JP2006171301A - Display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display apparatus capable of sufficiently reducing power consumption, without generating deterioration in the image quality, when a normal operation state is changed to a stand-by mode state. <P>SOLUTION: When it is decided that shift has been made to the stand-by state, based on a stand-by mode signal STB indicating the normal operation state or the stand-by state, the operation of an internal clock and a counter in a timing generation circuit 4 is stopped, and the inversion timing of AC signals (WR, Vcom, HLD) to be applied to a liquid crystal cell 31 is delayed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a display device having a display unit in which pixels are arranged in a matrix, and in particular, a peripheral drive circuit for driving the display unit is integrally mounted on the same transparent insulating substrate as the display unit. The present invention relates to a drive circuit integrated display device.

In the field of flat panel display devices typified by liquid crystal display devices and EL (electroluminescence) display devices, in recent years, the same as a display unit in which pixels are arranged in a matrix in order to narrow the panel and thin the panel. Development of a so-called drive circuit integrated display device in which peripheral drive circuits for driving the display unit are integrally mounted on a transparent insulating substrate is underway.
In liquid crystal display devices and EL display devices, TFTs are used as pixel transistors. Therefore, when a drive circuit is mounted on a transparent insulating substrate, the drive circuit is also formed using TFTs.

  In such a drive circuit integrated display device, a timing generation circuit that generates various timing signals for operating the drive circuit has a large variation in element characteristics on an insulating substrate such as a glass substrate and a high threshold Vth. In the case of forming with a transistor, for example, a thin film transistor (TFT), there is a concern that the operation margin of the counter in the timing generation circuit is lost when the frequency of the master clock supplied to the timing generation circuit is high. Further, when the counter is operated at a high frequency, the power consumed by the timing generation circuit increases.

  Therefore, for example, in Patent Document 1 below, the timing generation circuit generates an operation clock having a frequency slower than the master clock, and generates a plurality of timing signals based on the generated operation clock having a slower frequency. Techniques relating to a timing generation circuit and a display device that enable stable operation because the operation speed is low and reduce power consumption are disclosed.

JP 2003-345457 A

  By the way, the conventional display device has a function of switching between the normal operation mode and the standby mode (standby mode) in accordance with the switching between the normal power consumption state and the low power consumption state of the electronic device body on which the display device is mounted. There is something that is. In the standby mode, since the display on the display is suppressed to the minimum necessary while the supply of the power supply voltage is received from the electronic device main body side, the power consumption of the display device can be reduced.

However, in the conventional standby mode, since there is insufficient means for suppressing power consumption on the display device side, a sufficient power saving effect has not been obtained in the standby mode, which is a problem to be solved.
Hereinafter, this problem will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, but the basic configuration is the same as that of a conventional display device. That is, as shown in FIG. 1, also in the conventional display device, pixels are arranged in a matrix in the display unit, and each row of the display unit is sequentially selected by the pixel switch pulse PSW, and each column of the selected row is displayed. The pixel write signal WR is given to the pixel.

FIG. 9 is a timing chart showing the operation when the conventional display device changes from the normal operation mode to the standby mode, where (a) is a standby mode signal STB, (b) is a counter operation in the timing generation circuit, (C) is a horizontal synchronization signal Hsync, (d) is a write enable signal WEN, (e) to (h) are vertical shift pulses VSP of each row of the display portion, and (i) to (l) are pixels of each row of the display portion. The switch pulse PSW, (m) indicates the pixel write signal WR, and (n) indicates the counter potential Vcom (common potential).
10A and 10B are diagrams for explaining image quality deterioration in a conventional display device, where FIG. 10A shows a pixel switch signal PSW, and FIG. 10B shows a pixel write signal WR.

