WO2011033813A1 - 表示装置および表示装置の駆動方法 - Google Patents
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- WO2011033813A1 WO2011033813A1 PCT/JP2010/057286 JP2010057286W WO2011033813A1 WO 2011033813 A1 WO2011033813 A1 WO 2011033813A1 JP 2010057286 W JP2010057286 W JP 2010057286W WO 2011033813 A1 WO2011033813 A1 WO 2011033813A1
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3648—Control of matrices with row and column drivers using an active matrix
- G09G3/3659—Control of matrices with row and column drivers using an active matrix the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes
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- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3607—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels
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- G09G2300/00—Aspects of the constitution of display devices
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- G09G2300/0861—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
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- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
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- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
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- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3648—Control of matrices with row and column drivers using an active matrix
- G09G3/3655—Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
Definitions
- the present invention relates to a display device having a memory function and a driving method thereof, and particularly to a technique for eliminating screen noise caused by the existence of a plurality of driving methods according to a display form.
- liquid crystal display devices include a memory type liquid crystal display device that includes a pixel with a built-in memory (hereinafter referred to as a pixel memory) and has a memory function capable of holding image data.
- image data once written in a pixel can be held by refreshing while inverting the polarity, and a still image can be displayed.
- the pixel In the normal operation (normal mode) not using the memory function, the pixel is rewritten to new image data every frame through the data signal line, while in the memory operation (memory mode) using the memory function, the image data is retained. It is not necessary to supply rewrite image data to the data signal line.
- the operation of the circuit that drives the scanning signal line and the data signal line can be stopped, and the power consumption can be reduced. Furthermore, it is possible to reduce the power consumption by reducing the number of times of charging / discharging the data signal line having a large capacity and not transmitting the image data corresponding to the memory operation period to the controller.
- the memory-type liquid crystal display device is often used for a liquid crystal display device that displays an image that is strongly demanded to reduce power consumption, such as a standby screen of a mobile phone.
- FIG. 11 is a diagram showing only the circuit configuration of the pixel memory (memory circuit MR100) extracted from the memory type liquid crystal display device.
- the memory circuit MR100 is equivalent to that disclosed in Patent Document 1, for example.
- the memory circuit MR100 includes a switch circuit SW100, a first data holding unit DS101, a data transfer unit TS100, a second data holding unit DS102, and a refresh output control unit RS100.
- data transfer control lines DTx, gate lines GLx, and high power supply lines are provided for each row of the pixel matrix as wirings for driving the memory circuits MR100.
- PHx, Low power supply line PLx, refresh output control line RCx, and auxiliary capacitance line CSx are provided, and a source line SLx is provided for each column of the pixel matrix.
- the switch circuit SW100 includes a transistor N100 that is an N-channel TFT (Thin Film Transistor).
- the first data holding unit DS101 includes a capacitor Ca100.
- the data transfer unit TS100 includes a transistor N101 that is an N-channel TFT.
- the second data holding unit DS102 includes a capacitor Cb100.
- the refresh output control unit RS100 includes an inverter INV100 and a transistor N103 which is an N-channel TFT.
- the inverter INV100 includes a transistor P100 that is a P-channel TFT and a transistor N102 that is an N-channel TFT.
- drain / source terminal of a field effect transistor such as the above TFT is referred to as a first drain / source terminal, and the other drain / source terminal is referred to as a second drain / source terminal.
- the drain terminal and the source terminal are fixedly determined based on the direction in which the current can flow between the first drain / source terminal and the second drain / source terminal, respectively, the drain terminal and the source It shall be called a terminal.
- the transistor N100 has a gate terminal connected to the gate line GLx, a first drain / source terminal connected to the source line SLx, and a second drain / source terminal connected to the node PIX which is one end of the capacitor Ca100.
- the other end of the capacitor Ca100 is connected to the auxiliary capacitor line CSx.
- the transistor N101 has a gate terminal connected to the data transfer control line DTx, a first drain / source terminal connected to the node PIX, and a second drain / source terminal connected to the node MRY which is one end of the capacitor Cb100.
- the other end of the capacitor Cb100 is connected to the storage capacitor line CSx.
- the input terminal IP of the inverter INV100 is connected to the node MRY.
- the transistor P100 has a gate terminal connected to the input terminal IP of the inverter INV100, a source terminal connected to the high power line PHx, and a drain terminal connected to the output terminal OP of the inverter INV100.
- the transistor N102 has a gate terminal connected to the input terminal IP of the inverter INV100, a drain terminal connected to the output terminal OP of the inverter INV100, and a source terminal connected to the low power supply line PLx.
- Transistor N103 has a gate terminal connected to refresh output control line RCx, a first drain / source terminal connected to output terminal OP of inverter INV100, and a second drain / source terminal connected to node PIX.
- a counter substrate (not shown) including a common electrode (counter electrode) COM is provided at a position facing the substrate on which the memory circuit MR100 is formed.
- the substrate and the counter substrate are disposed so as to sandwich liquid crystal therebetween, and a liquid crystal panel is formed including these configurations.
- a node PIX (pixel electrode) of the memory circuit MR100 forms a liquid crystal capacitance Clc via a liquid crystal between the node PIX (pixel electrode) and the common electrode COM.
- FIG. 12 is a timing chart showing various signal waveforms in the memory mode in the memory circuit MR100.
- the data transfer control line DTx, the gate line GLx, and the refresh output control line RCx are supplied from a drive circuit (not shown) to a binary level potential consisting of High (active level) and Low (inactive level). Is applied.
- the high and low potential levels may be individually set for the lines and lines.
- a binary level data signal (also referred to as “binary data”) including a high potential and a low potential is output to the source line SLx from a drive circuit (not shown).
- the potential supplied by the high power line PHx is equal to the high level of the binary level data signal
- the potential supplied by the low level power line PLx is equal to the low level of the binary level data signal.
- the potential supplied from the storage capacitor line CSx may be constant or may change at a predetermined timing, but here it is assumed to be constant for the sake of simplicity.
- a full writing period T101 and a refresh period T102 are provided.
- the entire writing period T101 is a period in which data to be held in all the memory circuits MR100 is written for each row, and is composed of a period t101 and a period t102 that are successively arranged.
- writing to the memory circuit MR100 is performed line-sequentially, so that the period t101 is provided so that different rows do not overlap. Therefore, the start timing of the period t101 is different for each row. Further, the end timing of the period t102, that is, the end timing of the entire writing period T101 is the same for all the rows.
- the scanning completion timing (period t101) of the gate line GL is shifted in order so that the timing of data writing completion to the memory circuit MR100 for each row is different.
- the timing for scanning the gate line GL may be simultaneous in different rows. For example, a method of scanning the gate line GL for every two rows skipped may be used. In this method, the scanning timing may be overlapped for each row, but the scanning timing for completing the data writing is different.
- the refresh period T102 is a period in which the data written in the memory circuit MR100 in the entire writing period T101 is held by refreshing, and has consecutive periods t103 to t110.
- the refresh period T102 is started simultaneously for all the rows.
- the potential of the gate line GLx becomes High.
- the potentials of the data transfer control line DTx and the refresh output control line RCx are Low. Accordingly, the transistor N100 is turned on, so that the data potential (here, High) supplied to the source line SLx is written to the node PIX.
- the potential of the gate line GLx becomes Low.
- the transistor N100 is turned off, so that charge corresponding to the written data potential is held in the capacitor Ca100.
- the node PIX is in a floating state while the transistor N100 is in the OFF state. At this time, in an ideal state, electric charge is held in the capacitor Ca100 so that the potential of the node PIX is maintained at High.
- the data transfer unit TS100, the second data holding unit DS102, and the refresh output control unit RS100 are caused to function by refreshing the potential of the node PIX so that the written data is not lost.
- the potential of the data transfer control line DTx becomes High.
- the potentials of the gate line GLx and the refresh output control line RCx are Low.
- the transistor N101 is turned on, and the capacitor Cb100 is connected in parallel to the capacitor Ca100 via the transistor N101. Therefore, the electric potential moves between the capacitor Ca100 and the capacitor Cb100, so that the potential of the node MRY becomes High.
- the capacitance value of the capacitor Ca100 is set larger than that of the capacitor Cb100. From the capacitor Ca100, positive charges move to the capacitor Cb100 through the transistor N101 until the potential of the node PIX becomes equal to the potential of the node MRY. As a result, the potential of the node PIX is slightly lower than the voltage in the period t102 by a voltage ⁇ V1, but is in the High potential range.
- the potential of the data transfer control line DTx becomes Low. Accordingly, the transistor N101 is turned off, so that the charge is held in the capacitor Ca100 so that the potential of the node PIX is maintained high, and the charge is stored in the capacitor Cb100 so that the potential of the node MRY is maintained high. Retained.
- the potential of the refresh output control line RCx becomes High.
- the transistor N103 is turned on, so that the output terminal OP of the inverter INV100 is connected to the node PIX. Since the inverted potential (here, Low) of the potential of the node MRY is output to the output terminal OP, the node PIX is charged to the inverted potential.
- the potential of the refresh output control line RCx becomes Low.
- the transistor N103 is turned off, so that charge is held in the capacitor Ca100 so that the potential of the node PIX is maintained at the inversion potential.
- the potential of the data transfer control line DTx becomes High.
- the transistor N101 is turned on, so that the capacitor Cb100 is connected in parallel to the capacitor Ca100 via the transistor N101. Therefore, the electric potential moves between the capacitor Ca100 and the capacitor Cb100, so that the potential of the node MRY becomes Low.
- positive charge moves from the capacitor Cb100 to the capacitor Ca100 through the transistor N101 until the potential of the node MRY becomes equal to the potential of the node PIX.
- the potential of the node PIX rises by a slight voltage ⁇ V2 from that in the period t106, but is in the Low potential range.
