JPH11282435A - Display device and driving circuit of display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which has a simple structure, a power-saving feature and is capable of displaying only a PICT display part. SOLUTION: A liquid crystal display element 10 is a simple matrix type provided with two lines of a PICT display part and five lines of a dot display part. A driving circuit 20 boosts a power supply voltage VDD in normal times and divides the boosted voltage to generate voltages V0-V4, and drives the liquid crystal display element 10 in time-division manner with 1/7 duty and 1/4 bias. When a power-saving mode is instructed, the driving circuit stops the operation of the booster circuit and generates three voltages V0-V2 from the power supply voltage VDD, and turns off all the dot display part, and drives a PICT display part in a power-saving mode with a 1/2 duty and a 1/2 bias.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a display element having a dot matrix display section and a pictogram section, and a display device capable of performing dot matrix display and pictogram display.

[0002]

2. Description of the Related Art Since portable small electronic devices are driven by batteries, it is desired to reduce power consumption. For this reason, a liquid crystal display device that can operate with lower power consumption than a CRT or the like is generally used as a display device. In particular, personal handy phones (PHS), mobile phones, and the like are required to be formed in a very small size, and a power supply battery used therein is also required to be small and have a small capacity. For this reason, power saving is also performed for the display devices provided in these portable devices. Further, in the conventional liquid crystal display device, in a standby state, for further power saving,
There is known a device in which a booster circuit included in the drive circuit is stopped, a display is turned off, and a power saving mode is set to reduce power consumed by the booster circuit.

[0003]

In the conventional liquid crystal display device, when the power saving mode is set, all the display disappears. For example, whether a portable device such as a cellular phone is in a standby state or a power It is not possible to know whether the battery has been turned off, and it is not possible to know the remaining battery power. In a conventional liquid crystal display device, in order to display the state of such a portable device, an electrode is provided only in a pictogram portion,
It has been proposed to reduce power consumption by individually driving these parts. However, the method of individually providing electrodes for each pictogram has a disadvantage that a circuit for driving only the pictogram display section of the liquid crystal display device is required, so that the number of components is increased and the structure is complicated.

The present invention has been made in view of the above circumstances, and displays a liquid crystal display device having a plurality of display areas such as a dot matrix display section and a pictogram display section with a simple configuration and with low power consumption. It is an object of the present invention to provide a display device and a driving circuit which can perform the operation.

[0005]

In order to achieve the above object, a display element driving circuit according to a first aspect of the present invention comprises a plurality of first display elements formed by opposing electrodes. A first display region in which the respective electrodes are connected in a matrix, and a second display element formed by electrode portions opposed to each other in a matrix together with the electrodes of the first display region. In order to time-divisionally drive a display element having two display areas,
A first voltage group generated from a boosted voltage obtained by boosting a power supply voltage, and a second voltage group for driving one of the first display region and the second display region with a power supply voltage are selected. Power supply circuit, and a first voltage group,
A first drive signal for driving the display area and the second display area in a time-division manner, and a second drive signal for driving one of the display areas by a second voltage group are selectively generated. A drive unit, the power supply circuit, and the drive unit are selectively controlled to generate either a first voltage group and a first drive signal or a second voltage group and a second drive signal. And a control circuit.

[0006] The drive circuit of the display element boosts the input power supply voltage and divides the boosted high voltage during normal operation when displaying all of the first display area and the second display area. A first voltage group having a plurality of different values is generated, and the display element is driven for display by the first voltage group. Meanwhile, the first
In the power saving mode in which only one of the display area and the second display area is displayed to save power, the boosting operation is stopped, and the second voltage group is generated by driving the power supply. Displays one display area. In the power saving mode, since the booster circuit is stopped, power consumption in the booster circuit can be reduced. Further, since the boosting operation is stopped, the second voltage group becomes lower in voltage than the first voltage group, and the one display area can be driven at a low voltage, thereby further reducing power consumption. Can be. In addition, power consumption can be reduced with a simple circuit configuration without providing a special driving circuit for driving with low power consumption.

The power supply circuit includes a booster circuit that boosts a power supply voltage, a voltage divider circuit that divides an input voltage to generate a plurality of different voltages, and a voltage divider that boosts the boosted voltage by the booster circuit. Switching means may be provided for switching between supply to a circuit and supply of the power supply voltage to a voltage dividing circuit by stopping operation of the booster circuit, and changing a voltage dividing ratio of the voltage dividing circuit.

