JP2000278938A - Power supply circuit and opto-electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply power corresponding to the value of a load efficiently. SOLUTION: A transistor 204 which is turned on in accordance with a signal CTR corresponding to the value of a load, a reactor L in which power is accumulated when the transistor 204 is turned on and which, on the other hand, discharges the accumulated power when the transistor 204 is turned off and supplies the power to the load and an operational amplifier 206 which controls the on-period of the transistor 204 in accordance with the comparison result between a voltage supplied by the reactor L and a target voltage which is to be supplied to the load and operates as a hysteresis comparator, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for supplying power with low loss, and an electro-optical device for supplying power with low loss in accordance with the content to be displayed to reduce power consumption.

[0002]

2. Description of the Related Art In general, a linear regulator is considered to be inefficient because all the voltage difference between input and output is consumed as power transistor loss. On the other hand, in the chopper type regulator, constant voltage control is performed to change the on / off ratio of the switching transistor according to the voltage difference between the input and output, so that the loss increases in proportion to the voltage difference between the input and output. There is no. Therefore, it is said that the chopper type regulator is more efficient than the linear regulator.

[0003]

However, in the conventional chopper type regulator, on / off of the switching transistor is controlled in accordance with a comparison result between a reference waveform such as a reference triangular wave or sawtooth wave and an output voltage. Configuration. For this reason, even in the almost no-load state, there is a problem that the switching transistor is turned on and off, and accordingly, a loss is generated.

[0004] The present invention has been made in view of such circumstances, and its object is to provide a power supply circuit capable of supplying power corresponding to a load with low loss, and contents to be displayed. An object of the present invention is to provide an electro-optical device in which power is supplied with low loss according to (1) and low power consumption is achieved.

[0005]

In order to achieve the above object, in a power supply circuit according to the present invention, switching means for turning on according to a signal corresponding to the magnitude of a load; Power storage means for storing the power and releasing the stored power to supply to the load when the switching means is turned off;
And a control unit that controls an on-period of the switching unit based on a comparison result between a voltage supplied from the power storage unit and a target voltage to be supplied to the load.

According to the present invention, the switching means is turned on in accordance with a signal corresponding to the magnitude of the load, and when the switching means is on, the storage means stores power, while when the switching means is off, Since the storage means discharges the power and supplies the power to the load, the power is efficiently supplied according to the size of the load, so that the power consumption can be reduced. Further, the ON period of the switching means is controlled in accordance with the result of comparison between the voltage actually supplied to the load from the power storage means and the target voltage to be supplied to the load. It is also possible to make the average voltage value constant at the target voltage. In this configuration, a negative voltage can be supplied to the load by connecting one end of the storage means to the lower side, and a load can be supplied to the load by connecting one end of the storage means to the higher side. Alternatively, a positive voltage can be supplied.

[0007] The specific control contents of the control means according to the present invention include the following: when the voltage supplied from the power storage means is smaller in absolute value than a target voltage to be supplied to the load, On the other hand, if the voltage supplied from the power storage means is larger in absolute value than the target voltage to be supplied to the load, the on time of the switching means is shortened. It is desirable to control in such a way. According to such a configuration, it is possible to reduce the power consumption and to supply the voltage from the storage means at a constant target voltage.

On the other hand, in order to achieve the above object, in a power supply circuit according to the present invention, a switching element that is turned on in accordance with a signal having a pulse interval corresponding to the size of a load, and the switching element is turned on. Then, while the power is stored, when the switching element is turned off, the reactor that releases the stored power and supplies the load to the load, and the voltage supplied from the reactor is absolutely higher than the voltage to be supplied to the load. When the voltage is small, the on-period of the switching element is controlled so as to be long. On the other hand, when the voltage supplied from the reactor is larger in absolute value than the voltage to be supplied to the load, the switching is performed. It is characterized in that the ON period of the element is controlled to be short. Also in this configuration, similarly, power is efficiently supplied in accordance with the size of the load, so that power consumption is reduced, and the average voltage supplied from the storage unit can be made constant at the target voltage. It becomes possible.

