JPH11183901A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lengthen a lighting period of backlight without causing malfunction of a main body circuit in a display device having a back light function of a display screen with an EL(electroluminescence) panel, etc., as a light source in an electronic information equipment. SOLUTION: A backlight 18 of a liquid crystal display(LCD) part 16 is composed of two comb-like halved EL panels (1) 18a and (2) 18b in a backlighting state alternately from the right and left sides of the screen by a regular width in the vertical direction of a display screen, and when an output voltage of a battery powder source 19 is normally 5.5 volts or higher, the two EL panels (1) 18a, (2) 18b are driven to be turned on, but when the battery power source 19 is consumed and the output voltage becomes lower than 5.5 V, an output signal of low level '0' from a voltage detector DET 2 is supplied to AND gate AND 2 and the lighting drive of one EL panel (2) 18b is prohibited, but it is possible to maintain the backlight function by the lighting only of the other EL panel (1) 18a and thereby to halve the power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having a backlight function of a display screen using a panel as a light source in an electronic information device.

[0002]

2. Description of the Related Art Conventionally, in a small information device such as an electronic organizer,
A backlight function of a liquid crystal display screen is realized using an EL (Electro Luminescence) panel or the like as a light source. In general,
The driving of the backlight requires relatively large power consumption, and if the power is shared with the power supply of the control system main circuit, the power supply voltage greatly fluctuates particularly when the light is turned on.
The operation of the main circuit may be adversely affected.

For this reason, when the power source of the backlight is not the power source of the main circuit but a common battery power source, the voltage drop due to the load when the light is lit is considered. The voltage detector detects the electromotive force of the battery power so that the minimum operating voltage of the main circuit is guaranteed, and the lighting of the backlight is prohibited when the battery is exhausted.

That is, in an information device having a large liquid crystal screen size, the area of an EL panel used as a light source for a backlight increases in accordance with the screen size, and the power consumption at the time of lighting is also proportional to the area of the EL panel. Therefore, when the EL panel is turned on and when the EL panel is turned off, the load fluctuates more, and the power supply voltage also fluctuates greatly.

In particular, when a small battery such as a lithium battery is used as a power source, the output voltage level of the power source greatly differs between when the backlight is turned on and when the backlight is turned off, and the difference increases as the battery is consumed. Become.

[0006]

Therefore, in the display device having the conventional backlight function, the detection voltage level of the power supply voltage detector for judging whether the backlight can be turned on or off is appropriately adjusted. Although it is necessary to set, if the detection voltage is set high, the voltage that dropped when the light is turned on is detected and the battery is judged to be exhausted even if the battery is low, and the backlight is prohibited from being turned on. There is a problem that the possible period is shortened.

On the other hand, if the detection voltage of the voltage detector is set to be low, the period during which the backlight can be turned on is prolonged. There is a high possibility that the voltage becomes lower than the minimum operating voltage of the circuit, which causes a problem of malfunction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to provide a display device capable of extending a period in which a backlight can be turned on without causing a malfunction of a main circuit. Aim.

[0009]

That is, the display device according to the first aspect of the present invention is driven by a battery power supply common to the main body circuit, and has a backlight function for illuminating the entire area of the display screen. The device comprises two light source panels that are divided into two in a comb shape in such a manner that an area to be illuminated corresponding to the size of the display screen is alternately interleaved with a certain width in the vertical direction from the right side and the left side of the screen. A backlight, power supply voltage detecting means for detecting a voltage level of the battery power supply, and two light source panels constituting the backlight in accordance with the voltage level of the battery power detected by the power supply voltage detecting means. Backlight control means for separately controlling lighting / non-lighting for each light source panel.

That is, in the display device according to the first aspect of the present invention, the two light source panels divided into two in a comb shape in such a manner as to alternately intersect the right side and the left side of the screen by a constant width in the vertical direction of the display screen. The lighting / non-lighting of each of the two light source panels of the backlight is separately controlled for each light source panel according to the voltage level of the battery power detected by the power supply voltage detecting means. Even if the voltage level of the backlight decreases and the backlight is turned on only by one of the light source panels, the entire display screen can be evenly illuminated, and the operation of the main body can be continued without turning off the backlight entirely. .

