JP2001147672A - Portable type electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problem that it is impossible to display correct colors on a liquid crystal display by control using only temperature value in the case of portable type electronic equipment. SOLUTION: The CPU 10 of the portable type electronic equipment 1 is connected with a temperature detection circuit 5 and a voltage detection circuit 6. The temperature detection circuit 5 detects an operating temperature of the liquid crystal display 4, and the voltage detection circuit 6 detects a power source voltage supplied to the liquid crystal display 4. The CPU 10 determines a driving voltage of the liquid crystal display 4 according to a program stored in built-in ROM 13 and based on the values detected by the temperature detection circuit 5 and the voltage detection circuit 6. A liquid crystal driving circuit 14 drives the liquid crystal display 4 at a drive voltage instructed from the CPU 10. Thus, the liquid crystal display 4 is able to display correct colors even if the liquid crystal display 4 is of an electric field control double refraction system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable electronic device for performing a liquid crystal display, and more particularly to a portable electronic device for detecting an operating temperature and a power supply voltage and adjusting a driving voltage of a liquid crystal display.

[0002]

2. Description of the Related Art A liquid crystal display for displaying a screen with low power consumption is a display device suitable for a portable electronic device such as a portable game machine or a portable telephone. In recent years, as one type of liquid crystal display corresponding to color display, an electric control birefringence method (Electrically Controlled)
Liquid crystal displays (d Birefringence system, hereinafter referred to as ECB) have been put to practical use. The ECB liquid crystal display changes the inclination of the liquid crystal molecules by changing the voltage applied to the liquid crystal layer, and performs color display by the resulting change in the birefringence of the liquid crystal layer. Since the ECB liquid crystal display does not use a backlight, color display can be performed with low power consumption.

On the other hand, the ECB liquid crystal display has a feature that a display color changes according to an operating temperature. This is because when the operating temperature changes, the birefringence of the liquid crystal layer changes. FIG. 15 is a diagram illustrating an example of a relationship between a temperature and a voltage and a display color in an ECB liquid crystal display. The display color of the ECB liquid crystal display changes, for example, from green to yellow via purple, as the voltage increases.
The display color of the ECB liquid crystal display changes with a change in the operating temperature.

[0004] Even in a portable electronic device provided with an ECB liquid crystal display, it is necessary that the liquid crystal display correctly display a predetermined color even when the operating temperature changes. However, the operating temperature of the portable electronic device changes depending on the usage conditions, and accordingly, the display color of the ECB liquid crystal display also changes. Therefore, for the purpose of correctly displaying colors on the ECB liquid crystal display, the operation temperature of the liquid crystal display is detected, and the driving voltage of the liquid crystal display is adjusted according to the detected temperature value.

[0005]

In a portable electronic device, a drive voltage for a liquid crystal display is generated by boosting a power supply voltage supplied from a battery. For this reason, ECB
The display color of the liquid crystal display is easily affected by fluctuations in the power supply voltage. However, conventional portable electronic devices do not consider this point and adjust the drive voltage of the liquid crystal display using only the temperature, so that there is a problem that a correct color cannot be displayed.

[0006] Further, the detected values of the operating temperature and the power supply voltage of the liquid crystal display are required to have sufficient accuracy for adjusting the drive voltage of the liquid crystal display. However, conventionally, the temperature and the voltage are separately detected by the temperature detection circuit and the voltage detection circuit. For this reason, a circuit with high detection accuracy is required to correctly perform color display on the ECB liquid crystal display, and there is a problem that the price of the portable electronic device increases. On the other hand, when a circuit with low detection accuracy is used, there is a problem that the ECB liquid crystal display cannot display a correct color.

Therefore, an object of the present invention is to provide a portable electronic device capable of displaying correct colors on an ECB liquid crystal display by controlling the driving voltage of the liquid crystal display based on the detected operating temperature and power supply voltage. is there.