  The timing chart shown in FIG. 9 is an example when the display device is driven by 1H inversion (H is a horizontal period), and as shown in FIGS. 9 (m) and 9 (n), the pixels corresponding to the pixels in the display panel are shown. AC driving is performed in which the writing signal WR and the counter potential Vcom serving as the reference potential for writing are inverted every 1H. Then, as shown in FIGS. 9 (i) to (l), the pixel switch signal PSW becomes high level on condition that both the write enable signal WEN and the vertical shift pulse VSP are high level, and the display section A pixel write signal WR is given to the pixels in each column. Thus, writing to the display portion is performed in a stable period in which the pixel writing signal WR and the counter potential Vcom are not inverted.

However, when the counter in the timing generation circuit is stopped after changing from the normal operation mode to the standby mode at time t1 (time t2), the timing generation circuit cannot generate the write enable signal WEN thereafter. As shown in 9 (l) to (n), the timing of the level change of the pixel switch signal PSW and the timing of inversion of the pixel write signal WR and the counter potential Vcom overlap.
As a result, as shown in FIG. 10, the pixel takes in the potential during which the pixel write signal WR and the counter potential Vcom are inverted, and the pixel potential is determined at an unexpected potential, so that the image quality deteriorates.

  Therefore, in the conventional display device, the counter in the timing generation circuit cannot be stopped even in the case of changing from the normal operation mode to the standby mode so as not to deteriorate the image quality. The power consumption could not be reduced sufficiently.

  The present invention has been made in view of the above-described viewpoints, and an object of the present invention is to prevent image quality deterioration and sufficiently reduce power consumption when changing from a normal operation state to a standby mode state. An object of the present invention is to provide such a display device.

  In order to overcome the above-described problems, the present invention provides a display unit in which pixels are arranged in a matrix, and a vertical drive unit that generates vertical shift pulses that are sequentially transferred to each row of the display unit every horizontal period. The polarity is inverted every horizontal period with the first signal generation unit that generates a write permission signal for permitting writing to the pixels of each column of the display unit for the row specified by the vertical drive unit. A second signal generation unit that generates a write signal and a common potential; a horizontal drive unit that applies the write signal and the common potential to a pixel at a timing synchronized with the write enable signal; and a display target of the display region of the display unit An inversion delay unit that delays the inversion timing of the write signal and the common potential on the condition that the transition to the non-display area is performed

  Preferably, the first signal generation unit includes a counter for counting a reference clock, and delays the inversion timing when the writing target shifts from a display area of the display unit to a non-display area. Later, the counter is stopped.

  Specifically, a standby mode signal indicating whether or not a writing target is a display area of the display unit is given, and the inversion delay unit determines whether or not to delay the inversion timing based on the standby mode signal. Determine whether.

  Specifically, the inversion delay unit generates a first inversion signal in synchronization with a horizontal synchronization signal, and selects either the first inversion signal or a second inversion signal obtained by delaying the first inversion signal. The second signal generator is selectively supplied to the second signal generator based on the standby mode signal, and the second signal generator inverts the write signal and the common potential in synchronization with the inverted signal supplied from the inversion delay unit. .

The operation of the present invention is as follows.
That is, the vertical drive unit generates a vertical shift pulse that is sequentially transferred to each row of the display unit for each horizontal period, and the first signal generation unit displays the row specified by the vertical shift pulse. A write permission signal for permitting writing to pixels in each column of the section is generated. The second signal generation unit generates a write signal and a common potential whose polarity is inverted every horizontal period. Then, the horizontal drive unit provides the pixel with the write signal generated by the second signal generation unit and the common potential at a timing synchronized with the write permission signal.

At this time, the inversion delay unit delays the inversion timing of the write signal and the reference potential on the condition that the writing target has shifted from the display area of the display unit to the non-display area.
Preferably, the first signal generation unit includes a counter for counting a reference clock, and stops the counter after delaying the inversion timing.