- the potential of the data transfer control line DTx becomes Low.
- the transistor N101 is turned off, so that charge is held in the capacitor Ca100 so that the potential of the node PIX is kept low, and charge is kept in the capacitor Cb100 so that the potential of the node MRY is kept low. Retained.
- the potential of the refresh output control line RCx becomes High.
- the transistor N103 is turned on, so that the output terminal OP of the inverter INV100 is connected to the node PIX. Since the inverted potential (here, High) of the potential of the node MRY is output to the output terminal OP, the node PIX is charged to the inverted potential.
- the potential of the refresh output control line RCx becomes Low.
- the transistor N103 is turned off, so that charge is held in the capacitor Ca100 so that the potential of the node PIX is maintained at the inversion potential.
- the operations in the period t103 to the period t110 are repeated until the next all writing period T101 or the normal mode is entered.
- the potential of the node PIX is refreshed to the inverted potential in the period t105, and is refreshed to the potential at the time of writing in the period t109. Note that in the period t101 of the entire writing period T101, when a low data potential is written to the node PIX, the potential waveform of the node PIX is obtained by inverting the potential waveform of FIG.
- the memory circuit MR100 can refresh the data written in the entire writing period T1 by the data inversion method in the refresh period T2. Thereby, it is possible to suppress the influence of charge reduction due to off-leakage. Further, the potential of the common electrode COM is inverted between High and Low in accordance with the timing at which the data written in the node PIX is refreshed, that is, the timing at which the polarity is inverted. Thereby, the screen can be refreshed while the liquid crystal capacitor Clc is AC driven.
- Patent Document 2 discloses a technique for holding all black / all white data in all the pixel memories at the end of the still image display period in the memory mode, that is, initializing the data holding unit of the pixel memory. Are listed. Thus, screen noise is prevented by preventing the previous data from being displayed when the normal mode is switched to the memory mode next time.
- FIG. 13 is a timing chart showing various signal waveforms when screen noise occurs when switching from the normal mode to the memory mode in the conventional liquid crystal display device including the memory circuit MR100.
- CSx1, CSx2, and CSx480 indicate the potentials of the auxiliary capacitance lines CSx in the 1, 2, and 480th rows, respectively.
- PIX1, PIX2, and PIX480 indicate the potentials of the pixel electrodes of the memory circuit MR100 in the 1, 2, and 480th rows, respectively.
- COM1, COM2, and COM480 indicate the potential of the common electrode COM in the first, second, and 480th rows, respectively, but the potential of the common electrode COM is common.
- the potential of the common electrode COM is kept constant, and the potential of the auxiliary capacitance line CSx is set to High and Low in accordance with the data write timing of the corresponding memory circuit MR100. Inverted between.
- the potential of the common electrode COM and the potential of the auxiliary capacitance line CSx are fixed at a predetermined potential (here, Low).
- the predetermined potential of the common electrode COM may be set to a value different from the potential of the common electrode COM set in the normal mode.
- the potential of the common electrode COM and the potential of the storage capacitor line CSx may change before and after the transition from the normal mode to the memory mode, respectively.
- the potential of the storage capacitor line CSx varies (shifts to a predetermined potential), so that the node PIX is subjected to variation.
- the potential of the common electrode COM which is a reference voltage, also fluctuates, the liquid crystal application voltage changes greatly and screen noise occurs.
- the present invention has been made in view of the above-described conventional problems, and an object of the present invention is to eliminate screen noise caused by fluctuations in the potential of the common electrode and the potential of the auxiliary capacitance line when switching between the normal mode and the memory mode. It is an object of the present invention to provide a display device that can be prevented and a method for driving the display device.
- a display device of the present invention includes a display panel in which memory circuits are provided in a matrix, and a normal mode in which display is performed using a data signal potential written to the memory circuit for each frame;
- a display device having a memory mode for performing display by refreshing and holding a data signal potential written in a memory circuit, wherein the display panel shares a data signal line, a scanning signal line, and an auxiliary capacitance line
- An electrode and the memory circuit includes a pixel electrode and a first switch circuit that selectively conducts and cuts off between the data signal line and the pixel electrode in accordance with the potential of the scanning signal line;
- the display device driving method of the present invention includes a display panel in which memory circuits are provided in a matrix, and performs display using a data signal potential written to the memory circuit for each frame.
- a display device driving method having a normal mode and a memory mode in which a display is performed by refreshing and holding a data signal potential written in the memory circuit, wherein the display panel includes a data signal line, a scanning signal line And the auxiliary capacitance line and the common electrode, and the memory circuit selectively turns on and off the pixel electrode and the data signal line and the pixel electrode in accordance with the potential of the scanning signal line.
- a first switch circuit a first capacitor formed between the pixel electrode and the auxiliary capacitance line, and a refresh that controls refresh of the potential of the pixel electrode.
- the change in the potential is This is performed while the potential of the data signal line is fixed and the pixel circuit of the memory circuit is electrically connected to the data signal line with the first switch circuit in a conductive state.
- the change in the potential is performed. Is performed while the potential of the data signal line is fixed and the first switch circuit is turned on to electrically connect the pixel electrode of the memory circuit to the data signal line. That is, with the pixel electrode of the memory circuit fixed, the potential of the common electrode and the potential of the storage capacitor line are changed (transitioned) to a predetermined potential. As a result, the pixel electrode of the memory circuit is not affected by fluctuations, and thus screen noise can be prevented.
- the display device of the present invention includes a display panel in which memory circuits are provided in a matrix, and includes a normal mode in which display is performed using the data signal potential written to the memory circuit for each frame, and the memory circuit.
- the memory circuit includes a pixel electrode, a first switch circuit that selectively conducts and cuts off between the data signal line and the pixel electrode in accordance with a potential of the scanning signal line, and the pixel electrode Including a first capacitor formed between the common electrode and the auxiliary capacitance line, and a refresh control unit that controls refresh of the potential of the pixel electrode.
- the pixel electrode of the memory circuit is fixed and the common electrode
- the pixel electrode of the memory circuit is not affected by the variation, so that it is possible to prevent screen noise.
- FIG. 4 is a diagram showing a data holding operation in the memory mode in the pixel memory, where (a) shows data transition in the entire writing period, and (b) to (h) show data transition in the refresh period.
- FIG. 6 is a timing chart showing various signal waveforms when screen noise occurs when switching from the normal mode to the memory mode in the conventional liquid crystal display device.
- 11 is a timing chart showing various signal waveforms when an operation for preventing screen noise is performed when switching from the normal mode to the memory mode in the pixel memory of FIG. 11 according to another embodiment of the present invention. It is.
- the liquid crystal display device of the present embodiment includes the memory circuit MR100 shown in FIG. 11 as a pixel memory.
- the memory circuit MR100 can prevent screen noise that occurs when the potential of the common electrode COM and the potential of the auxiliary capacitance line CSx fluctuate when switching between the normal mode and the memory mode. Is the operation. Therefore, next, the operation of the memory circuit MR100 in the above case will be described.
- FIG. 14 is a timing chart showing various signal waveforms when an operation for preventing screen noise is performed when switching from the normal mode to the memory mode in the liquid crystal display device of the present embodiment.
- the various signals shown in FIG. 14 are the same as those shown in FIG. 13, and a gate full ON signal is further added.
- the liquid crystal display device when it is necessary to change the potential for switching between the normal mode and the memory mode for each of the common electrode COM and the auxiliary capacitance line CSx, The change is output to all the source lines SLx with the same potential as the potential of the common electrode COM, and the gate lines GLx of all rows are set to a high (active) potential to turn on the transistors N100 of all the memory circuits MR100. This is performed while the node PIX of the memory circuit MR100 is set to the same potential as the potential of the common electrode COM.
- the node PIX of the memory circuit MR100 being fixed to the same potential as the common electrode COM, the potential of the common electrode COM and the potential of the auxiliary capacitance line CSx are changed (transitioned) to a predetermined potential. As a result, the node PIX of the memory circuit MR100 is not affected by fluctuations, so that screen noise can be prevented.
- the pixel is set to the black potential when switching from the normal mode to the memory mode.
- the screen noise can be prevented by changing (transitioning) the potential of the common electrode COM and the potential of the auxiliary capacitance line CSx to a predetermined potential.
- the node PIX of the memory circuit MR100 is fixed to the same potential as the potential of the common electrode COM by outputting the same potential as the potential of the common electrode COM to all the source lines SLx.
- the potential of the node PIX may be fixed by electrically connecting the node PIX to the source line SLx in a state where the potential of the source line SLx is fixed.
- the potential of the data transfer control line DTx is inactive (here, the refresh period T102).
- the node MRY is disconnected from the node PIX and is in a floating state.
- the node PIX has a potential corresponding to Low, while the node MRY has a potential corresponding to High.
- the node PIX has a potential corresponding to High, whereas the node MRY has a potential corresponding to Low. Therefore, in these periods, although the transistor N101 is in an OFF state, the potential of the node MRY gradually varies with time due to the off-leak current of the transistor N101.
- each node in the floating state is also affected by potential fluctuations due to parasitic capacitances such as transistors and wirings.
- parasitic capacitances such as transistors and wirings.
- the potential fluctuations due to parasitic capacitances are excluded from consideration for the sake of simplicity. Yes.
- the potential of the node MRY in the period t103 to the period t105 becomes (High potential ⁇ V1 ⁇ ), and further potential fluctuation in addition to the potential fluctuation ⁇ V1 due to charge distribution. In combination, this causes a potential fluctuation of ( ⁇ V1 + ⁇ ).
- the potential of the node MRY in the period t107 to the period t109 becomes (Low potential + ⁇ V2 + ⁇ ), which causes further potential variation in addition to the potential variation ⁇ V2 due to charge distribution, and causes a potential variation of ( ⁇ V2 + ⁇ ).