On the other hand, in order to achieve the above object, an electro-optical device according to the present invention has an electro-optical device having a plurality of pixels in which an electro-optical material is sandwiched between two substrates facing each other. A driving unit that supplies a signal for driving the plurality of pixels; a signal output unit that outputs a signal corresponding to the number of pixels to be driven; a switching unit that turns on according to the signal; When the means is turned on, the power is stored, while when the switching means is turned off, the stored power is released to the driving means and supplied to the driving means, a voltage supplied from the power storage means, Control means for controlling an ON period of the switching means based on a result of comparison with a target voltage to be supplied to the load.

According to the present invention, the switching means is turned on in accordance with a signal corresponding to the number of pixels to be driven, and when the switching means is on, the storage means stores power while the switching means is off. In that case, the storage means releases power and supplies it to the load,
The power according to the number of pixels is efficiently supplied to the driving unit that outputs a signal for driving the pixels. Therefore, low power consumption is achieved. further,
Since the ON period of the switching means is controlled according to the result of comparison between the voltage supplied to the load from the power storage means and the target voltage to be supplied to the load, the average value of the voltage supplied from the storage means Can be made constant at the target voltage.

[0011]

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

First Embodiment First, a power supply circuit according to a first embodiment of the present invention will be described. FIG. 1 is a circuit diagram showing a configuration of the power supply circuit 200.

In this figure, a signal CTR is a pulse signal supplied at intervals according to the size of the load. Specifically, when the load is high, as shown in FIG.
The signal is a signal in which the interval between pulses having a constant width W becomes longer as shown by P1, while the pulse interval becomes shorter as shown by P2 when the load is low, as shown in FIG. Such a signal CTR is supplied to the inverter 202 via the capacitor C1 in FIG.
The input terminal of the inverter 202 is grounded via the resistor R1. That is, the signal CTR is configured to be supplied to the inverter 202 via a differentiating circuit including at least the capacitor C1 and the resistor R1. Here, for convenience of explanation, an input terminal of the inverter 202 is a terminal.

Next, the output terminal of the inverter 202 is connected to the gate of the p-channel transistor 204. Here, for convenience of explanation, the output terminal of the inverter 202, that is, the gate of the transistor 204 is used as a terminal. The source of this transistor 204 has a voltage V
While connected to the cc supply line, the drain is connected to the other end of the reactor L, one end of which is grounded. The other end of the reactor L is connected via a diode D1 to a capacitor C2 and an output terminal o of the power supply circuit 200.
ut, and this voltage Vout is supplied to the load. The other end of the capacitor is grounded. Here, for convenience of description, the drain of the transistor 204,
That is, the other end of the reactor L is used as a terminal.

An output terminal of the power supply circuit 200 is connected to a supply line of the voltage Vcc via resistors R2 and R3. Here, for convenience of explanation, the connection point of the resistors R2 and R3 is used as a terminal, and the voltage of this terminal, that is, the voltage Vou
The voltage obtained by dividing the line voltage of t and the voltage Vcc by the resistors R2 and R3 is defined as Vin. Note that the voltage Vout is a negative voltage, and the voltage Vin is obtained by dividing the line voltage of the voltage Vout and the voltage Vcc by the resistors R2 and R3.
When the absolute value of the voltage between the voltage Vout and the ground level increases), the voltage Vin also decreases. Comparison circuit 20
6, a voltage Vin is supplied to one input terminal, and the other input terminal is connected to a reference voltage Vr.
ef is connected to the supply line. The comparison circuit 206 amplifies the voltage (Vin-Vref), and is configured as, for example, a non-inverting amplifier including an operational amplifier and a resistor, or an integrating amplifier further including a capacitor. Therefore, the output voltage Vcp moves to the negative side when the voltage Vin decreases and falls below the reference voltage Vref, while the output voltage Vcp increases to increase the reference voltage Vre.
When f exceeds f, the lens moves to the positive side.