[0008]

A first aspect of the present invention is a portable electronic device that performs liquid crystal display, wherein a liquid crystal display that displays image data, and an image data that is displayed on the liquid crystal display. Image data storage means for storing, image data stored in the image data storage means, liquid crystal driving means for driving the liquid crystal display, and temperature detection means for detecting an operating temperature of the liquid crystal display; Voltage detection means for detecting a power supply voltage; program storage means for storing a program; image data written to the image data storage means in accordance with a program stored in the program storage means; And driving the liquid crystal driving means based on the voltage detection value obtained by the voltage detection means. And control means for determining the pressure.

According to the first aspect, the liquid crystal display is driven by the driving voltage obtained based on the temperature detection value and the voltage detection value. Therefore, even when the display color of the liquid crystal display changes depending on the operating temperature and the power supply voltage, the change in the temperature and the voltage can be compensated, and the screen can be displayed in a predetermined display color.

In a second aspect based on the first aspect, the liquid crystal display is an electric field control birefringent liquid crystal display.

According to the second aspect of the present invention, even for an electric field control birefringence type liquid crystal display in which the color changes depending on the operating temperature and the power supply voltage, the change in temperature and voltage is compensated and the predetermined The screen can be displayed in the display color.

In a third aspect based on the first aspect, the control means obtains a temperature correction value and a voltage correction value by a correction calculation based on the temperature detection value and the voltage detection value. .

According to the third aspect of the invention, the temperature correction value and the voltage correction value are obtained by the program correction calculation based on the temperature detection value and the voltage detection value. By performing such a correction calculation, the temperature and the voltage can be obtained with high accuracy. Further, the temperature and the voltage can be obtained with high accuracy even when the detection accuracy is low and the inexpensive temperature detection means and voltage detection means are used. Further, since the control means operates according to the program, it is possible to perform an appropriate correction calculation determined according to the characteristics of the detected temperature value and the detected voltage value.

In a fourth aspect based on the first aspect, the control means selects a specific color from colors included in the image data, and based on the temperature detection value and the voltage detection value, controls the liquid crystal display. Wherein the driving voltage is determined such that the selected color is displayed in a predetermined color.

According to the fourth aspect of the invention, the liquid crystal display is driven by a voltage for displaying a specific color in a predetermined color. For this reason, even when the display color of the liquid crystal display changes depending on the operating temperature and the power supply voltage,
Changes in temperature and voltage are compensated, and at least a specific color can be displayed in a predetermined color.

[0016]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram illustrating a configuration of a portable electronic device 1 according to an embodiment of the present invention. In FIG.
The portable electronic device 1 includes a battery 2, an IC 3, a liquid crystal display 4, a temperature detection circuit 5, a voltage detection circuit 6, an operation key 7,
And a speaker 8. The IC 3 is an IC in which functions required for the portable electronic device 1 are integrated,
10, display RAM 11, work RAM 12, built-in ROM
13 and a liquid crystal drive circuit 14. As described later, both the temperature detection circuit 5 and the voltage detection circuit 6
It is composed of a circuit in the IC 3 and external components.

The battery 2 supplies a power supply voltage to the portable electronic device 1. The CPU 10 writes image data into the display RAM 11 according to a program stored in the built-in ROM 13, takes in key input from the operation keys 7, and outputs sound from the speaker 8. The liquid crystal display 4 is an ECB liquid crystal display for performing multi-color display, and displays image data including characters, figures, images, and the like.
The liquid crystal drive circuit 14 reads the image data written in the display RAM 11 and drives the liquid crystal display 4.
Thus, the image data generated by the CPU 10 is displayed on the liquid crystal display 4. The drive voltage of the liquid crystal display 4 is generated by boosting the power supply voltage supplied from the battery 2 in the liquid crystal drive circuit 14. CPU10
Controls the drive voltage of the liquid crystal display 4 by controlling the drive voltage adjustment circuit 15 in the liquid crystal drive circuit 14.