The display device according to a second aspect of the present invention is the display device according to the first aspect, wherein the power supply voltage detecting means includes a first voltage lower than a rated voltage of the battery power supply by a predetermined value. Power supply voltage detecting means for detecting whether the voltage level is equal to or higher than a voltage level and a second voltage level lower than the first voltage level; and detecting the backlight control means by the power supply voltage detecting means When the voltage level of the battery power supply is equal to or higher than the first voltage level, lighting control is performed on both of the two light source panels constituting the backlight, and is lower than the first voltage level and equal to or higher than the second voltage level. In this case, the backlight control means controls the lighting of only one of the light source panels, and controls the non-lighting of both of the two light source panels when the voltage is lower than the second voltage level. To.

That is, in the display device according to claim 2 of the present invention, the voltage level of the battery power supply detected by the power supply voltage detecting means is equal to or higher than the first voltage level lower than the rated voltage of the battery power supply by a predetermined value. In some cases, both of the two light source panels constituting the backlight are controlled to be turned on, and when the light source panel is lower than the first voltage level and equal to or higher than the second voltage level lower than the first voltage level, one of them is controlled. When only the light source panel is turned on and the voltage is lower than the second voltage level, both of the two light source panels are turned off, so that the main body can be operated while uniformly illuminating the entire display screen. Voltage level can be maintained as long as possible.

According to a third aspect of the present invention, there is provided a display device which is driven by a battery power supply common to a main body circuit and has a backlight function of illuminating an entire area of a display screen. A backlight comprising two light source panels, which are divided into two in a comb-shape in such a manner that an area to be illuminated corresponding to the size of the screen is alternately interleaved with a predetermined width in the vertical direction from the right side of the screen and the left side of the screen; A power supply voltage detecting means for detecting whether or not a predetermined voltage level which is lower than a rated voltage of the power supply by a predetermined value, and a power supply voltage detecting means in a non-lighting state of two light source panels constituting the backlight; When the voltage level of the battery power supply is equal to or higher than the predetermined voltage level, only one of the light source panels is controlled to be lit, and only one of the light source panels is controlled to be lit. , When the voltage level of the battery power detected by the power supply voltage detecting means is continued over a predetermined voltage level, also other light source panel, characterized by comprising a backlight control unit that controls lighting.

That is, in the display device according to the third aspect of the present invention, the two light source panels divided into two in a comb shape in such a manner as to alternately intersect with the right side and the left side of the screen by a predetermined width in the vertical direction of the display screen. When the voltage level of the battery power supply detected by the power supply voltage detecting means is equal to or higher than a predetermined voltage level lower than the rated voltage by a predetermined value in the non-lighting state of the two light source panels,
Only one of the light source panels is controlled to be turned on, and in a lighting control state of only one of the light source panels, when the voltage level of the battery power detected by the power supply voltage detecting means is still higher than or equal to a predetermined voltage level, the other is controlled. Since the lighting of the light source panel is also controlled, the flickering phenomenon of the light source panel does not occur due to the load fluctuation accompanying the lighting of the light source panel. It is possible to illuminate the entire screen as long as possible while maintaining normal operation of the main body.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a configuration of an electronic information device provided with a display device according to a first embodiment of the present invention.

The electronic information device includes a control unit (CPU) 1
1 is provided. The control unit (CPU) 11 activates a system program stored in the ROM 12 in response to an input signal from an input device (not shown),
Is used as a work memory to control the operation of each part of the circuit. The control unit (CPU) 11 includes the ROM 12,
The RAM 13 is connected via a data bus (DATA BUS) 14 and an address bus (ADDRESS BUS) 15, and a display drive circuit (D / D) 17 of a liquid crystal display (LCD) 16 is connected via the data bus 14. Connected.

