JP5062388B2 - Display panel and display device - Google Patents

Description

The present invention relates to a display device using the display panel having a memory means for storing data for driving a liquid crystal display unit and, more specifically, the display unit such as a liquid crystal display unit in standby mode there is provided a display device using the same and a display panel having a function of holding data for generating a voltage for driving the.

A display unit of a liquid crystal display device as a conventional example is composed of, for example, a liquid crystal display panel and peripheral circuits such as a data processing circuit, a signal generation circuit having a timing generation circuit, a horizontal drive circuit, a vertical drive circuit, and a power supply circuit. .
In the data processing circuit, display data is read according to the timing signal supplied from the signal generation circuit, and this display data is held and supplied to the horizontal drive circuit.
The horizontal drive circuit converts the display data supplied from the data processing circuit into an analog signal by the DA conversion circuit and supplies it to the horizontal line of the active matrix LCD panel according to the timing signal. As a result, the signal selected by the vertical drive circuit The display data voltage is supplied to the intersection with the line.
In the active matrix LCD panel, a voltage corresponding to the display data of the intersection sequentially selected by the horizontal drive circuit and the vertical drive circuit is held, and characters, images, etc. corresponding to the display data are displayed in color.
In the power supply circuit, for example, two or four types of common voltages (common electrode voltage; VCOM) are generated. The common voltage is supplied to the vertical drive circuit via the selection circuit, and the common voltage and the source voltage are alternately inverted for each field or frame in accordance with a control signal supplied from the control circuit. It was.

In Patent Document 1 (Japanese Patent Laid-Open No. 7-152347), the liquid crystal display device is provided with a CPU, two gamma correction data storage means, a gamma correction circuit, and the like to perform gamma correction.
After turning on the power, external and internal CPUs, gamma correction circuits, etc. are operated, and test signal data signals, mode switching signals, and gate control signals are output from the external CPU, and the test signal data is supplied to the gamma correction circuit and internal CPU. The
An address is output from the address decoder by the internal CPU, the latch circuit is selected, and the test signal data is D / A converted and then supplied to the liquid crystal panel.
The gamma characteristic of the liquid crystal panel is measured based on the test signal data and temporarily stored in the external CPU. Further, gamma characteristic correction data is obtained by the external CPU, and the gamma correction data is stored in the first storage means.

Next, the switch is switched to the second storage means for storing the gamma correction data by the switch, and the gamma correction data stored in the storage means of the external CPU is transferred and stored in the internal first storage means.
Then, the internal storage unit is selected by the internal CPU, gamma correction data not considering the gamma characteristic of the video signal not subjected to gamma correction is read out and input to the gamma correction circuit, and the correction data is written in the second storage unit. .
As described above, two storage units are provided, and the gamma correction data not considering the gamma characteristic of the video signal not subjected to the gamma correction and the gamma correction data considering the gamma correction are stored in different first and second storage units. ing.
As a result, two types of storage means are provided, and switching between the storage means makes it possible to adapt to either a video signal considering gamma correction or a video signal not subjected to gamma correction.

As described above, in the conventional liquid crystal display unit, the output terminal of the external CPU is connected to the input terminal of the liquid crystal unit. However, control signals and input data are supplied from the CPU. However, the above-described Patent Document 1 does not disclose a circuit, a system configuration, and an operation related to data setting and resetting of storage means related to the standby mode.
In general, an input terminal to which an STB (standby) mode signal is supplied is provided at a terminal other than the external CPU, and the normal operation mode and the STB mode are switched.
Further, the standby mode power supply (PVDD1) is also supplied to the liquid crystal display unit via the input terminal in response to the STB mode signal.

