JPH11102169A - Display device, power supply circuit for driving the display device, and electronic equipment including the same - Google Patents

Abstract

(57) Abstract: Provided is a device capable of reducing an oscillation sound generated from a capacitor in a power supply circuit for driving a display device such as an LCD. According to the present invention, for example, a scanning signal generation circuit (60) in a driving power supply circuit (50) of a display device includes:
In addition to a conventional first capacitor (63), a second capacitor (66) having substantially the same characteristics as this is provided close to the first capacitor (63). The two capacitors are switched based on switching signals having phases opposite to each other. Therefore, when the first capacitor is charged and discharged, the second capacitor discharges and discharges the charge in reverse. It is desirable that the load (68) for the second capacitor has substantially the same impedance as the liquid crystal panel (10) that is the load of the first capacitor. Thereby, the first and second
The phases of the oscillating sounds generated by the capacitors are reversed and cancel each other, and the resulting noise is significantly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, a power supply circuit for driving the display device, and an electronic apparatus including the same.

[0002]

2. Description of the Related Art In recent years, a liquid crystal display (LCD), which is one of flat panel display devices, is widely used in electronic devices such as electronic notebooks, personal computers, and mobile phones as a low power consumption and lightweight display device. ing.

An active matrix liquid crystal display device using an MIM device capable of high-definition display close to a TFT device and advantageous in manufacturing cost is mainly used for a car navigation system and a vehicle-mounted television using a medium-sized or small-sized display device. It has been used for electronic devices such as portable information terminals.

[0004] TFT-LCD and MIM-LCD are
Each of the active elements uses a transistor and a diode, and the LCD panel includes a pixel electrode, an active element, a liquid crystal layer, and the like, and is provided with a plurality of scanning line electrodes and data line electrodes. A driving circuit IC for supplying signals to these scanning line electrodes and data line electrodes
Are connected to the LCD panel by a COG method, a TAB method, or the like. Further, a display control circuit for generating signals required for display and a drive power supply circuit for supplying various power supplies to the drive circuit are arranged on the printed wiring board.

[0005]

However, such L
During operation of an electronic device using a CD, an oscillating sound like a flying insect may be heard. This is a harsh sound for the user of the electronic device, and particularly, in the case of a personal digital assistant (PDA) having the function of a mobile phone, the user has many opportunities to use the electronic device close to the ear. Is especially problematic. Also, in electronic devices used in a closed space, such as a car navigation system, and other electronic devices used in a relatively quiet environment, this noise is unpleasant for the user.

According to the research by the present inventors, this noise is
In the case of the MIM-LCD, it has been concluded that the power source circuit for driving the liquid crystal display device, in particular, the aluminum electrolytic capacitor constituting the switching unit for the scanning signal generation circuit is the generation source. A signal generated by charging / discharging of this capacitor is subjected to level conversion or the like and given to a scanning line driving circuit of the MIM-LCD. However, noise is generated at the time of charging / discharging of this capacitor. I knew it was there.

[0007] This oscillation noise is caused by the aluminum foil electrode inside the capacitor vibrating due to the charging and discharging of the capacitor.
It seems to have been transmitted to the condenser container. Also, it seems that the oscillating sound from the capacitor is transmitted to the printed wiring board on which the capacitor is mounted, thereby acting to increase the sound.

Accordingly, the present invention provides a display device capable of eliminating noise caused by charging and discharging of a capacitor generated from an electronic device, a power supply circuit for driving the display device, and an electronic device using such a display device or circuit. The purpose is to:

[0009]

According to the present invention, a pulse signal, which is a basis of at least one of a scanning signal and a data signal supplied to a display panel, for example, a liquid crystal panel, is generated by charging and discharging a first capacitor. In the driving power supply circuit, a second capacitor is provided close to the first capacitor. The second capacitor is discharged when the first capacitor is charged, and charged when the first capacitor is discharged.

