JP2008216526A - Liquid crystal device and voltage supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a transition voltage and a normal voltage with simple configurations in a liquid crystal device using an OCB (Optical Compensated Bend) liquid crystal. <P>SOLUTION: A voltage boosting device 200 has a boosting circuit and a control part 210. The boosting circuit has a capacitor C1 in which electric charges are accumulated based upon a boosted voltage, resistances R1 and R2 dividing the voltage developed across the capacitor, and a transistor Tr2 discharging the electric charges accumulated in the capacitor C1 when turning on. The control part 210 once detecting a voltage Vn3 reaching a first reference voltage Vref1 after the boosting circuit begins to boost a source voltage maintains the voltage for a predetermined time to place the liquid crystal device in initial transition operation, makes the transistor Tr1 turn on the predetermined time later, and maintains the voltage Vn3 once detecting the voltage Vn3 reaching a second reference voltage Vref2 to drive the liquid crystal panel with the normal voltage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal device using a liquid crystal having a first alignment state that can be displayed as an alignment state and a second alignment state that cannot be displayed, and a voltage supply device therefor.

  A liquid crystal device that performs display by changing the transmittance of liquid crystal is widely used as a display device such as an information processing device or a television. Conventionally, a TN (Twisted Nematic) method has been generally used as a display method for liquid crystal devices, but various methods have been developed in recent years in order to improve response characteristics and viewing angles.

For example, Patent Document 1 discloses a surface liquid crystal display device using an OCB (Optical Compensated Bend) type liquid crystal display element. The OCB type liquid crystal device can operate at high speed and has excellent moving image characteristics as compared with the TN type liquid crystal device. In addition, since the viewing angle is wide, research is being promoted toward practical use.
JP 2002-278524 A

  The OCB type liquid crystal device is in a state called splay alignment in which liquid crystal molecules are not suitable for displaying an image before the power is turned on. For this reason, when displaying an image, it is necessary to perform an initial transition operation at the time of power-on or the like to shift liquid crystal molecules to a state called bend alignment suitable for image display.

As described in Patent Document 1, at the time of initial transition, a relatively high voltage of more than 10 V is usually applied to the liquid crystal panel for a predetermined time. In order to obtain such a voltage with an information processing device using a power supply voltage of about 3.3 V, for example, a mobile phone, it is necessary to boost the power supply voltage by about five times.
Further, after the initial transition is completed, it is necessary to supply a normal driving voltage to the liquid crystal panel, which is lower than the voltage required for the transition.

  If these voltage controls are performed by a semiconductor device such as an IC, the semiconductor device needs to have a relatively high voltage resistance. However, since a semiconductor device having high withstand voltage is generally expensive, performing voltage control with the semiconductor device causes an increase in cost. In addition, it is desirable that the configuration for shifting to the voltage for normal driving after the transition is as simple as possible from the viewpoint of cost reduction.

  The present invention has been made in view of the above-described circumstances, and an object thereof is a liquid crystal that requires a voltage obtained by boosting a power supply voltage for an initial transition operation and is driven at a normal voltage lower than the transition voltage after the initial transition operation. The purpose of the apparatus is to reduce the cost of the apparatus that performs voltage control.

  In order to solve the above-described problems, the liquid crystal device according to the present invention requires an initial transition operation using a transition voltage in order to transition from the non-display state to the display state, and is driven at a normal voltage lower than the transition voltage after the initial transition operation. A booster circuit (for example, L1, Tr1, D1 shown in FIG. 3) that boosts the power supply voltage and outputs the boosted voltage, and accumulates charges based on the boosted voltage, Of the capacitor is electrically connected to the booster circuit, a fixed potential is supplied to the other terminal, a resistor that divides the voltage generated at one terminal of the capacitor, and stored in the capacitor in the on state. A switch (for example, Tr2 shown in FIG. 3) for discharging the charged electric charge, and a voltage control device for controlling a voltage supplied to the liquid crystal panel. When it is detected that the divided voltage divided by the resistor (for example, Vn3 shown in FIG. 3) has reached the first reference value after the power supply voltage is increased by the circuit, the first reference is output for a predetermined time. By maintaining the divided voltage that has reached the value, the initial transition operation is performed, and after the predetermined time has elapsed, the switch is turned on to detect that the divided voltage has reached the second reference value. Then, the drive by the normal voltage is performed by maintaining the divided voltage that has reached the second reference value.