As described above, conventionally, in the drive circuit of the liquid crystal display device, it was difficult to generate a reset pulse from the power source in the standby mode because of the system configuration, and thus the liquid crystal display device was formed on the insulating substrate on which the display panel was formed. The system was such that all the circuits were reset.
For example, VCOM voltage data and γ correction data for driving the liquid crystal are reset, and it is necessary to set these data again when the power is turned on.
Therefore, when the standby mode is canceled, it is necessary to give an input signal from the set side again.
Japanese Patent Laid-Open No. 7-152347 JP 2001-222262 A

As described above, when the liquid crystal display unit is released from the standby mode, it is necessary to supply an input signal from the set side again to input VCOM voltage data and γ (gamma) correction data, and to control the system by an external CPU. There was a load.
In order to reduce this system load, the present invention has a storage means for generating a reset signal in the liquid crystal unit or an insulating substrate on which the liquid crystal display substrate is configured without receiving an STB mode signal from the outside of the liquid crystal display unit. A drive circuit is provided.
Further, this drive circuit holds, for example, the VCOM voltage (common electrode voltage) and the gamma correction value during the STB (standby) mode period, thereby eliminating the need to set data again from the standby mode to the normal operation rising edge.
By adopting such a configuration, the system configuration is further simplified.

The display panel of the present invention includes an insulating substrate, a display unit formed on the insulating substrate, and a driving unit that is formed on the insulating substrate and drives the display unit, and the driving unit is turned on. is driven by the power supply voltage supplied from the outside in response to an input circuit for inputting the gamma correction data for performing gamma correction on the input video signal, to have a possible storage means holding said data A driving circuit that operates with an external power supply voltage that is supplied during driving and stopped during standby, and drives the display unit, and the storage means holds data during a period when the power supply voltage is supplied are possible, the standby time of holding the final of the gamma correction data at the time immediately before the drive, the said until the rewriting of the gamma correction data were retained gamma correction de after driving resumption You maintain the output state of the data.
The display panel of the present invention includes an insulating substrate, a display unit formed on the insulating substrate, and a driving unit that is formed on the insulating substrate and drives the display unit, and the driving unit includes: An input circuit that is driven by a power supply voltage supplied from the outside in response to power-on, inputs VCOM voltage data serving as a reference of a video signal for driving the pixels, and has a storage means capable of holding the data; A driving circuit that operates with an external power supply voltage that is supplied at the time of driving and stopped at the time of standby, and drives the display unit, and the storage means holds data during a period when the power supply voltage is supplied The data of the last VCOM voltage at the time of the previous driving is held during the standby, and the VCOM voltage held until the data of the VCOM voltage is rewritten after the driving is resumed Maintaining the output state of the pressure data.

The display device of the present invention includes a display panel, a power supply unit that supplies a power supply voltage to the display panel, a control unit, and a power switch that controls the shutoff of the power supply voltage under the control of the control unit, The display panel includes an insulating substrate, a display unit formed on the insulating substrate, and a driving unit that is formed on the insulating substrate and drives the display unit. The driving unit is connected to the power source unit. Storage means that is driven by a power supply voltage supplied without going through the power switch and receives gamma correction data for performing gamma correction on an input video signal from the control unit, and can hold the data. an input circuit for chromatic, the power supply voltage from the power supply unit during operation is operated by being supplied through the power switch turned on to drive the display unit, of the power switch in the standby And a drive circuit for the power supply is stopped by the full, the storage unit, the period in which power supply voltage is supplied is capable of data retention, the last of the gamma correction data at the time immediately before the drive during the standby It holds, until the rewriting of the gamma correction data after the drive resumption that to maintain the output state of the gamma correction data is retained.
Further, the display device of the present invention includes a display panel, a power supply unit that supplies a power supply voltage to the display panel, a control unit, and a power switch that controls the interruption of the power supply voltage under the control of the control unit. The display panel includes: an insulating substrate; a display unit formed on the insulating substrate; and a driving unit that is formed on the insulating substrate and drives the display unit. A storage unit that is driven by a power supply voltage supplied from the control unit without passing through the power switch and that receives VCOM voltage data serving as a reference of a video signal for driving the pixel from the control unit, and can store the data. An input circuit having a power supply voltage supplied from the power supply unit through an on-state power supply during driving to drive the display unit and to turn off the power supply switch during standby The storage circuit is capable of holding data during a period when the power supply voltage is supplied, and the data of the final VCOM voltage at the time of the previous drive during the standby. And the output state of the data of the held VCOM voltage is maintained until the data of the VCOM voltage is rewritten after the driving is resumed.