The control circuit controls the power supply circuit and the drive circuit to control a first voltage group and a first drive signal in response to a command for controlling display of only one of the first and second display areas. Operation switching means may be provided for controlling the operation to be performed to the operation to generate the second voltage group and the second drive signal.

[0009] The control circuit, by a command for instructing a power saving mode for reducing power consumption, switches the power supply circuit and the drive unit from an operation of generating a first voltage group and a first drive signal. Operation switching means for controlling to a power saving operation for generating the second voltage group and the second drive signal may be provided.

In order to achieve the above object, in a display device according to a second aspect of the present invention, a plurality of first display elements formed by opposing electrode portions are arranged, and each electrode is arranged in a matrix. A display element having a connected first display region and a second display region in which a second display element formed by electrode portions facing each other is connected in a matrix with the electrodes of the first display region. When,
A first voltage group generated from a boosted voltage obtained by boosting a power supply voltage for time-divisionally driving the first display area and the second display area, and a first display area and a second display area And a power supply circuit for selectively generating a second voltage group for driving either one of the first and second display regions by a power supply voltage, and time-divisionally driving the first and second display regions by the first voltage group. A drive circuit for selectively generating a first drive signal to be driven, and a second drive signal for driving one of the display regions by a second voltage group; and the power supply circuit and the drive circuit.
The control circuit selectively controls to generate either the first voltage group and the first drive signal or the second voltage group and the second drive signal.

This display device normally boosts the input power supply voltage, divides the boosted high voltage to generate a first voltage group having a plurality of different values, and generates the first voltage group. To drive the display element to display all of the first display area and the second display area, stop the boosting operation in the power saving mode, and generate the second voltage group by driving the power supply. , Only one of the first display area and the second display area is displayed. Therefore, in the power saving mode, since the booster circuit is stopped, power consumption in the booster circuit can be reduced. In addition, the second voltage group is lower in voltage than the first voltage group, and the one display region can be driven with a low voltage, so that power consumption can be further reduced. In addition, power consumption can be reduced with a simple circuit configuration without providing a special driving circuit for driving with low power consumption.

The first display area of the display element comprises a dot matrix display area in which scanning electrodes and signal electrodes are arranged so as to intersect each other. It may consist of a pictogram display area in which electrodes of a predetermined shape are formed.

For example, the first display area is composed of a dot matrix display section composed of signal electrodes and first scanning electrodes, and the second display area is composed of the signal electrodes and second scanning electrodes. It is composed of a pictogram display section composed of electrodes. In this case, for example, the power supply circuit receives a voltage, boosts the voltage, and responds to N drive voltages for driving the display element from the boosted voltage and a control signal instructing a power saving mode. And stopping the boosting operation and generating M drive voltages less than the N drive voltages, wherein the control circuit is connected to the signal electrode and the scan electrode of the display element, and according to the control of the drive circuit, The display element is driven by a time-division driving method using N drive voltages supplied from the power supply circuit, and a non-display scan signal is supplied to the first scan electrode using the M drive voltages. , A scanning signal for image display is applied to the second scanning electrode, and a signal for pictograph display is applied to the signal electrode to display the second display area.

Further, for example, the first display area is composed of a dot matrix display section composed of signal electrodes and i first scanning electrodes, and the second display area is composed of the signal electrodes. And a pictograph display unit including two second scanning electrodes.

In this case, the power supply circuit receives a voltage,
The voltage is boosted, N drive voltages for driving the liquid crystal display element are generated from the boosted voltage, and the boost operation of the power supply circuit is stopped in response to a control signal instructing a power saving mode. And generates three drive voltages less than the N. The control circuit is connected to the signal electrodes and the scan electrodes of the display element, and normally generates N drive voltages supplied from the power supply circuit. And the liquid crystal display element is set to 1 / (i + 2) duty, 1 / (N−1)
In the power saving mode, a non-selection signal is applied to the i first scan electrodes by using the three drive voltages in a power saving mode, and に is applied to the second scan electrodes.
By applying a selection voltage of the duty, the pictogram display section may be driven with デ ュ ー duty and バ イ ア ス bias.