- the transistor P100 and the transistor N102 constituting the inverter INV100 are Vth, when the potential of the node MRY (High potential ⁇ V1 ⁇ ) becomes lower than (High potential ⁇ Vth), the transistor P100 Gradually turns ON. At this time, since the transistor N102 is in the ON state, a through current flows from the high power supply line PHx to the low power supply line PLx through the transistor P100 and the transistor N102, which causes a problem that a large consumption current is generated.
- the output of the inverter INV100 gradually becomes a potential between High and Low.
- the potential of the node PIX also becomes a potential between High and Low, and if the potential cannot be distinguished from either High or Low, the memory circuit MR100 malfunctions.
- the pixel electrode node PIX
- the memory electrode charge is transferred from the pixel electrode to refresh the potential of the pixel electrode.
- Node MRY and a transfer element (transistor N101) provided between the pixel electrode and the memory electrode
- the potential of the memory electrode is caused by the presence of off-leakage current in the data transfer element.
- the circuit that performs the refresh operation based on the above cannot properly perform the original operation.
- liquid crystal display device including a memory circuit that can appropriately perform an original operation in a circuit that performs a refresh operation even when an off-leak current is present in the transfer element.
- FIG. 1 is a block diagram illustrating a configuration example of the liquid crystal display device 10 of the present embodiment.
- the liquid crystal display device 10 is a memory-type liquid crystal display device, and as shown in FIG. 1, a pixel array 11, a drive signal generation circuit / video signal generation circuit 12, a demultiplexer 13, a gate driver / CS driver 14, and a control A signal buffer circuit 15 is provided.
- the pixel array 11 includes pixel memories 20 (shown as “MR” in the figure) arranged in a matrix of n rows and m columns.
- pixel memories 20 shown as “MR” in the figure
- a gate line GL (i) scanning signal line
- an auxiliary capacitance line CS (i) a data transfer control line DT (i) (data transfer line)
- a refresh output control line RC (i) refresh output line
- a source line SL (j) data signal line
- i is an integer satisfying 1 ⁇ i ⁇ n
- j is an integer satisfying 1 ⁇ j ⁇ m.
- the pixel memory 20 has a memory function and holds data independently.
- the writing and holding of the data signal to the pixel memory 20 located at the intersection of the i-th row (Row) and the j-th column (Column) is performed by the gate line GL (i) connected to the i-th row,
- the storage capacitor line CS (i), the data transfer control line DT (i), the refresh output control line RC (i), and the source line SL (j) connected to the jth column are controlled.
- the drive signal generation circuit / video signal generation circuit 12 controls the supply of the video signal (data signal) to the pixel memory 20 and the operation of the gate driver / CS driver 14 and the control signal buffer circuit 15 according to the drive method.
- This is a control drive circuit for driving, and has functions equivalent to those of a display data processing circuit, an input / output interface, an instruction decoder, a timing control circuit, and the like.
- the drive signal generation circuit / video signal generation circuit 12 inputs / outputs data between the liquid crystal display device 10 and the outside of the liquid crystal display device 10, and fetches data write / data retention command data and display data from the outside.
- the drive signal generation circuit / video signal generation circuit 12 generates a data signal to be supplied to the pixel array 11 based on the captured display data, and outputs an output signal line vd (k) (k is 1 ⁇ k) from the video output terminal. ⁇ l ⁇ m integer).
- the drive signal generation circuit / video signal generation circuit 12 interprets an instruction from the fetched instruction data, selects a drive method according to the instruction, and drives / controls the gate driver / CS driver 14 with a signal s 1. s2 and a signal s3 for driving and controlling the control signal buffer circuit 15 are generated and output, respectively.
- the driving method includes a “normal mode” and a “memory mode” as will be described later.
- the drive signal generation circuit / video signal generation circuit 12 outputs a multi-gradation video signal as a data signal to the output signal line vd (k) and also outputs a signal s1 to the gate driver / CS driver 14.
- the drive signal generation circuit / video signal generation circuit 12 outputs binary data as a data signal to the output signal line vd (k) and controls the signal s2 to the gate driver / CS driver 14.
- the signal s3 is output to the signal buffer circuit 15, respectively.
- the clock signal serving as the basis of timing may be input from an external system, or may be generated inside the liquid crystal display device 10 or inside the drive signal generation circuit / video signal generation circuit 12 by an oscillator or the like.
- the drive signal generation circuit / video signal generation circuit 12 generates not only the timing used for the memory operation but also the timing of the gate start pulse, the gate clock, the source start pulse, and the source clock used for the display operation. Can also serve as a circuit.
- the demultiplexer 13 distributes the output of the output signal line vd (k) to the corresponding source line SL (j).
- the gate driver / CS driver 14 is a circuit that drives and controls the writing operation of the pixel memory 20 of the pixel array 11 via the gate line GL (i) and the auxiliary capacitance line CS (i).
- the gate driver / CS driver 14 controls the gate line GL (i) and the auxiliary capacitance line CS (i) according to the signals s1 and s2 supplied from the drive signal generation circuit / video signal generation circuit 12.
- the control signal buffer circuit 15 is a circuit that drives and controls the data holding operation of the pixel memory 20 of the pixel array 11 via the data transfer control line DT (i) and the refresh output control line RC (i).
- the control signal buffer circuit 15 controls the data transfer control line DT (i) and the refresh output control line RC (i) in accordance with the signal s3 supplied from the drive signal generation circuit / video signal generation circuit 12.
- the pixel array 11 is formed on a substrate (not shown).
- the drive signal generation circuit / video signal generation circuit 12, the demultiplexer 13, the gate driver / CS driver 14, and the control signal buffer circuit 15 may be monolithically formed on the substrate.
- a counter substrate (not shown) provided with a common electrode (counter electrode) COM is provided at a position facing the substrate.
- the substrate and the counter substrate are disposed so as to sandwich liquid crystal therebetween, and a liquid crystal panel (hybrid memory liquid crystal panel) (display panel) is formed by the configuration.
- the common voltage Vcom applied to the common electrode COM may be supplied from, for example, a Vcom driver provided in the liquid crystal display device 10 or supplied from a power supply provided in the drive signal generation circuit / video signal generation circuit 12.
- the liquid crystal display device 10 may be directly driven from the outside.
- the common electrode COM may be on the same substrate as the substrate.
- the pixel electrode of the pixel memory 20 forms a liquid crystal capacitor Clc via a liquid crystal between the pixel electrode and the common electrode COM.
- An image is displayed by applying a voltage corresponding to the potential difference between the pixel electrode and the common electrode COM to the liquid crystal capacitor Clc.
- the drive signal generation circuit / video signal generation circuit 12 and the demultiplexer 13 constitute a column driver.
- the gate driver / CS driver 14 and the control signal buffer circuit 15 constitute a row driver.
- the control signal buffer circuit 15 and the CS driver in the case of driving all the auxiliary capacitance lines CS (i) at the same time may constitute a column driver or may be directly driven from the outside of the liquid crystal display device 10. May be.
- the gate line GL (i), the auxiliary capacitance line CS (i), the data transfer control line DT (i), the refresh output control line RC (i), and the source line SL (j) may be collectively referred to.
- the liquid crystal display device 10 having the above configuration has a “normal mode” and a “memory mode” as driving methods for displaying an image.
- FIG. 2 shows types of driving methods that the liquid crystal display device 10 has.
- the normal mode AC driving is performed to display a moving image / still image with multiple gradations based on the multiple gradation video signal supplied for each frame.
- a normal writing period for writing a multi-gradation video signal corresponding to one frame period is repeated.
- FIG. 3 is a timing chart showing various signal waveforms in the normal mode in the liquid crystal display device 10.
- the signal waveform is shown.
- GL1, GL2, and GL480 indicate the potentials of the gate lines GL in the 1, 2, and 480th rows, respectively.
- CS1, CS2, and CS480 indicate the potentials of the auxiliary capacitance lines CS in the first, second, and 480th rows, respectively.
- PIX1, PIX2, and PIX480 indicate the potentials of the pixel electrodes of the pixel memory 20 in the first, second, and 480th rows, respectively.
- a dotted line shown overlapping the signal waveforms of PIX1, PIX2, and PIX480 indicates the potential of the common electrode COM.
- FIG. 3 shows a case where the first row is selected as the start row and the 480th row is selected as the end row.
- writing to the pixel memory 20 is performed by 1H (one horizontal period) inversion driving.
- CC (Charge-Coupling) driving is performed, the potential of the common electrode COM is made constant, and the potential of the auxiliary capacitance line CS is set to High in accordance with the data write timing of the corresponding pixel memory 20. Inverted between potential and low potential.
- the control signal buffer circuit 15 prevents the potential of the data transfer control line DT and the potential of the refresh output control line RC from affecting the pixel electrode and the liquid crystal capacitance Clc.
- the same function as that of the display device can be realized by the liquid crystal display device 10.
- AC driving is performed to display an image with little change in time such as a still image based on binary data held by the data holding operation of the pixel memory 20 in light and dark (black and white).
- the binary data is data (data signal) that takes one of a High potential and a Low potential.
- all the pixel memories 20 are provided with a whole writing period in which data to be held is written for each row and a refresh period in which the data written in the whole writing period is refreshed all at once.
- FIG. 4 is a timing chart showing various signal waveforms in the memory mode in the liquid crystal display device 10. Various signals shown in FIG. 4 are the same as the signals shown in FIG.
- the gate line GL is changed.
- the scanning timing may be simultaneous in different rows. For example, a method of scanning the gate line GL for every two rows skipped may be used. In this method, the scanning timing may be overlapped for each row, but the scanning timing for completing the data writing is different.
- 1V (one vertical period) inversion driving is performed in the entire writing period, and the polarity of the voltage applied to all the liquid crystal capacitors Clc is the same.
