable BL. BL = 8
0 × １ ／ = 20% is set, transferred to the internal register of the digital potentiometer 26a, and stored.

As a result, the frequency of the inverter circuit 24 is further reduced, and the brightness of the backlight 22 is reduced by 75% compared to the original brightness.

If the timer continues counting up 30 seconds and the state of no access continues for 2 minutes from the start of no access, then N = 0 is set in the decrement of step S23. Proceed to S26.

At step S26, the backlight
Off signal / BLOFF and liquid crystal display / off signal / LCDO
FF are both inverted to “L” level. This allows
The inverter circuit 24 becomes inactive, the backlight 22 is turned off, and the AND gate 18 is turned off, so that the display state of the liquid crystal display panel 20 is released.

At any point before the two minutes elapse, an input operation on the keyboard 8, a read / write access to the floppy disk device 10, a read / write access to the hard disk device 12, or a VRAM 14 If there is any access such as read / write, step S
In step S11, the access flag is set to "1", and in step S12, a variable BL indicating the brightness of the backlight 22 is set again to the initial set value BLo (= 80%) and stored in the digital potentiometer 26a. The backlight 22 will return to the initial 80% brightness. Also, in step S14, OFF
The timer counting TIME (2 minutes) is also reset and initialized.

Even after the backlight 22 is turned off and the display on the liquid crystal display panel 20 is turned off, if the user performs any key input with the keyboard 8, the process proceeds to step S.
The process proceeds from step 11 to step S12, where the backlight 22
Is turned on with the initial set value BLo (= 80%), and the liquid crystal display panel 20 is set to the display state.

As described above, when there is no access for more than a predetermined time (30 seconds), the backlight 22 is dimmed stepwise, and finally, the backlight 22 and the liquid crystal display panel 20 are turned off. However, if there is any access during the stepwise dimming, the backlight 22 is returned to the original brightness, so that the power consumption can be reduced and the life of the battery can be extended. Also, OFF
If TIME is set longer, the user
You have more time to think without manipulating or to temporarily sit up. That is, it is easy to avoid a situation in which the liquid crystal display panel 20 and the backlight 22 are suddenly turned off against the user's intention.

The initial setting value BLo of the brightness of the backlight 22, OFFTIME until the display is turned off, a variable N indicating the number of steps of the backlight 22 stepwise dimming, and a time until the timer interrupt processing routine is entered. The count time and the like can be set arbitrarily.

[0054]

As described above, according to the present invention, when there is no access for more than a predetermined time, the backlight is dimmed stepwise, and finally the backlight and the liquid crystal display panel are turned off. While the backlight is turned off, the backlight is returned to the original brightness when it returns to the state with access, so even if the set time from the start of no access to off is longer, power consumption is reduced. While trying to
The usability can be improved by reducing the possibility that the liquid crystal display panel and the backlight will disappear against the user's intention.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a portable information processing device (notebook type personal computer) according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment.

FIG. 3 is a flowchart for explaining the operation of the embodiment.

FIG. 4 is a flowchart for explaining the operation of the embodiment.

FIG. 5 is a block diagram showing an electrical configuration of a conventional portable information processing device (notebook type personal computer).

FIG. 6 is a flowchart for explaining the operation of the conventional example.

FIG. 7 is a flowchart for explaining the operation of the conventional example.

FIG. 8 is a flowchart for explaining the operation of the conventional example.

[Explanation of symbols]

 2 CPU (Central Processing Unit) 10 Floppy Disk Device 12 Hard Disk Device 14 VRAM (Video RAM) 16 Display Control Unit 18 AND Gate 20 Liquid Crystal Display Panel 22 Backlight 24 Inverter Circuit 26a Digital Potentiometer

Claims (1)

(57) [Claims] 1. A liquid crystal display panel with a backlight,
A portable information processing device comprising an inverter circuit for adjusting the brightness of the backlight, wherein a digital potentiometer is provided as adjusting means for the inverter circuit, and the inverter circuit is provided when there is no access for more than a predetermined time. The output of the inverter circuit is reduced by one step, and when such a state of no access exceeding a predetermined time repeats, the output of the inverter circuit is reduced stepwise while the access of the inverter circuit is reduced within a predetermined time. Means for controlling the digital potentiometer so as to return to an initial state; and means for turning off the backlight and the liquid crystal display panel when the number of repetitions exceeds a predetermined number. Information processing device.