Further, for example, the first display area is composed of a dot matrix display section composed of signal electrodes and i first scanning electrodes, and the second display area is composed of the signal electrodes. And a single second scanning electrode. In this case, the power supply circuit receives the voltage, boosts the voltage, generates N driving voltages for driving the liquid crystal display element from the boosted voltage, and responds to the control signal in the power saving mode. hand,
The boosting operation is stopped, and two drive voltages less than N are generated. The control circuit is connected to the signal electrodes and the scan electrodes of the display element, and normally receives N drive voltages supplied from the power supply circuit. The liquid crystal display element is set to 1 / (i + 1) duty and 1 / (N−1)
A non-display scanning signal is applied to the i first scanning electrodes using the two driving voltages in the power saving mode by driving in a time-division driving method with a bias, and the second scanning electrode The picto display unit may be driven in a multi-static manner by applying a scanning signal for image display to the device and applying a signal for driving the picto display unit to the signal electrode.

In order to achieve the above object, a display device according to a third aspect of the present invention is arranged such that a plurality of first display elements formed by electrode portions facing each other are arranged, and each electrode is formed in a matrix. Having a first display region connected to the first display region and a second display region in which a second display element formed by electrode portions facing each other is connected in a matrix with the electrodes of the second display region. To drive a first voltage group generated by dividing a boosted voltage obtained by boosting a power supply voltage and one of the first display area and the second display area in order to drive the element in a time division manner. A power supply circuit for selectively generating a second voltage group generated by dividing a voltage lower than the boosted voltage; a first display area and a second display area by the first voltage group; Drive signal for time-divisionally driving A drive circuit for selectively generating a second drive signal for driving one of the display regions by a second voltage group, and the power supply circuit and the drive circuit, And a control circuit selectively controlling to generate one of the first drive signal or the second voltage group and the second drive signal.

In this display device, when displaying all of the first display area and the second display area, the input power supply voltage is boosted, and the boosted voltage is divided to obtain a plurality of different values. In the power saving mode in which the first voltage group is generated, the display element is driven for display by the first voltage group, and only one of the first display area and the second display area is displayed, the boost operation is performed. Then, the power supply voltage is divided to generate a second voltage group having a plurality of different values, and the one display area is displayed by the second voltage group.

Therefore, in the power saving mode, since the booster circuit is stopped, the power consumption in the booster circuit can be reduced.
Further, the second voltage group is lower in voltage than the first voltage group, and the one display region can be driven at a low voltage, so that power consumption can be further reduced. Moreover, power saving can be achieved with a simple circuit configuration without providing a special driving circuit for driving with low power consumption.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a liquid crystal display device and a driving circuit according to an embodiment of the present invention will be described below.
A liquid crystal display device having a pictogram display section and a dot matrix display section and driving the pictogram display section and the dot matrix display section at 1/7 duty and 1/4 bias will be described as an example.

This liquid crystal display device, as shown in FIG.
It comprises a liquid crystal display element 10 and a drive circuit 20.

The liquid crystal display element 10 includes a plurality of scanning electrodes 11 which substantially form a matrix and a plurality of signal electrodes 1.
3 and a liquid crystal layer 15 interposed between these electrodes. The drive circuit 20 includes a power supply circuit 21 for generating a power supply voltage VDD, a scan drive circuit 23 for applying a scan signal to the scan electrode 11 of the liquid crystal display element 10, and a signal electrode 13 in accordance with the supplied display data. A signal driving circuit 25 for applying a data signal;
A control circuit 27 for controlling the operation of the scan drive circuit 23 and the signal drive circuit 25;

As schematically shown in FIG. 1, the liquid crystal display element 10 has a plurality of scanning electrodes (common electrodes, x1 to x7) 1
1 and the common electrode x
A plurality of signal electrodes (segment electrodes, y1 to y7) 13 each having a pictogram electrode portion formed at a portion facing the first and x2, and a portion where the scanning electrode 11 and the signal electrode 13 face each other, and This is a simple matrix element in which a plurality of pixels are formed by the liquid crystal layer 15 disposed.
That is, the liquid crystal display element 10 has a dot matrix display in which a plurality of dot-shaped first display elements formed by electrode portions facing each other are arranged, and each scanning electrode 11 and signal electrode 13 are connected in a matrix. An area and a pictogram display area in which pictogram display elements formed by opposing electrode portions are connected in a matrix with the electrodes of the dot matrix display area.

