JP2002341818A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display which turns on only desired segments. SOLUTION: The display consists of a microcomputer 14 (a control means) which outputs driving signals to a plurality of common terminals and a plurality of segment terminals, a liquid crystal display plate 5a (a liquid crystal display means) in which a plurality of segment electrodes are made into groups, common electrodes are provided corresponding to the groups and the segments corresponding to the segment terminals are displayed when the voltage difference between the driving signals given to the common terminals and the driving signals given to the segment terminals exceeds a prescribed value, a voltage dividing circuit 11 (a voltage supplying means) which supplies direct current voltages VLCD1 to VLCD3 (driving voltages) having different voltage values to output driving signals to the computer 14 by dividing a power supply voltage through resistors 11a to 11c (dividing resistors), and a voltage adjusting circuit 12 (a voltage adjusting means) which adjusts the voltages VLCD1 to VLCD3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device provided in a household electric appliance such as a rice cooker.

[0002]

2. Description of the Related Art A home electric appliance such as a rice cooker is provided with a microcomputer for executing various controls including control of a heater or an electromagnetic induction heating coil, timer control, and the like. In general, a configuration for driving a liquid crystal display device has been generalized.

A liquid crystal display device of a rice cooker displays a large number of information such as, for example, a rice cooking menu, rice cooking status, and time.
As a method of displaying such information, there are a static drive and a time division drive. The static drive has the advantage of high contrast, but has the drawback that when the number of segments increases, the number of drive circuits increases and the connection of electrode terminals becomes complicated. Therefore, a liquid crystal display device that displays a relatively large amount of information, such as a rice cooker, employs a time division driving method.

In this time-division driving method, a plurality of segment electrodes for displaying each information are grouped into a plurality of groups, and a common electrode is provided for each group. The common electrodes are connected to the corresponding common terminals, and the segment electrodes selected from each group are connected to the same segment terminal, thereby reducing the total number of electrode terminals.

[0005] The common terminals are sequentially scanned, and a drive signal is applied to each common terminal, and a drive signal is also applied to each segment terminal. At this time, if the voltage difference between the drive signal applied to the common terminal and the drive signal applied to the segment terminal exceeds a predetermined value,
The segment is displayed.

[0006]

However, in the conventional liquid crystal display device, a drive voltage change occurs in a drive voltage for outputting a drive signal applied to a common terminal or a segment terminal, and the drive signal waveform changes ( (Whiskers) may occur. For example, when a waveform change occurs in the drive signal waveform applied to the common terminal, the voltage difference between each drive signal applied to, for example, two segment terminals in the corresponding group exceeds a predetermined value, and the voltage difference between the drive signal and the drive signal increases. One segment may be displayed at a time.

Therefore, an object of the present invention is to provide a liquid crystal display device capable of lighting only a desired segment.

[0008]

According to the present invention, a control means for outputting a drive signal to a plurality of common terminals and a plurality of segment terminals and a plurality of control means corresponding to a plurality of information are provided. The segment electrodes are grouped into a plurality of groups, a common electrode is provided corresponding to each group, the segment electrodes selected from the respective groups are respectively connected to the segment terminals, and the common electrodes are respectively connected to the plurality of common terminals. A liquid crystal display means for connecting and displaying the segment corresponding to the segment terminal when a voltage difference between the drive signal applied to the common terminal and the drive signal applied to the segment terminal exceeds a predetermined value; The control means has a different voltage value for outputting the drive signal by dividing the power supply voltage via the dividing resistor. And voltage supply means for supplying a driving voltage that is made of an adjustable voltage regulator the driving voltage.

In the above invention, the voltage adjusting means can adjust the drive voltage for outputting the drive signal. As a result, for example, a voltage change occurs in the drive signal applied to one common terminal, and the voltage difference between the drive signal applied to the segment terminals that do not need to be displayed in the group of the segment terminals corresponding to the common terminal is determined by a predetermined value. It is possible to prevent segments that exceed the value and do not need to be displayed to be displayed at the same time as desired segments.