  According to the present invention, when the normal operation state is changed to the standby mode state, the image quality is not deteriorated and the power consumption can be sufficiently reduced.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The display unit 3 is an embodiment of the display unit of the present invention.
The timing generation circuit 4 is an embodiment of the first signal generation unit, inversion delay unit, and delay means of the present invention.
The vertical drive circuit 5 is an embodiment of the vertical drive unit and row selection means of the present invention.
The reference signal generation circuit 6 and the counter / holding signal generation circuit 8 are an embodiment of the second signal generation unit and signal inversion means of the present invention.
The horizontal drive circuit 7 is an embodiment of the horizontal drive unit and writing means of the present invention.

  FIG. 1 is a block diagram showing a configuration example of a display device according to the present invention, for example, a liquid crystal display device 1. In FIG. 1, a display unit 3 in which pixels are arranged in a matrix is formed on a transparent insulating substrate such as a glass substrate. Such a glass substrate is disposed opposite to another glass substrate with a predetermined gap, and a liquid crystal material is sealed between the two substrates to constitute a display panel (LCD panel).

  In the display unit 3, each of the pixels arranged in a matrix includes a TFT (Thin Film Transistor) 32 that is a pixel transistor, a liquid crystal cell 31 in which a pixel electrode is connected to a drain electrode of the TFT 32, and a TFT 32. The storage capacitor 33 has one electrode connected to the drain electrode. Here, the liquid crystal cell 31 means a liquid crystal capacitance generated between a pixel electrode and a counter electrode formed opposite to the pixel electrode.

  In this pixel structure, the TFT 32 has a gate electrode connected to a gate line (scanning line) 34 and a source electrode connected to a data line (signal line) 35. A counter electrode of the liquid crystal cell 31 is applied to the Vcom line 36 in common to each pixel. A counter potential Vcom (common potential) is applied to the common electrode of the liquid crystal cell 31 via the Vcom line 36. In the holding capacitor 33, the other electrode (terminal on the counter electrode side) is connected to the holding signal line 37 in common for each pixel, and the holding signal HLD is applied.

Here, the liquid crystal cell 31 is generally AC driven. That is, the polarity of the pixel write signal WR written to the liquid crystal cell 31 via the data line 35 is periodically inverted. In accordance with this, the polarity of the counter potential Vcom of the liquid crystal cell 31 also needs to be periodically inverted. Here, the liquid crystal cell 31 and the TFT 32 that performs switching driving thereof have asymmetry with respect to polarity. For this reason, if the center level is matched between the pixel electrode side and the counter electrode side, an asymmetry related to the polarity appears, and image quality degradation such as image sticking occurs. As a countermeasure, the counter potential Vcom is offset by a predetermined voltage with respect to the pixel write signal WR to cancel the asymmetry regarding the polarity.
The storage capacitor 33 also needs to be AC-operated in accordance with the AC driving of the liquid crystal cell 31. For this reason, similarly, it is necessary to apply the holding signal HLD whose polarity is inverted at a predetermined cycle to the holding signal line 37 commonly connected to the holding capacitors 33.

  In FIG. 1, on the same glass substrate as the display unit 3, for example, an interface (I / F) circuit 2 and an opposing / holding signal generation circuit 8 are provided above the display unit 3, and a timing generation circuit is provided on the left side of the display unit 3. 4 and the reference signal generation circuit 6 are mounted with a horizontal drive circuit 7 on the lower side of the display unit 3 and a vertical drive circuit 5 on the right side of the display unit 3, respectively. These peripheral drive circuits are manufactured using low-temperature polysilicon or CG (Continuous Grain) crystal together with the pixel transistors of the display unit 3.

The interface circuit 2 starts from the electronic device main body (referred to as a set) on which the liquid crystal display device 1 is mounted, from the master clock MCK, parallel input display data, synchronization signals (horizontal synchronization signal Hsync, vertical synchronization signal Vsync), standby mode A signal STB is input.
The standby mode signal STB is “1” (high level) when a normal display operation state is requested, and “0” (low level) when a standby state is requested from the set side. Is a signal.