As schematically shown in FIG. 2, the liquid crystal display element 10 has a pictograph display section 10P for displaying a plurality of pictograms and a dot matrix display section 10D for displaying characters, numerals, etc. by combining a plurality of dots. . The pictograph display unit 10P is disposed adjacent to the dot matrix display unit 10D of the liquid crystal display element 10, and has a pictogram-shaped pictogram electrode part formed on a part of the signal electrode 13 extended from the dot matrix display unit 10D. It is formed of opposing electrode portions that form pictograms of the scanning electrodes 11 in the first and second rows, which are opposed to this, and a plurality of these opposing electrode portions are connected. The scanning electrodes 11 of the first and second rows are formed. The dot matrix display section 10D is formed of an area in which a plurality of pixels formed by intersections of the plurality of signal electrodes 13 and the scanning electrodes 11 in the third to seventh rows are arranged in the row and column directions.

The drive circuit 20 is a circuit for controlling and driving the liquid crystal display element 10. As shown in FIG. 1, the power supply circuit 21, the scan drive circuit 23, and the signal drive circuit 25
And a control circuit 27, for example, an LSI.

The power supply circuit 21 comprises a double booster circuit 211 and a bias circuit 212 as shown in FIG. The double boosting circuit 211 doubles the supplied power supply voltage VDD and outputs a voltage V4 (= 2VDD). The bias circuit 212 includes a voltage dividing circuit in which four resistors R1 to R4 are connected in series, divides the voltage V4 by the voltage dividing circuit, and outputs five different voltages V0 to V4.

Between the power supply voltage input terminal and the boosted voltage output terminal of the double booster circuit 211 and between the boosted voltage output terminal and the resistors R2 and R2.
The switches SW1 and SW2 are connected to the connection point 3 respectively. Each of the switches SW1 and SW2 is composed of a MOS transistor or the like, and is operated by a power saving instruction signal Ss applied from the outside.

The switches SW1 and SW2 are closed when the power saving instruction signal Ss is applied, as shown in FIG. 3B, and the input and output of the double booster circuit 211 are short-circuited to stop the operation. The power supply voltage VDD is supplied to the connection point between the resistors R2 and R3 by short-circuiting both ends of the series connection circuit of the resistors R1 and R2, so that the power supply voltage VDD is connected to the resistors R3 and R3.
The voltage is divided by R4, and the ternary voltages V0, V1, and V2 are output from the bias circuit 212.

The scan driving circuit 23 normally supplies voltages V0 to V0 supplied from the power supply circuit 21 when driving both the dot matrix display section 10D and the pictograph display section 10P in accordance with a control signal from the control circuit 27. Using V4, the scanning signal having the waveform shown in FIG.
In the power saving mode in which only the pictograph display unit 10P is driven by applying the voltage to the scan electrodes x1 to x7 while being shifted by seven, the voltages V0 to V2 supplied from the power supply circuit 21 are used.
A scan signal having a waveform shown in (a) to (c) is generated and applied to scan electrodes x1 to x7.

The signal drive circuit 25 includes a control circuit 27
It operates according to the control signal and the display data from. Normally, the signal drive circuit 25 is connected to the dot matrix display 1
Upon receiving display data for controlling the display of both the 0D and the pictograph display unit 10P, a data signal for displaying all pixels having a waveform as shown in FIG. It is applied to the signal electrodes y1 to y7. In the power saving mode, the signal drive circuit 25 applies the data signals S1 to S4 shown in FIG. 5D for controlling the pictographs of the first and second rows to the signal electrodes y1 to y7.

The control circuit 27 operates by the power supply voltage VDD, and controls the operations of the scanning drive circuit 23 and the signal drive circuit 25. The control circuit 27 applies a signal instructing normal driving to the power supply circuit 21 when the power saving instruction signal Ss is not applied to the power supply circuit 21 as shown in FIG.
The W1 and SW2 are turned off, and the scanning drive circuit 23 and the signal drive circuit 25 are controlled so as to drive the liquid crystal display element 10 with 1/7 duty and 1/4 bias. Further, when the power saving instruction signal Ss is applied, the control circuit 27 switches the switches SW1 and SW1 as shown in FIG.
At the same time, W2 is closed, and the scan drive circuit 23 and the signal drive circuit 25 are operated in a power saving mode different from the normal mode at 1/2 duty and 1/2 bias.

Next, the operation of the liquid crystal display device configured as described above will be described.

In a normal state in which both the dot matrix display section 10D and the pictograph display section 10P are driven for display, the power saving instruction signal Ss is off, and the control circuit 27 opens the switches SW1 and SW2 and sets the liquid crystal. Display element 1
A control signal for driving 0 with 1/7 duty and 1/4 bias is supplied to the scanning drive circuit 23 and the signal drive circuit 25.