At this time, it is preferable that the voltage adjusting means adjusts the divided drive voltage by connecting a resistor in parallel with the divided resistor.

The voltage adjusting means may adjust the drive voltage in accordance with a mode in which the type of the segment to be displayed is different. Here, the modes include, for example, a reservation time setting mode for setting a reservation time, a rice cooking process selection mode for selecting a rice cooking process, and the like. Different segments are displayed in the reservation time setting mode and the rice cooking process selection mode. At this time, since the length of the wiring connecting the segment electrode and the segment terminal corresponding to the displayed segment is different for each segment terminal, by adjusting the drive voltage corresponding to each mode, the liquid crystal display means Can perform optimal display.

The voltage adjusting means may adjust the driving voltage in accordance with the ambient temperature of the liquid crystal display means. Thereby, when the ambient temperature of the liquid crystal display means changes and the resistance value of the wiring connecting the segment electrode and the segment terminal changes, the liquid crystal display means can adjust the optimum display by adjusting the drive voltage. Can do it.

A switch may be provided for arbitrarily selecting the display density of the segment of the liquid crystal display means, and the voltage adjusting means may adjust the drive voltage in accordance with the display density selected by the switch. Good. Thereby, it is possible to perform an optimum display according to the user's preference.

The voltage adjusting means may be a digital potentiometer capable of arbitrarily adjusting the divided resistance.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a rice cooker to which the liquid crystal display device according to the present invention is applied. In this rice cooker, an inner pot 3 is disposed so as to be able to be taken out inside a rice cooker main body 2 to which a lid 1 is attached and opened by a hinge. The rice cooker main body 2 is provided with a heater 4a, a driving circuit 4b composed of elements such as a triac and a diode for driving the heater 4a, and an inner pot temperature sensor (not shown). On the other hand, a liquid crystal display device 5 (drive voltage is about 3 V) for performing various displays such as a clock display and a mode display is provided on the lid 1. This liquid crystal display device 5
Liquid crystal display panel 5a (liquid crystal display means) and liquid crystal display panel 5a
And a power supply circuit 6 connected to the microcomputer 14 (control means). Further, a lid temperature sensor 7 is provided at a position relatively close to the liquid crystal display panel 5a of the lid 1.

As shown in detail in FIG.
Is interposed between the commercial power supply 8 (100V AC power supply) and the liquid crystal display panel 5a. The power supply circuit 6
A power supply unit 10 includes a voltage dividing circuit (voltage supply unit) 11 and a voltage adjustment circuit (voltage adjustment unit) 12.

The power supply section 10 is connected to the commercial power supply 8 by the conductive path 2.
0a and 20b, while the conductive paths 2 are connected to ports 14a and 14b of the microcomputer 14, respectively.
0c and 20d. The power supply unit 10
The AC voltage supplied from the commercial power supply 8 is converted into DC voltages VCC and VDD having a first voltage value (5 V in this embodiment).
D to the port 14 of the microcomputer 14
a, 14b.

The voltage dividing circuit 11 converts a DC voltage supplied from the power supply unit 10 into a plurality of DC voltages (VLCD3, VLCD2, VLCD) for driving the liquid crystal display device 5.
The pressure is divided into 1) and the port 14 of the microcomputer 14 is
c, 14d, and 14e. This voltage dividing circuit 11 is connected to a branch point 2 located on the conductive path 20d.
2b and four resistors 11a, 11a,
11b, 11c, and 11d, and a branch point 22 between the resistors.
c, 22d and 22e are the microcomputer 1 respectively.
4 ports 14c, 14d, and 14e.