The liquid crystal display device of the present invention is provided with a drive circuit that generates a reset signal in the liquid crystal unit or an insulating substrate on which the liquid crystal display substrate is configured without receiving an STB mode signal from the outside of the liquid crystal display unit. By configuring the storage means in this drive circuit, for example, the VCOM voltage and the gamma correction value can be held during the STB mode period, and there is no need to set data again from the standby mode to the normal operation rising.
With such a configuration, the load on the external CPU can be reduced and the system configuration can be further simplified.

Hereinafter, embodiments of the present invention of a liquid crystal display device will be described with reference to the drawings.
FIG. 1 is a block diagram showing the overall configuration of a liquid crystal display device 10 of the present invention.
As shown in the block diagram of FIG. 1, the configuration of the liquid crystal display device 10 includes a liquid crystal panel (display unit) 11 which is a liquid crystal (effective display area) panel 12, and RefDriver G13, RefDriver RB14, InterFace15, VCOM Driver16, and others in its outer peripheral region. A vertical drive circuit, a horizontal drive circuit, a timing signal generation circuit, and a power supply circuit (not shown) are included.
Further, the outside of the liquid crystal panel includes a set power source 17, an external CPU (microcomputer) 18, STB SW1 (standby switch), and the like.

The effective display area 12 of the liquid crystal panel 11 is composed of liquid crystal cells arranged in a matrix, and the liquid crystal cell is composed of a polysilicon TFT (Thin Film Transistor) as a switching element and an auxiliary capacitor. The TFT is driven using a horizontal drive circuit and a vertical drive circuit, an electric field is applied to the liquid crystal, and the light transmittance is varied according to the electric field level.
Further, the voltage applied to the source of the TFT is set so that a different voltage is supplied for each field or frame, and becomes a positive or negative inversion signal centering on the VCOM voltage (common electrode voltage). .

  The RefDriver G (reference driver G) 13 generates a voltage for driving the G (green) pixel of the liquid crystal panel 12 based on the signal level of the G (green) signal output from the Interface (interface) 15. Similarly, the RefDriver RB (reference driver RB) 14 also generates voltages for driving the R (red) and B (blue) pixels of the liquid crystal panel 12 based on the RB signal output from the Interface (interface) 15.

A horizontal drive circuit (not shown) includes a sampling latch, a (second) latch, a level shift circuit, a DAC (digital / analog converter), and the like. The sampling latch latches input data according to the raster scanning order for pixels in the line direction.
The (second) latch latches (gradation) data output from the sampling latch at a horizontal scanning cycle, and supplies the data to the subsequent level shift circuit in line units.
The level shift circuit converts the data output from the (second) latch into a level that can drive the subsequent DAC and outputs the converted level. Since this DAC is generally composed of an N-channel or P-channel MOS transistor, it is necessary to adjust the input of the DAC to a signal level (voltage) that can be digitally driven.
Since the DAC receives the gradation data supplied from the level shift circuit as a digital signal, it converts the input digital signal (data) into an analog signal. Then, an analog voltage corresponding to the input digital data is generated, and this analog voltage is supplied to the TFT source of the liquid crystal cell selected according to the timing.

  A vertical drive circuit (not shown) sequentially selects row lines of liquid crystal cells arranged in a matrix and supplies a gate pulse to the gate of the TFT. As a result, the TFTs at the intersections of the row (row) lines and the column (column) lines are sequentially turned on, and the liquid crystal panel (effective display area) 12 can display an image corresponding to the gradation data.