On the other hand, an output terminal of the comparison circuit 206 is connected to a terminal which is an input terminal of the inverter 202 via a diode D2 and a resistor R6. Here, in a region where the potential of the terminal is more positive than the voltage obtained by adding the forward voltage of the diode D2 to the output voltage Vcp of the comparison circuit 206,
Since the diode D2 is forward-biased, the resistance of the differentiating circuit is substantially a parallel resistance of the resistors R2 and R6,
In other regions, the diode D2 is reverse-biased, so that the resistance of the differentiating circuit is substantially only the resistor R2. Therefore, the output voltage Vcp of the comparison circuit 206
, The substantial time constant from the Vcc voltage of the differentiating circuit to the threshold value Vth of the inverter is varied.

Next, the operation of the power supply circuit 200 will be described. First, an operation under a high load will be described with reference to FIG. Note that, for convenience of explanation, a case where the output signal Vcp of the comparison circuit 206 is saturated on the positive side will be described.

In this case, the signal supplied to the input terminal of the inverter 202 is the signal CTR that has passed through the differentiating circuit including the capacitor C1 and the resistor R1, so that the signal CTR changes to the voltage Vcc at the moment the signal CTR changes to the voltage Vcc. The voltage jumps from the level GND to the voltage Vcc. Therefore, the voltage of the terminal exceeds the threshold value Vth of the inverter 202, and the voltage of the terminal changes to the ground level GND, so that the transistor 204 is turned on. Therefore, the voltage of the drain of the transistor 204, that is, the terminal at the other end of the reactor L is substantially equal to the voltage Vcc.
A current flows from the terminal to the ground in the reactor L, and energy is accumulated.

On the other hand, a substantial time constant from when the voltage of the output terminal of the differentiating circuit reaches the threshold voltage Vth of the inverter 202 to the Vcc voltage of the differentiating circuit according to the output voltage Vcp of the comparing circuit 206 described above. When the voltage falls below the threshold value Vth of the inverter 202, the voltage at the terminal transitions to Vcc, so that the transistor 204 is turned off. Here, in the reactor L,
In order to maintain the current flowing from the terminal to the ground point, the voltage of the terminal is largely shifted to the negative side. At this time, if the voltage at the terminal falls below a value Vd1 obtained by subtracting the forward voltage of the diode D1 from the voltage at the output terminal out held by the capacitor C2, the diode D1 becomes forward-biased, and the energy stored in the reactor L Moves to the capacitor C2. And
All the energy stored in the reactor L is the capacitor C
At the time when the current has moved to 2, the current of the reactor L also becomes 0, and the diode D1 becomes reverse biased again. Thereafter, such an operation is repeated. The power required as the output voltage Vout of the power supply circuit 200 is supplied by the capacitor C2.

Here, the time constant of the differentiating circuit is the voltage Vin
And the reference voltage Vref. For example, when the output voltage Vout drops below a predetermined voltage (when the absolute value of the output voltage Vout increases), the comparison circuit 20
The output signal Vcp of No. 6 moves to the negative side, and the time constant of the differentiating circuit decreases. Therefore, the voltage of the terminal is equal to the signal CTR.
After the transition to the H level, the voltage attenuates from the voltage Vcc in a shorter time. For this reason, the on-time of the transistor 204 is shortened, and the energy stored in the reactor L is reduced, so that the control in the direction of increasing the output voltage Vout (decreasing the absolute value of the output voltage Vout) is performed. .

On the other hand, when the output voltage Vout increases above a predetermined voltage, the output signal Vcp of the comparison circuit 206 moves to the positive side, and the time constant of the differentiating circuit increases. For this reason, the on-time of the transistor 204 becomes longer, so that control is performed to decrease the output voltage Vout (increase the absolute value of the output voltage Vout).