The display screen of the liquid crystal display (LCD) 16 includes an EL panel (1) 18a and an EL panel (2) 1.
A backlight 18 according to 8b is provided. FIG. 2 is a diagram showing a configuration of a backlight provided in a liquid crystal display unit of the electronic information device.

The backlight 18 is a comb-shaped two-divided area in which the area to be illuminated corresponding to the size of the display screen is alternately interleaved from the right and left sides of the screen by a certain width in the vertical direction. It consists of an EL panel (1) 18a and an EL panel (2) 18b.
One of the L panel (1) 18a and the EL panel (2) 18b
The power consumption of the panel is about half that of a conventional EL panel in which the entire area of the display screen is backlit with one sheet.

Also, one of the EL panels (1) 18
a or by lighting only the EL panel (2) 18b,
Because of the comb-shaped configuration in which the illumination range is evenly distributed over the entire display screen, sufficient illumination as the backlight 18 is possible.

The control unit (CPU) 11 connected to the data bus 14 and the address bus 15 and the ROM 1
2, a comb-shaped EL panel (1) 18a, an EL panel constituting a backlight 18 and a control system circuit of a device main body including a RAM 13, a liquid crystal display (LCD) 16, and a display drive circuit (D / D) 17 (2) The 18b uses, for example, a 6V battery power supply 19 in which two lithium batteries are connected in series as a common power supply, and a power supply voltage is supplied to each of them via a 5V regulator 20.

The EL panel (1) 18a, EL
The power supply voltage supplied to the panel (2) 18b is adjusted via the corresponding EL power supply ICs 21a and 21b.

On the other hand, the power supply voltage output from the battery power supply 19 has three voltage detectors (open drain type) DET.
0, DET1, and DET2, each of which is detected and monitored as three different voltage levels. The detection voltage of the voltage detector DET0 is less than 4V, the detection voltage of DET1 is less than 5V, and the detection voltage of DET2 is 5. Each of the voltage detectors DET0, DET1, DET2 is set to less than 5V.
Pull-up resistors R0, R1, and R2 are connected to output signal lines from the respective regulators and to a 5 V voltage supply line from the regulator 20.

That is, each of the voltage detectors DET0, DET
1, the output signal from DET2 becomes high level (5V) "1" when the power supply voltage level output from the battery power supply 19 is 5.5V or more and no voltage is detected, and when the voltage drops below 5.5V. When only the output signal of DET2 becomes low level (0V) "0" and drops to less than 5V, the output signal of DET1 also becomes low level (0V) "0" and when it drops to less than 4V, the output signal of DET0 further drops. The output signal also becomes low level (0 V) “0”.

The voltage drop detection signal "1" of less than 5.5 V from the voltage detector DET2 is supplied to the second input AND gate AND2 for on / off control of the EL panel (2) 18b of the backlight 18 for on / off. 1 terminal is supplied as a lighting inhibition signal, and 5V from the voltage detector DET1
The voltage drop detection signal “1” of less than 2 is used for the on / off control of the backlight 18 with respect to the EL panel (1) 18a.
It is supplied as a lighting inhibition signal to the first terminal of the input AND gate AND1, and is further supplied with a voltage of 4 V from the voltage detector DET0.
The voltage drop detection signal “1” less than “1” is output from the control unit (CPU) 1
It is supplied to one input port Port0 as a stop signal for system operation. From an output port Port2 of the control unit (CPU) 11, a first terminal of each of the two 2-input AND gates AND1 and AND2 is
A lighting control signal for each corresponding EL panel (1) 18a, (2) 18b is supplied.

Next, the operation of the display device of the first embodiment in the electronic information device having the above configuration will be described. First, the consumption of the battery power supply 19 is small, and the specified power supply voltage 6 V
Are obtained, three voltage detectors DET0, DET0,
The output signals of DET1 and DET2 are high level (5 level) by the corresponding pull-up resistors R0, R1 and R2.
V) "1" and AND gates AND1 and AN
A high-level "1" signal is supplied to each of the first terminals of D2 and the input port Port0 of the control unit (CPU) 11.