A timing generation circuit (not shown) supplies a timing signal to a horizontal driving circuit and a vertical driving circuit so that horizontal scanning, vertical scanning, and the like can be performed.
A VCOMDriver (common electrode voltage driving circuit) 16 generates a VCOM voltage according to a digital signal (data) output from the interface 15 and supplies the VCOM voltage to the common electrode of each cell of the liquid crystal panel.

The set power supply 17 not only supplies voltage to the liquid crystal display and its peripheral circuits, but also supplies voltage to the entire set. For example, power is supplied to the entire mobile phone device.
A CPU (microcomputer) 18 performs system control of a set such as a mobile phone device, and also transfers, for example, VCOM adjustment data, gamma correction data (VC0 to VC5), etc. to the Interface 15. Further, power on / off control during STB (standby) is performed via SW1, and supply of voltage VDD1 to the VCMDdriver 16 of the liquid crystal display device and other circuit power supplies is stopped during standby. When the standby period is canceled, SW1 is turned on to supply the voltage VDD1 to VCMDdriver and other circuit power supplies.

Next, the operation of the liquid crystal display device 10 shown in FIG. 1 will be described.
In the normal operation, SW1 is set to ON by the CPU 18, and the voltage VDD1 is supplied to the VCMDdriver 16 and other circuit power supplies. In addition, other circuits are also supplied with the voltage PVDD1 from the set power supply 17 and become in an operating state.
The storage means built in the Interface 15 is reset when the power is turned on, and after that, data can be rewritten (details will be described later), and the rewritten data is supplied to the RefDriver G13, RefDriver RB14 and VCOMMDriver 16, and each color (R, G , B) and the VCOM voltage are set.

  On the other hand, image input data is supplied to a horizontal drive circuit, and digital data of the input data is converted into an analog signal by a DAC and supplied to a TFT source of a liquid crystal cell according to a horizontal timing signal. The column (row) lines are sequentially driven in the vertical direction in accordance with the vertical timing signal, and an image is displayed according to the signal level output from the DAC of the horizontal drive circuit.

In the standby (pause) mode, the CPU 18 sets SW1 to OFF, and the supply of the voltage VDD1 to the VCOMMDriver 16 and other circuit power supplies is stopped. However, the other circuits are in an operating state when the voltage PVDD1 is supplied from the set power source 17.
In the standby mode, the data stored in the storage means built in the Interface 15 holds the final value.
That is, data (a combination of VC0 and VC1 to VC5) supplied from the CPU 18 is held in the storage unit of the Interface 15. As a result, when the transition from the standby mode to the normal mode is performed, the data stored in the storage means can be used, so there is no need to perform initialization again using the external CPU 18 again.
The advantage of using the setting data held in the storage means is that the data VC0 to VC5 output from the CPU 18 to the Interface 15 cannot be serially output on the set side, or the VCOM adjustment is not performed digitally but analogly. It is set to a certain value on the insulating substrate (liquid crystal display device 11), and can display as requested by a set only with a certain DC (direct current) value from the outside.

Next, an embodiment of the interface 15 is shown in FIG.
A voltage PVDD1 is supplied from the set power supply 17 to an input terminal of a RamRSTgen (ram reset signal generation circuit) 51, an output terminal is connected to a reset terminal of a phase correction circuit 56 and a RamBlock (storage means) 55, and PVDD1 delayed by a predetermined time. Is supplied as a reset signal (RamRST).
Vsync (vertical synchronization signal) and Hsync (horizontal synchronization signal) inverted by the inverter INV3A are supplied to the input terminal of the ED3 (edge signal generation circuit) 52, and a V synchronization edge signal synchronized with Hsync is output from the output terminal. The

The output terminal of ED3 is connected to one input terminal of AND3A and AND3B, and the VC0 signal is input to the other input terminal of AND3A. The other input terminal of AND3B is supplied with VC0 via INV3B.
The output terminal of AND3A is connected to the input terminal of BUF (buffer) 3A, and this output terminal is connected to the Wgam (gamma correction write) terminal of RamBlock55. The output terminal of AND3A is connected to the input terminal of INV3C, this output terminal is connected to the input terminal of BUF3B, and the output terminal is connected to the xWgam (inversion of Wgam) input terminal of RamBlock55.