As a result of such control, that is, the line voltage of the output voltage Vout and the voltage Vcc is changed by the resistors R2 and R2.
As a result of performing control such that the voltage Vin divided by 3 falls within a constant width centered on the reference voltage Vref, the average value of the output voltage Vout is stabilized at a voltage at which control in both directions is balanced. . Therefore, the following equation is established.

Vref = Vin = (Vcc-Vout)
R3 / (R2 + R3) Therefore, the average value of the output voltage Vout is ΔVcc−
Vref · (R2 + R3) / R3}. The voltage Vout is a negative value including a sign as described above.

In the operation under a low load, as shown in FIG. 3, since the pulse interval P2 of the signal CTR is longer than the pulse interval P1 under a high load, the switching cycle of the transistor 202 also becomes longer. Otherwise, the operation is basically the same as at the time of high load. However, because of the low load, the discharge of the capacitor C2 also proceeds slowly.
Also at this low load, control is performed to make the average value of the output voltage Vout constant as in the case of the high load.

According to the power supply circuit 200, basically, as the load increases, the transistor 204 turns on and off in accordance with the signal CTR in which the interval of the pulse having the constant width W becomes longer. Energy can be well stored and released. In particular, in an almost no-load state, the interval between pulses becomes very long, and the switching frequency of the transistor 204 is reduced. Therefore, loss caused by switching can be reduced. Further, the voltage Vi
As a result of controlling the ON width of the transistor 204 so that n becomes constant at the reference voltage Vref, the voltage Vo at the output terminal is
It is also possible to make ut constant.

Although the inverter in this embodiment has been described as a normal inverter, it may be a Schmitt trigger input. The diode has been described as a normal diode, but may be a Schottky diode. In particular, the diode D1 is preferably a Schottky diode having a small forward voltage in terms of efficiency. In order to further improve the efficiency, the diode D1
Can be replaced with a synchronous rectifier circuit using a transistor or the like.

Second Embodiment Next, an electro-optical device to which the power supply circuit of the present invention is applied will be described. FIG. 4 is a block diagram illustrating an electrical configuration of a liquid crystal display device as an example of the electro-optical device. As shown in this figure, in the liquid crystal display panel 10, a plurality of pixels 16 are formed at respective intersections of i data lines X1 to Xi and j scanning lines Y1 to Yj. Liquid crystal display element (liquid crystal layer) 1
8 and a TFD (Thin Film Diode) element 20 are connected in series. In the figure, the TFD element 20 is connected to the data line side, and the liquid crystal layer 18 is connected to the scanning line side.
May be connected to the scanning line side, and the liquid crystal layer 18 may be connected to the data line side.

Here, a detailed configuration of the liquid crystal display panel 10 will be described. FIG. 5 is a partially broken perspective view schematically showing one example. As shown in FIG. 1, the liquid crystal display panel 10 includes an element substrate 30 and an opposing substrate 32 disposed to oppose the element substrate 30. Among them, the element substrate 30
A plurality of pixel electrodes 34 are respectively arranged in a matrix on the opposing surface. Here, the pixel electrodes 34 arranged in the same column have data lines X1 to Xi extending in a strip shape in the column direction.
Are connected via the TFD elements 20 respectively. Here, when the TFD element 20 is viewed from the substrate side,
A first metal film 22, an oxide film 24 obtained by anodizing the first metal film 22, and a second metal film 26 have a metal / insulator / metal sandwich structure. For this reason,
The TFD element 20 has positive and negative bidirectional diode switching characteristics.

On the other hand, in the opposite substrate 32, the element substrate 3
The scanning lines Y1 to Yj extend in the row direction orthogonal to the data lines X1 to Xi and are arranged on the opposing surface of the pixel electrodes 34 so as to be opposite electrodes of the pixel electrodes 34.

Now, the element substrate 30 constructed as described above will be described.
The opposing substrate 32 maintains a constant gap (gap) by a sealing agent applied along the periphery of the substrate and spacers appropriately dispersed.
A TN (Twisted Nematic) type liquid crystal is sealed, whereby the liquid crystal layer 18 in FIG. 4 is formed. That is, the liquid crystal layer 18 is composed of the data line, the pixel electrode 34, and the liquid crystal located between the data line and the scanning line at the intersection of the data line and the scanning line.

In addition, the opposing substrate 32 is provided with, for example, color filters arranged in a stripe shape, a mosaic shape, a triangle shape, or the like according to the use of the liquid crystal display panel 10. A black matrix such as a resin material in which a metal material such as nickel or carbon or titanium is dispersed in a photoresist is provided. In addition, the element substrate 30 and the counter substrate 32
Each of the opposing surfaces is provided with an alignment film or the like that has been rubbed in a predetermined direction, and a polarizing plate corresponding to the alignment direction is provided on each back surface (both are not shown).

However, in the liquid crystal display panel 10,
The use of polymer-dispersed liquid crystal in which liquid crystals are dispersed as fine particles in a polymer eliminates the need for the above-mentioned alignment film, polarizing plate, etc., thereby increasing the light use efficiency and thus increasing the brightness of the liquid crystal display panel. And low power consumption.
When the liquid crystal display panel 10 is of a reflective type, the pixel electrode 34 is made of a metal film having a high reflectivity such as aluminum, and an SH (super homeotropic) type in which liquid crystal molecules are almost vertically aligned in the absence of a voltage. Liquid crystal or the like may be used.

The TFD element 20 is an example of a two-terminal switching element. In addition, an element using a ZnO (zinc oxide) varistor, an MSI (Metal Semi-Insulator) or the like, or two of these elements Devices connected in series or parallel in the opposite direction can be applied as the two-terminal switching element.

The description returns to FIG. The scanning line signal driving circuit 110 outputs a voltage V1 supplied from the power supply circuit 210 according to a signal supplied from the driving control circuit 130,
V2, V3, V4, and V7 are selected and supplied as scanning signals to the respective scanning lines Y1 to Yj. here,
As a waveform example of the scanning signal, for example, a waveform shown in FIG. 6 is given. In the waveforms shown in this figure, scanning signals supplied to a certain scanning line Ym (Y1 ≦ Ym <Yj) and a scanning line Ym + 1 located next to the scanning line Ym, respectively, are shown. It is. As shown in these figures, the scanning signal is
The charge mode and the discharge mode are alternately switched for each row of the scanning lines, and when focusing on one scanning line, the mode is switched for each vertical scanning period TV. Here, when a certain scanning line is selected in the charging mode, the first one is selected.
In the second half of the horizontal scanning period, the scanning signal supplied to the scanning line is the voltage V1. As a result, the TFD element 20 becomes conductive, and a voltage corresponding to the data signal is charged in the liquid crystal layer. After a lapse of one vertical scanning period, the mode is switched to the discharge mode and a scanning line is selected. In the first half of the one horizontal scanning period, the scanning signal supplied to the scanning line is at the voltage V7. . For this reason,
Regardless of the data signal, the TFD element 20 conducts, and the liquid crystal layer is overcharged with a voltage having a polarity opposite to the voltage V1 with reference to an intermediate value between the data signals V3 and V4. Subsequently, in the latter half period, the scanning signal supplied to the scanning line becomes the voltage V2. As a result, the TFD element 20 becomes conductive, and the overcharged liquid crystal is discharged according to the data signal. The waveform of the scanning signal is
Various waveforms other than this can be applied, for example, a waveform in which only the charging mode is alternately output with the positive electrode and the negative electrode,
A waveform whose polarity is inverted every horizontal scanning period, and further, n
The polarity may be inverted every horizontal scanning period.
It is also possible to perform only frame inversion without performing inversion driving every one horizontal scanning period.

The data signal drive circuit 120 supplies a data signal to each of the data lines X1 to Xi. This data signal is defined by voltages V3 and V4 selected during a part of the scanning signal. Further, the drive control circuit 130 generates a clock signal, a control signal, and the like based on an externally supplied image signal and a synchronization signal, and controls the scan signal drive circuit 110 and the data signal drive circuit 120, respectively. . Here, the clock signal, the control signal, and the like generated by the drive control circuit 130 include the above-described clock signal that defines the timing of each scanning signal, a signal for selecting the voltage of the scanning signal, and the like. In addition, for example, as shown in FIG. 7, the display screen of the liquid crystal display panel 10 may be divided into display areas for the area A along the extending direction of the scanning lines, and the non-display area may be set for the area B. When instructed by the display switching signal, the drive control circuit 130 generates the signal CTR as follows. That is, first, as shown in FIG. 8, the drive control signal 130
The logical product of a signal a for defining a period during which the voltages V1, V2, and V7 are to be supplied to .about.Yj and a signal b that becomes H level during a period in which the scanning line included in the region A is selected is obtained. Second, the signal C is obtained by calculating the logical sum of this logical product and the signal c obtained by dividing the signal a by an appropriate multiple.
Generate TR.

The signal CTR generated in this manner is used during a period in which a scanning line included in the display area A is selected.
The interval between pulses having a constant width becomes dense, and the non-display area B
In the period in which the scanning lines included in the period are selected, the intervals between the pulses are sparse. That is, the pulse interval of the signal CTR is generated so as to be dense when the number of pixels to be driven is assumed to be large, and to be sparse when the number of pixels to be driven is assumed to be small. . Strictly speaking, the number of pixels to be driven is zero during a period in which a scanning line included in the non-display area B is selected.
Even in this case, since each drive circuit consumes power to some extent, a pulse is supplied as a signal CTR to some extent.

The power supply circuit 210 has basically the same configuration as the power supply circuit 200 according to the first embodiment described above.
After the above-described voltages V1 and V7 are generated by the respective systems, voltages V2 and V3, which are intermediate voltages between them, are generated. In the liquid crystal display device 100, since the voltage V4 is at the ground level, the voltages V1, V2, V3, and V7 excluding the voltage V4 are actually supplied to the scanning signal drive circuit 110, while the voltage V3 is the data level. The signal is supplied to the signal drive circuit 120.

Since the voltage V1 has a positive polarity,
The system that generates the voltage V1 has a configuration in which the polarity is inverted with respect to the ground level with respect to the power supply circuit 200 according to the first embodiment. Further, as the reference voltage Vref of each system, it is necessary to set the output terminal voltages to V1 and V7, respectively, so that (Vcc−V1) · R3 / (R2 + R
3) and (Vcc-V7) .R3 / (R2 + R3). The power supply circuit 210 has a voltage V
1, V2, V3, and V7 may be individually generated by four systems. When the four systems are separately generated as described above, the voltages V1 and V2 are applied to the liquid crystal display panel 10.
When compensating according to the temperature of the liquid crystal display panel 1,
The temperature of 0 may be detected by a temperature-sensitive element such as a thermistor or a diode, and the detected temperature may be converted into a voltage by a temperature / voltage conversion table, and the converted voltage may be set as a reference voltage Vref. .

As described above, the voltages V1, V2, V3, and V7 used in the scanning signal driving circuit 110 for supplying the scanning signal to the liquid crystal display panel 10 and the data signal driving circuit 120 for supplying the data signal are controlled by the power supply circuit 210. When a configuration is adopted in which the signal CTR having a pulse interval corresponding to the number of pixels to be driven is supplied to the power supply circuit 210, the switching frequency of the transistor increases when the number of pixels to be driven is large. When the number of pixels to be driven is small, the switching frequency of the transistor increases, so that the scanning signal driving circuit 110 and the data signal driving circuit 120 can be driven according to display contents. As a result, unnecessary switching in the power supply circuit is suppressed, so that loss is reduced and power consumption is reduced.