Since the switches SW1 and SW2 are open, the double boosting circuit 211 of the power supply circuit 21 supplies the power supply voltage V
DD is doubled to output a voltage V4, and the bias circuit 212 divides the voltage V4 to output voltages V0 to V4. Under the control of the control circuit 27, the scan drive circuit 23 generates a scan signal having a waveform as shown in FIG. 4A using the voltages V0 to V4, and shifts the cycle by 1/7 to the scan electrode 11 Apply. In addition, the signal drive circuit 25 generates, for example, a data signal as shown in FIG. 4B from the voltages V0, V2, and V4 according to the supplied display data,
It is applied to the signal electrode 13 in synchronization with the scanning signal.

As described above, the entire liquid crystal display element 10 is driven with 1/7 duty and 1/4 bias.

When the power saving instruction signal Ss for driving only the pictogram display section is supplied to the control circuit 27, the control circuit 27 sets the scanning drive circuit 23, the signal drive circuit 25, and the power supply circuit 21 in the power save mode. Set to. First, the control circuit 27 closes the switches SW1 and SW2 of the power supply circuit 21. When the switch SW1 is closed, the booster 21
1 is short-circuited at the input terminal and the output terminal, and the double boosting circuit 21
1 is stopped, and the power supply voltage VDD is directly supplied to the bias circuit 212. When the switch SW2 is closed, the resistors R1 and R2 are disabled, and the bias circuit 212 outputs voltages V0, V1, to V2 (= VDD) obtained by dividing the power supply voltage VDD by the resistors R3 and R4.

The scanning drive circuit 23 uses the voltages V0, V1 and V2 according to the control of the control circuit 27, as shown in FIG.
Among the waveforms shown in (b) and (c), the pictogram display unit 10
The scan electrodes x1 and x2 that constitute P are shown in FIG.
As shown in FIG. 5C, a scanning signal whose phase is shifted by ４ period is applied to the scanning electrodes x3 to x7 constituting the dot matrix display section 10D as shown in FIG. Is applied. Also, the signal electrode dynamic circuit 2
Reference numeral 5 denotes one of the data signals S1 to S4 having the waveform shown in FIG. 5D according to the supplied data for controlling the display of each pictograph of the pictograph display unit (or may be fixed in advance). Select and apply to the signal electrode 13. Here, when the data signal S1 is selected, the dot matrix display 1
0D and the pictogram display section 10P are all in a non-lighting state, and when the data signal S2 is selected, the pictogram display section 10P in the first row is selected.
Only lights up. When the data signal S3 is selected, only the pictogram display section 10P in the second row is turned on, and when the data signal S4 is selected, both the pictogram display sections 10P in the first row and the second row are turned on. Thus, the pictogram display section 10P of the liquid crystal display element 10 is driven with 1/2 duty and 1/2 bias.

As described above, the driving circuit 20 of this embodiment normally drives the liquid crystal display element 10 with 1/7 duty and 1/4 bias, and in the power saving mode,
The step-up circuit 211 is stopped, and the liquid crystal display element 10 is driven with 1/2 duty and 1/2 bias. Therefore, the minimum required pictograms can be displayed while significantly reducing the power consumption compared to the normal state. There is no need to provide a special pin or the like for displaying the pictogram.

The present invention is not limited to the above embodiment, and various modifications and applications are possible. For example, the boosting circuit 211 is a double boosting circuit, but may be an arbitrary multiple of three times, four times,.... In the above embodiment,
In the power saving mode, the booster circuit 211 is stopped and the power supply voltage V
Although DD is supplied directly to the bias circuit 212, the output may be directly supplied to the bias circuit 212 by operating the booster circuit 211 as usual or operating with a reduced number of boosting stages.

In the above embodiment, in the power saving mode, V4 and V2 are short-circuited to generate voltages V0 to V2 for 1/2 bias, but V4 and V3 and V1 and V2 are generated.
0, respectively, and V1 (= V0), V2, V3
(= V4) may be used for display driving. V2 and V
0 may be short-circuited and V2 (= V0, V1), V3, and V4 may be used for display. Similarly, V3 and V1 may be short-circuited, and V0, V2 (= V1 = V3), and V4 may be used as a display power supply.

In the above embodiment, in the power saving mode, V0 to V2 are created by short-circuiting the resistance inside the bias circuit. However, another bias circuit for the power saving mode is prepared. In addition, it may be used by switching from a normal bias circuit.