FIG. 2 is a diagram illustrating the display state of the display unit 3 in the normal operation state and the standby state.
As shown in FIG. 2, in the standby state, a non-display area of black (FIG. 2A) or white (FIG. 2B) is displayed according to the characteristics of the display unit 3.

Returning to the description of FIG.
The timing generation circuit 4 is necessary for driving the vertical drive circuit 5, the reference signal generation circuit 6, the horizontal drive circuit 7, and the opposing / holding signal generation circuit 8 based on the master clock MCK, the synchronization signal, and the standby mode signal STB. Various timing signals are generated.
The configuration of the timing generation circuit 4 will be described later.

The reference signal generation circuit 6 selects an analog potential corresponding to the bit of display data and supplies it to the horizontal drive circuit 7. For example, when the display data is 6 bits and 64 gradations, an analog potential REF of 64 gradations that is a reference potential generated by dividing the power supply voltage by a ladder resistor is supplied to the horizontal drive circuit 7.
At this time, since the pixel writing signal WR is AC driven, it is necessary to invert the polarity of the analog potential generated by the reference signal generation circuit 6 in a predetermined cycle (for example, 1H). Then, the reference signal generation circuit 6 inverts the polarity of the analog potential in synchronization with the inversion signal REV given from the timing generation circuit 4.

The horizontal drive circuit 7 includes, for example, a horizontal shift register (not shown), a data sampling latch circuit, and a DA (digital-analog) conversion circuit.
The horizontal shift register starts a shift operation in response to the horizontal start pulse HST supplied from the timing generation circuit 4, and sequentially transfers in one horizontal period in synchronization with the horizontal clock pulse HCK supplied from the timing generation circuit 4 as well. A sampling pulse is generated.
The data sampling latch circuit sequentially samples and latches display data supplied from the interface circuit 2 in one horizontal period in synchronization with the sampling pulse generated by the horizontal shift register. The latched digital data for one line is converted into an analog display signal by a DA conversion circuit.
The DA conversion circuit selects a reference voltage corresponding to digital data from the reference voltages REF corresponding to the number of gradations supplied from the reference signal generation circuit 6, and outputs a pixel write signal WR as an analog display signal.

The vertical drive circuit 5 includes a vertical shift register and a gate buffer (not shown).
The vertical shift register starts a shift operation in response to the vertical start pulse VST supplied from the timing generation circuit 4 and sequentially transfers in one vertical period in synchronization with the vertical clock pulse VCK supplied from the timing generation circuit 4. The vertical shift pulse VSP is generated.
The vertical drive circuit 5 is supplied with a write enable signal WEN having a pulse width shorter than that of the vertical shift pulse VSP from the timing generation circuit 4. Then, the vertical drive circuit 5 generates the pixel switch signal PSW at the timing when the sequentially transferred vertical shift pulse VSP and the write enable signal WEN are both at a high level.
The generated pixel switch signal PSW is sequentially output through the gate buffer to the gate line wired in each row of the display unit 32.

  When the pixel switch signal PSW is sequentially output to the gate lines of each row by the vertical scanning by the vertical drive circuit 5, each pixel of the display unit 3 is sequentially selected in units of rows. Then, the pixel write signal WR for one line output from the DA conversion circuit of the horizontal drive circuit 7 is written simultaneously to the selected pixels for one line via the data line 35. By repeating the writing operation in units of lines, an image for one screen is displayed.

The counter / holding signal generation circuit 8 generates the above-described holding signal HLD and supplies it to the other electrode of the holding capacitor 33 via the holding signal line 37 in common to each pixel.
Here, for example, when 1H inversion driving is employed, the holding signal HLD repeats AC inversion in which the polarity is inverted every 1H in accordance with the pixel write signal WR.