  On the other hand, the output terminal of AND3B is connected to the input terminal of BUF (buffer) 3C, and this output terminal is connected to the WVCOM (VCOM write) terminal of RamBlock55. The output terminal of AND3B is connected to the input terminal of INV3D, this output terminal is connected to the input terminal of BUF3D, and the output terminal of BUF3D is connected to the xWVCOM (inversion of WVCOM) input terminal of RamBlock55.

The output terminal of the CPU 18 shown in FIG. 1 is connected to each input terminal (in) of DFFA to DFFE constituting the phase correction circuit 56. The output terminal of ED3 is also connected to the ck (clock) input terminal of DFFA to DFFE so that the digital data of VC1 to VC5 are supplied in synchronization with the edge of the vertical synchronizing signal (Vsync).
Further, the output terminal of the RamRSTgen 51 described above is connected to the rst (reset) terminal of each DFF (D-type flip-flop) A to DFFE, and a delayed RamRST (ram reset) signal of PVDD1 is supplied.

The output terminals of each DFF (D-type flip-flop) A to DFFE are respectively connected to the input terminals of sel1 to sel5 of RamBlock55, and the data of VC1 to VC5 stored in DFFA to DFFE is synchronized with the V synchronization edge signal. And output to RamBlock55.
Further, the RamBlock 55 has a RamRST terminal in addition to the input terminals of sel1 to sel5. The RamBlock 55 is connected to the output of the RamRSTgen 51 and supplied with a reset signal, so that VCOM and gamma correction data are reset, for example, when the power is turned on.
Further, the VCOM adjustment signal and the γ (gamma) adjustment signal stored in the RamBlock 55 are output in accordance with the control signals of Wgam, xWgam, WVCOM, and xWVCOM.

When VC0 is at "L" level, the output of AND3A is at "L" level, so Wgam is at "L" level and xWgam is at "H" level. On the other hand, the output of AND3B becomes “H” level in synchronization with the V sync edge signal from ED3, WVCOM becomes “H” level, xWVCOM becomes “L” level, and RamBlock55 is written and controlled according to these signal levels. .
When VC0 is at "H" level, the output of AND3A is at "H" level in synchronization with the V sync edge signal output from ED3. At this time, Wgam is at “H” level and xWgam is at “L” level. On the other hand, since the output of the AND3B becomes “L” level, WVCOM becomes “L” level and xWVCOM becomes “H” level, and the RamBlock 55 is controlled to be written according to these signal levels.

Next, an embodiment of the RamRSTgen (ram reset signal generating circuit) 51 shown in FIG. 2 is shown in FIGS. 3, 4A, and 4B.
FIG. 3 shows a specific circuit configuration of the RamRSTgen 70 (51). The output terminal of the set power source 17 shown in FIG. 1 is connected to the input terminal Tin, and the voltage PVDD1 is supplied. The input terminal Tin is connected to the input terminal of the BUF 3-1, and the output terminal is connected to one input terminal of the AND 3-1. The output terminal of the AND 3-1 is connected to the output terminal Tout via the BUF 3-3.
The input terminal Tin is connected to the input terminal of INV3-1, and the output terminal is connected to the input terminal of the next stage INV3-2 and also connected to the ground via the capacitor C1.
The output of INV3-2 is connected to the input of INV3-3 and connected to the ground via a capacitor C2.
Thereafter, the same connection configuration is repeated from INV3-3, C3 to INV3-8, C8. The output terminal of INV3-8 is connected to the input terminal of BUF3-2, and the output terminal is connected to the other input terminal of AND3-1.
Among INV3-1 to INV3-8, odd-numbered INVs have the same circuit configuration (described as 6-1), and even-numbered INVs have the same circuit configuration (described as 6-2).