In the present embodiment, the voltage adjusting circuit 12 includes four resistors 12a, 12b, 12 connected in series.
c, 12d, and branch points 22f, 22g,
22h is each branch point 22c, 22d, 2 of the voltage dividing circuit 11.
2e. One end of the resistor 12a is connected to the collector of the transistor 12e, and the emitter of the transistor 12e is connected to the microcomputer 1
4 is connected to the port 14a to receive a signal. The base of the transistor 12e is connected to the port 14i of the microcomputer 14. A resistor 12f is provided between the emitter and the base of the transistor 12e to apply a voltage difference between the emitter and the base to switch the transistor 12e. A phototransistor of a photocoupler 12g is provided between the resistor 12b and the branch point 22g,
The cathode of the light emitting diode of the photocoupler 12g is connected to the port 14h of the microcomputer 14 via the resistor 12h, and the anode is connected to the port 14a of the microcomputer 14 to input a signal. A phototransistor of a photocoupler 12i is provided between the resistor 12c and the branch point 22h. The cathode of the light emitting diode of the photocoupler 12i is connected to the microcomputer 14 via a resistor 12j.
, And the anode is connected to the port 14a of the microcomputer 14 to input a signal. One end of the resistor 12d is connected to the collector of the transistor 12k, and the emitter of the transistor 12k is grounded. The base of the transistor 12k is connected to the port 14f of the microcomputer 14 and to the ground via a resistor 121.

The microcomputer 14 includes a plurality of DC voltages VLCD1 to VLCD1 supplied from the voltage dividing circuit 11.
In addition to controlling the driving of the liquid crystal display device 5 by the control unit 3, various elements including the heater 4a are controlled based on input signals from various sensors including the cover temperature sensor 7 and an operation panel (not shown).

FIG. 3 shows the liquid crystal display device 5, showing a liquid crystal display plate 5a and a microcomputer 14.

On the liquid crystal display panel 5a, "reserved", "1", and "2" segment electrodes are displayed as reservation display, and "current", "am", "pm", "minute",
Segment electrodes of "time", "after", "cook up" and a segment electrode of time display (see Fig. 4) and segment electrodes of "heat preservation", "preheating", and "purple" as indications of the rice cooking process , "Rice" as a rice cooking menu display,
The segment electrodes of "soft", "kake", "quick rice", "porridge", "brown rice", "sushi" and a "panless" segment electrode as a warning display are provided, respectively. As the pictogram display, segment electrodes indicating “pan,” “lid,” “face,” “flame (left),” “flame (medium),” “flame (right),” “cooked rice,” and “steam” are displayed. Are located.

Each of the segment electrodes is grouped into three groups, each of the groups is arranged so as to face the common electrode, and each of the common electrodes is connected to the common terminals A20, A21, and A22, respectively. The segment electrodes selected from each group are collectively connected to one segment terminal. For example, "time"
The segment electrodes of “Kakewara” and “Brown rice” are connected to one segment terminal A1 and “cook up”,
The segment electrodes “soft” and “porridge” are connected to one segment terminal A2.

The microcomputer 14 has three common terminals COM0, COM1, COM2 and 19 drive signal output terminals SEG12 to SEG30. The common terminals COM0, COM1, and COM2 are connected to the liquid crystal panel 5
a are connected to the common terminals A20, A21, and A22, respectively. Further, drive signal output terminals SEG12 to SE
G30 is a segment terminal A19 to A of the liquid crystal display panel 5a.
1 respectively.

FIG. 5 shows segment terminals A1 to A19 and common terminals A20 to A22 of the liquid crystal display panel 5a.
Common terminals COM0 to C of the microcomputer 14
5 shows the correspondence between OM2 and drive signal output terminals SEG12 to SEG30.

The microcomputer 14
Needs to display by scanning the common terminals COM0 to COM2 in a certain frame period in a time-division manner and outputting drive signals from the respective drive signal output terminals SEG12 to SEG30 in synchronization with the scan as described later. A predetermined display is performed by applying a voltage to the segment electrodes.