The counter / hold signal generation circuit 8 generates the counter potential Vcom described above. The counter potential Vcom is commonly applied to the Vcom line 36 connected to the counter electrode of the pixel 33 via the counter connection electrode 9.
Here, an alternating voltage having substantially the same amplitude as the holding signal HLD is used as the counter potential Vcom. However, in actuality, in FIG. 1, when a signal is written from the data line 35 to the pixel electrode of the liquid crystal cell 31 through the TFT 32, a voltage drop occurs in the TFT 32 due to a parasitic capacitance or the like. It is necessary to use an AC voltage that is DC-shifted by the voltage drop.

  The counter / holding signal generation circuit 8 is supplied with the inversion signal REV from the timing generation circuit 4 and inverts the holding signal HLD and the counter potential Vcom in synchronization with the inversion signal REV.

  In the liquid crystal display device 1 having the above-described configuration, the interface circuit 2, the timing generation circuit 4, and the reference signal generation circuit are provided on the same panel (glass substrate) as the display unit 3 in addition to the horizontal drive circuit 7 and the vertical drive circuit 5. 6. Peripheral drive circuits such as the opposing / holding signal generation circuit 8 are integrally mounted, so that a display panel integrated with all drive circuits can be configured, and it is necessary to provide a separate substrate, IC, and transistor circuit outside. Therefore, the entire system can be reduced in size and cost.

Next, the configuration of the timing generation circuit 4 will be described with reference to FIG.
FIG. 3 is a block diagram illustrating a configuration example of the timing generation circuit 4.

  As shown in FIG. 3, the timing generation circuit 4 includes an internal clock generation circuit 41, a counter (CTR) 42, a horizontal drive signal generation circuit 43, a vertical drive signal generation circuit 44, and an inversion timing adjustment circuit 45.

  The internal clock generation circuit 41 divides the master clock MCK to generate an internal clock signal having a frequency lower than that of the master clock MCK. The internal clock signal includes a horizontal internal clock signal (horizontal clock) S41_H and a vertical internal clock signal (vertical clock) S41_V. This internal clock signal becomes a base signal for operating the counter 42.

The horizontal drive signal generation circuit 43 and the vertical drive signal generation circuit 44 operate the counter 42 to generate various signals necessary for driving.
The horizontal drive signal generation circuit 43 generates a horizontal clock pulse HCK, a horizontal start pulse HST, and a write enable signal WEN.
The vertical drive signal generation circuit 44 generates a vertical clock pulse VCK and a vertical start pulse VST.

  The vertical drive signal generation circuit 44 can generate the vertical clock pulse VCK and the vertical start pulse VST without using the counter 42 based on the vertical clock signal S41_V.

The inversion timing adjustment circuit 45 operates the counter 42 to generate the inversion signal REV to be supplied to the reference signal generation circuit 6 and the counter / holding signal generation circuit 8. For example, in the case of 1H inversion driving, the inversion signal REV is a signal that is inverted every horizontal period.
Further, the inversion timing adjusting circuit 45 determines whether or not to delay the inversion timing of the inversion signal REV based on the standby mode signal STB. As a result, as described later, even when the normal operation mode is changed to the standby mode, the pixel potential is prevented from being determined to an unexpected value at the timing of polarity switching due to inversion.

Further, when the timing generation circuit 4 determines that the normal operation mode has changed to the standby mode, the horizontal clock generation unit of the internal clock generation circuit 41 and the counter 42 are stopped after a certain period of time has elapsed. Thereby, power consumption is reduced.
The predetermined period is set according to the delay amount of the inversion timing adjustment circuit 45 described later.

FIG. 4 is a diagram illustrating a circuit configuration example of a portion that delays the inverted signal REV in the inversion timing adjusting circuit 45.
In FIG. 4, an inversion signal P_REV is an inversion signal corresponding to the normal operation mode. For example, in the case of 1H inversion driving, the inversion signal P_REV is an inversion signal every horizontal period.
The inversion timing adjustment circuit 45 includes a delay circuit 451, a switch 452, and a buffer 453. Delay circuit 451 includes a gate circuit formed of TFTs and a differential circuit formed of a resistor and a capacitor. Needless to say, the delay amount can be appropriately set according to the number of stages of the gate circuit and the characteristics of the resistor and the capacitor.