- the potential of the common electrode COM and the potential of the auxiliary capacitance line CS are fixed to one of the High potential and the Low potential (Low potential in the drawing).
- the refresh period is started simultaneously for all the pixel memories 20 after the writing of data to all the pixel memories 20 is completed in the entire writing period. That is, all the pixel memories 20 perform a refresh operation simultaneously.
- the data written in the pixel memory 20 in the entire writing period is refreshed at least once, and at that time, the potential level is inverted (High ⁇ Low, Low ⁇ High).
- the potential of the common electrode COM is inverted between the high potential and the low potential in response to data refresh.
- the potential of the auxiliary capacitance line CS is fixed at Low.
- the refresh period may be repeated any number of times.
- the number of times of writing per predetermined period is 1/4 compared with the normal mode.
- binary data is written in the pixel memory 20, so that when the color is not assigned, black and white is displayed, but when the color is assigned by a color filter or the like, it is set to 2.
- display is performed with the number of colors that is a power of the number of other pixels for color. For example, when one pixel is constituted by a plurality of pixel memories 20 to which R (red), G (green), and B (blue) are respectively assigned, since 3 power of 2 is equal to 8, 8 colors Is displayed.
- FIG. 5 shows a conceptual configuration of the pixel memory 20.
- the pixel memory 20 includes a switch circuit SW1, a first data holding unit DS1, a data transfer unit TS1, a second data holding unit DS2, a refresh output control unit RS1, and a supply source VS1 (potential supply source). It has.
- the switch circuit SW1 is selectively driven and cut off between the source line SL and the first data holding unit DS1 by being driven via the gate line GL by the gate driver / CS driver 14.
- the first data holding unit DS1 holds binary data input to the first data holding unit DS1.
- the data transfer unit TS1 is driven by the control signal buffer circuit 15 via the data transfer control line DT, so that the binary data held in the first data holding unit DS1 is converted into data by the first data holding unit DS1.
- a transfer operation for transferring to the second data holding unit DS2 while holding it and a non-transfer operation for not performing the transfer operation are selectively performed. Since the potential supplied to the data transfer control line DT is common to all the pixel memories 20, the data transfer control line DT is not necessarily provided for each row and driven by the control signal buffer circuit 15. It may be driven by the driver / CS driver 14 or others.
- the second data holding unit DS2 holds binary data input to the second data holding unit DS2.
- the refresh output control unit RS1 is selectively controlled to be in a state of performing the first operation or a state of performing the second operation by being driven by the control signal buffer circuit 15 via the refresh output control line RC. Since the potential supplied to the refresh output control line RC is common to all the pixel memories 20, the refresh output control line RC is not necessarily provided for each row and driven by the control signal buffer circuit 15. It may be driven by the driver / CS driver 14 or others.
- the first operation takes in the input to the refresh output control unit RS1 in accordance with control information indicating whether the binary data held in the second data holding unit DS2 is a high potential or a low potential. This is an operation for selecting whether the active state is to be supplied to the first data holding unit DS1 as the output of the refresh output control unit RS1 or the inactive state in which the output of the refresh output control unit RS1 is stopped.
- the second operation is an operation to stop the output of the refresh output control unit RS1 regardless of the control information.
- the supply source VS1 supplies a set potential to the input of the refresh output control unit RS1.
- FIG. 6A and 6B are diagrams showing a data holding operation in the memory mode in the pixel memory 20.
- FIG. 6A shows data transition in the entire writing period T1
- FIGS. 6B to H show data transition in the refresh period T2. Show.
- “H” is shown as the High potential (first potential)
- “L” is shown as the Low potential (second potential).
- the upper stage indicates a potential transition state when “H” is written in the pixel memory 20
- the lower stage indicates “L” in the pixel memory 20. The potential transition states when writing are shown.
- the entire writing period T1 is started.
- the switch circuit SW1 is turned on by the gate line GL, and the first data holding unit DS1 is switched from the source line SL through the switch circuit SW1. Data to be held represented by either the first potential or the second potential is input.
- the switch circuit SW1 When data is input to the first data holding unit DS1, the switch circuit SW1 is turned off by the gate line GL. At this time, the data transfer unit TS1 is turned on by the data transfer control line DT, that is, the transfer operation is performed, and the data input to the first data holding unit DS1 is held and the data is transferred from the first data holding unit DS1. Data is transferred to the second data holding unit DS2 via the transfer unit TS1. When data is transferred to the second data holding unit DS2, the data transfer unit TS1 is in an OFF state, that is, a state in which a non-transfer operation is performed.
- the switch circuit SW1 is turned on by the gate line GL, and the first potential data is transferred from the source line SL to the first data holding unit DS1 via the switch circuit SW1. Is entered.
- the switch circuit SW1 is turned off by the gate line GL.
- the refresh output control unit RS1 is controlled to perform the first operation by the refresh output control line RC.
- the first operation of the refresh output control unit RS1 uses control information indicating which of the first potential data and the second potential data is stored in the second data holding unit DS2. Depending on.
- the refresh output control unit RS1 has the first potential data held in the second data holding unit DS2. Is transmitted to the refresh output control unit RS1 from the second data holding unit DS2, and the input to the refresh output control unit RS1 is taken in as the output of the refresh output control unit RS1. Then, the operation of supplying to the first data holding unit DS1 is performed.
- the refresh output control unit RS1 When the refresh output control unit RS1 performs this first operation, the potential of the supply source VS1 is at least finally in the period during which the first control information is transmitted to the refresh output control unit RS1. Is set so that the second potential data can be supplied to the input. In this case, the first data holding unit DS1 holds the data of the second potential supplied from the refresh output control unit RS1 in a state where the data held so far is overwritten.
- the refresh output control unit RS1 when data of the second potential is held in the second data holding unit DS2, the refresh output control unit RS1 is in an inactive state, and data of the second potential is held in the second data holding unit DS2.
- the second control information indicating that the output has been performed is transmitted from the second data holding unit DS2 to the refresh output control unit RS1, thereby stopping the output (indicated by “x” in the figure).
- the first data holding unit DS1 continues to hold the data of the first potential held so far.
- the refresh output control unit RS1 is controlled to perform the second operation by the refresh output control line RC.
- the data transfer unit TS1 is set in a transfer operation state by the data transfer control line DT and has been held in the first data holding unit DS1 until then.
- the data is transferred from the first data holding unit DS1 to the second data holding unit DS2 via the data transfer unit TS1 while being held in the first data holding unit DS1.
- the data transfer unit TS1 is in an OFF state, that is, a state in which a non-transfer operation is performed.
- the switch circuit SW1 is turned on by the gate line GL, and the first potential is supplied from the source line SL to the first data holding unit DS1 via the switch circuit SW1. Data is entered.
- the switch circuit SW1 is turned off by the gate line GL.
- the refresh output control unit RS1 is controlled to perform the first operation by the refresh output control line RC.
- the refresh output control unit RS1 is in the active state, and the data of the second potential supplied from the supply source VS1 is held in the first data.
- the operation of supplying the unit DS1 is performed.
- the first data holding unit DS1 holds the data of the second potential supplied from the refresh output control unit RS1 in a state where the data held until then is overwritten.
- the refresh output control unit RS1 becomes inactive and stops outputting.
- the first data holding unit DS1 continues to hold the data of the first potential held so far. Thereafter, the refresh output control line RC is controlled to perform the second operation by the refresh output control line RC, and the output is stopped.
- the data transfer unit TS1 is set in a transfer operation state by the data transfer control line DT, and the data held in the first data holding unit DS1 until then is stored in the first data holding unit DS1. While being held in the data holding unit DS1, the data is transferred from the first data holding unit DS1 to the second data holding unit DS2 via the data transfer unit TS1. When data is transferred from the first data holding unit DS1 to the second data holding unit DS2, the data transfer unit TS1 is in an OFF state, that is, a state in which a non-transfer operation is performed.
- the memory mode it is possible to display still images while refreshing the screen with the stored data.
- the above-described operation logic may be inverted.
- the refresh output control unit RS1 supplies the second potential data from the supply source VS1 to the first data holding unit DS1, and therefore it is necessary to provide a conventional inverter for performing the refresh operation. Absent.
- the liquid crystal display device 10 after data is written to the first data holding unit DS1 for each pixel memory 20, one of the first potential and the second potential is used without using an inverter. Is supplied from the source line SL and the other data is supplied from the supply source VS1, whereby the data written in the pixel memory 20 can be refreshed while inverting the potential level.
- the refreshed data can be held in both the first data holding unit DS1 and the second data holding unit DS2 for a long time while the data transfer unit TS1 is in a transfer operation state.
- the first data holding unit DS1 and the second data holding unit DS2 are connected via the data transfer unit TS1, the presence of an off-leakage current in the transfer element of the data transfer unit TS1 Become irrelevant.
- the data is held in a large electric capacity represented by the sum of the first data holding unit DS1 and the second data holding unit DS2 as a whole, and the potential of the data is also affected by the influence of external noise. Difficult to fluctuate.
- the potential of the holding node that holds the data in the second data holding unit DS2 is long together with the potential of the holding node in the first data holding unit DS1. Because it is held for a long time, it is hard to fluctuate.
- the first data holding unit DS101 and the second data holding unit DS102 are connected to the transfer elements (transistors N101) of the data transfer unit TS100. ), It takes a long time to hold different data in an electrically separated state, so that the off-leak current of the transfer element has a great influence on the potential of the second data holding unit DS102.
- the control information for the refresh output control unit RS1 performing the first operation is switched between the active level and the inactive level.
- the fluctuation time is not so long.
- an inverter exists in the refresh output control unit RS1
- the range in which the potential of the part DS2 can exist as a level that allows the inverter to stably maintain the same operation is narrow. For example, when the inverter is operated so that the potential of the second data holding unit DS2 is set to the low level and the P-channel transistor is turned on and the N-channel transistor is turned off, the gate potential of the P-channel transistor When the voltage rises a little, there is a risk that the N-channel transistor becomes conductive.
- the threshold voltage of the N-channel transistor is designed to be large in order to avoid this situation, the High level is active when it is desired to operate the P-channel transistor in the OFF state and the N-channel transistor in the ON state.
- the range that functions as a level is narrowed.
- the active level of the refresh output control unit RS1 is one of the first potential and the second potential, so that the control information for the refresh output control unit RS1 is set to the inactive level.
- the risk of the inactive level changing to the active level is reduced.
- the active level functions in the initial stage of the active state in the first operation of the refresh output control unit RS1, the purpose of output from the supply source VS1 to the first data holding unit DS1 can be easily achieved. Even if the level changes to an inactive level, it is difficult for the refresh output control unit RS1 to malfunction.
- the refresh output control unit RS1 does not malfunction.
- the threshold voltage of the transistor is increased to increase the potential of the second data holding unit DS2 to be inactive level. This is equivalent to designing such that the gate-source voltage does not easily exceed the threshold voltage of the transistor even if the voltage fluctuates.
- FIG. 7 shows an example of the configuration of the pixel memory 20 of the present embodiment as a memory circuit MR1 as an equivalent circuit.
- the memory circuit MR1 includes a transistor N1, a transistor N2, a transistor N3 (first switch), a transistor N4 (second switch), a capacitor Ca1 (first capacitor), and a capacitor Cb1 (second capacitor). It has.
- the pixel array 11 is provided with a source line SL, a gate line GL, an auxiliary capacitance line CS, a data transfer control line DT, and a refresh output control line RC as wirings for driving the memory circuit MR1.
- the configuration shown in FIG. 5 corresponds as follows. That is, the transistor N1 constitutes the switch circuit SW1.
- the capacitor Ca1 constitutes the first data holding unit DS1.
- the transistor N2 serves as a transfer element and constitutes a data transfer unit TS1.
- the capacitor Cb1 constitutes the second data holding unit DS2.
- the transistor N3 and the transistor N4 constitute a refresh output control unit RS1. Therefore, the memory circuit MR1 includes the switch circuit SW1 (first switch circuit), the first data holding unit DS1, the data transfer unit TS1 (second switch circuit), the second data holding unit DS2, and the refresh output control unit RS1 ( It can of course be said that a control unit and a third switch circuit are provided.
- the transistors N1 to N4 are N-channel TFTs (field effect transistors). Accordingly, in FIG. 7, since all the transistors constituting the memory circuit MR1 are N-channel TFTs, the memory circuit MR1 can be easily formed in amorphous silicon.
- one drain / source terminal is called a first drain / source terminal
- the other drain / source terminal is called a second drain / source terminal.
- the transistor N1 has a gate terminal connected to the gate line GL, a first drain / source terminal connected to the source line SL, and a second drain / source terminal connected to the node PIX which is one end of the capacitor Ca1.
- the other end of the capacitor Ca1 is connected to the auxiliary capacitor line CS.
- the transistor N2 has a gate terminal connected to the data transfer control line DT, a first drain / source terminal connected to the node PIX, and a second drain / source terminal connected to the node MRY which is one end of the capacitor Cb1.
- the other end of the capacitor Cb1 is connected to the auxiliary capacitor line CS.
- the transistor N3 has a gate terminal connected to the node MRY as the control terminal CNT1 of the refresh output control unit RS1, a first drain / source terminal connected to the data transfer control line DT as the input terminal IN1 of the refresh output control unit RS1, and a second drain.
- the / source terminal is connected to the first drain / source terminal of the transistor N4.
- the transistor N3 uses the potential held at the node MRY as a control signal for interrupting conduction.
- the transistor N4 has a gate terminal connected to the refresh output control line RC and a second drain / source terminal connected to the node PIX as the output terminal OUT1 of the refresh output control unit RS1. That is, the transistor N3 and the transistor N4 are serially connected to each other such that the transistor N3 is disposed on the input side of the refresh output control unit RS1 between the input of the refresh output control unit RS1 and the output of the refresh output control unit RS1. It is connected to the.
- the transistor N4 uses the potential of the refresh output control line RC as a control signal for interrupting conduction.
- connection positions of the transistor N3 and the transistor N4 may be interchanged with those in the above example, and the transistor N3 and the transistor N4 are connected between the input of the refresh output control unit RS1 and the output of the refresh output control unit RS1. What is necessary is just to be mutually connected in series.
- the refresh output control unit RS1 When the transistor N4 is in the ON state, the refresh output control unit RS1 is controlled to perform the first operation. When the transistor N4 is in the OFF state, the refresh output control unit RS1 performs the second operation. Controlled. Since the transistor N3 is an N-channel type, when the refresh output control unit RS1 performs the first operation, the control information that becomes active, that is, the active level is High, and the control information that becomes inactive, that is, the inactive level is Low. It is.
- the node PIX and the data transfer control line DT become conductive, and when the transistors N3 and N4 are in the OFF state, the node PIX and the data transfer control line DT are brought into conduction. Will be blocked.
- the capacity Ca1 is set so that the capacity value is larger than the capacity Cb1.
- each of the capacitance values of the capacitor Ca1 and the capacitor Cb1 has a potential fluctuation of the node PIX (pixel electrode) when the charge is transferred between the capacitor Ca1 and the capacitor Cb1, as will be described later. (Potential and low potential).
- a liquid crystal capacitor Clc is connected between the node PIX and the common electrode COM.
- the node PIX corresponds to a pixel electrode, and the capacitor Ca1 also functions as an auxiliary capacitor for the pixel memory 20.
- FIG. 8 is a timing chart showing various signal waveforms in the memory mode of the memory circuit MR1 having the above configuration.
- FIG. 8 shows a case where High data is written as data of the first potential in the entire writing period T1. 8 also shows the potential of the node PIX (left side) and the potential of the node MRY (right side) in each period corresponding to (a) to (h) of FIG. FIG. 8 shows the signal waveforms of the elements in the row to be scanned first. As described above, since the refresh operation is simultaneously performed in all rows, the signal waveform in the refresh period T2 occurs in common in all rows. .
- display data and a data holding command are input to the drive signal generation circuit / video signal generation circuit 12 from the outside of the liquid crystal display device 10 via the transmission line, and the command is interpreted to enter the memory mode. Is done.
- the drive signal generation circuit / video signal generation circuit 12 generates binary data to be supplied to the pixel array 11 based on the display data, and controls the source line SL via the output signal line vd (k) and the demultiplexer 13. To do.
- the drive signal generation circuit / video signal generation circuit 12 generates signals s2 and s3 along the memory mode, and controls the gate driver / CS driver 14 and the control signal buffer circuit 15.
- the gate driver / CS driver 14 and the control signal buffer circuit 15 are arranged in accordance with the signals s2 and s3 supplied from the drive signal generation circuit / video signal generation circuit 12, and the gate line GL, the auxiliary capacitance line CS, the data transfer control line DT, The refresh output control line RC is controlled.
- a binary level potential consisting of High (active level) and Low (inactive level) is applied to the gate line GL from the gate driver / CS driver 14.
- a binary level potential consisting of High and Low is applied from the control signal buffer circuit 15 to the data transfer control line DT and the refresh output control line RC.
- the High and Low levels may be set individually for each of the lines and lines.
- the auxiliary capacitance line CS is fixed at a constant potential by the gate driver / CS driver 14.
- Binary data (data signal potential) consisting of High and Low lower than the High potential of the gate line GL is output from the demultiplexer 13 to the source line SL.
- the high potential of the data transfer control line DT is equal to either the high potential of the source line SL or the high potential of the gate line GL, and the low potential of the data transfer control line DT is equal to the low potential of the binary data. .
- the total writing period T1 is composed of a period t1 and a period t2 that are successively arranged.
- the potentials of the gate line GL and the data transfer control line DT are both High.
- the potential of the refresh output control line RC is Low.
- the transistors N1 and N2 are turned on, so that the switch circuit SW1 is in a conductive state, the data transfer unit TS1 is in a transfer operation state, and the first data supplied to the source line SL at the node PIX (here, High and Is written).
- the potential of the gate line GL becomes Low, while the potential of the data transfer control line DT continues to be High.
- the potential of the refresh output control line RC is Low.
- the transistor N1 is turned off, and the switch circuit SW1 is turned off.
- the data transfer unit TS1 maintains the state in which the transfer operation is performed. Therefore, the data of the first potential is transferred from the node PIX to the node MRY, and the nodes PIX and MRY are disconnected from the source line SL.
- the process from the period t1 to the period t2 corresponds to the state shown in FIG.
- the start time tw of the period t1 is different for each row. This is because, as described above, the switch circuits SW1 of the memory circuits MR1 in different rows can be simultaneously turned on so that the data writing period cannot overlap between the rows. However, in the entire writing period T1, the period t1 may be overlapped between rows if the end timing of the period t1 for each row is set to be different. The period t2 can also be said to be a period during which another row is written.
- the refresh period T2 starts at the same time from time tr in all the memory circuits MR1.
- the potential of the source line SL is set to High, which is the data potential of the first potential data.
- the refresh period T2 has successive periods t3 to t14.
- the potential of the gate line GL becomes Low
- the potential of the data transfer control line DT becomes Low
- the potential of the refresh output control line RC becomes Low.
- the transistor N2 is turned off, so that the data transfer unit TS1 enters a non-transfer operation state, and the node PIX and the node MRY are separated from each other. Both the node PIX and the node MRY hold High.
- the process in the period t3 corresponds to the state shown in FIG.
- the potential of the gate line GL becomes High
- the potential of the data transfer control line DT continues to be Low
- the potential of the refresh output control line RC continues to be Low. Accordingly, since the transistor N1 is turned on, the switch circuit SW1 is turned on, and the high potential is again written from the source line SL to the node PIX.
- the potential of the gate line GL becomes Low
- the potential of the data transfer control line DT continues Low
- the potential of the refresh output control line RC continues Low. Accordingly, since the transistor N1 is turned off, the switch circuit SW1 is turned off, and the node PIX is disconnected from the source line SL and holds High.
- the process from the period t4 to the period t5 corresponds to the state shown in FIG.
- the potential of the gate line GL continues to be Low
- the potential of the data transfer control line DT continues to be Low
- the potential of the refresh output control line RC becomes High.
- the transistor N4 is turned on, and the refresh output control unit RS1 performs the first operation.
- the transistor N3 is in the ON state, so that the refresh output control unit RS1 is in the active state, and the Low potential is applied from the data transfer control line DT to the node PIX via the transistors N3 and N4. Supplied. That is, the data transfer control line DT also serves as the supply source VS1 in FIG.
- period t7 the potential of the gate line GL continues to be Low, the potential of the data transfer control line DT continues to be Low, and the potential of the refresh output control line RC becomes Low.
- the transistor N4 is turned off, so that the refresh output control unit RS1 enters the second operation state, and the node PIX is disconnected from the data transfer control line DT and holds Low.
- the process from the period t6 to the period t7 corresponds to the state shown in FIG.
- period t8 the potential of the gate line GL continues to be low, the potential of the data transfer control line DT becomes high, and the potential of the refresh output control line RC continues to be low.
- the transistor N2 is turned on, so that the data transfer unit TS1 is in a transfer operation state.
- charge movement occurs between the capacitor Ca1 and the capacitor Cb1, and the potentials of both the node PIX and the node MRY become Low.
- the potential of the node PIX rises by a slight voltage ⁇ Vx due to the transfer of positive charge from the capacitor Cb1 to the capacitor Ca1 through the transistor N2, but is within the low potential range.
- This period t8 is a period in which the refreshed data is held by both the first data holding unit DS1 and the second data holding unit DS2 connected to each other via the data transfer unit TS1, and can be set long. Is possible.
- the potential of the gate line GL is kept low, the potential of the data transfer control line DT is low, and the potential of the refresh output control line RC is kept low.
- the transistor N2 is turned off, so that the data transfer unit TS1 performs a non-transfer operation, and the node PIX and the node MRY are separated from each other. Both the node PIX and the node MRY hold Low.
- the potential of the gate line GL becomes High
- the potential of the data transfer control line DT continues to be Low
- the potential of the refresh output control line RC continues to be Low. Accordingly, the transistor N1 is turned on, so that the switch circuit SW1 is turned on, and the high potential is again written from the source line SL to the node PIX.
- the potential of the gate line GL becomes low, the potential of the data transfer control line DT continues to be low, and the potential of the refresh output control line RC continues to be low. Accordingly, since the transistor N1 is turned off, the switch circuit SW1 is cut off, and the node PIX is disconnected from the source line SL and holds High.
- the process from the period t10 to the period t11 corresponds to the state of (f) in FIG.
- the potential of the gate line GL is kept low, the potential of the data transfer control line DT is kept low, and the potential of the refresh output control line RC becomes High.
- the transistor N4 is turned on, so that the refresh output controller RS1 is in a state of performing the first operation.
- the transistor N3 is in the OFF state, so the refresh output control unit RS1 is in an inactive state and the output is stopped. Therefore, the node PIX remains holding High.
- period t13 the potential of the gate line GL continues to be Low, the potential of the data transfer control line DT continues to be Low, and the potential of the refresh output control line RC becomes Low.
- the transistor N4 is turned off, so that the refresh output control unit RS1 enters a state in which the second operation is performed, and the node PIX holds High.
- the above process from the period t12 to the period t13 corresponds to the state shown in FIG.
- the potential of the gate line GL is kept low, the potential of the data transfer control line DT is high, and the potential of the refresh output control line RC is kept low.
- the transistor N2 is turned on, so that the data transfer unit TS1 is in a transfer operation state.
- charge movement occurs between the capacitor Ca1 and the capacitor Cb1, and the potentials of both the node PIX and the node MRY become High.
- the potential of the node PIX decreases by a slight voltage ⁇ Vy due to the transfer of positive charge from the capacitor Ca1 to the capacitor Cb1 via the transistor N2, but is within the High potential range.
- the process in the period t14 corresponds to the state shown in FIG.
- This period t14 is a period in which the refreshed data is held by both the first data holding unit DS1 and the second data holding unit DS2 connected to each other via the data transfer unit TS1, and can be set long. Is possible.
- the data written in the period t1 of the entire writing period T1 is restored in the node PIX and the node MRY.
- the potential of the node PIX is High in the periods t1 to t5 and the periods t10 to t14, and is Low in the periods t6 to t9.
- the potential of the node MRY is High in the periods t1 to t7 and the period t14, and is Low in the periods t8 to t13. .
- the drive signal generation circuit / video signal generation circuit 12 repeats the operations from the period t3 to the period t14.
- the drive signal generation circuit / video signal generation circuit 12 controls to perform the writing operation, and ends the refresh period T2.
- the data of the first potential is supplied from the source line SL without using the inverter after the data is written in the first data holding unit DS1 to the memory circuit MR1. Then, by supplying the second potential data from the data transfer control line DT, the data written in the pixel memory 20 can be refreshed while the level is inverted.
- the polarity of the liquid crystal when the polarity of the liquid crystal is not reversed in an AC manner, it causes burn-in and deterioration of the liquid crystal. Therefore, even when a voltage is applied to the liquid crystal and when it is not applied, the polarity of the voltage applied to the liquid crystal is kept the same. Must be reversed. Therefore, as shown in FIG. 8, the potential of the common electrode COM is driven so as to be inverted between High and Low every time the potential of the gate line GL becomes High and the transistor N1 is turned on. The In this way, by driving the common electrode COM to the binary level by inversion AC driving, it is possible to display light and dark while AC driving the liquid crystal capacitor Clc positively and negatively.
- the inversion of the potential level of the common electrode COM is performed only during the period in which the switch circuit SW1 is conductive. According to this, since the binary level supplied to the common electrode COM is inverted only during a period in which the pixel electrode (node PIX) is connected to the source line SL via the switch circuit SW1, the pixel electrode potential is changed to the source. The common electrode potential is inverted while being fixed to the potential of the line SL. Therefore, the pixel electrode potential being held, particularly the pixel electrode potential in the refresh period, is not subject to fluctuations that are caused by inversion of the common electrode potential when the node PIX is floating.
- 6A to 6H represent state transitions of the pixel memory 20, but the operation steps of the memory circuit MR1 in FIG. 8 can be classified as follows.
- Step A period t1 to period t2 (all writing periods T1)
- the first potential data or the second potential data is supplied to the source line SL from the drive signal generation circuit / video signal generation circuit 12 and the demultiplexer 13, and the refresh output control unit RS1 receives the first potential data.
- the data is written in the pixel memory 20 by turning on the switch circuit SW1 in the state in which the operation 2 is performed, the state in which the data is written in the pixel memory 20, and the second operation in the refresh output control unit RS1.
- the data transfer unit TS1 performs a transfer operation.
- Step B (period t3 to period t4 and period t9 to period t10, respectively)
- the switch output SW1 is turned on by causing the refresh output control unit RS1 to perform the second operation and causing the data transfer unit TS1 to perform the non-transfer operation.
- data having the same potential as the level corresponding to the control information for setting the refresh output control unit RS1 in the active state is input to the first data holding unit DS1 through the source line SL.
- Step C (period t5 to period t6 and period t11 to period t12, respectively)
- the refresh output control unit RS1 performs the first operation with the switch circuit SW1 being shut off and the data transfer unit TS1 performing a non-transfer operation.
- the inversion level data corresponding to the control information for making the refresh output control unit RS1 active is supplied from the supply source VS1 to the input of the refresh output control unit RS1.
- Step D (each of period t7 to period t8 and period t13 to period t14)
- step D following step C, the transfer operation is performed by the data transfer unit TS1 in a state where the switch circuit SW1 is cut off and the second operation is performed by the refresh output control unit RS1.
- step A is first executed, and following step A, a series of operations (period t3 to period t8) from the start of step B to the end of step D are executed one or more times. It becomes the operation to do.
- the operation command in the refresh period T2 in the memory mode may be generated by a clock generated internally by an oscillator or the like instead of an external signal.
- the liquid crystal display device 10 in the memory mode, circuits such as an amplifier and data for displaying multiple gradations can be stopped by the drive signal generation circuit / video signal generation circuit 12, and thus low power consumption can be realized. It becomes possible.
- the memory mode since the data potential can be refreshed in the pixel memory 20, it is not necessary to rewrite the data potential while charging and discharging the source line SL for refreshing, so that power consumption can be reduced. It becomes.
- the data polarity can be inverted in the pixel memory 20, it is not necessary to rewrite the data polarity while charging / discharging the source line SL at the time of polarity inversion, so that power consumption can be reduced.
- the memory circuit MR1 as a memory circuit does not include elements that greatly increase power consumption such as through current of an inverter for performing a refresh operation, the power consumption of the memory mode itself is significantly reduced compared to the conventional case. can do.
- screen noise may occur when the mode is switched between the normal mode and the memory mode.
- FIG. 9 is a timing chart showing various signal waveforms when screen noise occurs when the liquid crystal display device 10 is switched from the normal mode to the memory mode.
- CS1, CS2, and CS480 indicate the potentials of the auxiliary capacitance lines CS in the first, second, and 480th rows, respectively.
- PIX1, PIX2, and PIX480 indicate the potentials of the pixel electrodes of the pixel memory 20 in the first, second, and 480th rows, respectively.