FIG. 2 is a memory map of the portable electronic device 1 according to the present embodiment. The CPU 10 has a display RAM 1
1. Access the work RAM 12 and the built-in ROM 13. The display RAM 11 is a display RAM of the liquid crystal display 4, and includes a display image data area 20 for storing a display screen. The work RAM 12 stores program variables, and includes a counter area 21 and a register area 22. The counter area 21 includes a clock counter 30 that stores clock information. The register area 22 includes a temperature register 31 for storing a temperature and a voltage register 32 for storing a voltage. The built-in ROM 13 includes a program area 23 and an image data area 24. The program area 23 stores a program executed by the CPU 10, and the image data area 24 stores image data displayed on the liquid crystal display 4.

FIG. 3 is an example of a display screen of the portable electronic device 1 according to the present embodiment. The portable electronic device 1 selects image data to be displayed based on the input from the operation keys 7 and displays the image data as shown in FIG.
To be displayed. On the liquid crystal display 4, a part of the image data is displayed in yellow and black, respectively. In order to correctly display these colors on the liquid crystal display 4 irrespective of the operating temperature of the liquid crystal display 4 and the power supply voltage supplied from the battery 2, the CPU 10 adjusts the driving voltage of the liquid crystal display 4 as follows.

FIG. 4 is a main flowchart showing the operation of the CPU 10 in the portable electronic device 1 according to the present embodiment. After performing the initial setting (step S101), the CPU 10 repeatedly performs the operations from steps S102 to S107. The CPU 10 adjusts the driving voltage of the liquid crystal display 4 based on the detected values of the temperature and the voltage, the temperature detection processing using the temperature detection circuit 5 (Step S102), the voltage detection processing using the voltage detection circuit 6 (Step S103). Liquid crystal control processing (step S104), and temperature and voltage correction processing (step S105) for correcting the detected temperature and voltage. Thereafter, the CPU 10 selects image data based on the input from the operation keys 7 and displays the selected image data on the display RAM 1.
1 and a screen is displayed (step S106).
Thereafter, the CPU 10 proceeds to step S
It returns to 102 (step S107). Thereby, the portable electronic device 1 detects the operating temperature of the liquid crystal display 4 and the power supply voltage supplied from the battery 2 at regular intervals,
The liquid crystal display 4 is driven by the voltage obtained based on these detected values, and a screen is displayed in a correct color.

Hereinafter, four subroutines included in the flowchart shown in FIG. 4 will be described. First, a temperature detection process, which is a first subroutine, will be described with reference to FIGS. FIG. 5 is a circuit diagram illustrating details of the temperature detection circuit 5 of the portable electronic device 1 according to the present embodiment. The temperature detection circuit 5 includes a thermistor R1, a reference resistor R2, and a capacitor C externally connected to the IC 3, and an internal circuit of the IC 3. Thermistor R1
Are arranged adjacent to the liquid crystal display 4. CPU
10 is for writing a value to the registers X1 and X2,
Further, the counter CNT is initialized and the count value is read.

When the CPU 10 writes the values 0 and 1 to the registers X1 and X2, respectively, the switch SW1 becomes conductive, and an oscillation circuit including the thermistor R1 and the capacitor C (hereinafter referred to as an oscillation circuit on the OUT1 side) is formed. Is done. When the CPU 10 writes the value 1 to both the registers X1 and X2, the switch SW2 is turned on, and an oscillation circuit (hereinafter referred to as O) including a reference resistor R2 and a capacitor C is provided.
(Referred to as an oscillation circuit on the UT2 side). CPU10
Operates each oscillation circuit for a certain period, and the counter CNT counts the number of signal changes of each oscillation circuit in that period. When the operating temperature of the liquid crystal display 4 changes, the resistance value of the thermistor R1 changes, and accordingly, the count value of the oscillation circuit on the OUT1 side also changes. Therefore, the temperature can be detected by calculating the count values of the two oscillation circuits in the temperature detection circuit 5 and performing arithmetic processing on the two count values in the CPU 10.