For this reason, the control unit (CPU) 11 controls the system normally and, of course, the two comb-shaped EL panels (1) 18a, 18a,
(2) 18b is connected to the two AND gates AND1, A from the output port Port1 of the control unit (CPU) 11.
Both are turned on by a lighting control signal output to each second terminal of the ND2, and the display screen of the liquid crystal display (LCD) 16 is brightly illuminated.

Then, when the battery power supply 19 is consumed and its output voltage falls to less than 5.5 V, the voltage detector DET2 performs a detection operation and its output signal becomes low level (0 V) "0". , A low-level “0” signal is supplied to the first terminal of the AND gate AND2.
One EL panel (2) 18 in the backlight 18
The lighting drive of b is prohibited, and the other EL panel (1)
Only 18a remains lit.

In this case, the illuminance of the display screen of the liquid crystal display (LCD) 16 as the backlight 18 is reduced by half as compared with the case where both of the two EL panels (1) 18a and (2) 18b are turned on. Since each of the EL panels (1) 18a and (2) 18b is divided into two parts in a comb shape so that the illumination is evenly distributed over the entire area of the display screen, the display screen has no practical problem. Illuminated.

In this case, the backlight 18
The power consumption of the battery power supply 19 is greatly reduced, and the period during which the control unit (CPU) 11 can obtain a power supply voltage that can be normally controlled by the system is greatly extended.

Further, when the battery power supply 19 wears down and its output voltage drops below 5.0 V, DET 1 is also detected in addition to the voltage detector DET 2, and its output signal goes low (0 V). ) "0", and a low-level "0" signal is supplied to the first terminals of the two AND gates AND2 and AND1, so that the backlight 1
8, two EL panels (2) 18b and (1) 18
In both cases, the lighting drive is prohibited and the liquid crystal display (LCD) 16
Is not illuminated.

Thereafter, when the battery power supply 19 further depletes and its output voltage falls below 4.0 V,
DET0 is also detected in addition to the voltage detectors DET2 and DET1, and the output signal thereof becomes low level (0V) "0".
The first terminals of the two AND gates AND2 and AND1 and the input port Por of the control unit (CPU) 11
Since a low-level "0" signal is also supplied to t0, not only the driving of the backlight 18 is prohibited, but also the control operation of the entire system is prohibited.

Therefore, according to the display device of the first embodiment in the electronic information device having the above configuration, the liquid crystal display (L
Backlight 1 for illuminating the display screen of CD) 16
8 are divided into two in a comb shape in such a manner as to be alternately interleaved from the right side and the left side of the screen by a constant width in the vertical direction of the display screen, and two EL panels (1) 18a and EL panel (2) 1
8b, and the output voltage of the battery power supply 19 is 5.5 V
In the above normal state, the two EL panels (1) 18
a and (2) 18b are driven to light up, and when the battery power supply 19 is exhausted and its output voltage falls below 5.5 V, the output signal of low level "0" from the voltage detector DET2 is ANDed. It is supplied to the gate AND2 to prohibit the lighting drive of one of the EL panels (2) 18b and the other EL panel (2) 18b.
By illuminating only the L panel (1) 18a, the power consumption can be reduced by half while maintaining the function as the backlight 18, so that the consumption of the battery power supply 19 is suppressed and the control unit (CPU) 1
1, the time for illuminating the display screen with the backlight 18 can be extended while continuing the normal operation of the system control according to 1.

(Second Embodiment) FIG. 3 is a block diagram showing a configuration of an electronic information device provided with a display device according to a second embodiment of the present invention.