Although the liquid crystal display panel 100 has been described by using an example using a TFD element as a switching element, the present invention is not limited to this. One substrate is provided with scanning lines and data lines, and at each intersection thereof. The TFT (Thin FilmT) is connected to the gate to the scanning line, the source to the data line, and the drain to the pixel electrode.
ransistor (thin film transistor). In addition, without using these switching elements, S
The present invention is also applicable to a passive liquid crystal using a TN (Super Twisted Nematic) liquid crystal. Further, the present invention can be applied to a display device that performs display using various electro-optical effects, such as an electroluminescence display device in which a light emitting layer is disposed instead of a liquid crystal.

[0041]

As described above, according to the present invention, power is efficiently supplied in accordance with the size of the load, so that the power consumed in the power supply circuit can be kept low.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a power supply circuit according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining an operation of the power supply circuit under a high load.

FIG. 3 is a waveform chart for explaining an operation of the power supply circuit under a low load.

FIG. 4 is a block diagram illustrating an electrical configuration of a liquid crystal display device as an example of an electro-optical device according to a second embodiment of the invention.

FIG. 5 is a partially broken perspective view showing a configuration of a main part of a liquid crystal display panel in the liquid crystal display device.

FIG. 6 is a waveform chart showing an example of a scanning signal in the same liquid crystal display panel.

FIG. 7 is a diagram for explaining screen division in the liquid crystal display panel.

FIG. 8 is a diagram illustrating a process of generating a signal CTR in the liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 10 liquid crystal display panel 100 liquid crystal display device 110 scanning signal driving circuit 120 data signal driving circuit 130 driving control circuit 200, 210 power supply circuit 202 inverter 204 transistor 206 Operational amplifier L ... Reactor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H093 NB30 NC03 NC05 NC06 NC10 NC12 NC34 NC37 NC57 NC63 ND39 NF05 NH18 5C006 AC11 AF51 BB12 BB16 BB17 BF14 BF27 BF31 BF36 BF37 BF38 BF42 BF49 FA19 FA47 5C080 AA03 DD30 FF12 JJ02 JJ03 JJ04 JJ06 5H730 AA14 BB15 BB57 DD04 FD01 FG02 FG07

Claims (4)

[Claims] A switching unit that is turned on in accordance with a signal corresponding to a magnitude of a load; and stores power when the switching unit is turned on, and releases the stored power when the switching unit is turned off. A power storage unit that supplies the load to the load, and a control unit that controls an ON period of the switching unit based on a comparison result between a voltage supplied from the power storage unit and a target voltage to be supplied to the load. A power supply circuit, comprising: 2. The control device according to claim 1, wherein when the voltage supplied from the power storage device is smaller in absolute value than a target voltage to be supplied to the load, the ON period of the switching device is extended. On the other hand, when the voltage supplied from the power storage means is larger in absolute value than the target voltage to be supplied to the load, control is performed so as to shorten the ON period of the switching means. The power supply circuit according to claim 2. 3. A switching element which is turned on in accordance with a signal having a pulse interval corresponding to the magnitude of a load, and stores power when the switching element is turned on, and stores the power when the switching element is turned off. A reactor that emits power and supplies the load, and when a voltage supplied from the reactor is smaller in absolute value than a voltage to be supplied to the load, control is performed such that an ON period of the switching element is lengthened. While
When the voltage supplied from the reactor is higher in absolute value than the voltage to be supplied to the load, control is performed so as to shorten the ON period of the switching element. 4. An electro-optical device having a plurality of pixels in which an electro-optical material is sandwiched between two substrates facing each other, comprising: driving means for supplying a signal for driving the plurality of pixels; A signal output unit that outputs a signal corresponding to the number of pixels to be driven; a switching unit that is turned on in accordance with the signal; when the switching unit is turned on, power is stored, and when the switching unit is turned off, The switching means is turned on based on a result of comparison between a power storage means that discharges stored power to supply the driving means and a voltage supplied from the power storage means and a target voltage to be supplied to the load. An electro-optical device comprising: control means for controlling a period.