  According to this liquid crystal device, the power supply voltage is boosted to generate the transition voltage, and the charges accumulated in the capacitor are discharged using the switch, so that a normal voltage lower than the transition voltage can be generated. Therefore, it is not necessary to separately prepare a power supply for the transition voltage, and the configuration of the entire apparatus can be simplified. The resistor for dividing the voltage generated at one terminal of the capacitor includes a first resistor and a second resistor connected in series between the one terminal of the capacitor and a node to which a fixed potential is supplied. It is preferable to extract the divided voltage from the connection point between the resistor and the second resistor.

Here, the first reference value corresponds to a value obtained by dividing the transition voltage by the resistor, and the second reference value corresponds to a value obtained by dividing the normal voltage by the resistor. preferable. As a result, the transition voltage and the normal voltage can be monitored and reflected in the step-up operation and the step-down operation to perform feedback control.
The withstand voltage of the voltage control device is preferably lower than the transition voltage. By incorporating the voltage divided by the resistor into the voltage control device, the withstand voltage of the voltage control device can be lowered. In this way, the system that handles a relatively high voltage such as a transition voltage is separated from the system that controls this, so that the breakdown voltage of the semiconductor element used in the voltage control device can be lowered, and the cost of the voltage control device is reduced. can do.

  In the liquid crystal device described above, the liquid crystal used for the liquid crystal panel has a first alignment state and a second alignment state as alignment states, and the transition voltage changes the alignment state of the liquid crystal from the first alignment state to the second alignment state. It is preferably used for transition to the alignment state. Such a liquid crystal corresponds to an OCB liquid crystal having a splay alignment state and a bend alignment state as alignment states.

Next, the voltage supply device according to the present invention requires an initial transition operation using a transition voltage to transition from the non-display state to the display state, and supplies a normal voltage lower than the transition voltage to the liquid crystal panel after the initial transition operation. A booster circuit that boosts a power supply voltage and outputs a boosted voltage;
Charges are accumulated based on the boosted voltage, one terminal is electrically connected to the booster circuit, and a fixed potential is supplied to the other terminal, and a voltage generated at one terminal of the capacitor is divided. A resistor for pressing, a switch for discharging the charge accumulated in the capacitor in an on state, and a voltage control device for controlling a voltage supplied to the liquid crystal panel. When it is detected that the divided voltage divided by the resistor has reached the first reference value after the start of voltage boosting, the divided voltage that has reached the first reference value for a predetermined time is maintained. The initial transition operation is performed, and after the predetermined time has elapsed, the switch is turned on, and when it is detected that the divided voltage has reached a second reference value, the second reference value has been reached. Characterized in that to perform driving by the normal voltage by maintaining voltage.
According to this voltage supply device, the power supply voltage is boosted to generate the transition voltage, and the charges accumulated in the capacitor are discharged using the switch, so that a normal voltage lower than the transition voltage can be generated. Therefore, it is not necessary to prepare a separate power supply for the transition voltage.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a block diagram of a liquid crystal device according to the present embodiment. The liquid crystal device 700 includes a booster 200 that generates a predetermined voltage based on a power supply voltage, and uses liquid crystal as an electro-optic material. The liquid crystal device 700 includes a liquid crystal panel AA as a main part. In the liquid crystal panel AA, an element substrate on which a TFT (thin film transistor) is formed as a switching element and a counter substrate are pasted with their electrode formation surfaces facing each other with a certain gap therebetween, and liquid crystal is sandwiched between the gaps. Has been. The liquid crystal in this example is an OCB liquid crystal.

  The liquid crystal device 700 includes a timing generation circuit 130, an image processing circuit 140, a main control circuit 150, and a backlight 160. On the element substrate of the liquid crystal panel AA, an image display area A, a scanning line driving circuit 110, and a data line driving circuit 120 are formed.