In the first embodiment shown in FIG. 1, the voltage detectors DET1, DET for detecting the degree of consumption of the battery power supply 19 are provided.
Each AND gate AND for setting lighting / non-lighting of each of the two EL panels (1) 18a and (2) 18b in the backlight 18 according to the output signal from T2.
1 and AND2 are directly controlled on / off. As shown in FIG. 3, the two voltage detectors DET
1 and DET2 are output to the control unit (CP
U) The EL panels (1) 18a and EL are supplied from the output ports Port1 and Port2 by program control based on the detection state of the power supply voltage supplied to the input ports Port3 and Port4 of the port 11 and the input ports Port3 and Port4. The lighting / non-lighting control signal may be supplied to each of the EL power supply ICs 21a and 21b for driving the panel (2) 18b.

FIG. 4 is a flowchart showing a backlight control process in an electronic information device equipped with a display device according to the second embodiment of the present invention. That is, the battery power source 1
In a normal state in which the output voltage of the control unit 9 is 5.5 V or more, the corresponding input ports Port0, P of the control unit (CPU) 11 from the three voltage detectors DET0, DET1, DET2.
An output signal of a high level “1” is supplied to each of ort3 and Port4.

In this case, the system control by the control unit (CPU) 11 is normally performed, and the corresponding power supply ICs for EL are output from the output ports Port1 and Port2.
A lighting control signal is supplied to each of the LED panels 21a and 21b, and the backlight 18 includes two EL panels (1) 18
a, (2) Lighting state by 18b.

Then, due to the consumption of the battery power supply 19, its output voltage drops to less than 5.5V, and the voltage detector DET
When a low-level “0” detection signal is supplied to the input port Port 4 of the control unit (CPU) 11 by the detection operation of the control unit (CPU) 11, one of the ELs is output from the output port Port 2.
A lighting prohibition control signal is supplied to the power supply IC 21b, and the driving of the corresponding one of the EL panels (2) 18b is prohibited (steps S1 → S2).

In this case, the illuminance of the display screen of the liquid crystal display (LCD) 16 as the backlight 18 is halved as compared with the case where both of the two EL panels (1) 18a and (2) 18b are turned on. Since each of the EL panels (1) 18a and (2) 18b is divided into two parts in a comb shape so that the illumination is evenly distributed over the entire area of the display screen, the display screen has no practical problem. Illuminated.

In this case, the backlight 18
The power consumption of the battery power supply 19 is greatly reduced, and the period during which the control unit (CPU) 11 can obtain a power supply voltage that can be normally controlled by the system is greatly extended.

Further, when the battery power supply 19 is consumed, its output voltage is reduced to less than 5.0 V, and the control unit (CPU) 1 is newly detected by the voltage detector DET1.
When a low-level “0” detection signal is supplied to any one of the input ports Port4 and Port3, the output port P
The power supply ICs 21 for each EL are also provided from ort2 and Port1.
A lighting prohibition control signal is supplied to b and 21a, and lighting driving of both EL panels (1) 18a and (2) 18b is prohibited (steps S3 → S4).

Therefore, according to the display device of the second embodiment in the electronic information device having the above configuration, the consumption of the battery power supply 19 is suppressed and the control unit (C
While the normal operation of the system control by the PU 11 continues, the time for illuminating the display screen with the backlight 18 can be extended, the hardware configuration of the display device can be simplified, and the size and cost of the device can be reduced. It can be realized.

(Third Embodiment) FIG. 5 is a flowchart showing a backlight control process in an electronic information device equipped with a display device according to a third embodiment of the present invention.

In the first and second embodiments, the voltage detector DET is set regardless of whether the backlight 18 is on or off.
2, the lighting / non-lighting of each of the EL panels (2) 18b and (1) 18a is directly controlled according to the output signal from the DET1, but the EL panel (1) 18a,
(2) When the 18b is turned on and off, the voltage detector DET is used.
2, the output voltage of the battery power supply 19 detected by DET1 changes due to additional fluctuation, and the voltage detector DET2 or DET2
The EL panel (2) 18b,
(1) There is a possibility that the 18a may cause a blinking phenomenon.