Next, the operation of the RamRSTgen circuit 70 will be described.
When the voltage PVDD1 is supplied from the set power supply 17, it rises at a predetermined time constant at t0 in the timing chart of FIG. 5, and becomes a constant voltage at time t1. The PVDD1 voltage is supplied to the BUF 3-1, and is supplied to the input terminal of the AND circuit 3-1.
On the other hand, the voltage PVDD1 is supplied to the input of the BUF3-2 as a waveform delayed by a predetermined time by a delay circuit composed of INV3-1 to INV3-8 and capacitors C1 to C8, and the output thereof is the other input terminal of the AND3-1. To be supplied.
A logical product is obtained by AND 3-1, a signal in which both input waveforms are at “H” level is taken out, and a RamRST signal is derived from the output terminal Tout through BUF 3-3 (FIG. 5E).
As described above, INV3-1, INV3-3, INV3-5, and INV3-7 have the same circuit configuration, and set the operation speed at which the voltage of the INV output falls. INV 3-2, INV 3-4, INV 3-6, and INV 3-8 have the same circuit configuration, and set the operation speed of the rise of the voltage of the INV output.

Next, FIG. 4 shows an embodiment of each circuit configuration of INV3-1 to INV3-8 shown in FIG.
In the circuit configuration shown below, an arbitrary time constant is formed by using an ON resistance of an INV (inverter) and a capacitor, and an input signal is delayed. Since the ON resistance of INV used in FIGS. 4A and 4B can be set larger than the resistance value formed by the IC, the delay amount can be further increased.
FIG. 4A shows an embodiment of a circuit configuration of INV3-1, INV3-3, INV3-5, and INV3-7 that configure odd-numbered stages.
A power supply terminal to which the voltage PVDD1 is supplied is connected to the source of the PMOS transistor P1, and the drain is connected to the output OUT and the drain of the NMOS transistor N1. On the other hand, the input terminal is connected to the gate of each PMOS transistor P1 and the gates of the NMOS transistors N1 to Nn, and the source of the NMOS transistor N1 is connected to the drain of the NMOS transistor N2. Thereafter, the same connection is repeated, and the source of the NMOS transistor Nn-1 is connected to the drain of the NMOS transistor Nn, and the source of the NMOS transistor Nn is connected to the ground.
When the input voltage is equal to or lower than the threshold value, the NMOS transistors N1 to Nn are turned off, and the PMOS transistor P1 is turned on. As a result, a current flows from PVDD1 to the output terminal Out through the source and drain of the PMOS transistor. On the other hand, when the input voltage exceeds the threshold value, the PMOS transistor P1 is turned off, the NMOS transistor N1 to the NMOS transistor Nn is turned on, and a current flows from the output terminal Out to the ground through the NMOS transistors N1 to Nn. The potential of the output terminal Out decreases.
With this circuit configuration, the rising speed of the output waveform is reduced and the falling speed is increased.

On the other hand, FIG. 4B shows an embodiment of a circuit configuration of INV (inverter) that constitutes INV3-2, INV3-4, INV3-6, INV3-8P shown in FIG.
A power supply terminal to which the voltage PVDD1 is supplied is connected to the source of the PMOS transistor P1A, and the drain is connected to the source of the PMOS transistor P2A. On the other hand, the input terminal In is connected to the gates of the PMOS transistors P1A to PnA and the gates of the NMOS transistor N1A. The drain of the PMOS transistor P1A is connected to the source of the PMOS transistor P2A. Thereafter, similar connections are repeated, the drain of the PMOS transistor PnA is connected to the drain of the NMOS transistor NnA, and the source of the NMOS transistor NnA is connected to the ground.