In the reserved time setting mode for setting the reserved time, as shown in FIG. 6A, of the segment electrodes on the liquid crystal display panel 5a, "reserved", "1",
“2”, “present”, “morning”, “afternoon”, “minute”, “hour”, “after”, “to cook” segment electrode and time display segment electrode (see FIG. 4) Is displayed. In addition, in the rice cooking process selection mode in which the rice cooking process is selected, as shown in FIG. 6B, the segment electrodes on the liquid crystal display panel 5a are “heat-retained”, “preheated”, “purple”, “normal”. , "Soft", "kake", "rapid rice", "porridge",
"Brown rice", "sushi", "no pan", "pan",
One of the segment electrodes of “lid”, “face”, “flame (left)”, “flame (medium)”, “flame (right)”, “pressure cooked rice”, and “steam” is displayed. Has become. In addition, when the time is set or in the time display mode at the time of standby in which the rice cooking operation is not performed, as shown in FIG.
One of the segment electrodes “current”, “morning” and “pm” and the segment electrode of the time display segment electrode (see FIG. 4) are displayed. Also,
During the rice cooking operation, any one of the segment electrodes is displayed.

Next, the operation of the liquid crystal display device 5 having the above configuration will be described.

An AC voltage is supplied from the commercial power supply 8 to the power supply unit 10, and DC voltages VCC and VDD of 5 V are supplied to the ports 14a and 14b of the microcomputer 14 through the conductive paths 20c and 20d, respectively. The microcomputer 14 outputs a low-level signal from the port 14i, and the resistor 12a of the voltage adjusting circuit 12 and the resistors 11a, 11b, 11c of the voltage dividing circuit 11 are connected in parallel and supplied to the voltage dividing circuit 11. The DC voltage is 3V. This 3V
DC voltage VLC for driving liquid crystal display device 5 generated by resistors 11a, 11b, 11c from the DC voltage of
D3, VLCD2, VLCD1 are connected to the microcomputer 1 from branch points 22c, 22d, 22e of the voltage dividing circuit 11.
4 ports 14c, 14d, and 14e.

The microcomputer 14 time-divides one frame period into three, and connects three common terminals COM0 to COM2 with 1/3 duty to the ports 14c, 14d, 14
DC voltage VLCD3, VLCD2, VL supplied to e
Scanning is performed using CD1, and SEGs 12 to 3 are synchronized with the scanning.
The required drive signal is output from 0.

More specifically, as shown in FIG. 7A, for example, a drive signal is output from the COM2, and in synchronization with the drive signal, for example, as shown in FIG. A drive signal is output from the drive signal output terminal SEG12 connected to the segment electrode of "". And CO
As shown in FIG. 7C, the voltage difference V1 between the voltage applied to the common terminal A22 by the drive signal output from M2 and the voltage applied to the segment terminal A19 by the drive signal output from SEG12 is: When the predetermined value v is exceeded, the segment of “preheating” is displayed (lighted).

For example, when the rice cooking is started, the process of "preheating" is displayed, and the current time (10: 0 am
0), COM0 to COM2 are scanned and C
When a signal arrives at OM0, the pictograph “flame (right)”, the pictograph “lid”, “4f”, “4a”, “3f”, “3”
SEG13, SEG14, SEG16, SE corresponding to the segments "a", "2f", "2a", and "current".
G17, SEG20, SEG21, SEG23, SEG
24, and a drive signal is output from SEG27.
When the signal comes, the pictogram “Flame (medium)”, “4e”,
"4b", "3e", "3b", "2e", "2b",
SEG12, SEG16, SEG18, SEG corresponding to the segments "1a, 1b", "morning", and "normal"
EG20, SEG21, SEG22, SEG23, SE
Drive signals are output from G25, SEG26, SEG27, and SEG28, and when a signal comes to COM2, "preheat", pictograph "flame (left)", "4d", "4c",
SEG12, SEG15, SEG17 corresponding to the segments "3d", "3c", "2d", and "2c",
Drive signals are output from SEG18, SEG21, SEG22, SEG24, and SEG25. As a result, as shown in FIG. 10A, the current time, the preheating step, and the “normal” rice cooking menu are displayed on the liquid crystal display panel 5a.