[0010] With this configuration, the phase of the oscillation sound generated from the first capacitor and the phase of the oscillation sound generated from the second capacitor are reversed, and cancel each other. Sound is reduced. It is sufficient that this oscillation sound can be reduced to such a degree that humans cannot hear it.

It is desirable to select the first capacitor and the second capacitor which have substantially the same characteristics and generate oscillation sounds having substantially the same amplitude during charging and discharging. It is desirable to adjust equally. By doing so, the oscillating sound generated from the first capacitor and the oscillating sound generated from the second capacitor can be canceled almost completely.

In one embodiment of the present invention, a dummy load is used as the load of the second capacitor. The impedance of the dummy load is adjusted to a value that takes into account the resistance and capacitance of the liquid crystal panel to which the first capacitor is connected, the resistance of other circuits, and the like.

In another embodiment of the present invention, a liquid crystal panel is driven by using a signal obtained by charging and discharging the second capacitor. The same liquid crystal panel as that driven by the signal obtained by charging and discharging the first capacitor may be driven, or a separate liquid crystal panel may be driven. By doing so, the second
The signal obtained by charging and discharging the capacitor can be effectively used.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of a display device according to the present invention will be described with reference to the drawings. In Figure 1, the liquid crystal panel 10 includes a plurality of data lines X ₁ to X _n, a plurality of scan lines Y ₁ to Y _m, between the data lines and the scan lines,
Active elements, for example, an MIM element 12 and a liquid crystal element 14 are electrically connected in series. The connection between the MIM element 12 and the liquid crystal element 14 is not limited to the configuration in which the MIM element 12 is connected to a scanning line and the liquid crystal element 14 is connected to a data line as shown in FIG. Conversely, the MIM element 12 may be connected to a data line, and the liquid crystal element 14 may be connected to a scanning line. Also, a back-to-back configuration in which two MIM elements are connected in series in opposite directions can be adopted, and various modifications can be made.

The scanning line driving circuit 20 supplies scanning signals to the scanning lines Y _{1 to} Y _m and sequentially selects the scanning lines. Scanning line Y1
Are supplied with the selection voltage to the n MIM elements connected to the scanning line Y1 at the same time.

The data line driving circuit 30 includes data lines X ₁ to X ₁ .
Supply various data voltages to _Xn . A voltage corresponding to the difference between the selection voltage applied to the scanning line and the data voltage applied to the data line is applied to the MIM element 12 selected by the scanning signal and the liquid crystal element 14 connected in series to the MIM element 12. You. A predetermined voltage is applied to the liquid crystal element 14 by the MIM element 12 in the conductive state.

The display control circuit 40 inputs a video signal, a synchronization signal, and the like, processes display information based on the input, and
The data is supplied to the scanning line driving circuit 20 and the data line driving circuit 30. The display control circuit 40 can include, for example, an amplification / polarity inversion circuit, a phase expansion circuit, a rotation circuit, a gamma correction circuit, or a clamp circuit. The driving power supply circuit 50 generates various power supply voltages necessary for the components of the display device, for example, the scanning signal 21 and the data signal 31, and supplies them to the scanning line driving circuit 20 and the data line driving circuit 30, respectively.

FIG. 2 shows the internal configuration of the driving power supply circuit 50.
Shown in FIG. 2 shows a scanning signal generation circuit 60 included in the driving power supply circuit 50. Scanning signal generation circuit 6
0 is the switching unit 61 and the signal level conversion unit 6
2 inclusive. The switching unit 61 has a capacitor 63 therein, receives a switching signal and a DC voltage from the power source, and switches a switch element (not shown) to charge and discharge the capacitor 63 and output an AC pulse signal. I do. As the capacitor 63, for example, an aluminum electrolytic capacitor is used. MIM-LC
In D, a capacitor of several μF is used as the capacitor 63 of the switching unit.

The AC pulse signal from the switching section 61 is supplied to a signal level conversion section 62. The signal system level conversion unit 62 receives clock signals and the like in addition to the AC pulse signal from the switching unit 61, generates a scan signal, and supplies the scan signal to the scan line drive circuit 20. More than,
5 is a diagram illustrating a configuration of a scanning signal generation circuit 60 in a power supply unit 50 according to the related art.