  The main control circuit 150 converts the input image signal Vin supplied from an external device in an analog format into a digital signal, and supplies it to the image processing circuit 140 as input image data Din. The main control circuit 150 controls the lighting of the backlight 160. In the present embodiment, the backlight 600 is provided on the opposite side of the surface on which the image of the liquid crystal panel AA is displayed. Note that the backlight 600 may be configured to control lighting / extinguishing in a plurality of regions obtained by dividing the liquid crystal panel AA in the scanning line direction.

  The booster 200 generates a relatively high transition voltage Vcom1 for transitioning the liquid crystal from the splay alignment to the bend alignment when the power is turned on, etc., and during the normal driving after the transition, the relatively low normal voltage Vcom2 for normal driving is used. Is generated. The main control circuit 150 and the booster 200 are connected by a control signal line, and voltage switching timing adjustment and the like can be performed by a control signal CTL output from the main control circuit 150. The transition voltage Vcom1 and the normal voltage Vcom2 are supplied as a common voltage Vcom to the counter electrode 62 formed on the entire surface of the counter substrate.

  The input image data Din supplied from the main control circuit 150 to the image processing circuit 140 is in a 24-bit parallel format, for example. The timing generation circuit 130 is synchronized with a control signal such as a horizontal scanning signal and a vertical scanning signal supplied from the image processing circuit 140, and generates a Y clock signal YCK, an X clock signal XCK, a Y transfer start pulse DY, and an X transfer start. A pulse DX is generated and supplied to the scanning line driving circuit 110 and the data line driving circuit 120. The timing generation circuit 130 generates various timing signals for controlling the image processing circuit 140 and outputs them.

Here, the Y clock signal YCK specifies a period for selecting the scanning line 20, and the X clock signal XCK specifies a period for selecting the data line 10. The Y transfer start pulse DY is a pulse for instructing the start of selection of the scanning line 20, while the X transfer start pulse DX is a pulse for instructing the start of selection of the data line 10.
Next, the image processing circuit 140 performs gamma correction and the like on the input image data Din in consideration of the light transmission characteristics of the liquid crystal panel AA, and then D / A converts the image data of each RGB color to obtain the image signal VID. Generated and supplied to the liquid crystal panel AA.

  FIG. 2 shows a detailed configuration of the image display area A. In the image display area A, m (m is a natural number of 2 or more) scanning lines 20 are formed in parallel along the X direction, while n (n is a natural number of 2 or more) data. Lines 10 are formed in parallel along the Y direction. Then, m × n pixel circuits P are arranged corresponding to the intersection of the data line 10 and the scanning line 20.

  As shown in the figure, the pixel circuit P includes a liquid crystal element 60 and a TFT 50. The liquid crystal element 60 is configured by sandwiching an OCB liquid crystal between a pixel electrode 61 and a counter electrode 62. A common voltage Vcom is supplied to the counter electrode 62. The gate electrode of the TFT 50 is electrically connected to the scanning line 20, one of its drain electrode or source electrode is electrically connected to the data line 10, and the other is electrically connected to the pixel electrode 61. Therefore, the voltage applied to the liquid crystal can be changed by changing the common voltage Vcom.

  The data line driving circuit 120 shown in FIG. 1 outputs data signals X1 to Xn to n data lines 10. If the signal polarity is determined based on the common voltage Vcom of the counter electrode 62 as a high potential, the low potential is defined as a negative polarity, the data signal polarity is positive in the odd-numbered frame and the data signal in the even-numbered frame. The polarity is negative. This inverts the voltage applied to the liquid crystal on a frame basis. Note that the voltage applied to the liquid crystal may be inverted in units of lines, or the voltage applied to the liquid crystal may be inverted in units of dots.