For example, as shown in FIG. 8B, a drive signal is output from a drive signal output terminal SEG19 connected to the segment electrode for "warming". At this time, as shown in FIG. 8 (a), the time _t 1, t
₂ , when a voltage change occurs in the DC voltage VLCD3 supplied to the microcomputer 14 and a voltage change (whisker) occurs in the drive signal output from the COM2,
The common terminal A2 according to the drive signal output from COM2
The voltage difference V2 between the voltage value applied to No. 2 and the voltage applied to the segment terminal A12 by the drive signal output from the SEG 19 exceeds the predetermined value v as shown in FIG. At that time, as shown in FIG.
Segment is displayed for a moment.

In this case, the microcomputer 14
As shown in FIG. 9B, at times t ₁ and t ₂ , a low-level signal is output from the port 14 g to connect the resistance 12 c of the voltage adjustment circuit 12 and the resistance 11 b of the voltage division circuit 11 in parallel, and The voltage VLCD1 is changed. As a result, as shown in FIG. 9C, since the voltage difference V2 does not exceed the predetermined value v, the segment of "warming" is not displayed.
In this way, unnecessary segments can be prevented from being displayed.

In the liquid crystal display panel 5a of the embodiment, the lengths of the wires connecting the segment terminals A1 to 19 and the corresponding segment electrodes are different. For example, the length of the wiring connecting the segment terminal A18 and the segment electrodes respectively indicating "Murashi", "Panless" and "Flame (right)" is the length of the segment terminal A4 and "Current", "AM" and "AM". It is longer than the length of the wiring connecting the segment electrodes respectively indicating “PM”. Then, in the rice cooking process selection mode in which the segment shown in FIG. 6A is displayed, FIG.
The segment electrode having a relatively long wiring length is displayed as compared with the reserved time setting mode for displaying the segment shown in FIG. In this case, the microcomputer 14 controls the resistors 12b, 12c,
A voltage dividing circuit 11 corresponding to at least one resistor 12d
The DC voltages VLCD1 to VLCD3 can be adjusted by connecting them in parallel to the resistors 11a, 11b, and 11c, respectively, and an optimal display can be performed.

The microcomputer 14 also controls the DC voltage VLC based on an input signal from the lid temperature sensor 7 provided at a position relatively close to the liquid crystal display panel 5a of the lid 1.
D1 to D3 may be adjusted. Thereby, when the ambient temperature of the liquid crystal display means 5a changes when the rice cooker is used and the resistance value of the wiring connecting the segment electrode and the segment terminal changes, the DC voltages VLCD1 to 3 are adjusted. The liquid crystal display means can perform optimal display.

As a modification of the above-described embodiment, a variable resistor (digital potentiometer) capable of arbitrarily adjusting the resistance value is provided instead of the voltage adjustment circuit 12 having the resistors 12a, 12b, 12c, and 12d. 14, the DC voltages VLCD1 to VLCD3 may be adjusted by arbitrarily adjusting the resistance value. Thus, the segments can be displayed with the density according to the user's preference.

[0039]

As is apparent from the above description, according to the present invention, since the voltage adjusting means adjusts the drive voltage for outputting the drive signal, the voltage is applied to, for example, one common terminal. A voltage change occurs in the drive signal, and the voltage difference between the drive signal applied to the segment terminal that does not need to be displayed in the group of the segment terminals corresponding to the common terminal and the drive signal applied to the segment terminal exceeds a predetermined value, so that the segment that need not be displayed is desired Can be prevented from being displayed simultaneously with the segment.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a rice cooker provided with a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a power supply circuit of the liquid crystal display device of FIG.

FIG. 3 is a diagram showing a microcomputer and a liquid crystal display panel of the liquid crystal display device of FIG.

FIG. 4 is a diagram showing a time display segment electrode of the liquid crystal display panel of FIG. 3;

FIG. 5 is a table showing the correspondence between segment terminals and common terminals of the liquid crystal display panel of FIG. 3, and common terminals and drive signal output terminals of a microcomputer;

FIG. 6A is a diagram showing segments displayed in correspondence with a reserved time setting mode of the liquid crystal display panel of FIG. 3;
FIG. 4B is a diagram showing segments displayed corresponding to the rice cooking process selection mode of the liquid crystal display panel of FIG. FIG. 4C is a diagram showing segments displayed corresponding to the time mode of the liquid crystal display panel of FIG.