For this reason, for example, each EL panel (2) 1 at the time of the initial operation accompanying the system startup of the electronic information equipment.
8b, (1) in a state prior to the lighting drive of 18a, the backlight control process started by pressing a test key such as a backlight key as shown in FIG. 5 causes the voltage detector DET2 or DET1 to operate. It is also possible to adopt a configuration in which there is no possibility of occurrence of a blinking phenomenon in the EL panels (2) 18b and (1) 18a at the setting detection voltage.

In the third embodiment, the voltage detector DET1 in FIG. 3 is omitted. That is, the output voltage from the battery power supply 19 is normal at 5.5 V or more,
When the normal detection signal of the high level “1” is supplied from the voltage detector DET2 to the input port Port4 of the control unit (CPU) 11, once one EL is output from the output port Port1 of the control unit (CPU) 11. Power supply IC 21a
Supply a high level “1” lighting control signal to only
Only the panel (1) 18a is driven to light (step A1).
→ A2).

Further, in this state, there is no large change in the output voltage of the battery power supply 19, and the normal detection signal of the high level "1" is continuously output from the voltage detector DET2 to the input port Port4 of the control unit (CPU) 11. If supplied, the output port Po of the control unit (CPU) 11
A high-level “1” lighting control signal is also supplied from rt2 to the other EL power supply IC 21b to drive the EL panel (2) 18b to light (step A3 → A).
4).

Then, in accordance with the processing of steps A1 → A2, when only one of the EL panels (1) 18a is turned on, the output voltage of the battery power supply 19 fluctuates greatly to less than 5.5V. When a low level “0” abnormality detection signal is supplied from the voltage detector DET2 to the input port Port4 of the control unit (CPU) 11, the EL panel (2) 18b is kept in a non-lighting state. Liquid crystal display (LC) by only the EL panel (1) 18a of
D) With the display screen 16 kept illuminated, the operation shifts to the system control operation (step A3 → END).

Therefore, according to the display device of the third embodiment in the electronic information device having the above-described configuration, the first and second electronic information devices can be used.
Similarly to the embodiment, the time for illuminating the display screen with the backlight 18 can be extended while the normal operation of the system control by the control unit (CPU) 11 is suppressed while the consumption of the battery power supply 19 is suppressed. The hardware configuration of the display device can be further simplified, the size of the device can be reduced, and the price can be reduced. Further, the possibility of the backlight 18 flickering at the set detection voltage of the battery power supply 19 can be eliminated.

[0049]

As described above, according to the display device of the first aspect of the present invention, the display device is formed in a comb-like shape in which the display device alternately intersects from the right side of the screen and the left side of the screen by a constant width in the vertical direction of the display screen. Lighting / non-lighting of each of the two light source panels of the backlight composed of the two divided light source panels is separately performed for each light source panel according to the voltage level of the battery power detected by the power supply voltage detecting means. Therefore, even if the voltage level of the battery power source is reduced and the backlight is provided by turning on only one of the light source panels, the entire display screen can be evenly illuminated, without turning off the backlight entirely. Main body operation can be continued.

Further, according to the display device of the second aspect of the present invention, the voltage level of the battery power detected by the power supply voltage detecting means is the first voltage level lower than the rated voltage of the battery power by a predetermined value. In the case described above, both of the two light source panels constituting the backlight are controlled to be turned on,
When the voltage is lower than the first voltage level and is equal to or higher than a second voltage level lower than the first voltage level, only one of the light source panels is controlled to be turned on, and when the light source panel is lower than the second voltage level, Since both the two light source panels are controlled to be turned off, the voltage level at which the main body can be operated can be maintained as long as possible while uniformly illuminating the entire display screen.