  Further, scanning signals Y1, Y2,..., Ym are applied to each scanning line 20 from the scanning line driving circuit 110 in a pulse-sequential manner. For this reason, when a scanning signal is supplied to a certain scanning line 20, the TFT 50 is turned on in the pixel circuit P of the row, and the data signal supplied via the data line 10 is written into the liquid crystal element 60. Since the orientation and order of liquid crystal molecules change according to the voltage level applied to each pixel, gradation display by light modulation becomes possible. For example, in the normally white mode, the amount of light passing through the liquid crystal is limited as the applied voltage increases. In the normally black mode, the amount of light is reduced as the applied voltage increases. As a whole, light having contrast according to the image signal is emitted for each pixel. The liquid crystal device 700 in this example is normally white. Note that a storage capacitor may be added in parallel with the liquid crystal capacitor formed between the pixel electrode 61 and the counter electrode 62 in order to prevent the stored image signal from leaking.

  FIG. 3 is a block diagram showing a configuration of the booster 200. The booster 200 supplies a common voltage Vcom obtained by boosting the input voltage V1 to the counter electrode 62 of the liquid crystal panel AA. The step-up device 200 of this example includes a step-up circuit including an inductor L1, a transistor Tr1, and a diode D1 and a control unit 210. The transistor Tr1 is repeatedly switched by the oscillator 211 to generate an electromotive force in the inductor L1. Then, the control unit 210 controls the generated voltage to generate a common voltage Vcom and supply it to the liquid crystal device 700. Here, the common voltage Vcom is the transition voltage Vcom1 and the normal voltage Vcom2 as described above.

Specifically, the control unit 210 divides the voltage of the capacitor C1 generated by the booster circuit by the resistor R1 and the resistor R2, and compares the voltage of the resistor R2 with the reference voltage by the comparator 214, thereby turning on / off the transistor Tr1. A first switching signal Vsw1 for controlling the off state and a second switching signal Vsw2 for controlling the on / off state of the transistor Tr2 are generated.
Here, the control unit 210 can be configured by a semiconductor device such as an IC, and the resistance R1 and the resistance R2 are determined by the voltage Vn3 of the node N3 and the withstand voltage value of the semiconductor device constituting the control unit 210. It is possible to choose not to exceed. For this reason, the semiconductor device constituting the control unit 210 does not need voltage resistance against the high transition voltage Vcom2 necessary for the transition, and the cost can be reduced. Further, since the power supply voltage is boosted, it is not necessary to prepare a separate power supply for transfer.

As the reference voltage compared by the comparator 214, the first reference voltage Vref1 for detecting the transition voltage Vcom1 and the second reference voltage Vref2 for detecting the normal voltage Vcom2 are used and are switched by the switch 213. ing.
A transistor Tr2 is connected to the capacitor C1 in parallel. The transistor Tr2 is turned on during a period in which the common voltage Vcom is changed from the transition voltage Vcom1 to the normal voltage Vcom2, and functions as a means for discharging the charge accumulated in the capacitor C1.

  The control unit 210 includes a sequencer unit 212 that manages a voltage control procedure. The sequencer unit 212 performs processing for boosting the input voltage V1 by switching on and off the transistor Tr1, processing for detecting the voltage Vn3 by switching the switch 213, processing for holding the transition voltage Vcom1 by switching on and off the transistor Tr2, and the normal voltage Vcom2 Processing to maintain is performed. In the process of boosting the input voltage V1, the sequencer unit 212 supplies an enable signal EN that goes high to one terminal of the AND circuit 216. An oscillation signal OSC is supplied from the oscillator 211 to the other terminal of the AND circuit 216. The AND circuit 216 outputs the logical product of the oscillation signal OSC and the enable signal EN to the transistor Tr1 as the first switching signal Vsw1. That is, when the enable signal EN becomes active, the transistor Tr1 is repeatedly turned on and off, and when the enable signal EN becomes inactive, the transistor Tr1 is turned off.

  Further, the transition voltage Vcom1 is held in order to secure a time necessary for the liquid crystal to transition to the bend alignment state. For this purpose, the sequencer unit 212 includes a timer 215 that measures the time required for the liquid crystal to transition to the bend alignment state. For example, the timer 215 includes a counter. The timer 215 performs counting when the timer enable signal Ten is at a high level, and activates the output signal Tout when the count value reaches a predetermined value. The sequencer unit 212 sets the timer enable signal Ten to a high level when the comparator 214 detects that the common voltage Vcom has reached the transition voltage Vcom1, and sets the timer enable signal Ten to a low level when the output signal Tout becomes active. . Note that the timer 215 may count pulses of the oscillation signal OSC.