In the scanning signal generating circuit 60 according to the first embodiment of the present invention, as shown in FIG.
A switching unit 65 having the same configuration as that of the switching unit 65 is provided. The switching section 65 includes a second capacitor 63. This capacitor 63 is composed of a capacitor 63 and its capacitance,
Those having substantially the same external dimensions are used. Inverter (Negative Logic circuit) 67 shifts the phase of the switching signal by 180 degrees and supplies the same to switching section 65. Note that the means for shifting the phase of the switching signal by 180 degrees is not limited to the inverter 67, and any other means such as a delay circuit may be used as long as the signal can be delayed by 180 degrees in phase.

The dummy load 68 supplied with the output of the switching section 65 has an impedance substantially equal to the load on the capacitor 63 for supplying current by discharging, that is, the impedance including the liquid crystal panel 10 and other circuits.

An equivalent circuit for one pixel of the liquid crystal panel 10 can be represented as shown in FIG. 3, the impedance of the MIM element 12 is represented as a parallel circuit of a resistance and a capacitance, and R _M and C _M are M
These are the resistance and capacitance of the IM element. The impedance of the liquid crystal element 14 is also expressed as a parallel circuit of a resistance and a capacitance, and R _L and C _L are the resistance and the capacitance of the liquid crystal element, respectively. Note that V _MIM , V _LC , and V _D are M
This is a voltage applied to the IM device 12, the liquid crystal device 14, and a serially connected body thereof.

Therefore, the impedance value of the dummy load 68 is determined by calculating the combined impedance of the impedance of the liquid crystal panel 10 and a circuit between the capacitor and the capacitor 63, for example, the signal system level conversion circuit 62 and the scanning line drive circuit 20. Set almost equal to the value.

The condenser 63 and the condenser 66 are arranged close to each other. Preferably, the two capacitors are joined so as to be in close contact with each other. For example, two capacitors are brought into close contact with each other and then joined with an epoxy resin adhesive.

The switching of the switching unit 51 and the switching of the switching unit 55 are performed so that the phases thereof are different from each other by 180 degrees. The capacitor 66 is discharged when the capacitor 63 is charged, and the capacitor 66 is charged when the capacitor 63 is discharged. become. When capacitors having substantially the same characteristics are selected as the capacitors 63 and 66, and the load impedances thereof are adjusted to be substantially equal, the vibration waves generated by the capacitors have substantially the same magnitude and the phases are exactly opposite.

Therefore, the two capacitors 63 and 66
Are arranged as close as possible in space, the vibration waves generated from each are canceled out, and the resulting oscillating sound is sufficiently reduced to such an extent that it is almost inaudible to human ears.

Various embodiments for joining two capacitors 63 and 66 are shown in FIG. In FIG. 4 (a), capacitors 63 and 6 having a cylindrical outer container are shown.
6 is mounted on a printed wiring board 80 on which a driving power supply circuit is mounted, with its side walls adhered by an adhesive. The capacitors 63 and 66 are mounted upright on the substrate 80 in the same direction.

In FIG. 4 (b), the bottom surface of the capacitor 66 from which the two extraction terminals are exposed is bonded to the circular upper surface of the capacitor 63 on the side where the terminals are not exposed. Then, the combined body including the two capacitors 63 and 66 is mounted upright on the substrate 80.

In FIG. 4C, capacitors 63 and 6
6 are joined together. The two joined capacitors are mounted sideways so that their axial directions are substantially parallel to the substrate 80.

In FIG. 4 (d), the two capacitors 63 and 66 have their side walls joined with their directions reversed. Thus, the terminals come out from the opposite sides of the capacitor combination. The combined body of the capacitors is mounted sideways so that the axial direction thereof is substantially parallel to the substrate 80.

In addition, various joining forms and arrangement forms of the capacitors 63 and 66 are possible. In the above embodiment, an example in which the two capacitors are joined by an adhesive is shown. However, for example, the two capacitors can be joined by other ordinary means such as covering with a resin tube and joining by shrinking the resin tube. The joining method may be selected in consideration of the ease of mounting components on the substrate 80 and the like.