According to the display device of the third aspect of the present invention, the two light sources are divided into two in a comb shape in such a manner as to alternately intersect the right and left sides of the screen by a constant width in the vertical direction of the display screen. When the voltage level of the battery power detected by the power supply voltage detecting means is equal to or higher than a predetermined voltage level lower than the rated voltage by a predetermined value in a non-lighting state of the two light source panels of the panel backlight. The lighting control of only one light source panel is performed. If the voltage level of the battery power detected by the power supply voltage detecting means is still higher than the predetermined voltage level in the lighting control state of only one light source panel, Of the light source panel is also controlled to be turned on, so that the flickering phenomenon of the light source panel that is turned on does not occur due to the load fluctuation accompanying the lighting of the light source panel. A scaling bisected also allow illumination equally as long as possible the entire screen while maintaining suppressing normal body operating consumption of the battery power source to. Therefore,
According to the present invention, without causing an operation failure of the main circuit,
The period during which the backlight can be turned on can be extended.

[Brief description of the drawings]

FIG. 1 is an exemplary block diagram showing the configuration of an electronic information device including a display device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a backlight provided in a liquid crystal display unit of the electronic information device.

FIG. 3 is a block diagram showing a configuration of an electronic information device including a display device according to a second embodiment of the present invention.

FIG. 4 is a flowchart illustrating a backlight control process in an electronic information device including a display device according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing a backlight control process in an electronic information device including a display device according to a third embodiment of the present invention.

[Explanation of symbols]

 11: control unit (CPU), 12: ROM, 13: RAM, 14: data bus (DATA BUS), 15: address bus (ADDRESS BUS), 16: liquid crystal display unit (LCD), 17: display drive circuit (D) / D), 18 backlight, 18a EL panel (1), 18b EL panel (2), 19 battery power supply, 20 regulator, 21a power IC for EL (1), 21b power IC for EL (2), DET0-DET2 ... voltage detector, R0-R2 ... pull-up resistor, AND1 ... EL1 drive gate circuit, AND2 ... EL2 drive gate circuit.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09G 3/18 G09G 3/20 612G 3/20 612 G06F 1/00 332Z 333D

Claims (3)

[Claims] 1. A display device which is driven by a battery power supply common to a main body circuit and has a backlight function of illuminating an entire area of a display screen, wherein an area to be illuminated corresponding to a size of the display screen is provided. A backlight composed of two light source panels divided into two in a comb shape in such a manner as to be alternately interleaved from the right side of the screen and the left side of the screen by a constant width in the vertical direction; and power supply voltage detection means for detecting a voltage level of the battery power supply. Backlight control for separately controlling lighting / non-lighting of each of the two light source panels constituting the backlight according to the voltage level of the battery power detected by the power supply voltage detecting means; And a display device. 2. The power supply voltage detection means, wherein the power supply voltage is equal to or higher than a first voltage level lower than a rated voltage of the battery power supply by a predetermined value, and is equal to or higher than a second voltage level lower than the first voltage level. Power supply voltage detection means for detecting whether the battery power supply voltage level detected by the power supply voltage detection means is equal to or higher than a first voltage level. Do 2
The lighting control of both of the two light source panels is performed. When the light source panel is lower than the first voltage level and equal to or higher than the second voltage level, only one of the light source panels is controlled to be turned on. 2. A backlight control means for controlling non-lighting of both of the two light source panels.
The display device according to claim 1. 3. A display device which is driven by a battery power supply common to a main body circuit and has a backlight function for illuminating an entire area of a display screen, wherein an area to be illuminated corresponding to the size of the display screen is provided. A backlight composed of two light source panels divided into two in a comb shape in a state of being alternately interleaved from the right side of the screen and the left side of the screen by a constant width in a vertical direction; and a predetermined voltage level lower than a rated voltage of the battery power supply by a predetermined value. A power supply voltage detecting means for detecting whether the power supply voltage is equal to or less than a value, and a voltage level of the battery power detected by the power supply voltage detecting means being equal to or higher than a predetermined voltage level in a non-lighting state of two light source panels constituting the backlight. In this case, only one of the light source panels is controlled to be lit, and in a state where only one of the light source panels is controlled to be lit, the light is detected by the power supply voltage detecting means. A display device, comprising: backlight control means for controlling lighting of the other light source panel when the voltage level of the battery power supply is still higher than the predetermined voltage level.