When the input voltage is equal to or lower than the threshold value, the PMOS transistors P1A to PnA are turned on, and the NMOS transistor N1A is in the off state, so that current flows from the power source to the output terminal Out via the PMOS transistors P1A to PnA. Rises. When the input voltage further rises and exceeds the threshold value, the PMOS transistors P1A to PnA are turned off and the NMOS transistor N1A is turned on. As a result, a current flows from the output terminal Out to the ground via the NMOS transistor N1A. With this circuit configuration, the waveform at the output terminal rises faster and the falling speed slows down.

2 will be described with reference to FIGS. 1 and 5. FIG.
A voltage of PVDD1 is supplied from the set power source 17 shown in FIG. 1 (time t0 in FIG. 5), and becomes a constant value at time t1. At this time t1, Ram_H_out (FIG. 5G) transitions from the “L” level to the “H” level.
At time t2, a Ram reset (RamRST) signal is generated in which the voltage waveform of PVDD1 is delayed for a predetermined time by RamRSTgen51 at RamRSTgen51 (FIG. 5E). In a state where PVDD1 is at the “H” level, the STB switch SW1 is turned on by a control signal from the CPU 18, and VDD1 is supplied as the VCMDdriver 16 and other circuit power at time t4.

From time t0 to t5, an ON sequence is performed, and the period RamBlock55 from time t1 to t2 after the power supply of PVDD1 is turned on is reset. In the period Ram_H_out between time t1 and time t5, the initial value of the specified value = High is read into the RAM (RamBlock55) when the specified value = High when the “H” level is set, and the specified value = Low is read when the Ram_L_out is the “L” level. The specified value is set after the power is turned on.
At the time t4, the RamBlock 55 is reset first at the time of the VDD11. At the time t4, the SW1 is controlled by the CPU 18 and the VDD1 is turned on. The waveform of the VDD1 rises, becomes a constant voltage at the time t5, and then maintains the “H” level until the time t11. (FIG. 5B). That is, this period set is in a normal operation (mode) state. Then, control data can be transferred while the data transfer path between the CPU 18 and the Interface 15 is in the Active state, and the control signal (data) VC is transferred to the Interface 15 in synchronization with the edge signal of Vsync (FIG. 5 (C), ( D)).
Data can be written to the RamBlock 55 during the period of time t6 to t11. Write data includes, for example, a VCOM voltage and a gamma correction value, and data is written according to Ram_L_out and Ram_H_out.
At time t11, the CPU 18 switches the switch SW1 to the off state, and stops the power supply of VDD1. At time t11, VDD1 changes to the “L” level.
The period from time t11 to t19 is called a standby mode period. The data written in RamBlock 55 during this period, for example, the above-mentioned VCOM voltage data and gamma correction data are held.
At time t18, VDD1 is supplied and becomes ON, and settles to a constant value of “H” level at time t19 (FIG. 5B). This state is maintained until time t25, and the above-described normal operation and operations similar to those at times t5 to t11 are repeated. That is, VC is active, and control data (VC1 to VC5) can be Ram rewritten to RamBlock 55 in accordance with Ram_L_out and Ram_H_out (FIGS. 5F and 5G).
At time t25, VDD1 changes from "H" level to "L" level (FIG. 5B), settles to "L" level at time t26, and maintains that state until time t30.
On the other hand, at time t29, the power supply of PVDD1 is turned off (FIG. 5A), and accordingly RamRST also changes from the “H” level to the “L” level. At time t30, PVDD1, RamRST, Ram_L_out, and Ram_H_out also become “L” level. Times t <b> 25 to t <b> 30 are referred to as an “off sequence” and hold the final set value written in the RamBlock 55.
Thereafter, when the power supply PVDD1 is turned on, the operations of the ON sequence, the normal operation, and the standby mode are performed by the operation from the time t0 described above.

  Next, an embodiment of an operation for writing data to the RamBlock 55 will be described with reference to FIGS. 2, 6, 7, and 8. As examples of data, two types of VCOM data (FIG. 7) and gamma (γ) correction data (FIG. 8) will be described. However, the example of data is not limited to this, and other data may be used. good.