FIG. 6 is a flowchart of a temperature detection processing subroutine of the portable electronic device 1 according to the present embodiment. The CPU 10 initializes the counter CNT (step S201), and stores the value 1 in both the registers X1 and X2.
Is written to operate the oscillation circuit on the OUT2 side (step S202). Next, the CPU 10 sets the clock counter 3
Wait for a predetermined measurement time using 0 (step S20).
3). The counter CNT counts the number of signal changes of the oscillation circuit on the OUT2 side during this period. Next, CPU1
0 writes the value 0 into the register X2, stops the oscillation circuit on the OUT2 side (step S204), and sets the counter CN
The counter value of T is written into the register F2 in the register area 22 (Step S205). Next, the CPU 10
The same operation as in steps S201 to S205 is performed for the oscillation circuit on the OUT1 side, and the count value of the counter CNT is written to the register F1 in the register area 22 (steps S211 to S215). Furthermore, CPU
10 is a step S2 for the oscillation circuit on the OUT2 side.
The same operation from 01 to S205 is performed again, and the count value of the counter CNT is written to the register F3 in the register area 22 (steps S221 to S225). Finally, the CPU 10 calculates the thermistor resistance value R by the following equation (1).
(Step S231), and writes the calculated thermistor resistance value R to the temperature register 31 (step S231).
232). R = (F2 + F3) / (2 × F1) (1)

The value of the temperature register 31 is not the temperature value itself but a value having a one-to-one relationship with the temperature value. In the flowchart shown in FIG. 6, the count value is measured three times.
The measurement of the second count value may be omitted, and in step S231, the thermistor resistance value R may be obtained by the following equation (2). R = F2 / F1 (2)

FIG. 7 is a signal waveform diagram of the temperature detection circuit 5 of the portable electronic device 1 according to the present embodiment. The period from time a to time b is from step S202 to step S2.
This corresponds to the period up to 04. During this period, the oscillation circuit on the OUT2 side oscillates, and the signal at the output terminal OUT2 changes. During the period from time c to time d, step S212
To step S214. During this period, the oscillation circuit on the OUT1 side oscillates and the output terminal OUT1
Signal changes. The period from time e to time f corresponds to the period from step S222 to step S224. During this period, the oscillation circuit on the OUT2 side oscillates again, and the signal at the output terminal OUT2 changes. The lengths of these three periods are all the same.

Next, a voltage detection process, which is a second subroutine, will be described with reference to FIGS. FIG.
FIG. 2 is a circuit diagram showing details of a voltage detection circuit 6 of the portable electronic device 1 according to the embodiment. The voltage detection circuit 6 is an IC
3 includes a resistor R4 and a Zener diode D externally provided, a variable resistor VR, a resistor R3, and an operational amplifier OP built in the IC3. CP
U10 switches the resistance value of the variable resistor VR by setting a value in the register X3, and reads out the register X4 to set the two input voltages V1 and V of the operational amplifier OP.
Compare with 2. Using these mechanisms, the CPU 10 uses the power supply voltage Vcc supplied from the battery 2 as follows.
Is detected.

FIG. 9 is a flowchart of a voltage detection processing subroutine of the portable electronic device 1 according to the present embodiment. First, the CPU 10 sets the resistance value of the variable resistor VR to the maximum value (Step S301). Next, CPU1
0 compares the two input voltages V1 and V2 of the operational amplifier OP (step S302). When V1 is smaller than V2, if the resistance value of the variable resistor VR is not the minimum value, the CPU 10 reduces the resistance value of the variable resistor VR by one level (Steps S303 and S304). The CPU 10
If 1 is equal to or greater than V2, the resistance value of the variable resistor VR is written to the voltage register 32 (Step S305). The value of the voltage register 32 is not the voltage value itself but a value having a one-to-one relationship with the voltage value.