(Second Embodiment) In the first embodiment, the pictogram display section is provided for two scanning electrodes and the dot matrix display section is provided for five scanning electrodes. The number of rows in the dot matrix display section is arbitrary, and may be appropriately selected according to the display target. Hereinafter, a second embodiment in which the pictogram display unit is for one row of scanning electrodes and the dot matrix display unit is for six rows of scanning electrodes will be described.

The structure of this liquid crystal display device is almost the same as that of the first embodiment. However, the switch SW2 is connected between the boosted voltage input terminal and the connection point of the resistors R3 and R4, as shown in FIG. 6, and in the power saving mode, the bias circuit 212 controls only the voltages V0 and V1. Output.

In the power saving mode, the scanning drive circuit 23 generates the scanning signals shown in FIGS. 7A and 7B using the voltages V0 and V1 supplied from the power supply circuit 21,
It is applied to the scanning electrodes x1 to x7. The signal drive circuit 25 includes:
Using the voltages V0 and V1 supplied from the power supply circuit 21, according to the data for displaying each pictograph of the pictograph display unit, FIG.
The data signal having the waveform shown in (c) is selectively applied to the signal electrodes y1 to y7.

Next, the operation of the liquid crystal display device thus configured will be described.

Normally, since the power-saving instruction signal Ss is not applied, as shown in FIG.
Supplies a control signal for opening the switches SW1 and SW2 and driving the liquid crystal display element 10 at 1/7 duty and 1/4 bias to the scan driving circuit 23 and the signal driving circuit 2.
5 and the pictograph display unit and the dot matrix display unit are both driven at 1/7 duty and 1/4 bias as in the first embodiment described above.

That is, since the switches SW1 and SW2 of the power supply circuit 21 are open, the double boosting circuit 211 of the power supply circuit 21 doubles the power supply voltage VDD and outputs the voltage V4, and the bias circuit 212 divides the voltage V4 and outputs voltages V0 to V4. Scan drive circuit 23
Generates a scanning signal having a waveform as shown in FIG. 4A using the voltages V0 to V4 under the control of the control circuit 27, and applies it to the scanning electrode 11. Further, the signal drive circuit 25
Applies a data signal as shown in FIG. 47B to each signal electrode 13 in accordance with the display data. In this way, the liquid crystal display element 10 has 1/7 duty, 1 /
Driven by 4 biases.

Next, when the power saving instruction signal Ss is supplied to the control circuit 27, the control circuit 27
3, the signal drive circuit 25 and the power supply circuit 21 are switched to the power saving mode. First, the control circuit 27 closes the switches SW1 and SW2 of the power supply circuit 21, turns off the boosting operation of the double boosting circuit 211, and applies V1 (= VD
D) and V0 are output.

The scan drive circuit 23 uses the supplied voltages V0 and V1 (= VDD) in accordance with the supplied data for controlling the display of the pictographs of the pictograph display section, as shown in FIG.
Among the waveforms shown in (b), the scanning electrodes for display shown in FIG. 7A are applied to the scanning electrodes x1 constituting the pictograph display section 10P, and the scanning electrodes x2 to x7 constituting the dot matrix display section 10D are applied. As shown in FIG. 7B,
A non-display scanning signal whose phase is shifted by 1/4 cycle from the scanning signal shown in FIG. Also, the signal electrode driving circuit 25
Selects one of the data signals S 1 and S 2 having the waveform shown in FIG. 7C and applies it to the signal electrode 13. Here, when the data signal S1 is selected, the pictogram display section 10P of the first row is selected.
When only the data signal S2 is turned on and the data signal S2 is selected, the dot matrix display section 10D and the pictogram display section 10P are all turned off. In this way, the pictograph display section 10P of the liquid crystal display element 10 is driven by the multi-static method of 1/2 duty and 1/1 bias.

As described above, in this embodiment, the liquid crystal display element 10 is driven with 1/7 duty and 1/4 bias in the normal state, and the booster circuit 2 is operated in the power saving mode.
11 is stopped, and the liquid crystal display element 10 is driven with 1/2 duty and 1/1 bias. Therefore, it is possible to greatly reduce the power consumption as compared with the normal time, and to display the minimum required pictograms.

In the second embodiment, the scan driving circuit 23 applies the display scan signal shown in FIG. 7A to the scan electrode x1, and applies the scan signals shown in FIG. 7B to the scan electrodes x2 to x7. The scanning signals for non-display shown in FIG.
The scanning signals shown in (a) and (b) may be applied. In this case, the signal drive circuit 25 selects one of the data signals S1 and S2 having the waveform shown in FIG. 8C instead of the data signals S1 and S2 having the waveform shown in FIG. 13 is applied. Thus, the scanning electrode 11 and the signal electrode 13
Can be arbitrarily changed and modified as long as the desired driving can be achieved.