In the above example, two capacitors 6
3 and 66 were joined so as to cancel out the vibration waves generated from each capacitor most effectively, but the arrangement of the two capacitors is not limited to this. Even if the two capacitors 63 and 66 are not joined, if they are arranged on the substrate 80 to some extent close to each other, the vibration wave generated from one capacitor is canceled to some extent by the vibration wave of the opposite phase from the other capacitor. Therefore, the vibration sound is attenuated to a considerable extent.

In the embodiment shown in FIG. 2, the dummy load 68 is used in order to make the load impedances of the two capacitors 63 and 66 substantially equal. However, as shown in FIG. On the output side,
The second liquid crystal panel 15 may be connected and driven. In this case, a second signal system level conversion unit 64 is provided on the output side of the switching unit 65, and a second scanning line drive circuit 25 and a second data line drive circuit 35 are provided on the liquid crystal panel 15.

As the second liquid crystal panel 15, it is desirable to select a panel having a load impedance substantially equal to that of the first liquid crystal panel 10. In this way, the load impedances of the capacitors 63 and 66 become substantially equal, and the absolute values of the opposite-phase vibration waves generated from each become substantially equal, so that they can be effectively canceled.

Different information can be displayed on the liquid crystal panels 10 and 15, respectively. On the other hand, these two liquid crystal panels 10 and 15 may function as one display device to display one piece of information. FIG.
Is particularly suitable for an electronic device using two liquid crystal panels.

Next, an embodiment in which one liquid crystal panel 10 is used as a load of the capacitors 63 and 66 will be described with reference to FIG. In FIG. 6, an inverter 68 is provided on the output side of the second switching unit 65, inverts the AC pulse signal output from the switching unit 65, and shifts its phase by 180 degrees. The output of the inverter 68 is input to the adder 69 together with the output of the switching unit 61, and is added. The output of the adder 69 is provided to the signal system level converter 62.

FIG. 7 shows an example of a signal waveform in each section of the configuration of FIG. As shown in FIGS. 7A and 7B, the output signals of the switchings 61 and 65 have waveforms whose phases are different by 180 degrees. The output signal of the inverter 69 is, as shown in FIG.
The output signal (a) of the switching unit 61 has the same phase as the output signal (a).

A scanning signal shown in FIG. 7D is supplied to the first scanning line Y 1 of the liquid crystal panel 10 by the scanning line driving circuit 20. Scanning signal during one vertical scanning period V1, 1 relatively large selection voltage applied to the horizontal scanning period H ₁ of the scanning line Y ₁ is selected, consisting of holding the voltage applied to the rest of the period.

The data signal shown in FIG. 7E is supplied to the data line X ₁ of the first column by the data line driving circuit 30. MIM element 12 constituting one pixel of liquid crystal panel 10
In addition, a voltage corresponding to the difference between the voltage of the corresponding scanning line and the voltage of the data line is applied to the liquid crystal element 14. FIG. 7F shows a voltage waveform of the liquid crystal display element 14 in the first row and first column.

According to the configuration shown in FIG. 6, the output of the second switching unit 65 can be effectively used by the single signal system level conversion unit 62. The load on the capacitors 63 and 66 is the same scanning line of one liquid crystal panel 10 at any time. Therefore, the load impedances of the two capacitors 63 and 66 become almost equal at any time, and the oscillation sound can be attenuated extremely well.

The liquid crystal display device does not perform interlaced (interlaced) scanning unlike the CRT television. This is because flicker becomes a problem when the driving frequency is lowered, and it is necessary to drive at a frequency of about 30 Hz. That is, the signal of the first field is written to a certain pixel, and the second field is written so as to overlap the same pixel, and the resolution in the vertical direction is halved.