Next, a liquid crystal control process as a third subroutine will be described with reference to FIGS. FIG. 10 is a flowchart of a liquid crystal control processing subroutine of the portable electronic device 1 according to the present embodiment. CPU10
Calculates the drive voltage _Vdr of the liquid crystal display 4 from the value t of the temperature register 31 and the value v of the voltage register 32 (step S401), and sets the calculated drive voltage _Vdr in the liquid crystal drive circuit 14 (step S402). .

[0029] In order to display the color set in the liquid crystal display 4, CPU 10, in step S401, for example, calculates the driving voltage V _dr as follows. FIG.
FIG. 1 is a diagram illustrating an example of a relationship between a temperature and a voltage and a drive voltage of a liquid crystal display 4 in the portable electronic device 1 according to the present embodiment. In FIG. 11, T _true and V _tr
ue is the true temperature value and the true voltage value, respectively, and t and v are the temperature detection circuit 5 under that condition, respectively.
And the voltage detection value by the voltage detection circuit 6. BIAS corresponds to the optimum drive voltage _{Vdr under the} condition. As an approximate expression representing the relationship between t and v and BIAS shown in FIG. 11, for example, the following expression (3) is obtained. The CPU 10 calculates BI from t and v by the following equation (3).
AS is calculated and set in the liquid crystal drive circuit 14. The liquid crystal drive circuit 14 drives the liquid crystal display 4 with a voltage corresponding to BIAS calculated by the CPU 10. BIAS = 65.545−0.240 × t−0.892 × v (3)

The method of calculating the drive voltage _Vdr is not limited to the above method. For example, a table shown in FIG. 11 is stored in the built-in ROM 13, and the CPU 10 refers to the table in step S401. BIAS may be required.

Finally, using FIGS. 12 to 14,
The temperature / voltage correction process, which is the fourth subroutine, will be described. FIG. 12 is a portable electronic device 1 according to the embodiment.
9 is a flowchart of a temperature voltage correction processing subroutine of FIG. The CPU 10 sets the values of the temperature register 31 and the voltage register 32 as the temperature detection value t and the voltage detection value v, respectively (step S501). Next, the CPU 10
Calculates the temperature correction value T and the voltage correction value V from the temperature detection value v and the voltage detection value t, as described later (step S502). Finally, the CPU 10 stores the calculated temperature correction value T and the calculated voltage correction value V in the temperature register 31 respectively.
And the voltage register 32 (step S50).
3).

The temperature detection value t by the temperature detection circuit 5 and the voltage detection value v by the voltage detection circuit 6 influence each other, and therefore both include an error. FIG. 13 is a schematic diagram illustrating a relationship between a detected value and a true value of temperature and voltage in the portable electronic device 1 according to the present embodiment. CP
U10 determines in step S502 as follows:
A temperature correction value T and a voltage correction value V are calculated from the temperature detection value t and the voltage detection value v. The temperature detection value t, based on the temperature characteristics of the Zener diode D and the power supply voltage characteristics of the oscillation circuit,
The voltage detection value v, the temperature correction value T, and the voltage correction value V have a relationship represented by the following equations (4) and (5). v = V + (T−T ₀ ) × a (4) t = T ₀ + (T−T ₀ ) × V / V ₀ (5)

Here, T₀ Is the thermistor resistance and reference
Temperature at which the resistance value of the resistor matches, V ₀ Is the power supply voltage reference
The value, a, is a proportionality constant. Equations (4) and (5)
Solving for the correction value T and the voltage correction value V gives the following equation
(6) and (7).

(Equation 1)

The CPU 10 calculates the equations (6) and (7) according to the program stored in the built-in ROM 13 and calculates the temperature correction value T and the voltage correction value V from the temperature detection value t and the voltage detection value v. Is calculated. For example, by substituting the actual coefficient values into equations (6) and (7) and rearranging, the following equations (8) and (9) are obtained.