Further, in the first and second embodiments,
The dot matrix display section 10D is provided for 5 rows or 6 scan electrodes.
The number of lines is set, but the number is arbitrary. Further, although the pictograph display section 10P has two or one scanning electrodes, the pictogram rows may be three, four,..., N rows. For example, assuming that the number of all the scanning electrodes is i and the number of the scanning electrodes 11 of the pictograph display 10P is k (k <i), the power supply circuit 21 normally uses N boosted outputs of the boosted circuit 211 In the power saving mode, the booster circuit 211 is turned off, and N
Output M fewer drive voltages. On the other hand, the scanning drive circuit 23 and the signal drive circuit 25 normally use the N drive voltages supplied from the power supply circuit 21 to make the entire display element 10 have 1 / i duty and 1 / (N−1) bias. In the power saving mode, the pictograph display section 10P of the liquid crystal display element 10 is displayed so that only the pixels at the intersections of the k scanning electrodes 11 for signal display and the signal electrodes 13 are displayed. It is driven with 1 / K duty and 1 / (M-1) bias.

The present invention is not limited to the case where the picto display unit is driven with power saving, but the case where the whole screen is driven with power saving in a partial area of the liquid crystal display element constituted by the dot matrix display unit. Is also applicable. Further, the present invention can be similarly applied to a case where a part of the pictograph display unit and the dot matrix display unit is driven with power saving.

[0054]

As described above, according to the present invention, it is possible to drive a display element with a simple configuration with low power consumption.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a liquid crystal display element.

FIG. 3A is a diagram illustrating a normal configuration of the power supply circuit according to the first embodiment; FIG. 3B illustrates a configuration of the power supply circuit according to the first embodiment in a power saving mode.

FIGS. 4A and 4B are timing charts of signals respectively applied to a scanning electrode and a signal electrode in a normal state of the first embodiment.

FIGS. 5A to 5C are timing charts of signals applied to scan electrodes in a power saving mode according to the first embodiment. (D) is a timing chart of signals applied to the signal electrodes in the power saving mode according to the first embodiment.

FIG. 6 is a diagram showing a configuration of a power supply circuit according to a second embodiment of the present invention.

FIGS. 7A and 7B are timing charts of signals applied to scan electrodes in a power saving mode according to the second embodiment. (C) is a timing chart of signals applied to the signal electrodes in the power saving mode according to the second embodiment.

FIG. 8 is a timing chart showing a modified example of the drive signal shown in FIG.

[Explanation of symbols]

10 ... Liquid crystal display element, 10P ... Pict display part, 10D
... dot matrix display unit, 11 ... scanning electrodes, 13 ...
・ Signal electrode, 15 ・ ・ ・ Liquid crystal layer, 20 ・ ・ ・ Drive circuit, 21 ・ ・ ・
Power supply circuit, 23: signal drive circuit, 25: scan drive circuit, 27: control circuit, 211: double booster circuit, 212
... Bias circuits

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09G 3/20 612 G09G 3/20 612G

Claims (9)