FIG. 7A shows a common terminal CO of the liquid crystal display panel of FIG.
FIG. 9 is a waveform chart showing an example of a drive voltage applied to M2.
(B) is a drive signal output terminal SEG of the liquid crystal display panel of FIG.
FIG. 13 is a waveform chart showing an example of a drive voltage given to the drive circuit 12.
(C) is a waveform diagram showing a drive voltage difference V1 applied to the common terminal COM2 and the drive signal output terminal SEG12 of the liquid crystal display panel of FIG.

8A shows a common terminal CO of the liquid crystal display panel of FIG.
FIG. 9 is a waveform chart showing an example of a drive voltage applied to M2.
(B) is a drive signal output terminal SEG of the liquid crystal display panel of FIG.
FIG. 21 is a waveform chart showing an example of a drive voltage applied to the drive signal 19;
(C) is a waveform diagram showing a drive voltage difference V2 applied to the common terminal COM2 and the drive signal output terminal SEG19 of the liquid crystal display panel of FIG.

9A shows a common terminal CO of the liquid crystal display panel of FIG.
FIG. 9 is a waveform chart showing an example of a drive voltage applied to M2.
(B) is a drive signal output terminal SEG of the liquid crystal display panel of FIG.
FIG. 21 is a waveform chart showing an example of a drive voltage applied to the drive signal 19;
(C) is a waveform diagram showing a drive voltage difference V2 applied to the common terminal COM2 and the drive signal output terminal SEG19 of the liquid crystal display panel of FIG.

FIG. 10A is a diagram showing an example of a liquid crystal display panel on which a plurality of segments are displayed during cooking rice.
FIG. 3B is a diagram illustrating a state in which a segment of “heat retention” is displayed on the liquid crystal display panel of FIG.

[Explanation of symbols]

 Reference Signs List 5 liquid crystal display device 5a liquid crystal display panel (liquid crystal display means) 11a to c resistance (division resistance) 11 voltage divider circuit (voltage supply means) 12 voltage adjustment circuit (voltage adjustment means) 14 microcomputer (control means) v predetermined value A1 -19 segment terminal A20-22 common terminal V1, V2 voltage difference VLCD1-3 DC voltage (drive voltage)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H093 NA10 NA21 NC04 NC12 NC50 NC58 NC62 NC90 ND07 ND37 ND40 ND44 ND48 NG01 5C006 AF52 BB01 BF43 EC08 FA31 5C080 AA10 BB01 DD12 JJ01 JJ02 JJ03 JJ04 JJ04 KK42

Claims (5)

[Claims] A control means for outputting a drive signal to a plurality of common terminals and a plurality of segment terminals, a plurality of segment electrodes corresponding to a plurality of information are grouped into a plurality of groups, and a common electrode corresponding to each group. And connecting the segment electrodes selected from the respective groups to the segment terminals, connecting the common electrodes to the plurality of common terminals, respectively, and applying a drive signal given to the common terminals and the segment terminals. When the voltage difference from the applied drive signal exceeds a predetermined value, the liquid crystal display means for displaying a segment corresponding to the segment terminal; and the control means, Voltage supply means for supplying drive voltages having different voltage values for outputting the drive voltage, and an electrode capable of adjusting the drive voltage. The liquid crystal display device characterized by comprising a regulating unit. 2. The liquid crystal display according to claim 1, wherein the voltage adjusting means adjusts the divided drive voltage by connecting a resistor in parallel with the divided resistor. apparatus. 3. The voltage adjustment unit according to claim 1, wherein the drive voltage is adjusted in accordance with a mode in which the type of the segment to be displayed is different.
3. The liquid crystal display device according to 1. 4. The liquid crystal display device according to claim 1, wherein said voltage adjusting means adjusts said driving voltage in accordance with an ambient temperature of said liquid crystal display means. . 5. The liquid crystal display device according to claim 1, wherein said voltage adjusting means is a digital potentiometer capable of arbitrarily adjusting said divided resistance.