(Equation 2)

FIG. 14 is a diagram showing the result of calculating the correction value when the equations (8) and (9) are used. In FIG. 14, T _true and V _true are a temperature true value and a voltage true value, respectively, and t and v are a temperature detection value by the temperature detection circuit 5 and a voltage detection value by the voltage detection circuit 6 under the conditions, respectively. It is. Also, T and V are
These are the temperature correction value and the voltage correction value calculated by substituting t and v into equations (8) and (9). As shown in FIG. 14, the calculated temperature correction value T and voltage correction value V are
These values are close to the _true temperature value T _true and the _true voltage value V _true , respectively. The temperature correction value and the voltage correction value thus calculated are used for various controls of the portable electronic device 1, for example, as shown in FIG.
1 is used to calculate the drive voltage of the liquid crystal display 4 with reference to the table shown in FIG.

In this embodiment, the temperature characteristics of the Zener diode D and the power supply voltage characteristics of the oscillation circuit are as follows.
Equations (4) and (5) were used, respectively. For this reason, the calculated correction value includes a slight error. In order to suppress this error, the CPU 10 may use a quadratic or higher order approximation or a more complicated approximation instead of the expressions (4) and (5). Further, the CPU 10 may calculate the correction value using an experimentally obtained relational expression instead of the approximate calculation using the approximate expression. According to the present embodiment, the CPU
Since the temperature-voltage correction process is performed by using the value 10, an appropriate correction calculation determined according to the characteristics of the temperature detection value and the voltage detection value can be performed.

As described above, according to the portable electronic device of the embodiment of the present invention, the operating temperature and the power supply voltage of the liquid crystal display are detected by the temperature detecting circuit and the voltage detecting circuit, and the detection is performed. The driving voltage of the liquid crystal display is calculated based on the value. Therefore, even when the display color of the liquid crystal display changes depending on the operating temperature and the power supply voltage, the change in the operating temperature and the power supply voltage can be compensated, and the screen can be displayed in a predetermined display color. In particular, even when an ECB liquid crystal display whose display color changes depending on the operating temperature and the power supply voltage is used, the screen can be displayed in a predetermined display color by compensating for the change in temperature and voltage.

Further, according to the present embodiment, a temperature correction value and a voltage correction value are obtained by performing a correction calculation by a program based on the temperature detection value and the voltage detection value. Thus CP
Since the correction calculation is performed using U, the temperature and the voltage can be obtained with high accuracy even when the detection accuracy is low and the inexpensive temperature detection circuit and voltage detection circuit are used. Also, C
Since the PU operates according to the program, an appropriate correction calculation determined according to the characteristics of the detected temperature value and the detected voltage value can be performed.

When the display voltage of the liquid crystal display is controlled by adjusting the drive voltage, not all colors displayed on the liquid crystal display are necessarily displayed correctly. For this reason, a technique of selecting a specific color from the colors included in the image data and adjusting the drive voltage so that the selected color is correctly displayed is practically effective. For example, in the screen shown in FIG. 3, the display color yellow in the image data is selected as a specific color, and the drive voltage of the liquid crystal display 4 is adjusted so that yellow is correctly displayed. By adjusting the drive voltage in this manner, at least a specific color can be displayed in a predetermined color.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a portable electronic device according to an embodiment of the present invention.

FIG. 2 is a memory map of the portable electronic device according to the embodiment of the present invention.

FIG. 3 is an example of a display screen of the portable electronic device according to the embodiment of the present invention.

FIG. 4 is a main flowchart of the portable electronic device according to the embodiment of the present invention.

FIG. 5 is a circuit diagram of a temperature detection circuit of the portable electronic device according to the embodiment of the present invention.

FIG. 6 is a flowchart of a temperature detection processing subroutine of the portable electronic device according to the embodiment of the present invention.