FIG. 4 is a timing chart showing how the booster 200 boosts the input voltage V1. This figure shows the relationship between the pulse voltage applied to the base of the transistor Tr1, the voltage Vn1 generated on the collector side of the transistor Tr1, and the voltage Vn2 generated on the capacitor C1.
As shown in this figure, in the initial state in which the transistor Tr1 is off, the voltage Vn1 at the node N1 and the voltage Vn2 at the node N2 are both the input voltage V1. When the transistor Tr1 is turned on at time t1, the voltage Vn1 falls to the ground potential GND. At this time, since the diode D1 is turned off, the voltage Vn2 at the node N2 is held at the input voltage V1 by the capacitor C1.

  When the transistor Tr1 is turned off at time t2, an electromotive force is generated in the inductor L1, and the capacitor C1 is charged. For this reason, the voltage Vn1 and the voltage Vn2 rise. On the other hand, since the electromotive force generated in the inductor L1 decreases toward the input voltage V1, the increase of the voltage Vn1 and the voltage Vn2 stops at time t3. Thereafter, the voltage Vn1 decreases toward the input voltage V1. Since the diode D1 is turned off, the voltage Vn2 at the node N2 is maintained.

When the transistor Tr1 is turned on again at time t4, the node N1 falls to the ground potential GND, but the voltage Vn2 is held by the diode D1. When the transistor Tr1 is turned off again at time t5, an electromotive force is generated in the conductor L1, and the capacitor C1 is further charged to increase the voltage Vn2.
By repeating such a cycle, a voltage Vn2 higher than the input voltage V1 is generated in the capacitor C1.

  Next, supply voltage control processing performed by the sequencer unit 212 of the control unit 210 will be described with reference to FIGS. FIG. 5 is a flowchart showing a processing flow of the sequencer unit 212, and FIG. 6 is a diagram showing a change with time of a voltage supplied from the booster 200 to the main control circuit 150. Hereinafter, the operation of the booster 200 will be described by dividing it into an initial state period d0, a boost period d1, a first holding period d2, a step-down period d3, and a second holding period d3.

In the initial state period d0, the liquid crystal molecules of the liquid crystal device 700 are in a splay alignment state before power-on, and are not suitable for display. Therefore, when the power is turned on at time t10, the boosting period d1 starts, and the booster 200 boosts the input voltage V1 toward the transition voltage Vcom1.
In the boost period d1, when the sequencer unit 212 detects power-on, the sequencer unit 212 turns the second switching signal Vsw2 low to turn off the transistor Tr2, and switches the switch 213 to the first reference voltage Vref1 (S101).

As a result, the voltage of the capacitor C1 increases as shown in FIG. In proportion to the increase, the voltage Vn3 of the node N3 also increases. The comparator 214 compares the voltage Vn3 with the first reference voltage Vref1, and outputs a detection signal to the sequencer unit 212 when detecting that the voltage Vn3 has reached the first reference voltage Vref1.
When the sequencer unit 212 detects from the detection signal from the comparator 214 that the voltage Vn3 has reached the first reference voltage Vref1, that is, boosted to a voltage necessary for the transition (S102: Y, FIG. 6: t10). ), The boosting period d1 is ended, and the first holding period d2 is started.

In the first holding period d2, the sequencer unit 212 sets the enable signal EN to low level in order to maintain the transition voltage Vcom1. As a result, the first switching signal Vsw1 output from the AND circuit 216 goes low, turning off the transistor Tr1. Further, the sequence unit 212 sets the timer enable signal Ten to a high level and starts the timer 215 (S103).
While the timer 215 is counting up, the transition voltage Vcom1 is supplied to the counter electrode 62 as the common voltage Vcom. As a result, the liquid crystal molecules of the liquid crystal panel AA transition from the splay alignment state to the bend alignment state.

  When the count value of the timer 215 reaches a predetermined value, the timer 215 activates the output signal Tout. When the sequencer unit 212 detects this (S104: Y, FIG. 6: t11), the sequencer unit 212 ends the first holding period d2 and starts the step-down period d3. Specifically, in order to step down the transition voltage Vcom1 generated in the capacitor C1 to the normal voltage Vcom2, the sequencer unit 212 controls the switch 213 to switch to the second reference voltage Vref2. Accordingly, the comparator 214 compares the second reference voltage Vref2 with the voltage Vn3. Based on the comparison result, the sequence unit 212 changes the second switching signal Vsw2 to a high level and turns on the transistor Tr2 (S105). Then, the electric charge of the capacitor C1 is discharged, and the voltage of the capacitor C1 decreases (FIG. 6: d3). The voltage Vn3 generated in the resistor R2 also decreases in proportion to the decrease.

  When the sequence unit 212 detects that the voltage Vn3 has reached the second reference voltage Vref2 based on the detection signal from the comparator 214, that is, the common voltage Vcom has been stepped down to the normal voltage Vcom2 (S106: Y, FIG. 6). : T12), the step-down period d3 is ended and the second holding period d4 is started. In the second holding period d4, the sequencer unit 212 controls the booster circuit so as to maintain the normal voltage Vcom2 (S107). Specifically, the detection signal of the comparator 214 is monitored, and when the voltage Vn3 falls below the second reference voltage Vref2, the enable signal EN is activated to supply a pulse from the oscillator 211 to the transistor Tr1 and boost by the booster circuit. To do. When the voltage Vn3 exceeds the second reference voltage Vref2, the normal voltage Vcom2 is held by turning on the transistor Tr2. That is, the normal voltage Vcom2 is held by feedback control. However, when the input voltage V1 is supplied to the liquid crystal device 700 as it is, boosting by the boosting circuit is not necessary.

  Thus, according to the present embodiment, the boost control for obtaining the transition voltage Vcom1 for transition and the transition control to the normal voltage Vcom1 after transition can be realized with a simple configuration. For this reason, cost reduction can be aimed at.

  Note that the booster circuit included in the booster 200 is not limited to the circuit shown in FIG. For example, a circuit as shown in FIG. 7 can be used. The booster 300 shown in FIG. 7 has a configuration in which a negative voltage is required as the voltage supplied to the main control circuit 150. In this example, a negative potential is generated in the capacitor C2. Even in this case, it is possible to reduce the cost of the semiconductor device constituting the control unit 310 by selecting a voltage that is divided by the resistors R3 and R4 and generated in the resistance R4 within the withstand voltage of the control unit 300. The configuration of the control unit 310 itself can be basically the same as the configuration shown in FIG. 3, and the cost can be reduced by a simple configuration.

  Next, electronic equipment using the liquid crystal device 700 according to the present invention will be described. FIG. 8 is a perspective view showing the configuration of a mobile personal computer that employs the liquid crystal device 700 described above as a display device. The personal computer 2000 includes a liquid crystal device 700 as a display device and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002.

  FIG. 9 shows a configuration of a mobile phone to which the liquid crystal device 700 according to the present invention is applied. A cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and a liquid crystal device 700 as a display device. By operating the scroll button 3002, the screen displayed on the liquid crystal device 700 is scrolled.

  FIG. 10 shows a configuration of a personal digital assistant (PDA) to which the liquid crystal device 700 according to the present invention is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and a liquid crystal device 700 as a display device. When the power switch 4002 is operated, various kinds of information such as an address book and a schedule book are displayed on the liquid crystal device 700.

  Electronic devices to which the liquid crystal device according to the present invention is applied include projectors, televisions, video cameras, car navigation devices, pagers, electronic notebooks, electronic papers, calculators, word processors in addition to those shown in FIGS. , Workstations, videophones, POS terminals, printers, scanners, copiers, video players, devices with touch panels, and the like.