- COM1, COM2, and COM480 indicate the potential of the common electrode COM in the first, second, and 480th rows, respectively, but the potential of the common electrode COM is common.
- the potential of the common electrode COM is kept constant, and the potential of the storage capacitor line CS is matched with the data write timing of the corresponding pixel memory 20. Inverted between High and Low.
- the potential of the common electrode COM and the potential of the storage capacitor line CS are fixed at a predetermined potential (here, Low).
- the predetermined potential of the common electrode COM may be set to a value different from the potential of the common electrode COM set in the normal mode.
- the potential of the common electrode COM and the potential of the storage capacitor line CS may change before and after the transition from the normal mode to the memory mode, respectively.
- the potential of the storage capacitor line CS varies (shifts to a predetermined potential), so that the node PIX is subjected to variation.
- the potential of the common electrode COM which is a reference voltage, also fluctuates, the liquid crystal application voltage changes greatly and screen noise occurs.
- liquid crystal display device 10 of the present embodiment performs the operation described below so that the potential of the common electrode COM and the auxiliary capacitance line CS can be changed when switching between the normal mode and the memory mode. It is possible to prevent screen noise caused by potential fluctuations.
- FIG. 10 is a timing chart showing various signal waveforms when an operation for preventing screen noise is performed when the liquid crystal display device 10 is switched from the normal mode to the memory mode.
- the various signals shown in FIG. 10 are the same as those shown in FIG. 3, and a gate full ON signal is further added.
- the potential Is output to all the source lines SL, and the gate lines GL of all the rows are set to a high (active) potential by turning on the transistors N1 of all the memory circuits MR1. This is performed while the node PIX of the memory circuit MR1 is set to the same potential as the potential of the common electrode COM.
- the node PIX of the memory circuit MR1 is fixed to the same potential as the common electrode COM, the potential of the common electrode COM and the potential of the auxiliary capacitance line CS are changed (transitioned) to a predetermined potential.
- the node PIX of the memory circuit MR1 is not affected by fluctuations, so that screen noise can be prevented.
- the pixel is set to a black potential when switching from the normal mode to the memory mode. Then, the screen noise can be prevented by changing (transitioning) the potential of the common electrode COM and the potential of the auxiliary capacitance line CS to a predetermined potential while the pixel is fixed at the black potential.
- the node PIX of the memory circuit MR1 is fixed to the same potential as that of the common electrode COM by outputting the same potential as that of the common electrode COM to all the source lines SL.
- the potential of the node PIX may be fixed by fixing the potential of the source line SL and electrically connecting the node PIX to the source line SL.
- FIGS. 3, 4, 9, and 10 show an example in which scanning is sequentially performed from the pixel memory 20 in the first row when data is written.
- the scanning order can be changed according to the design.
- the driving method in the normal mode is preferably AC driving, but various driving methods can be used.
- FIG. 7 shows the memory circuit MR1 including an N-channel transistor, but it is needless to say that the memory circuit MR1 may be configured using a P-channel field effect transistor. That is, the pixel memory 20 only needs to have a configuration for performing the data holding operation described with reference to FIGS.
- the memory circuit MR1 that performs the refresh operation with high accuracy is illustrated as the pixel memory 20.
- the memory circuit MR100 may be configured as a matter of course.
- the pixel memory 20 is a memory circuit including a refresh control unit that controls refresh, and switches between a normal mode in which the refresh operation is stopped and a memory mode in which the refresh operation is performed.
- the memory circuit that operates (drives) may be used, and similar effects can be achieved.
- the data held in the pixel memory 20 is binary (High potential and Low potential), it may be three or more.
- liquid crystal display device 10 can be applied to a display device that is not limited to liquid crystal.
- the present invention can be applied to a display device including a display element such as a dielectric liquid.
- a display device of the present invention includes a display panel in which memory circuits are provided in a matrix, and a normal mode in which display is performed using a data signal potential written to the memory circuit for each frame;
- a display device having a memory mode for performing display by refreshing and holding a data signal potential written in a memory circuit, wherein the display panel shares a data signal line, a scanning signal line, and an auxiliary capacitance line
- An electrode and the memory circuit includes a pixel electrode and a first switch circuit that selectively conducts and cuts off between the data signal line and the pixel electrode in accordance with the potential of the scanning signal line;
- the display device driving method of the present invention includes a display panel in which memory circuits are provided in a matrix, and performs display using a data signal potential written to the memory circuit for each frame.
- a display device driving method having a normal mode and a memory mode in which a display is performed by refreshing and holding a data signal potential written in the memory circuit, wherein the display panel includes a data signal line, a scanning signal line And the auxiliary capacitance line and the common electrode, and the memory circuit selectively turns on and off the pixel electrode and the data signal line and the pixel electrode in accordance with the potential of the scanning signal line.
- a first switch circuit a first capacitor formed between the pixel electrode and the auxiliary capacitance line, and a refresh that controls refresh of the potential of the pixel electrode.
- the change in the potential is This is performed while the potential of the data signal line is fixed and the pixel circuit of the memory circuit is electrically connected to the data signal line with the first switch circuit in a conductive state.
- the change in the potential is performed. Is performed while the potential of the data signal line is fixed and the first switch circuit is turned on to electrically connect the pixel electrode of the memory circuit to the data signal line. That is, with the pixel electrode of the memory circuit fixed, the potential of the common electrode and the potential of the storage capacitor line are changed (transitioned) to a predetermined potential. As a result, the pixel electrode of the memory circuit is not affected by fluctuations, and thus screen noise can be prevented.
- the potential fixed to the data signal line when the potential is changed is the same as the potential of the common electrode.
- the potential fixed to the data signal line when changing the potential is the same as the potential of the common electrode.
- the display panel includes a data transfer line and a refresh output line
- the refresh control unit includes a memory electrode and the pixel electrode according to the potential of the data transfer line.
- a second switch circuit that selectively conducts and shuts off the memory electrode; and supplies a potential for refreshing the potential of the pixel electrode according to the potential of the refresh output line and the memory electrode And a second capacitor formed between the memory electrode and the auxiliary capacitance line.
- control unit supplies a potential for refreshing the potential of the pixel electrode in the memory circuit, refresh from the outside of the memory circuit becomes unnecessary. Therefore, power consumption related to refresh can be reduced.
- the memory circuit further includes a potential supply source
- the control unit includes the potential supply source and the pixel electrode according to the potentials of the refresh output line and the memory electrode. It is preferable that the third switch circuit selectively performs conduction and interruption between the two.
- control unit can be realized with a configuration that does not use an inverter, an increase in power consumption due to a through current can be avoided, and the pixel electrode and the memory electrode can hold the same potential. By doing so, it is possible to avoid malfunction even if an off-leakage current exists in the transfer element used in the second switch circuit.
- the capacitance value of the first capacitor is larger than the capacitance value of the second capacitor, and the third switch circuit conducts and cuts off the potential held in the memory electrode.
- a first switch serving as a control signal; and a second switch using the potential of the refresh output line as a control signal for shutting off the continuity.
- the first switch and the second switch are connected to the potential supply source.
- the third switch circuit is preferably connected in series between the input of the third switch circuit and the output of the third switch circuit connected to the pixel electrode.
- the potential of the memory electrode is changed to the conductive state by the charge transfer between the first capacitor and the second capacitor only by making the second switch circuit conductive. It becomes easy to make it close to the potential of the pixel electrode before. This effect increases as the capacitance value of the first capacitor is larger than the capacitance value of the second capacitor. Further, according to the above configuration, after writing the data signal potential to the pixel electrode, the potential for refreshing the pixel electrode is selectively supplied from the potential supply source to the memory circuit without using an inverter. The configuration can be easily realized.
- the first switch circuit, the second switch circuit, the first switch, and the second switch are N-channel field effect transistors.
- the first switch circuit, the second switch circuit, the first switch, and the second switch are N-channel field effect transistors having the same polarity
- the first switch circuit, The two-switch circuit, the first switch, and the second switch can be simultaneously formed in the memory circuit, and the manufacturing process is facilitated.
- the memory circuit can be manufactured using amorphous silicon because of the N-channel type.
- the first switch circuit, the second switch circuit, the first switch, and the second switch are preferably P-channel field effect transistors.
- the first switch circuit, the second switch circuit, the first switch, and the second switch are P-channel field effect transistors having the same polarity, the first switch circuit, The two-switch circuit, the first switch, and the second switch can be simultaneously formed in the memory circuit, and the manufacturing process is facilitated.
- the present invention can be suitably used in the field related to a memory-type display device having a memory function and capable of performing display with data refreshed and held, as well as a display device driving method and display device manufacture.
- the present invention can be suitably used in a field related to a method, and can also be widely used in a field related to various electronic devices such as a display of a mobile phone.
- Liquid crystal display device (display device) 11 pixel array 12 drive signal generation circuit / video signal generation circuit 13 demultiplexer 14 gate driver / CS driver 15 control signal buffer circuit 20 pixel memory MR1, MR100 memory circuit SW1, SW100 switch circuit (first switch circuit) TS1, TS100 Data transfer unit (refresh control unit, second switch circuit) RS1 refresh output control unit (refresh control unit, control unit, third switch circuit) RS100 Refresh output control unit (refresh control unit, control unit) DS1, DS101 First data holding unit DS2, DS102 Second data holding unit VS1 supply source (potential supply source) Ca1, Ca100 capacity (first capacity) Cb1, Cb100 capacity (refresh control unit, second capacity) COM Common electrode Clc Liquid crystal capacitance PIX Node (pixel electrode) MRY node (refresh controller, memory electrode) N1, N2 transistor N3 transistor (first switch) N4 transistor (second switch) SL (j) (1 ⁇ j ⁇ m), SLx source line (data
Abstract
Description
本発明の一実施形態について図面に基づいて説明すれば、以下の通りである。なお、本実施の形態において説明すること以外の構成は、前記背景技術と同じである。また、説明の便宜上、前記の背景技術の図面に示した部材と同一の機能を有する部材については、同一の符号を付し、その説明を省略する。
本発明の他の実施の形態について図面に基づいて説明すれば、以下の通りである。
を出力するとともに、ゲートドライバ/CSドライバ14に信号s2を、制御信号バッファ回路15に信号s3をそれぞれ出力する。
ステップAでは、駆動信号発生回路/映像信号発生回路12およびデマルチプレクサ13からソースラインSLに第1の電位のデータまたは第2の電位のデータを供給した状態、かつ、リフレッシュ出力制御部RS1に第2の動作を行わせた状態としてスイッチ回路SW1を導通させることにより画素メモリ20に上記データを書き込み、画素メモリ20に上記データが書き込まれた状態、かつ、リフレッシュ出力制御部RS1に第2の動作を行わせた状態としてデータ転送部TS1によって転送動作を行う。
ステップBでは、ステップAに続いて、リフレッシュ出力制御部RS1に第2の動作を行わせた状態、かつ、データ転送部TS1に非転送動作を行わせた状態としてスイッチ回路SW1を導通させることにより、リフレッシュ出力制御部RS1をアクティブ状態とする制御情報に相当するレベルと同じ電位のデータをソースラインSLを介して第1データ保持部DS1に入力する。
ステップCでは、ステップBに続いて、スイッチ回路SW1を遮断した状態、かつ、データ転送部TS1に非転送動作を行わせた状態としてリフレッシュ出力制御部RS1によって第1の動作を行うとともに、第1の動作の終了時には供給源VS1からリフレッシュ出力制御部RS1の入力にリフレッシュ出力制御部RS1をアクティブ状態とする制御情報に相当するレベルの反転レベルのデータを供給している状態とする。
ステップDでは、ステップCに続いて、スイッチ回路SW1を遮断した状態、かつ、リフレッシュ出力制御部RS1に第2の動作を行わせた状態としてデータ転送部TS1によって転送動作を行う。
11 画素アレイ
12 駆動信号発生回路/映像信号発生回路
13 デマルチプレクサ
14 ゲートドライバ/CSドライバ
15 制御信号バッファ回路
20 画素メモリ
MR1,MR100 メモリ回路
SW1,SW100 スイッチ回路(第1スイッチ回路)
TS1,TS100 データ転送部(リフレッシュ制御部、第2スイッチ回路)
RS1 リフレッシュ出力制御部(リフレッシュ制御部、制御部、第3スイッチ回路)
RS100 リフレッシュ出力制御部(リフレッシュ制御部、制御部)
DS1,DS101 第1データ保持部
DS2,DS102 第2データ保持部
VS1 供給源(電位供給源)
Ca1,Ca100 容量(第1容量)
Cb1,Cb100 容量(リフレッシュ制御部、第2容量)
COM 共通電極
Clc 液晶容量
PIX ノード(画素電極)
MRY ノード(リフレッシュ制御部、メモリ用電極)
N1,N2 トランジスタ
N3 トランジスタ(第1スイッチ)
N4 トランジスタ(第2スイッチ)
SL(j)(1≦j≦m),SLx ソースライン(データ信号線)
GL(i)(1≦i≦n),GLx ゲートライン(走査信号線)
DT(i)(1≦i≦n),DTx データ転送制御線(データ転送線)
RC(i)(1≦i≦n),RCx リフレッシュ出力制御線(リフレッシュ出力線)
CS(i)(1≦i≦n),CSx 補助容量線
Claims (9)
- メモリ回路がマトリクス状に設けられた表示パネルを備え、上記メモリ回路にフレームごとに書き込んだデータ信号電位により表示を行う通常モードと、上記メモリ回路に書き込んだデータ信号電位をリフレッシュしながら保持して表示を行うメモリモードとを有する表示装置であって、
上記表示パネルは、データ信号線と、走査信号線と、補助容量線と、共通電極とを備え、
上記メモリ回路は、画素電極と、上記走査信号線の電位に応じて上記データ信号線と上記画素電極との間の導通と遮断とを選択的に行う第1スイッチ回路と、上記画素電極と上記補助容量線との間に形成された第1容量と、上記画素電極の電位のリフレッシュを制御するリフレッシュ制御部とを含み、
上記共通電極と上記補助容量線とのそれぞれについて、上記通常モードと上記メモリモードとの切替に伴って電位を変化させる必要がある場合には、当該電位の変化は、上記データ信号線の電位を固定し、上記第1スイッチ回路を導通状態として上記メモリ回路の画素電極を当該データ信号線に電気的に接続している間に行われることを特徴とする表示装置。 - 上記電位の変化が行われるときに上記データ信号線に固定される電位は、上記共通電極の電位と同電位にされることを特徴とする請求項1に記載の表示装置。
- 上記表示パネルは、データ転送線と、リフレッシュ出力線とを備え、
上記リフレッシュ制御部は、メモリ用電極と、上記データ転送線の電位に応じて上記画素電極と上記メモリ用電極との間の導通と遮断とを選択的に行う第2スイッチ回路と、上記リフレッシュ出力線および上記メモリ用電極の電位に応じて上記画素電極の電位をリフレッシュするための電位を供給する制御部と、上記メモリ用電極と上記補助容量線との間に形成された第2容量とを含むことを特徴とする請求項1または2に記載の表示装置。 - 上記メモリ回路は、電位供給源をさらに備え、
上記制御部は、上記リフレッシュ出力線および上記メモリ用電極の電位に応じて上記電位供給源と上記画素電極との間の導通と遮断とを選択的に行う第3スイッチ回路であることを特徴とする請求項3に記載の表示装置。 - 上記第1容量の容量値は、上記第2容量の容量値よりも大きく、
上記第3スイッチ回路は、上記メモリ用電極に保持されている電位を導通遮断の制御信号とする第1スイッチと、上記リフレッシュ出力線の電位を導通遮断の制御信号とする第2スイッチとを備えており、
上記第1スイッチと上記第2スイッチとは、上記電位供給源に接続される当該第3スイッチ回路の入力と上記画素電極に接続される当該第3スイッチ回路の出力との間に、互いに直列に接続されていることを特徴とする請求項4に記載の表示装置。 - 上記第1スイッチ回路、上記第2スイッチ回路、上記第1スイッチ、および上記第2スイッチは、Nチャネル型の電界効果トランジスタであることを特徴とする請求項5に記載の表示装置。
- 上記第1スイッチ回路、上記第2スイッチ回路、上記第1スイッチ、および上記第2スイッチは、Pチャネル型の電界効果トランジスタであることを特徴とする請求項5に記載の表示装置。
- メモリ回路がマトリクス状に設けられた表示パネルを備え、上記メモリ回路にフレームごとに書き込んだデータ信号電位により表示を行う通常モードと、上記メモリ回路に書き込んだデータ信号電位をリフレッシュしながら保持して表示を行うメモリモードとを有する表示装置の駆動方法であって、
上記表示パネルは、データ信号線と、走査信号線と、補助容量線と、共通電極とを備え、
上記メモリ回路は、画素電極と、上記走査信号線の電位に応じて上記データ信号線と上記画素電極との間の導通と遮断とを選択的に行う第1スイッチ回路と、上記画素電極と上記補助容量線との間に形成された第1容量と、上記画素電極の電位のリフレッシュを制御するリフレッシュ制御部とを含み、
上記共通電極と上記補助容量線とのそれぞれについて、上記通常モードと上記メモリモードとの切替に伴って電位を変化させる必要がある場合には、当該電位の変化を、上記データ信号線の電位を固定し、上記第1スイッチ回路を導通状態として上記メモリ回路の画素電極を当該データ信号線に電気的に接続している間に行うことを特徴とする表示装置の駆動方法。 - 上記電位の変化を行うときに上記データ信号線に固定する電位を、上記共通電極の電位と同電位とすることを特徴とする請求項8に記載の表示装置の駆動方法。
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US13/395,697 US8743042B2 (en) | 2009-09-16 | 2010-04-23 | Display device and drive method for display device |
JP2011531815A JP5485282B2 (ja) | 2009-09-16 | 2010-04-23 | 表示装置および表示装置の駆動方法 |
EP10816926A EP2479745A4 (en) | 2009-09-16 | 2010-04-23 | DISPLAY DEVICE AND CONTROL METHOD FOR DISPLAY DEVICE |
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SG11201400740TA (en) * | 2011-08-02 | 2014-08-28 | Sharp Kk | Liquid crystal display device and method for driving auxiliary capacitance lines |
US9311867B2 (en) * | 2012-11-13 | 2016-04-12 | Apple Inc. | Devices and methods for reducing power consumption of a demultiplexer |
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EP2124221A4 (en) * | 2007-03-16 | 2011-02-16 | Sharp Kk | LIQUID CRYSTAL DISPLAY APPARATUS, AND CONTROL METHOD |
JP4981928B2 (ja) * | 2007-12-28 | 2012-07-25 | シャープ株式会社 | 表示駆動回路及び表示装置 |
JP5206397B2 (ja) * | 2008-02-19 | 2013-06-12 | 株式会社Jvcケンウッド | 液晶表示装置及び液晶表示装置の駆動方法 |
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JP2002229532A (ja) | 2000-11-30 | 2002-08-16 | Toshiba Corp | 液晶表示装置及び液晶表示装置の駆動方法 |
JP2002175051A (ja) | 2000-12-06 | 2002-06-21 | Toshiba Corp | 表示装置の駆動方法 |
JP2003114651A (ja) * | 2001-10-03 | 2003-04-18 | Matsushita Electric Ind Co Ltd | 液晶表示装置および駆動方法 |
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US8743042B2 (en) | 2014-06-03 |
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