FIG. 7 is a signal waveform diagram of a temperature detection circuit of the portable electronic device according to the embodiment of the present invention.

FIG. 8 is a circuit diagram of a voltage detection circuit of the portable electronic device according to the embodiment of the present invention.

FIG. 9 is a flowchart of a voltage detection processing subroutine of the portable electronic device according to the embodiment of the present invention.

FIG. 10 is a flowchart of a liquid crystal control processing subroutine of the portable electronic device according to the embodiment of the present invention.

FIG. 11 is a diagram illustrating an example of a relationship between a temperature and a voltage and a driving voltage of a liquid crystal display in the portable electronic device according to the embodiment of the present invention.

FIG. 12 is a flowchart of a temperature / voltage correction processing subroutine of the portable electronic device according to the embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating a relationship between a detected value and a true value for temperature and voltage of the portable electronic device according to the embodiment of the present invention.

FIG. 14 is a diagram illustrating an example of a correction value calculation result of the temperature / voltage correction process of the portable electronic device according to the embodiment of the present invention.

FIG. 15 is a diagram showing an example of a relationship between a temperature and a voltage and a display color in an electric field control birefringent liquid crystal display.

[Description of Signs] 1 ... Portable electronic device 2 ... Battery 3 ... IC 4 ... Liquid crystal display 5 ... Temperature detection circuit 6 ... Voltage detection circuit 10 ... CPU 11 ... Display RAM 12 ... Work RAM 13 ... Built-in ROM 14 ... Liquid crystal drive Circuit 15: Drive voltage adjustment circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/13 505 G02F 1/13 505 5C080 1/133 580 1/133 580 9A001 G06F 15/02 315 G06F 15 / 02 315C G09G 3/20 642 G09G 3/20 642 J No. 22 Inside Sharp Corporation (72) Motoshi Kitao Inventor 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Prefecture Inside Sharp Corporation (72) Bunichi Omoto 22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka No. 22 F-term in Sharp Corporation (reference) 2C001 BA00 BA06 BB00 BB10 BC00 BC05 BC06 CA00 CA09 CB01 CC03 2 H088 EA22 HA06 JA09 MA05 2H093 NC02 NC27 NC28 NC50 NC57 ND17 ND45 NF09 NG01 5B019 CA04 EA01 HD09 5C006 AA22 AF13 AF46 AF51 AF52 AF53 AF64 AF85 BB11 BF02 BF14 BF15 BF22 BF29 BF38 JJ45 BF45 EC08 FA19 BF45 EC08 BB06 DD11 HH34 JJ28 KK54

Claims (4)

[Claims] 1. A portable electronic device that performs liquid crystal display, comprising: a liquid crystal display that displays image data; an image data storage unit that stores image data displayed on the liquid crystal display; Liquid crystal driving means for reading the stored image data and driving the liquid crystal display; temperature detecting means for detecting an operating temperature of the liquid crystal display; voltage detecting means for detecting a supplied power supply voltage; and storing a program. In accordance with a program stored in the program storage unit, the image data is written to the image data storage unit, and based on a temperature detection value by the temperature detection unit and a voltage detection value by the voltage detection unit, A portable device comprising: a control unit for obtaining a drive voltage in the liquid crystal drive unit. Equipment. 2. The portable electronic device according to claim 1, wherein the liquid crystal display is an electric field control birefringence liquid crystal display. 3. The portable electronic device according to claim 1, wherein the control unit calculates a temperature correction value and a voltage correction value by performing a correction calculation based on the temperature detection value and the voltage detection value. machine. 4. The liquid crystal display according to claim 1, wherein the control unit selects a specific color from colors included in the image data, and selects the predetermined color on the liquid crystal display based on the temperature detection value and the voltage detection value. The portable electronic device according to claim 1, wherein the driving voltage is obtained as indicated by: