JPH10104569A - Power supply circuit, liquid crystal device and electronic equipment - Google Patents

Abstract

(57) [Summary] A power supply circuit suitable for a liquid crystal drive circuit of a charge / discharge driving method is provided. A capacitor is charged to a predetermined voltage,
The voltage at one end is changed by the switch 102 in synchronization with the drive waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply circuit, a liquid crystal device using the same, and an electronic apparatus using the same.

[0002]

2. Description of the Related Art In recent years, liquid crystal devices have been used particularly as display devices.
As a lightweight display device with low power consumption, it is widely used in electronic devices such as televisions, electronic organizers, personal computers, and mobile phones. In recent years, it has a plurality of scanning electrodes and a plurality of signal electrodes intersecting with the scanning electrodes, and an MIM element, a back-to-back
In a so-called two-terminal type active matrix liquid crystal device including a non-linear switch element such as a diode element, a diode ring element, and a varistor element and a pixel, when the center voltage of a voltage waveform applied to a signal electrode is Vsig / 2, The first mode in which one selection voltage (Vs1) is applied to the scan electrodes, and the second selection voltage (Vs2) after applying the first precharge voltage (-Vpre). A new driving method (called a charging / discharging driving method) in which a liquid crystal element is driven by mixing the second mode given to the scanning electrode is being spotlighted. The charge / discharge driving method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-125225. In addition,
In the embodiment of 2-125225, a third selection voltage (-Vs) having the same absolute value as the first selection voltage and the opposite polarity with respect to the voltage Vsig / 2.
1 + Vsig) is applied to the scan electrodes, and after applying the precharge voltage (Vpre + Vsig) having the same absolute value and the opposite polarity as the first precharge voltage, the second select voltage has the same absolute value as the second selection voltage and the opposite. Polarity fourth selection voltage (-Vs2 + Vsig)
And the fourth mode in which the first and second modes are applied to the scanning electrodes.
In addition to the modes described above, there is disclosed a method of driving in a mixed manner. (The method of driving only in the first and second modes is a unipolar charge / discharge driving method, and the third and fourth modes are added to this method.
The method of driving the electrodes in a mixed manner is referred to as a bipolar charge / discharge driving method. Then, one of the binary non-selection voltages (0 V and Vsig) is applied to the scan electrodes to which the selection voltage and the precharge voltage are not applied.

FIG. 13 is a diagram showing a circuit configuration of a conventional general liquid crystal device.

In FIG. 1, reference numeral 1 denotes a two-terminal active liquid crystal element, and G1 and G2 are liquid crystal layers (not shown).
, A pair of substrates, Y1 to Y5 are a plurality of scanning electrodes provided on the substrate G1, and X1 to X5 are signal electrodes provided on the substrate 2.

[0005] S is a non-linear resistance element such as an MIM element.
Is a pixel electrode, which is represented by a symbol at only one place in the figure, but provided on the substrate G1 at each intersection of the scanning electrodes Y1 to Y5 and the signal electrodes X1 to X5. Also,
The non-linear resistance element S and the pixel electrode P are provided on the substrate G1, but may be provided on the substrate G2.

2 is a circuit (Y driver) for supplying a voltage waveform to be applied to the scanning electrodes Y1 to Y5, and 3 is a signal electrode X1 to X
A circuit (X driver) for supplying a voltage waveform to be applied to 5;
Reference numeral 5 denotes a signal necessary for driving the Y driver 2 and the X driver 3, and 5 denotes a power supply circuit for supplying a voltage required for driving the Y driver 2 and the X driver 3. The circuit configuration of a conventional general liquid crystal device has been described above.

Next, the voltage waveform of the charge / discharge driving method will be described. First, the unipolar charge / discharge driving method will be described.

FIG. 14 is a diagram showing driving waveforms in the case of driving by this driving method.

FIG. 14 shows a voltage waveform applied to the scanning electrodes Y1 to Y5 of the liquid crystal element 1 of FIG. 13, in which the horizontal axis represents time and the vertical axis represents voltage, and t1 to t5 and T1 to T5 represent scanning electrodes Y1 to Y5.
To Y5 indicate a period in which each of the scan electrodes Y1 to Y5 is selected.
The period until all 5 are selected is called a frame period,
In the figure, two consecutive frame periods are indicated as one frame and two frames. VY1 to VY5 are voltage waveforms applied to the scan electrodes Y1 to Y5.

In the first frame, in the latter half of the period t1, during the period t1 when the scanning electrode Y1 is selected, the scanning electrode Y
1 is applied with the first selection voltage Vs1 in the latter half thereof. That is,
Selected in the first mode. In the second frame, in the period T1 during which the scanning electrode Y1 is selected, the precharge voltage -Vpre is applied in the first half, and the second selection voltage Vs2 is applied in the second half. That is, the selection is made in the second mode.

Except for the selection period, a binary non-selection voltage (0 V
And Vsig) are applied. Similarly, the scanning electrode Y2
Similarly, Y5 is selected in the first mode or the second mode during the period tn (n = 2, 3, 4, 5). Here, the odd-numbered scan electrodes are selected in the first mode in the first frame, the even-numbered scan electrodes are selected in the second mode in the first frame, and the opposite mode is selected in the second frame. The driving waveform is as described above.

Next, the bipolar charge / discharge driving method will be described.

FIG. 15 is a diagram showing driving waveforms in the case of driving by this driving method.

In the figure, the scanning electrode Y of the liquid crystal element 1 shown in FIG.
5 shows voltage waveforms applied to 1 to Y5.
The frame is the same as in FIG.

In the a-frame, a third selection voltage (-Vs1 + Vsig) is applied to the scanning electrode Y1 in the latter half of the period t1 during the period t1 when the scanning electrode Y1 is selected.
That is, the selection is made in the third mode. In the b-th frame, in a period T1 during which the scanning electrode Y1 is selected, in the first half thereof, a precharge voltage (Vp) having a polarity opposite to that of the third selection voltage.
re + Vsig) is applied, and the fourth selection voltage (−Vs2 +
Vsig) is applied. That is, the selection is made in the fourth mode.
Therefore, driving in one frame and two frames is performed by the voltage Vsi
The drive voltage waveform is the polarity inverted around g / 2.

The bipolar charge / discharge driving method is a driving method in which one frame and two frames are repeated a plurality of times, and then the a frame and the b frame are repeated a plurality of times.

The charging / discharging driving method described above is a well-known four-value driving method, that is, Vs1 and -Vs1 +
It has various advantages in that display characteristics can be improved as compared with the driving method in which the driving method is driven by the Vsig selection voltage and the binary non-selection voltage (0 V and Vsig).

However, in the quaternary driving method, a Y driver for supplying these voltages to a plurality of scanning electrodes is provided by a four-driver.
While a switch configuration that selects and outputs one of a voltage of a value, that is, one of a binary selection voltage and a binary non-selection voltage, may be used. It is necessary to select and output one of a binary selection voltage, a binary non-selection voltage, and a binary precharge voltage. Voltage, ie 4
One of the value selection voltage, the binary non-selection voltage, and the binary precharge voltage must be selected and output.

Therefore, the Y driver used in the charge / discharge driving method is considerably more complicated than the Y driver used in the quaternary driving method, and the output range is Vs1 + in the unipolar charge / discharge driving.
Vpre is 2 · Vpre−Vsig in bipolar charge / discharge driving, and high withstand voltage is required. Therefore, there is a problem that the Y driver becomes expensive and the outer shape becomes large.

In order to solve this problem, the present inventors have disclosed a driving method for changing the driving voltage of the Y driver during the same application as the present invention. According to this, the voltage on the high side of the power supply voltage necessary for driving the Y driver is set to VDD.
Assuming that HY and the lower side voltage are GNDY, when any one of the voltages Vpre + Vsig, Vs1, and Vs2 is applied to the scan electrodes of the liquid crystal element by the charge / discharge drive, the power supply voltage VDD of the Y driver is applied.
HY is changed to Vpre, Vs1, and Vs2, respectively, and this voltage VDDH is output. At this time, the power supply voltage GNDY is simultaneously changed to be 0 V, Vs1−VDDH, and Vs2−VDDH. When any one of the voltages -Vpre, -Vs1 + Vsig, and -Vs2 + Vsig is applied to the scanning electrodes of the liquid crystal element, the voltage GNDY is applied to -Vpre, -Vs1 + Vsig, and -Vs2 + V, respectively.
sig, and output this voltage GNDY. At this time, the voltage VDDHY is also changed at the same time, and Vsig, VDDH-Vs1,
VDDH−Vs2. Here, VDDH = Vpre + Vsig.

By employing such a driving method, the voltage output from the Y driver becomes a total of four values of VDDHY, GNDY and two non-selection voltages, and the withstand voltage of the Y driver is at most VDD.
H = Vpre + Vsig, and the required breakdown voltage can be significantly reduced.

Further, one configuration example of a power supply circuit for realizing such driving is also shown in FIGS. 14 and 17 in the specification of the invention filed on the same date.

[0023]

According to the power supply circuit described above, the power supply voltage VDDHY of the Y driver is set to, for example,
V1, V2, V3,..., Vn (n is a positive integer) and the voltage V1, V2, V3,.
n, and n voltage sources each generating a voltage obtained by subtracting a fixed voltage (VDDH) from these voltages are provided, and voltages V1, V2, V3,...
Vn, a switch circuit of n inputs and one output, which selects one voltage out of Vn and outputs it as a voltage VDDY,
Constant voltage (VDDH) from each of V3, ..., Vn
Selects one of the voltages obtained by subtracting, and outputs it as voltage GNDY. A voltage for creating the power supply voltage VDDY necessary to operate the switch circuit with n inputs and one output and the logic circuit in the Y driver It is composed of a regulator circuit.

Therefore, for example, the power supply voltage of the Y driver is changed to three values in the case of unipolar charge / discharge drive and to six values in the case of bipolar charge / discharge drive.
You also need pieces. Further, two high-voltage switch circuits of three-value and six-value inputs are required, and a voltage regulator circuit is also required.

Therefore, the configuration of the power supply circuit becomes complicated, and each switch circuit must have a high withstand voltage. Therefore, the outer shape of the power supply circuit section is increased, and the cost is also increased. Therefore, the effect of downsizing and cost reduction obtained by changing the power supply voltage of the Y driver and performing charge / discharge driving is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to simplify a power supply circuit used in a liquid crystal device or the like that performs charge / discharge driving by changing a power supply voltage of a Y driver. It is an object of the present invention to provide a liquid crystal device and an electronic device including the liquid crystal device at low cost, small size, and light weight.

[0027]

According to a first aspect of the present invention, there is provided a power supply circuit comprising a plurality of voltage sources, a multi-input one-output switch circuit, and a first one-input one-output. A switch circuit and a first capacitor, wherein an input of the multi-input one-output switch circuit is connected to at least a part of a plurality of voltage sources or a ground voltage, and an output of the switch is connected to one of the capacitors; The other end of the capacitor is connected to the output of the one-input one-output switch circuit, and the input of the switch circuit is connected to one of the plurality of voltage sources or a ground voltage, and the multi-input one-output is connected. Performing a control to turn on the one-input / one-output switch circuit when the switch circuit selects a predetermined voltage;
Both ends of the first capacitor are first and second voltage output terminals, respectively.

The power supply circuit of the present invention can be applied to a power supply circuit of a liquid crystal device which performs charge / discharge driving by changing a power supply voltage of a Y driver, and a general power supply circuit of an electronic device which requires a changing power supply voltage.

According to the configuration of the present invention, a voltage source for one of the two voltages to be changed becomes unnecessary, and further, a multi-input one-output switch circuit for switching the unnecessary one power supply voltage. Is unnecessary, and the configuration of the power supply circuit can be simplified. A power supply circuit according to a second aspect of the present invention is the power supply circuit according to the first aspect, wherein the one-input one-output switch circuit is configured by a diode element.

As a result, the configuration of the one-input / one-output switch circuit can be simplified, and it is not necessary to control ON / OFF of this circuit.

According to a third aspect of the present invention, there is provided a power supply circuit according to the first aspect, wherein the one-input one-output switch circuit is constituted by an ideal diode circuit.

As a result, the structure of the one-input / one-output switch circuit can be simplified, and it is not necessary to control ON / OFF of this circuit, and the accuracy of the output voltage is further improved.

According to a fourth aspect of the present invention, in the power supply circuit of the first to third aspects, when m is a number of 2 or more, the second to mth capacitors and the second to the second m one-input one-output switch circuit, one of each of the second to m-th capacitors is connected to one or the other of the first capacitors, and each of the second to m-th capacitors is The other is the second
The input of the second to m-th one-input / one-output switch circuits is connected to the voltage source or one or more other voltage sources or to ground. The second to m-th one-input / one-output switch circuits are turned on when the multi-input / one-output switch circuit selects a predetermined voltage; Of the two ends of the capacitor that are not connected to the first capacitor are the (2 + 1) th to (m + 1) th voltage output terminals.

The power supply circuit of the present invention requires a power supply of a liquid crystal device which performs charge / discharge driving by changing a power supply voltage of a Y driver and a power supply voltage which changes like the power supply circuit of the present invention. The present invention can be applied to a general power supply of an electronic device, and further to a liquid crystal device and an electronic device generally requiring another power supply voltage in addition to the two power supplies such as a Y driver.

According to the structure of the present invention, claim 1
In addition to the two voltages output by the power supply circuit of the present invention described in (3) to (3), the third to (m + 1) th voltages can be further output.

A power supply circuit according to a fifth aspect of the present invention is the power supply circuit according to any one of the first to fourth aspects, further comprising a voltage amplifying means having an absolute value of the amplification degree larger than one, wherein the multi-input one-output switch circuit is provided. The voltage amplification means is inserted between the output and the first capacitor.

The power supply circuit of the present invention, like the power supply circuit of the first to fourth aspects of the present invention, requires a power supply of a liquid crystal device which performs charge / discharge driving by changing a power supply voltage of a Y driver and a power supply voltage which changes. It can be applied to a general power supply of an electronic device.

According to the configuration of the present invention, the multi-input 1
The withstand voltage required for the output switch circuit can be reduced.

According to a sixth aspect of the present invention, there is provided a liquid crystal device which performs charge / discharge driving by changing a power supply voltage of a Y driver, wherein a voltage circuit for supplying a driving voltage which changes the Y driver is provided. It is a power supply circuit.

According to the present invention, in the liquid crystal device which is driven by changing the power supply voltage of the Y driver, the power supply circuit is reduced in size and weight and the cost is reduced. Cost and cost can be reduced.

An electronic device according to a seventh aspect is provided with the power supply circuit according to the first to fifth aspects.

By doing so, not only the cost and the size and weight of the power supply circuit can be reduced, but also the withstand voltage of other circuit members can be reduced, so that the cost and the size and weight of the other circuit members can be reduced. Becomes possible.

An electronic device according to the present invention as set forth in claim 8 is provided with the liquid crystal device according to claim 6.

By doing so, the display characteristics of a liquid crystal device as a display device used for electronic devices such as a television, a remote controller, a calculator, a mobile phone, a portable information device, a projector, and a personal computer can be improved. It is possible to reduce cost, size, and weight.

[0045]

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

[Embodiment 1] This embodiment is related to the first aspect of the present invention, and FIG. 1 is a diagram showing a configuration example of a power supply circuit of the present invention. Here, a power supply circuit for a liquid crystal device which performs bipolar charge / discharge by changing the power supply voltage of the Y driver is taken as an example. As described above, bipolar charge / discharge drive is performed by changing the power supply voltage of the Y driver. If Y
The voltages supplied to the driver, that is, the voltages VDDHY and GNDY are
It is necessary to change to six sets of voltages shown in the table below.

[0047]

[Table 1]

In FIG. 1, reference numerals 101a to 101f denote voltage sources.
Vsig, VDDH-Vs1 + Vsig, VDDH-Vs2 +
Vsig, Vs2, Vs1, and Vpre + Vsig are output.
Reference numeral 102 denotes a six-value input / one output switch circuit,
Voltages of 1a to 101f are input, and any one voltage is output depending on the state of the 3-bit control signals Ssa2, Ssa1, and Ssa0 each having a value of 1 or 0. Here, when the control signal Ssa2 is the most significant bit and Ssa0 is the least significant bit, the numerical values represented by the three bits of the control signals Ssa2, Ssa1, and Ssa0 are Vsig when 0, VDDH−Vs1 + Vsig when 1 and VDDH when 2 −Vs2 + Vsig, 3 at Vs2, 4 at Vs1,
At the time of 5, Vpre + Vsig is set to be selected and output.

Reference numeral 103 denotes a one-input one-output switch circuit.
The switch circuit 103 is turned on or off depending on the state of the control signal Ssb which is 0 V input and becomes 0 or 1. Here, the control signal Ssb includes the control signals Ssa2, Ssa1, Ssa
Only when the value indicated by 0 is 5, the switch circuit 103 is turned on.

Reference numeral 104 denotes a capacitor, both ends of which are connected to the output of the switch circuit 102 and the output of the switch circuit 103, respectively. The upper end has the output end of the voltage VDDHY, and the lower end has the output end of the voltage GNDY. Output end.

The power supply circuit of the present embodiment has the above configuration.

Next, the operation will be described. First, the control signal Ss
The states of a2, Ssa1, and Ssa0 are set to state 5. Then, the switch circuit 102 outputs the voltage Vpre + Vsig, and the switch circuit 103 is turned on. Accordingly, the capacitor 104 is charged, and the voltage at the upper end of the capacitor 104 becomes Vpre, and the voltage at the lower end becomes 0V. Therefore, the output terminal VD
The voltage of DHY is Vpre + Vsig, the output terminal GNDY is 0V,
The voltage between both output terminals is Vpre + Vsig, that is, VDDH
Becomes

From this state, the control signals Ssa2, Ssa1, Ssa0
Is set to a state other than 5, the switch circuit 103 is turned off, and the capacitor 104 does not charge or discharge. Therefore, the voltage between both ends of the capacitor 104, in other words, the voltage between both output terminals VDDHY and GNDY is always VDDH, and the voltage at the output terminal GNDY is a voltage obtained by subtracting the voltage VDDH from the output terminal VDDHY.

Therefore, the voltages at the output terminal VDDHY and the output terminal GNDY when the control signals Ssa2, Ssa1, and Ssa0 are 0 to 5 are as shown in the table below.

[0055]

[Table 2]

Therefore, by changing the state of the control signals Ssa2, Ssa1, and Ssa0, the power supply voltage of the Y driver can be changed to supply the six sets of voltages required for bipolar charge / discharge driving. .

Therefore, a voltage source for outputting a voltage to the output terminal GNDY and a switch circuit for switching and outputting the voltage of the voltage source are not required, and the configuration of the power supply circuit can be simplified. And cost can be reduced.

[Embodiment 2] This embodiment is related to the second aspect of the present invention, and FIG. 2 is a diagram showing a configuration example of a power supply circuit of the present invention. This is the switching circuit 10 of FIG.
Reference numeral 3 is a diode element.

In FIG. 2, the configuration is the same as that shown in FIG. 1 except for 205, and the same operation is performed.

Reference numeral 205 denotes a diode element, which is preferably a diode having a small forward voltage drop (this voltage is referred to as Vf). For example, a diode of a Schottky barrier type or the like is used.

With such a configuration, when the switch circuit 102 outputs the voltage Vpre + Vsig, the diode element 205 becomes conductive only at this time, the capacitor 104 is charged, and the voltage between both ends is changed to Vpre + Vsig-Vf.
To Then, the switch circuit 102 outputs the voltage Vpre + Vs
When outputting a voltage other than ig, the diode element 205
Becomes negative voltage and becomes reverse bias voltage. Therefore, the diode element 205 is turned off, the capacitor 104 is neither charged nor discharged, and the voltage at both ends remains Vpre + Vsig-Vf. Therefore, FIG.
Will operate almost the same as the power supply circuit of FIG. And
Since the diode element 205 automatically works as an on / off switch, the control signal Ssb is unnecessary.

Here, the voltage Vf is a small voltage of about several hundred mV.
That is, an error voltage occurs in the voltage of the output terminal GNDY.

If the error is a concern, the voltage error can be eliminated by resetting the voltages of the voltage sources 101b and 101c by the voltage Vf, for example.

Therefore, the same effect as that of the first embodiment can be obtained, and the switch circuit is replaced with the diode element 205. Therefore, the switching circuit can be further simplified, and the control signal Ssb becomes unnecessary.

[Embodiment 3] This embodiment relates to the third aspect of the present invention, and FIG. 3 is a diagram showing an example of the configuration of a power supply circuit according to the present invention. This is the switching circuit 10 of FIG.
3 is an ideal diode circuit. Here, the ideal diode circuit is a circuit having a diode characteristic in which the voltage of the forward voltage drop is 0V.

In FIG. 3, except for 305, the configuration shown in FIG. 3 is the same as that shown in FIG. 1 and performs the same operation.

FIG. 4 shows an ideal diode circuit 305.
FIG. 3 is a diagram illustrating a configuration example of an ideal diode circuit.

In FIG. 4, the portion surrounded by the broken line is the ideal diode circuit 305, and the capacitor 104 and the output terminal GNDY are also shown in order to clarify the positional relationship with FIG.

In the figure, 41 is a negative voltage source of several volts, 402 and 4
04 is a diode element, 403 is a resistor, and 406 is a voltage follower circuit composed of an operational amplifier and the like.
This voltage follower circuit need not be provided. It is preferable that the diode elements 402 and 404 have uniform characteristics, particularly a forward voltage drop characteristic.

Here, since the diode element 402 is biased in the forward direction via the resistor 403 by the voltage of the negative voltage source 401, the voltage -Vf is applied to the voltage follower circuit 40.
6 will be supplied as the input voltage. Then, the voltage follower circuit 406 outputs the voltage −Vf in a form in which the impedance is lowered. Then, this voltage is supplied to the cathode of the diode element 404. Accordingly, the diode operates as an ideal diode that is turned on when the voltage on the anode side of the diode element 404 becomes 0 V or more, and turned off when the voltage becomes lower than 0 V.

The configuration of the power supply circuit of FIG. 3 is as described above.

Therefore, the same effect as that of the second embodiment can be obtained, and a voltage without a voltage error can be supplied.

Embodiment 4 As described above, in Embodiments 1 to 3, Y
The power supply circuit of the liquid crystal device which performs bipolar charge / discharge driving by changing the power supply voltage of the driver has been described as an example. In this example, 6
Although the voltage was changed between the voltage sets of the sets, the number of the changed sets is arbitrary and can be increased or decreased as necessary. This will be described using a specific example.

For example, in a power supply circuit of a liquid crystal device that performs unipolar charge / discharge driving by changing the power supply voltage of the Y driver, the voltage supplied to the Y driver, that is, the set of VDDHY and GNDY is changed to the three sets of voltages shown in the following table. Just change it.

[0075]

[Table 3]

FIG. 5 is a diagram showing an example of a power supply configuration in this case. Except for 502 and 505, the configuration and operation are the same as those in FIG. 502 is a three-input one-output switch circuit;
Since there are three inputs, the control signal is also two bits Ssa1 and Ssa0.

The control signals also correspond to the numerical values 0 to 2 represented by Ssa1 and Ssa0, and the three voltage sources 101b,
The switch circuit 502 outputs one of the voltages 101c and 101f. Therefore, it is possible to change and output the three sets of voltages shown in the above table.

In general, when it is desired to change to n sets of voltages, n voltage sources and a switch circuit having n inputs and 1 output may be provided. (n is a positive integer.)
With the configuration of the power supply circuit shown in 3 and 4, a set of voltages to be changed can be set arbitrarily, and the design of the power supply circuit can be facilitated.

[Embodiment 5] In Embodiments 1-4, the output terminal VD
Although the case where the voltage source on the DHY side is prepared has been described, a similar power supply configuration is possible even when the voltage source on the output terminal GNDY side is prepared.

FIG. 6 is a diagram showing a configuration example of a power supply circuit when a voltage source on the output terminal GNDY side is prepared.

In the figure, 205, 601a, 601c-60
Except for 1g, the operation is the same as that of FIG. Reference numeral 205 denotes the diode element 205 in FIG. 2, and the voltage of the forward voltage drop is the voltage Vf. 601a, 601c-6 in FIG.
01g is a voltage source, which is Vsig + Vf and Vs1 + Vsig, respectively.
−VDDH, Vs2 + Vsig−VDDH, −Vs2, −Vs1, −Vp
re. Therefore, the switch circuit 102 outputs the voltage −Vpre
Is output, the ideal diode circuit 505 is turned on, and the capacitor 104 is charged. However, the voltage at the upper end of the capacitor 104 at this time, that is, the output terminal VDDHY
Is the voltage V obtained by subtracting the voltage of the forward voltage drop of the diode element 205 from the voltage output from the voltage source 601a.
sig, the voltage at the lower end of the capacitor 104, that is, the output terminal GNDY becomes -Vpre, and the output terminal VDDHY becomes Vsig. Then, when the switch circuit 102 outputs a voltage other than the voltage −Vpre, the output terminal GNDY is at that voltage, and the ideal diode circuit 505 is turned off.
The output terminal VDDHY becomes a voltage obtained by adding VDDH to that voltage.

Therefore, even when a voltage source on the output terminal GNDY side is prepared, the same effect as in the third embodiment can be obtained.

[Embodiment 6] This embodiment is directed to a fourth aspect of the present invention. Here, for example, in a Y driver of a liquid crystal device, a drive voltage VDDY for operating a logic circuit unit inside the Y driver is required in addition to the two voltages VDDHY and GNDY. Thus, in addition to the two voltages VDDHY and GNDY,
Power supply voltage may be required. In such a case,
For example, by using a so-called voltage regulator, the voltage of the output terminal VDDY may be used as a reference and the voltage of the output terminal VDDHY may be used as an input to lower the voltage to produce a desired constant voltage with respect to the output terminal GNDY. However, this method is not advisable because the power loss increases.

In the present embodiment, a method of generating such another voltage without causing power loss will be described. Here, a voltage that always becomes a constant voltage VDD with respect to the output terminal GNDY is described. The power supply circuit of the liquid crystal device including the necessary Y driver is taken as an example, and the output terminal of this voltage source is VDDDY.

FIG. 7 is a diagram showing an example of the configuration of a power supply circuit in such a case.

In FIG. 3, except for 701, 702 and 703, FIG.
The same configuration and operation are performed.

Reference numeral 701 denotes a voltage source whose voltage is set to VDD. Reference numeral 902 denotes a one-input one-output switch circuit,
A voltage of 01 is input, and on / off control is performed by a control signal Ssc. 703 is a capacitor, one end of which is a switch circuit 702.
, And the output terminal is VDDY. The other end is connected to the output terminal GNDY side of the capacitor 104.

The control signal Ssc is supplied to the switch circuit 1
02 only outputs the voltage Vpre.
2 is turned on.

With the above configuration, when the switch circuit 102 outputs the voltage Vpre and charges the capacitor 104, the switch circuit 702 is also in the ON state, so that the capacitor 703 is charged. , Voltage VDD.

Then, the switch circuit 102 sets the voltage Vpre
When a voltage other than the above is output, the switch circuit 702 is turned off, so that the capacitor 703 does not charge or discharge. Therefore, the voltage across capacitor 703 is equal to voltage V
It remains DD. Therefore, the voltage of the output terminal VDDY is
The voltage is always constant VDD with respect to NDY.

Therefore, it is possible to generate the drive voltage VDDY for operating the logic circuit required by the Y driver.

In this embodiment, the case where the voltage VDD is generated has been described. However, any other number of voltage sources can be generated. That is, the required number of voltages and the corresponding number of switch circuits and capacitors are prepared, and the respective voltage sources, switch circuits, and capacitors are connected to the voltage source 7 shown in FIG.
01, the switch circuit 702, and the capacitor 703 in the same manner, and furthermore, the respective switch circuits are similarly turned on / off by the control signal Ssc, so that an arbitrary constant number of voltages is always generated with respect to the output terminal GNDY. It becomes possible.

Therefore, the effects described in the first to sixth embodiments can be obtained, and other necessary power sources can be generated without power loss.

[Embodiment 7] The voltage VDDY is based on the voltage GNDY.
However, depending on the configuration of the Y driver, the output terminal VDD
In some cases, a negative voltage VDDY is required based on HY.

This embodiment shows an example of the configuration of a voltage circuit in such a case. Here, a case where a voltage of -Vsig is output from the output terminal VDDY with reference to the output terminal VDDHY will be described.

FIG. 8 shows a configuration example of the voltage circuit in such a case.

In the figure, the configuration other than 802 and 803 and the control signal Ssd is the same as the configuration in FIG. 6 and performs the same operation. 8
Reference numeral 02 denotes a 1-input, 1-output switch circuit to which 0 V is input and which is turned on / off by a control signal Ssd. Reference numeral 803 denotes a capacitor, one end of which is the output of the switch circuit 802, and which is an output terminal VDDY. The other end is connected to the output terminal VDDHY of the capacitor 104.

The control signal Ssd is supplied to the switch circuit 1
02 only outputs the voltage -Vpre.
02 is turned on.

With the above configuration, when the switch circuit 102 outputs the voltage -Vpre and charges the capacitor 104, the switch circuit 802 is also in the ON state, so that the capacitor 803 is charged, Becomes the voltage Vsig.

The switch circuit 102 sets the voltage −Vpr
When a voltage other than e is output, the switch circuit 802 is turned off, so that the capacitor 803 does not charge or discharge. Therefore, the voltage across the capacitor 703 remains at the voltage Vsig. Therefore, the voltage of the output terminal VDDDY always becomes a constant voltage -Vsig with respect to the output terminal VDDHY.

Therefore, it is possible to generate a negative drive voltage for operating the logic circuit required by the Y driver.

Needless to say, the output terminal VDDHY is connected to the output terminal VDDY.
In addition to -Vsig, other voltage values can be output. In this case, a voltage source lower than the output terminal VDDHY by a desired voltage is prepared, and the voltage is switched to the switch circuit 8.
02 may be input, and an arbitrary number of voltages and voltages can be generated similarly to the seventh embodiment.

Therefore, even when a negative power supply based on the output terminal VDDHY is required, the same effect as in the eighth embodiment can be obtained.

[Embodiment 8] This embodiment relates to a fifth aspect of the present invention. In the first to eighth embodiments, the output terminal VDD
It requires a voltage source for generating a voltage to be output to one of the output terminals of HY and GNDY, and a switch circuit 102 of multi-level input and one output for switching the voltage source. Therefore, the voltage source configuration and the configuration of the high withstand voltage switch circuit 102 need to have a high withstand voltage configuration, which is not a good idea in terms of size reduction, weight reduction, and cost reduction.

In this embodiment, a configuration for minimizing the configuration with a high breakdown voltage will be described.

FIG. 9 is a diagram showing a configuration example of the power supply circuit in this case. Except for 901a to 901f and 902, the configuration is the same as that of FIG. Reference numerals 901a to 901f denote voltage sources, each of which outputs a voltage of 1 / k of each of the voltage sources 101a to 101f shown in FIGS. Here, k is a number greater than one. In FIG. 9, reference numeral 902 denotes an amplifier circuit which amplifies an input voltage by k times.

With the above configuration, the output terminal VDDH
The switch circuit 102 outputs one of the voltages that are 1 / k of the voltage to be output to Y, and the amplifier circuit 902 multiplies this voltage by k and outputs the same to the output terminal VDDHY. Therefore, the same operation as the third embodiment can be performed.

Here, the maximum voltage output to the output terminal VDDHY is several tens of volts. For example, if the value of k is 10,
The withstand voltages of the voltage sources 901a to 901f and the switch circuit 102 need only be several volts at most, and a high withstand voltage is required only for one amplifier circuit 9.
02 only.

In this embodiment, the case where the voltage source on the voltage VDDHY side is prepared has been described. Of course, the same can be applied to the case where the voltage source on the voltage GNDY side is prepared, and the detailed description is omitted. 6, the switch circuit 102 and the output terminal of FIG.
A similar effect can be obtained by inserting a similar amplifier circuit between GNDY and resetting the voltages of 601c to g to 1 / k.

Therefore, the same effects as those of the third embodiment can be obtained, the withstand voltage of most of the components of the power supply circuit can be reduced, and the size, weight, and cost can be further reduced.

[Embodiment 9] This embodiment is directed to a sixth aspect of the present invention, in which the power supply circuit described in Embodiments 1 to 9 is used as a power supply circuit of a liquid crystal device which is driven for charging and discharging.

FIG. 10 shows an example of the configuration of this liquid crystal device.

In the figure, reference numeral 1 denotes a two-terminal type active liquid crystal element, and G1 and G2 are liquid crystal layers (not shown).
, A pair of substrates G, Y1 to Y5 are a plurality of scanning electrodes provided on the substrate G1, and X1 to X5 are signal electrodes provided on the substrate 2.

S is a non-linear resistance element such as an MIM element.
Is a pixel electrode, which is represented by a symbol at only one place in the figure, but is provided on the substrate 1 at each intersection of the scanning electrodes Y1 to Y5 and the signal electrodes X1 to X5. Further, although the non-linear resistance element S and the pixel electrode P are provided on the substrate G1, they may be provided on the substrate G2.

2 is a circuit (Y driver) for supplying a voltage waveform to be applied to the scanning electrodes Y1 to Y5, and 3 is a signal electrode X1 to X
A circuit (referred to as an X driver) 4 for supplying a voltage waveform to be applied to 5 is a signal necessary for driving the Y driver 2 and the X driver 3. The configuration up to this point is the same as the configuration of the conventional liquid crystal device driven by charge / discharge.

A power supply circuit 1005 supplies a voltage necessary to drive the Y driver 2 and the X driver 3.

FIG. 11 shows an example of the configuration of the power supply circuit 1005. In the figure, the operation is the same as that of FIG. 7 except for 1101 and the output terminals Vns1, Vns0 and Vxdr. Reference numeral 1101 denotes a voltage source, which is a voltage source necessary for the X driver 3 and whose output terminal is an output terminal Vxdr. In the figure, there is one, but there may be more than one depending on the configuration of the X driver 3. Since the configuration of the X driver 3 and the necessary power supply are not directly related to the present invention, further description is omitted. Output terminals Vns1 and Vns0 are Y
This is an output terminal that outputs Vsig and 0 V as binary non-selection voltages to be output to the driver.

Therefore, the output terminals VDDHY, GNDY, VDDY, Vns1, V
The voltage of ns0 is supplied to the Y driver 2.

In FIG. 10, since the Y driver 2 is supplied with the voltages of the output terminals VDDHY, GNDY, and VDDY of the power supply 1005, the signal 4 causes the Y driver 2 to operate and the scanning electrodes Y1 to Y5 of the liquid crystal element 1 to operate. Either output terminal VDDHY or GNDY voltage is output to any of them, and output terminals Vns1 and Vns0 are
Voltage, that is, binary non-selection voltage (Vsig and 0V)
Is output.

Since the above operation is performed, it is possible to perform the charge driving in which the withstand voltage of the Y driver 2 is set to about VDDH (both electrodes). In the case of unipolar charge / discharge driving, a part of the power supply circuit configuration may be changed to the configuration shown in FIG. 5. Since this change can be made more easily than the above description, detailed description is omitted. The same applies to the power supply circuit configurations of the other embodiments described above.

As described above, by using the power supply circuit of the present invention for a power supply circuit of a liquid crystal device, the charge / discharge drive for enabling a display with extremely excellent image quality is reduced, the withstand voltage of the Y driver is reduced, and the power supply is further reduced. The circuit configuration can be simplified.

Therefore, a high-quality liquid crystal device can be provided with reduced size, weight, and cost.

[Embodiment 10] The present embodiment relates to the seventh aspect of the present invention, and in the above-described embodiment, the power supply circuit of the liquid crystal device has been mainly described as an example. However, the use of the power supply circuit is not limited to the use of the power supply circuit of the liquid crystal device. This will be described with a specific example.

Here, a device which needs to output a large amplitude voltage signal, specifically, a power supply such as an amplification device for amplifying a small amplitude signal voltage of about ± 3 V to a large amplitude voltage signal of about ± 30 V As the circuit, an example using the power supply circuit of the present invention shown in FIG. 5 described in Embodiment 4 will be described.

FIG. 12 is a diagram showing a configuration example of an amplifying device as an example of such an electronic apparatus.

In the drawing, reference numeral 1201 denotes an input signal source;
A small-amplitude signal source of about 3 V, 1202 compares the magnitude of each of the two reference voltages with the voltage of the small-amplitude signal source 1201, and outputs a voltage comparison circuit. 1203 is a voltage comparison circuit of the present invention shown in FIG. Power supply circuit 1204 is operational amplifier 1
This is a non-inverting amplifying resistor circuit including a resistor 204a and two resistors, and its amplification is set to 10 times. Vout is the output terminal.

Here, the power supply circuit 1203 has the circuit configuration shown in FIG. 5, and sets the voltage of the voltage source 101b to 0.
V, the voltage of 101c is 16V, and the voltage of 2101f is 32.
V and reset to + 32V and 0V, + 16V and -1
Three sets of voltages of 6V, 0V and -32V are output. Then, based on the voltage comparison result of the voltage comparison circuit 702, the output voltage is changed by three sets of voltages.

The voltage comparison circuit 1202 has ± 1.3 V as two reference voltages, and when the voltage of the small amplitude signal source 701 becomes higher than +1.3 V, the power supply circuit
The amplitude signal source 70 outputs a set of voltages of V and 0V.
1 becomes higher than -1.3 V, the power supply circuit 70
The control signals Sa1 and Sa0 are generated and supplied to the power supply circuit 703 so that 3 outputs a set of voltages of 0V and -32V, and otherwise outputs a voltage of ± 16V.

Operational amplifier 12 of non-inverting amplifier circuit 1204
The power supply 04a is supplied from the power supply circuit 703. The voltage on the positive side is VDDHY, and the voltage on the negative side is GNDY.

With the above configuration, the voltage of the small-amplitude signal source 1201 is set to 10
Amplify by a factor of two and output a voltage with an amplitude of ± 30V.

At this time, the non-inverting amplification resistance circuit 1204
When outputting a voltage exceeding 3 V, that is, when the small-amplitude signal source 1
When the voltage of 201 exceeds 1.3 V, the power supply circuit 12
03, that is, the power supply voltage of the operational amplifier 1204a is + 32V on the positive side and 0V on the negative side.

Similarly, the non-inverting amplification resistance circuit 1204
When a voltage lower than -13 V is output, that is, when the voltage of the small amplitude signal source 1201 is lower than -1.3 V, the voltage output by the power supply circuit 1203 is 0 V on the positive side and -3 on the negative side.
2V.

The non-inverting amplifying circuit 1204 has ± 1
When a voltage in the range of 3 V is output, the power supply circuit 12
03 outputs + 16V on the positive side and -16 on the negative side.
V.

Therefore, the withstand voltage required for the operational amplifier circuit of the amplifier that amplifies to a large amplitude of ± 30 V may be 32 V. Therefore, an expensive high withstand voltage operational amplifier is not required.

As described above, the power supply circuit of this embodiment is not limited to the power supply circuit of the liquid crystal device, but can be applied to a power supply circuit of general electronic equipment which needs to change the voltage. The configuration is the same as the circuit configuration of the fourth embodiment, so that the same effects as those of the fourth embodiment can be obtained.
Furthermore, by using the power supply circuit having the configuration of the present embodiment as a power supply circuit of an electronic device such as the amplifying device, the withstand voltage of other circuit components of the electronic device can be reduced. Cost reduction and reduction in size and weight are possible.

[Embodiment 11] The present embodiment relates to the invention of claim 7, in which a liquid crystal device whose power supply circuit is extremely simplified and whose cost is reduced is used as a display member of an electronic device, thereby achieving an electronic device. The quality of the whole equipment is improved, and the size, weight, and price are reduced. Examples include car navigation, portable information devices, LCD TVs, multi-function calculators such as graphic display functions, mobile phones, laptops, and various other devices that need to read small, lightweight and detailed information without misunderstanding. Ideal for personal computers.

Further, it is possible to provide a product which is free from display unevenness, reduced in cost, reduced in size and weight by using the light valve of a projection type display device such as a projector in which display unevenness is easily seen. Become.

[0138]

According to the first aspect of the present invention, for example, Y
In a power supply circuit or the like of a liquid crystal device that performs charge / discharge driving by changing a power supply voltage of a driver, a voltage source for one of the two voltages to be changed becomes unnecessary, and this unnecessary power supply voltage is further reduced. A multi-input, one-output switch circuit for switching is not required, and the configuration of the power supply circuit can be simplified.

According to the second aspect of the present invention, the configuration of the one-input one-output switch circuit of one of the constituent elements of the first aspect can be simplified, and ON / OFF of this circuit is controlled. Eliminates the need.

According to the third aspect of the present invention, the configuration of the one-input one-output switch circuit as one of the constituent elements of the first aspect can be simplified, and ON / OFF of this circuit is controlled. This eliminates the need, and further improves the accuracy of the output voltage.

According to the fourth aspect of the present invention, in addition to the two voltages output by the power supply circuit of the first to third aspects of the present invention, the third to (m + 1) th voltages can be output.