In the circuit shown in FIG. 4, the switch 452 selects either the contact C1 or C2 according to the level of the standby mode signal STB.
When the standby mode signal STB is “1”, that is, in the normal operation mode, the contact C1 is selected. Thereby, the inverted signal P_REV is output as it is as the inverted signal REV.
Further, when the standby mode signal STB is “0”, that is, in the standby mode, the contact C2 is selected. As a result, the inverted signal P_REV is delayed by a predetermined time by the delay circuit 451 and output as the inverted signal REV.

Note that the method of delaying the inverted signal P_REV is not limited to the circuit diagram shown in FIG.
FIG. 5 is a diagram illustrating another circuit configuration example of the part of the inversion timing adjustment circuit 45 that delays the inversion signal REV.
5A shows a circuit in which the delay circuit 451 is constituted by a gate circuit and a capacitor, FIG. 5B shows a circuit in which the delay circuit 451 is constituted by a gate circuit and a resistor, and FIG. 5B shows a delay. A circuit in which the circuit 451 is configured by only a gate circuit is shown.
In either case, the inversion signal P_REV can be delayed.

  Next, the display operation of the liquid crystal display device 1 will be described.

  FIG. 6 is a timing chart showing the operation in the normal operation mode in the liquid crystal display device 1 according to the embodiment, where (a) is a standby mode signal STB, (b) is a counter operation in the timing generation circuit, and (c) ) Is a horizontal synchronization signal Hsync, (d) is a write enable signal WEN, (e) to (h) are vertical shift pulses VSP of each row of the display section, and (i) to (l) are pixel switch pulses of each row of the display section. PSW, (m) indicates the inverted signal REV, (n) indicates the pixel write signal WR, and (o) indicates the counter potential Vcom and the holding signal HLD.

  Since the operation shown in FIG. 6 is always a normal operation, the counter CTR is always active as shown in FIG. 6B.

As shown in FIG. 6D, the write enable signal WEN is generated by the timing generation circuit 4 at a timing corresponding to the horizontal synchronization signal Hsync and supplied to the vertical drive circuit 5.
The vertical drive circuit 5 starts a shift operation in response to the vertical start pulse VST supplied from the timing generation circuit 4, and is also supplied from the timing generation circuit 4 as shown in FIGS. 6 (e) to 6 (h). A vertical shift pulse VSP that is sequentially transferred in one vertical period is generated in synchronization with the vertical clock pulse VCK.

Further, as shown in FIGS. 6I to 6L, the vertical drive circuit 5 sets the high level on condition that both the sequentially transferred vertical shift pulse VSP and the write enable signal WEN are high level. A pixel switch signal PSW is generated. That is, the pixel switch signal PSW is a logical sum of the vertical shift pulse VSP and the write enable signal WEN.
The generated pixel switch signal PSW is sequentially output to the gate line 34 wired in each row of the display unit 32.

  When the pixel switch signal PSW is sequentially output to the gate lines of each row by the vertical scanning by the vertical drive circuit 5, each pixel of the display unit 3 is sequentially selected in units of rows. Then, the pixel write signal WR for one line output from the DA conversion circuit of the horizontal drive circuit 7 is written simultaneously to the selected pixels for one line via the data line 35.

As shown in FIGS. 6 (m) to (o), the pixel write signal WR is a period in which the inversion signals REV, the pixel write signal WR, the counter potential Vcom, and the holding signal HLD are not inverted. And applied to the pixel.
That is, as shown in FIG. 6, since the pulse width of the write enable signal WEN is set to be narrower than the pulse width of the vertical shift pulse VSP, the pulse width of the pixel switch signal PSW that is the logical sum of these is set. However, since it becomes narrow like the write enable signal WEN, a state in which the pixel potential is fixed at an unstable timing at which the pixel write signal WR is inverted is avoided.