Therefore, a system for improving the vertical resolution as disclosed in Japanese Patent Application Laid-Open No. 8-334744 has been proposed. That is, in the odd field, two lines are selected at a time, such as the first row and the second row, the third row and the fourth row, the fifth row and the sixth row, and two scanning lines are simultaneously written, and the even number is selected. In the field, the second row and the third
In this method, two lines are selected and two scanning lines are written simultaneously, such as a line, a fourth line, a fifth line, a sixth line, and a seventh line. For this purpose, an analog switch is provided,
A set of scanning lines to be selected is switched between an odd field and an even field.

The present invention can be applied to such a driving method for simultaneously selecting two scanning lines. One method is to provide an analog switch as shown in Japanese Patent Application Laid-Open No. 8-334744 on the liquid crystal panel shown in FIG. 6 and apply the driving method as it is. Another method is to use switching units 61 and 6 as shown in FIG.
5 are used.

In FIG. 8, scanning signals of opposite phases output from a power supply unit 51 having the same configuration as that shown in FIG. 5 are supplied to two scanning line driving circuits 21 and 22, respectively. The scanning line driving circuit 21 supplies the scanning signal to the odd-numbered scanning lines Y ₁ , Y ₃ ,.
2 supplies the scanning signal to the even-numbered scanning lines Y ₂ , Y ₄ ,.

As a method of writing data to the active matrix liquid crystal panel, a line sequential method in which data to be written to a pixel connected to the next selected scanning line is read in advance and written to pixels of the selected scanning line at a time is used. is there. In FIG. 8, two data line drive circuits 31 and 32 are provided to drive the data line divided into two blocks.

The liquid crystal panel 10 has 632 × 2 pixels.
When using the MIM-LCD 32, as shown in FIG. 9, a data signal is supplied from the data line driving circuit 31 to the data lines X ₁ , X _{2 ,.
317,} X _318, ···, the X _632, the data line driving circuit 32
Supplies a data signal. The first scanning line Y1 and the second scanning line Y2 are supplied with scanning signals of opposite polarities shown in FIG. Since the same data signal cannot be simultaneously applied to the data lines connected to the selected two scanning lines, the driving shown in FIGS. 9 and 10 is performed.

As shown in FIG. 10, in odd frames, scanning signals are simultaneously applied to the scanning lines Y ₁ and Y ₂ . The selection period is divided into two, and in the first half periods T ₁ and T ₄ , a data signal is supplied from the data line driving circuit 31 to the pixel region (the left portion on the scanning line Y ₁ ), From the circuit 32, the pixel area (scanning line Y
₂₎ on the right side).

In the latter periods T ₂ and T ₃ , a data signal is supplied from the data line driving circuit 31 to the pixel area (the left portion on the scanning line Y ₂ ).
2, the pixel region (the right side of the portion located on the scanning line Y ₁₎
To the data signal.

[0049] In the even frame, the scanning lines Y ₂ and Y _3, the scanning signal is applied simultaneously. The selection period is divided into two, and in the first half periods T ₃ and T ₆ , a data signal is supplied from the data line driving circuit 31 to the pixel region (the left part on the scanning line Y ₂ ), from the circuit 32 provides data signals to the pixel area (the right part at the top scan line Y _3).

In the latter periods T ₄ and T ₅ , a data signal is supplied from the data line drive circuit 31 to the pixel area (the left portion on the scanning line Y ₃ ).
2, the pixel region (the right side of the portion located on the scanning line Y ₂₎
To the data signal.

[0051] In FIGS. 9 and 10, for example, a scanning signal supplied scan signal supplied to the scan line Y ₁ and the scanning line Y _2, are opposite phases to each other. For this reason, switches 33 and 34 for selecting a positive polarity video signal and a negative polarity video signal are provided on the input sides of the data line drive circuits 31 and 32, respectively.

Thus, the scanning signal obtained by the power supply circuit according to the present invention can be used for a driving method for simultaneously selecting two scanning lines. In this case, the two capacitors 63 and 66 load different pixels, but
Since the pixels are in one liquid crystal panel 10, their impedances are almost equal, which is effective in attenuating the oscillation sound. Although the data line is divided into two in the embodiment shown in FIG. 8, the data line can be divided into more blocks. Also, an example is shown in which the same video signal is written to the pixels connected to the two scanning lines selected at the same time. However, the pixels connected to the two scanning lines selected at the same time are
It is also possible to write data from different video signals respectively.

FIG. 11 shows a case in which the scanning signals of opposite phases obtained from the signal system level converters 62 and 64 are used for a driving method of 2H inversion, that is, a method of inverting the polarity every two scanning lines to reduce flicker. 1 shows an embodiment of the present invention. In FIG. 11, signal level converters 62 and 6
4 is provided with a selection switch 26 for selectively giving any one of the outputs to the scanning line drive circuit 20.

As shown in FIGS. 12A and 12B,
The output signal of the switching unit 61 and the output signal of the switching unit 65 have opposite phases to each other. When the selection pulse 26 selects the signal system level conversion unit 62, the scanning signal from the signal system level conversion unit 62 is given to the first line scanning line Y ₁ of the liquid crystal panel 10. The scanning signal has a select period H ₁ at the beginning portion of the vertical scanning period V _1. Leaving connecting the selector switch 26 to the signal system level converting unit 62 side, the scanning signal for the scanning line Y ₂ has a waveform as shown in FIG. 12 (e). When this is used, the driving method is 1H inversion, that is, the driving method in which the polarity is inverted for each scanning line.

In FIG. 11, when the second scanning line Y ₂ is selected, the selection switch 26 is switched to the signal system level converter 64. Waveform shown in FIG. 12 (d), i.e. the first same polarity scan signal and the horizontal scanning period H ₁ is in the second horizontal scanning period H _2, it is supplied to the scanning line Y _2.

In this case, capacitors 63 and 66 are
Although the liquid crystal panel 10 is not being driven at exactly the same time, the capacitors 63 and 6
Oscillation noise can be reduced by generating vibration waves of opposite polarities from 6 and canceling each other to some extent.

In the above description, the case where the liquid crystal panel constituted by the MIM elements is driven by the quaternary driving method is exemplified. The modulation may be performed by pulse modulation or pulse width modulation.

The application of the present invention is not limited to the power supply circuit for driving the MIM-LCD, but can be similarly applied to a TFT (thin film transistor) -LCD. However, TFT
-In the LCD drive power supply circuit, the second capacitor is provided in close proximity to the capacitor in the data signal generation circuit, and when the first capacitor is charged and discharged, the second capacitor is discharged and charged in reverse. Let it do.

Next, an example of the configuration of an electronic device using the liquid crystal display device described above will be described. The electronic device shown in FIG. 13 includes a display information output source 100, a display information processing circuit 1002, a driving circuit 104, a liquid crystal panel 10, a clock generation circuit 108, and a power supply circuit 101. The display information output source 100 includes a memory such as a ROM and a RAM, a tuning circuit, and the like, and outputs display information such as a video signal based on a clock from the clock generation circuit 108.

The display information processing circuit 102 processes and outputs display information based on the clock from the clock generation circuit 108. The display information processing circuit 102 can include, for example, an amplification / polarity inversion circuit, a phase expansion circuit, a rotation circuit, a gamma correction circuit, or a clamp circuit. The driving circuit 104 includes a scanning line driving circuit 20 and a data line driving circuit 30 and drives the liquid crystal panel 10. The power supply circuit 101 supplies power to each of these circuits.

As an electronic apparatus having such a configuration, FIG.
, A personal computer (PC) and an engineering workstation (EWS) compatible with multimedia shown in FIG. 15, a pager shown in FIG. 16, a mobile phone, a word processor, a television, a viewfinder type or a monitor direct view type. Video table recorder, electronic organizer, electronic desk calculator, car navigation device, POS terminal, device equipped with a touch panel, and the like.