[Claims] A plurality of first display elements formed by opposing electrode portions are arranged, and each electrode is formed by a first display region in which each electrode is connected in a matrix and an opposing electrode portion. A second display element is generated from a boosted voltage obtained by boosting a power supply voltage in order to time-divisionally drive a display element having a second display area connected in a matrix with electrodes of the first display area. A power supply circuit for selectively generating a first voltage group, and a second voltage group for driving one of the first display area and the second display area with a power supply voltage; A first drive signal for driving the first display area and the second display area in a time-sharing manner by using the voltage group of (1) and a second drive signal for driving one of the display areas by a second voltage group. And a drive unit that selectively generates A control circuit for selectively controlling the power supply circuit and the drive unit to generate either a first voltage group and a first drive signal or a second voltage group and a second drive signal; And a driving circuit for a display element. 2. A power supply circuit, comprising: a booster circuit for boosting a power supply voltage; a voltage divider circuit for dividing an input voltage to generate a plurality of different voltages; and a voltage divider for boosting the boosted voltage by the booster circuit. Switching means for switching between supply to the voltage divider circuit and supply of the power supply voltage to the voltage divider circuit by stopping the operation of the booster circuit, and changing the voltage division ratio of the voltage divider circuit. The driving circuit for a display element according to claim 1. 3. A control circuit for controlling the power supply circuit and the drive section to a first voltage group and a first drive signal by an instruction to control display of only one of the first and second display areas. 3. The display element driving circuit according to claim 1, further comprising operation switching means for controlling the operation of generating the second voltage group and the operation of generating the second drive signal from the operation of generating the second voltage group. 4. A control circuit for operating the power supply circuit and the drive unit to generate a first voltage group and a first drive signal in response to a command instructing a power saving mode for reducing power consumption. 3. The drive circuit for a display element according to claim 1, further comprising an operation switching unit configured to perform a power saving operation for generating a second voltage group and a second drive signal from the power supply. 5. A plurality of first display elements formed by opposing electrode portions are arranged, and each electrode is formed by a first display region in which each electrode is connected in a matrix and an opposing electrode portion. A display element having a second display element in which a second display element is connected in a matrix with electrodes of the first display area, and the first display area and the second display area are time-divided. A first voltage group generated from a boosted voltage obtained by boosting a power supply voltage for driving, and a second voltage for driving one of the first display area and the second display area with the power supply voltage A power supply circuit for selectively generating a group, a first drive signal for time-divisionally driving a first display area and a second display area by a first voltage group, The second driving one of the display areas A drive circuit for selectively generating a drive signal, and said power supply circuit and the driving circuit, a first voltage group first
And a control circuit that selectively controls to generate either the second drive signal or the second voltage group and the second drive signal. 6. A first display area of the display element comprises a dot matrix display area in which scanning electrodes and signal electrodes are arranged so as to intersect with each other, and the second display area includes figures, characters, and the like. 6. The display device according to claim 5, wherein the display device comprises a pictograph display area in which an electrode having a predetermined shape is formed. 7. The first display area includes a dot matrix display section including a signal electrode and a first scan electrode, and the second display area includes a signal electrode and a second scan electrode. The power supply circuit receives a voltage, boosts the voltage, and saves N driving voltages for driving the display element from the boosted voltage, and saves. In response to a control signal instructing the power consumption mode, the boosting operation is stopped, and M drive voltages less than the N drive voltages are generated. The control circuit controls the signal electrodes and the scan electrodes of the display element. Connected to drive the display element in a time-division driving manner using N drive voltages supplied from the power supply circuit under control of the drive circuit, and using the M drive voltages to drive the first display element. For non-display on the scanning electrodes Applying a scan signal for image display to the second scan electrode, and applying a signal for pictogram display to the signal electrode to display the second display area. The display device according to claim 5. 8. The first display area includes a dot matrix display section including signal electrodes and i first scanning electrodes, and the second display area includes the signal electrodes and two scan electrodes. A second pictorial display unit comprising a second scanning electrode, the power supply circuit receiving a voltage, boosting the voltage, and driving the liquid crystal display element from the boosted voltage. Generating a drive voltage, stopping a boosting operation of the power supply circuit, and generating three drive voltages less than the N in response to a control signal instructing a power saving mode; The liquid crystal display element is connected to the signal electrode and the scanning electrode of the element, and normally operates the liquid crystal display element by using N driving voltages supplied from the power supply circuit.
(I + 2) duty, 1 / (N-1) bias driving in a time-division driving method, and in the power saving mode, a non-selection signal is applied to the i first scanning electrodes using the three driving voltages. Is applied to the second scan electrode to apply a selection voltage of 1/2 duty, so that 1/2 duty,
The display device according to any one of claims 5 to 7, further comprising: driving the pictograph display unit with a 1/2 bias. 9. A plurality of first display elements formed by opposing electrode portions are arranged, and a first display region in which each electrode is connected in a matrix and an opposing electrode portion are formed. In order to time-divisionally drive a display element having a second display element having a second display area connected in a matrix with electrodes of the first display area, the boosted voltage obtained by boosting the power supply voltage is divided. And a second voltage group generated by dividing a voltage lower than the boosted voltage in order to drive a first voltage group generated by the compression and one of the first display area and the second display area. A power supply circuit for selectively generating a first voltage group, a first drive signal for time-divisionally driving a first display area and a second display area with the first voltage group, and a second voltage group. A second driving one of the display areas; A drive unit for selectively generating a first drive signal and a second drive signal, or a first voltage group and a first drive signal or a second voltage group and a second drive signal. And a control circuit for selectively controlling the display element to generate the image signal.