  FIG. 7 is a timing chart showing the operation when the liquid crystal display device 1 according to the embodiment changes from the normal operation mode to the standby mode, where (a) is a standby mode signal STB, and (b) is in the timing generation circuit. (C) is a horizontal synchronization signal Hsync, (d) is a write enable signal WEN, (e) to (h) are vertical shift pulses VSP of each row of the display unit, and (i) to (l) are display units. The pixel switch pulse PSW of each row of (1), (m) indicates the inverted signal REV, (n) indicates the pixel write signal WR, and (o) indicates the counter potential Vcom and the holding signal HLD.

In FIG. 7, at time t1, the level of the standby mode signal STB changes and changes from the display area to the non-display area. In this case, the timing generation circuit 4 stops the horizontal clock generation unit and the counter 42 of the internal clock generation circuit 41 at time t2 in order to reduce power consumption.
The reason why the generation of the horizontal clock and the counter operation are not stopped at the time t1 is because the delay of the inversion timing in the inversion timing adjustment circuit 45 is taken into consideration.

  As a result, the timing generation circuit 4 cannot generate the write enable signal WEN after time t2. Therefore, as shown in FIGS. 7H and 7L, the pixel switch signal PSW that is the logical sum of the vertical shift pulse VSP and the write enable signal WEN is the same pulse as the vertical shift pulse VSP.

When the level of the standby mode signal STB changes from “1” to “0”, the timing generation circuit 4 delays and outputs the inverted signal REV.
Thereby, the reference signal generation circuit 6 delays the reference signal REF and supplies it to the horizontal drive circuit 7, and the counter / holding signal generation circuit 8 delays the holding signal HLD and the counter potential Vcom to display the display unit 3. Therefore, as shown in FIGS. 7 (m) to (o), the inversion timing of AC driving of each signal is delayed.
As a result, a state where the timing of the level change of the pixel switch signal PSW and the inversion timing of the pixel write signal WR do not overlap and the pixel potential is determined to an unexpected value is avoided. Therefore, the state of image quality is maintained.

  FIG. 8 is a timing chart showing the operation state of each part when the liquid crystal display device 1 according to the embodiment is changed from the normal operation mode to the standby mode, where (a) is a standby mode signal STB and (b) is a master. Clock MCK, (c) horizontal synchronization signal Hsync, (d) horizontal internal clock S41_H, (e) counter (CTR) 42, (f) output of horizontal drive signal generation circuit 43, (g) vertical drive. This is the state of the output of the signal generation circuit 44.

As shown in FIG. 8, in the timing generation circuit 4, after the level of the standby mode signal STB changes, the internal clock generation circuit 41 stops the horizontal clock and the counter 42 stops. As a result, the output of the horizontal drive signal generation circuit 43 stops.
Therefore, many processes among the processes performed in the timing generation circuit 4 are stopped, so that the power consumption in the timing generation circuit 4 is reduced.

As described above, according to the liquid crystal display device 1 according to the present embodiment, when it is determined that the state has shifted to the standby state based on the standby mode signal indicating whether it is the normal operation state or the standby state. Since the operation of the internal clock and counter of the timing generation circuit 4 is stopped and the inversion timing of the AC signal applied to the liquid crystal cell is delayed, the following effects can be obtained.
That is, as a result of stopping the operation of the internal clock and counter of the timing generation circuit 4, the power consumed by the timing generation circuit 4 is reduced. Therefore, in particular, when the liquid crystal display device 1 is driven by a battery power source, it can be used for a long time.
In addition, when the internal clock and the counter are stopped, the write enable signal WEN for determining the write timing for the pixel is not output, and the write timing is defined by the vertical shift pulse VSP. By delaying the inversion timing, it is possible to prevent the pixel potential from being determined to an unexpected value and maintain the image quality.