According to the fifth aspect of the present invention, it is possible to reduce the withstand voltage required for one of the multiple input and one output switch circuits and the plurality of voltage sources in the first to fourth aspects of the present invention.

According to the sixth aspect of the present invention, not only the cost and the size and weight of the power supply circuit can be reduced, but also the withstand voltage of other circuit members can be reduced. It is possible to reduce the size, size, and weight.

According to the seventh aspect of the present invention, not only the cost and the size and weight of the power supply circuit portion of other electronic devices of the liquid crystal device but also the withstand voltage of other circuit members can be reduced. Thus, the cost, size, and weight of the circuit member can be reduced.

According to the invention of claim 8, the display characteristics of a liquid crystal device as a display device used for an electronic device such as a television, a remote controller, a calculator, a mobile phone, a portable information device, a projector, and a personal computer are improved. In addition, it is possible to reduce cost, size, and weight.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a power supply circuit according to a first embodiment.

FIG. 2 is a diagram illustrating a configuration example of a power supply circuit according to a second embodiment.

FIG. 3 is a diagram illustrating a configuration example of a power supply circuit according to a third embodiment.

FIG. 4 is a diagram illustrating a configuration example of an ideal diode circuit according to a third embodiment.

FIG. 5 is a diagram illustrating a configuration example of a power supply circuit according to a fourth embodiment.

FIG. 6 is a diagram illustrating a configuration example of a power supply circuit according to a fifth embodiment.

FIG. 7 is a diagram illustrating a configuration example of a power supply circuit according to a sixth embodiment.

FIG. 8 is a diagram illustrating a configuration example of a power supply circuit according to a seventh embodiment.

FIG. 9 is a diagram illustrating a configuration example of a power supply circuit according to an eighth embodiment.

FIG. 10 is a diagram illustrating a configuration example of a liquid crystal device according to a ninth embodiment.

FIG. 11 is a diagram illustrating a configuration example of a power supply circuit of a liquid crystal device according to a ninth embodiment.

FIG. 12 is a diagram illustrating a configuration example of an amplification device as an example of an electronic apparatus according to a tenth embodiment.

FIG. 13 is a diagram showing a circuit configuration of a conventional general liquid crystal device.

FIG. 14 is a diagram showing driving waveforms when driving by a unipolar charge / discharge driving method.

FIG. 15 is a diagram showing driving waveforms when driving by a bipolar charge / discharge driving method.

[Explanation of symbols]

 101a. Voltage source 101b. Voltage source 101c. Voltage source 101d. Voltage source 101e. Voltage source 101f. Voltage source 102.6 Value input 1 output switch circuit 103.1 Input 1 output switch circuit 104. Capacitor Ssa2. Control signal Ssa1. Control signal Ssa0. Control signal Ssb. Control signal VDDHY. Output terminal GNDY. Output terminal

Claims (8)

[Claims] 1. A switch circuit comprising a plurality of voltage sources, a multi-input one-output switch circuit, a first one-input one-output switch circuit, and a first capacitor. The output of the switch is connected to one of the capacitors, and the other of the capacitors is connected to the output of the one-input one-output switch circuit, and the switch circuit Is connected to one of the plurality of voltage sources or a ground voltage, and turns on the one-input one-output switch circuit when the multi-input one-output switch circuit selects a predetermined voltage. A power supply circuit which performs control and uses both ends of the first capacitor as first and second voltage output terminals, respectively. 2. The power supply circuit according to claim 1, wherein
A power supply circuit characterized in that a switch circuit of one input and one output is constituted by a diode element. 3. The power supply circuit according to claim 1, wherein
A power supply circuit characterized in that a switch circuit of one input and one output is constituted by an ideal diode circuit. 4. The power supply circuit according to claim 1, wherein when m is a number of 2 or more, the second to m-th capacitors and the second to m-th one-input / one-output switch circuits are provided. A switch circuit, one of each of the second to m-th capacitors is connected to one or the other of the first capacitors, and the other of each of the second to m-th capacitors is connected to the second to m-th capacitors. An input of the one-input one-output switch circuit is connected, and an input of the second through m-th one-input one-output switch circuits is connected to the voltage source or one or more other voltage sources or to a ground voltage. When the multi-input / one-output switch circuit selects a predetermined voltage, the second to m-th one-input / one-output switch circuits are controlled to be turned on, and both ends of the second to m-th capacitors are controlled. of A power supply circuit, wherein an end not connected to the first capacitor is a (2 + 1) th to (m + 1) th voltage output end. 5. A power supply circuit according to claim 1, further comprising a voltage amplifying means having an absolute value of an amplification degree larger than one, wherein an output of said multi-input one-output switch circuit and a first capacitor are provided. A power supply circuit, wherein the voltage amplifying means is inserted between the power supply circuits. 6. A two-terminal type active matrix liquid crystal element having a plurality of scanning electrodes and a plurality of signal electrodes intersecting the scanning electrodes and having a non-linear element and a pixel at each intersection, in a first mode. Applies a first selection voltage to each of the plurality of scan electrodes, and in the second mode, applies a precharge voltage having a polarity opposite to that of the first selection voltage to a non-selection voltage. In the third mode in addition to the driving method of applying a second selection voltage having a polarity opposite to the precharge voltage to each of the plurality of scan electrodes based on the selection voltage, or in addition to the first mode and the second mode, A third polarity opposite to the first selection voltage with respect to the non-selection voltage;
Is applied to each of the plurality of scan electrodes, and in the fourth mode, after applying a second precharge voltage having a polarity opposite to that of the third selection voltage to the non-selection voltage, A scanning method for applying a fourth selection voltage having a polarity opposite to the second precharge voltage to the plurality of scanning electrodes with reference to the selection voltage, and applying a voltage waveform to the plurality of scanning electrodes. 6. A liquid crystal device driven by a driving method of changing a driving voltage of a driving means, wherein a voltage circuit for supplying a changing driving voltage of the inspection electrode driving means is the power supply circuit according to claim 1. Liquid crystal device. 7. An electronic apparatus comprising the power supply circuit according to claim 1. 8. An electronic apparatus comprising the liquid crystal device according to claim 6.