The projector shown in FIG. 14 is a projection type projector using a transmission type liquid crystal panel as a light valve, and uses, for example, a three-plate prism type optical system.
In FIG. 14, in a projector 110, the projection light emitted from a lamp unit 112 of a white light source is divided into three primary colors of R, G, and B by a plurality of mirrors 116 and two dichroic mirrors 118 inside a light guide 114. And three active matrix liquid crystal panels 111R, 111G for displaying images of the respective colors.
And 111B.

Then, each of the liquid crystal panels 111R,
Light modulated by 111G and 111B is incident on dichroic prism 112 from three directions.
In the dichroic prism 112, the red R and blue B light are bent by 90 degrees, and the green G light goes straight, so that the images of the respective colors are combined, and a color image is projected on a screen or the like through the projection lens 114.

The personal computer 12 shown in FIG.
0 has a main body section 124 having a keyboard 122 and a liquid crystal display screen 126.

A pager 130 shown in FIG. 16 includes a liquid crystal display substrate 134 and a backlight 1 in a metal frame 132.
Light guide 136 with 36a, circuit board 130
8, first and second shield plates 1310, 1312, two elastic conductors 1314, 1316, and a film carrier tape 1318. Two elastic conductors 13
4,136, and film carrier tape 1318
Connects the liquid crystal display substrate 134 and the circuit board 1308.

Here, the liquid crystal display substrate 134 has liquid crystal sealed between two transparent substrates 134a and 134b, thereby forming at least a dot matrix type liquid crystal panel. The driving circuit 104 shown in FIG. 13 or the display information processing circuit 102 can be formed on one of the transparent substrates. Circuits not mounted on the liquid crystal display substrate 134 are external circuits of the liquid crystal display substrate, and can be mounted on the circuit substrate 1308 in the case of FIG.

FIG. 16 shows the structure of the pager, and therefore requires a circuit board 1308 in addition to the liquid crystal display substrate 134. However, this is a case where a liquid crystal display device is used as one component for electronic equipment. When a driving circuit or the like is mounted on a transparent substrate, the minimum unit of the liquid crystal display device is
The liquid crystal display substrate 134 or the liquid crystal display substrate 1
What fixed 34 to the metal frame 132 as a housing | casing can also be used as a liquid crystal display device which is one component for electronic devices.

Further, in the case of a backlight type, a liquid crystal display substrate 134 and a light guide 136 having a backlight 136a can be incorporated in a metal frame 132 to constitute a liquid crystal display device. Instead, as shown in FIG. 17, a polyimide tape 1322 having a metal conductive curtain formed on one of two transparent substrates 134a and 134b constituting a liquid crystal display substrate 134 has
TCP (Tape Car) mounting the C chip 1324
Further, a liquid crystal display device, which is one component of an electronic device, can be used by connecting a rear package 1320.

The present invention is particularly preferably applied to a liquid crystal display device, but can also be applied to other display panels, for example, an EL (electroluminescence), a plasma display and the like.

[0070]

As described above, according to the present invention, a display device capable of removing noise caused by charging and discharging of a capacitor generated from an electronic device, a power supply circuit for driving the display device,
An electronic device using such a display device or a circuit can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a liquid crystal display device to which the present invention is applied.

FIG. 2 is a block diagram showing a configuration of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram for one pixel of the MIM-LCD.

FIG. 4 is a block diagram showing an example of mounting first and second capacitors in the embodiment shown in FIG. 2;

FIG. 5 is a block diagram illustrating a configuration of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 7 is a time chart showing signal waveforms at various parts of the liquid crystal display device shown in FIG.

FIG. 8 is a block diagram illustrating a configuration of a liquid crystal display device according to a fourth embodiment of the present invention.

9 is a schematic diagram illustrating a driving method in the liquid crystal display device shown in FIG.

FIG. 10 is a time chart showing signal waveforms at various parts of the liquid crystal display device shown in FIG.

FIG. 11 is a block diagram illustrating a configuration of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 12 is a time chart showing signal waveforms at various parts of the liquid crystal display device shown in FIG.

FIG. 13 is an explanatory diagram of a configuration example of an electronic device using the present invention.

FIG. 14 is a diagram illustrating a projector as a specific configuration example of an electronic apparatus to which the invention is applied.

FIG. 15 is a diagram illustrating a personal computer as a specific configuration example of an electronic device to which the present invention is applied.

FIG. 16 is a diagram illustrating a pager as a specific configuration example of an electronic device to which the present invention is applied.

FIG. 17 is a diagram showing a liquid crystal display device to which the present invention is applied.

[Explanation of symbols]

 Reference Signs List 10 liquid crystal panel 12 MIM element 14 liquid crystal element 20 scanning line drive circuit 30 data line drive circuit 40 display control circuit 50 drive power supply circuit 60 scan signal generation circuit 61, 65 switching section 63, 66 capacitor 62 signal system level conversion section 67 inverter 68 Dummy load

Claims (10)

[Claims] 1. A plurality of scanning lines, a plurality of data lines, a display element driven by using the scanning lines and the data lines, and a drive for supplying a scanning signal and a data signal to the scanning lines and the data lines A display device, comprising: a circuit; and a driving power supply circuit that generates a pulse signal based on at least one of the scanning signal and the data signal by charging and discharging a first capacitor. A display device, comprising: a second capacitor provided as a first capacitor, wherein the second capacitor is discharged when the first capacitor is charged, and is charged when the first capacitor is discharged. 2. A dummy load whose impedance has been adjusted such that the load for the second capacitor is substantially equal to the load impedance for the first capacitor, 2. The display device according to claim 1, wherein the second capacitor generates an oscillating sound having substantially the same amplitude when charging and discharging the second capacitor. 3. A load for the second capacitor is a second display element separate from a display element driven by a signal based on a pulse generated by charging and discharging the first capacitor; The display device according to claim 1, wherein the second display element is driven by a signal based on a pulse generated by charging and discharging the second capacitor. 4. The display according to claim 1, wherein the load on the second capacitor is a display element driven by a signal based on a pulse generated by charging / discharging the first capacitor. apparatus. 5. The MIM-LCD panel, wherein the display element is a MIM-LCD panel, and a signal based on a pulse generated by charging and discharging the first capacitor is a scanning signal for the MIM-LCD panel. Claims 1, 2,
The display device according to 3 or 4. 6. The display device according to claim 1, wherein the containers are joined so that the first capacitor and the second capacitor are integrated. 7. A plurality of scanning line electrodes and data line electrodes,
In order to drive a display panel including a plurality of display elements connected thereto, a pulse signal serving as a basis of at least one of signals supplied to the scanning line and the data line is charged to a first capacitor. In a drive power supply circuit for a display device generated by discharging, a second capacitor provided close to the first capacitor is provided, and the second capacitor is discharged when the first capacitor is charged. And a power supply circuit for driving the display device, which is charged when discharged. 8. A load having an impedance substantially equal to a load impedance for the first capacitor is connected to the second capacitor, wherein the first capacitor and the second capacitor are connected to the first capacitor and the second capacitor. 8. The driving power supply circuit for a display device according to claim 7, wherein an oscillation sound having substantially the same amplitude is generated at the time of discharging. 9. A plurality of scanning lines, a plurality of data lines, a display element driven by using the scanning lines and the data lines, and a drive for supplying a scanning signal and a data signal to the scanning lines and the data lines. Circuit, a driving power supply circuit for generating a pulse signal as a basis of at least one of the scanning signal and the data signal by charging and discharging a first capacitor, and a display information output for supplying a video signal to the driving circuit An electronic device including a source and a clock generation circuit that supplies a clock signal to the drive circuit, comprising: a second capacitor provided in close proximity to the first capacitor, wherein the second capacitor is An electronic device, wherein the capacitor is discharged when the capacitor is charged, and is charged when the capacitor is discharged. 10. A load having an impedance substantially equal to a load impedance for the first capacitor is connected to the second capacitor, and wherein the first and second capacitors are connected to each other. 10. The electronic device according to claim 9, wherein an oscillation sound having substantially the same amplitude is generated at the time of discharging.