It is a block diagram of the liquid crystal device concerning this embodiment. It is a figure which shows the detailed structure of an image display area. It is a block diagram which shows the structure of a pressure | voltage rise apparatus. It is a timing diagram showing a state where the booster boosts the input voltage V1. It is a flowchart which shows the flow of a process of a sequencer part. It is explanatory drawing which shows the time change of a common voltage. It is a block diagram which shows the other example of a pressure | voltage rise apparatus. It is a perspective view which shows the structure of the mobile type PC which employ | adopted the liquid crystal device as a display apparatus. It is a figure which shows the structure of the mobile telephone to which the liquid crystal device is applied. It is a figure which shows the structure of the portable information terminal to which a liquid crystal device is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Data line, 20 ... Scan line, 60 ... Liquid crystal element, 61 ... Pixel electrode, 62 ... Counter electrode, 100 ... Scan line drive circuit, 110 ... Scan line drive circuit, 120 ... Data line drive circuit, 130 ... Timing generation Circuit: 140 Image processing circuit 150 Main control circuit 160 Backlight 200 Boosting device 210 Control unit 211 Oscillator 212 Sequencer unit 214 Comparator 300 Boosting device 310 Control , 600 ... Backlight, 700 ... Liquid crystal device, 2000 ... Personal computer, 3000 ... Mobile phone, 4000 ... Information portable terminal.

Claims (5)

A liquid crystal device having a liquid crystal panel that requires an initial transition operation by a transition voltage to transition from a non-display state to a display state and is driven at a normal voltage lower than the transition voltage after the initial transition operation,
A booster circuit that boosts the power supply voltage and outputs the boosted voltage;
A capacitor that accumulates electric charge based on the boosted voltage, one terminal is electrically connected to the booster circuit, and a fixed potential is supplied to the other terminal;
A resistor for dividing a voltage generated at one terminal of the capacitor;
A switch for discharging the charge accumulated in the capacitor in an on state;
A voltage control device for controlling a voltage supplied to the liquid crystal panel;
The voltage control device comprises:
When it is detected that the divided voltage divided by the resistor has reached the first reference value after starting the boosting of the power supply voltage by the booster circuit, the divided voltage that has reached the first reference value for a predetermined time. The initial transition operation is performed by maintaining a voltage, and after the predetermined time has elapsed, the switch is turned on, and when it is detected that the divided voltage has reached a second reference value, the second reference A liquid crystal device characterized in that driving by the normal voltage is performed by maintaining the divided voltage that has reached the value.   The first reference value corresponds to a value obtained by dividing the transition voltage by the resistor, and the second reference value corresponds to a value obtained by dividing the normal voltage by the resistor. The liquid crystal device according to claim 1.   The liquid crystal device according to claim 1, wherein a withstand voltage of the voltage control device is lower than the transition voltage. The liquid crystal device according to claim 1,
The liquid crystal used in the liquid crystal panel has a first alignment state and a second alignment state as alignment states, and the transition voltage is used to transition the alignment state of the liquid crystal from the first alignment state to the second alignment state. The liquid crystal device according to claim 1, wherein the liquid crystal device is a liquid crystal device. A voltage supply device that requires an initial transition operation by a transition voltage to transition from a non-display state to a display state, and supplies a normal voltage lower than the transition voltage to the liquid crystal panel after the initial transition operation,
A booster circuit that boosts the power supply voltage and outputs the boosted voltage;
A capacitor that accumulates electric charge based on the boosted voltage, one terminal is electrically connected to the booster circuit, and a fixed potential is supplied to the other terminal;
A resistor for dividing a voltage generated at one terminal of the capacitor;
A switch for discharging the charge accumulated in the capacitor in an on state;
A voltage control device for controlling a voltage supplied to the liquid crystal panel;
The voltage control device comprises:
When it is detected that the divided voltage divided by the resistor has reached the first reference value after starting the boosting of the power supply voltage by the booster circuit, the divided voltage that has reached the first reference value for a predetermined time. The initial transition operation is performed by maintaining a voltage, and after the predetermined time has elapsed, the switch is turned on, and when it is detected that the divided voltage has reached a second reference value, the second reference A voltage supply device characterized in that driving by the normal voltage is performed by maintaining the divided voltage that has reached the value.

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