The present invention is not limited to the above-described embodiments, and various modifications can be made without changing the gist of the present invention.
For example, in the above-described embodiment, the liquid crystal display device in which the display unit is integrally mounted with the drive circuit on an insulating substrate such as low-temperature polysilicon has been described. However, the present invention is not limited to this. The timing generation circuit, the counter / holding signal generation circuit, and the reference signal generation circuit may be configured by a silicon semiconductor circuit mounted on an insulating substrate, or may be configured by a silicon semiconductor circuit on a flexible substrate connected to the insulating substrate. May be.

It is a block diagram which shows the structural example of the display apparatus which concerns on this invention, for example, a liquid crystal display device. It is the figure which illustrated the display state of the display part in a normal operation state and a standby state. 3 is a block diagram illustrating a configuration example of a timing generation circuit 4. FIG. FIG. 5 is a diagram illustrating a circuit configuration example of a portion that delays an inverted signal REV in an inversion timing adjustment circuit. FIG. 11 is a diagram illustrating another circuit configuration example of a portion that delays an inversion signal REV in an inversion timing adjustment circuit. 5 is a timing chart illustrating an operation in a normal operation mode in the display device according to the embodiment. 5 is a timing chart illustrating an operation when the display device according to the embodiment is changed from a normal operation mode to a standby mode. 6 is a timing chart illustrating an operation state of each unit when the normal operation mode is changed to the standby mode in the display device according to the embodiment. It is a timing chart which shows operation | movement at the time of changing from normal operation mode to standby mode in the conventional display apparatus. It is a figure for demonstrating image quality degradation in the conventional display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Interface circuit, 3 ... Display part, 4 ... Timing generation circuit, 5 ... Vertical drive circuit, 6 ... Reference signal generation circuit, 7 ... Horizontal drive circuit, 8 ... Opposition / holding signal generation circuit, 9: Counter connection electrode.

Claims (6)

A display unit in which pixels are arranged in a matrix;
A vertical driving unit that generates vertical shift pulses that are sequentially transferred for each horizontal period for each row of the display unit;
A first signal generation unit that generates a write permission signal for permitting writing to pixels in each column of the display unit for the row designated by the vertical drive unit;
A write signal whose polarity is inverted every horizontal period and a second signal generation unit that generates a common potential;
A horizontal drive unit for applying the write signal and the common potential to a pixel at a timing synchronized with the write permission signal;
An inversion delay unit that delays the inversion timing of the write signal and the common potential on the condition that the writing target has shifted from the display region of the display unit to the non-display region;
A display device comprising: The first signal generator includes a counter for counting a reference clock,
The display device according to claim 1, wherein when the writing target is shifted from a display area of the display unit to a non-display area, the counter is stopped after delaying the inversion timing. A standby mode signal indicating whether the writing target is a display area of the display unit is given,
The display device according to claim 1, wherein the inversion delay unit determines whether to delay the inversion timing based on the standby mode signal. The inversion delay unit generates a first inversion signal in synchronization with a horizontal synchronization signal, and uses either the first inversion signal or a second inversion signal obtained by delaying the first inversion signal as the standby mode signal. Is selectively given to the second signal generator based on
The display device according to claim 3, wherein the second signal generation unit inverts the write signal and the common potential in synchronization with an inversion signal given from an inversion delay unit. The display device according to claim 4, wherein the inversion delay unit includes a delay element including a plurality of gate circuits. A display device having a display unit in which pixels are arranged in a matrix,
Row selection means for sequentially selecting each row of the display unit for each horizontal period;
Signal inversion means for alternating current inversion of the write signal every horizontal period;
Writing means for supplying a write signal that is AC inverted within a horizontal period to each pixel in the row selected by the row selection means;
A delay that delays the writing period so that the writing period of the writing unit and the period during which the writing signal is inverted do not overlap on the condition that the writing target has shifted from the display area of the display unit to the non-display area. Means,
A display device comprising:

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