6, PVDD1 becomes “H” level at time t50 (FIG. 6A), and the data of VC0 to VC5 is taken into DFFA to DFFE shown in FIG. 2 in synchronization with Vsync (the edge thereof).
At time t50, VC0 and VC1 to VC5 are all at the “L” level, and VCOMDC adjustment is performed when VC0 is at the “L” level. At this time, the voltage in the initial state of VCOMDC, for example, DC = 1.150 V is set in the VCOM register (FIG. 6 (I)) (see FIG. 7). This is a value automatically set when PVDD1 is started.
As described above, VC0 is at the “L” level during the period from time t51 to time t52. When VC0 is at "L" level, VCOMDC adjustment is set.
At time t51, the control data VC1 output from the CPU 18 is “H” level, VC2 is “L” level, VC3 is “H” level, V4 is “L” level, and V5 is “H” level. The signal is input to the input terminals in of DFFA to DFFE of the correction circuit 56 in synchronization with ck (clock). These data are written in sel1, sel2, sel3, sel4, and sel5 of RamBlock55, respectively. The VCOM data is digitally set as a value corresponding to 1.275 V with reference to FIG. Thereafter, this value is held at time (t52-).
Similarly, the data of VC1 to VC5 can be combined in 32 ways, and can be set to a DC level within a predetermined range as shown in FIG. Of course, other values may be set according to the system of the liquid crystal display device.

At time t52, VC0 becomes “H” level and is set to the gamma adjustment state. For example, the control data VC1 is “L” level, VC2 is “L” level, VC3 is “L” level, V4 is “H” level, and V5 is “L” level data of DFFA to DFFE of the phase correction circuit 56 The signal is input to the input terminal in in synchronization with ck (clock). These data are written in the γR (red gamma) registers of sel1, sel2, sel3, sel4, and sel5 of RamBlock55, respectively. Referring to FIG. 8, the gamma adjustment data input to the γR register is digitally set as a value corresponding to γ = 1.9.
The set data is held after time t53.
Similarly, at time t53, the control data VC1 is at “H” level, VC2 is at “H” level, VC3 is at “H” level, V4 is at “L” level, and V5 is at “H” level. Are input to the input terminals in of DFFA to DFFE in synchronization with ck (clock). These data are written in the γB (blue gamma) registers of sel1, sel2, sel3, sel4, and sel5 of RamBlock55. Referring to FIG. 8, the gamma adjustment data input to the γB register is digitally set as a value corresponding to γ = 2.5. The set data is retained after time t54.
Further, at time t54, the control data VC1 is “H” level, VC2 is “H” level, VC3 is “L” level, V4 is “H” level, and V5 is “H” level. The signals are input to the input terminals in of DFFA to DFFE in synchronization with ck (clock). These data are written to the γG (green gamma) registers of sel1, sel2, sel3, sel4, and sel5 of RamBlock55. The gamma adjustment data input to the γG register is digitally set as a value corresponding to γ = 2.35 with reference to FIG. The set data is retained after time t55.
As shown in FIG. 8, since there are three types of gamma adjustment, R, G, and B, there are only 32 combinations using VC1 to VC5 data, so each R, G, B has 3 bits (8 types). It is comprised by the data of.

As described above, according to the present invention, since the storage unit is provided on the insulating substrate on which the display panel is formed, data for driving the display panel can be prevented from being reset in the standby mode. Further, since the drive circuit is provided with a self-reset circuit, the output of the storage means can be reset and the output of the storage means can be set to a specified value when the power is turned on.
In the liquid crystal display device, the gamma correction of the storage means and the VCOM output data can be self-reset to a specified value when the power is turned on. Further, a display panel driving setting signal for setting the output of the storage means to a specified value during the standby period, for example, a VCOM voltage, gamma correction data, or the like can be held.
Therefore, when the standby mode is canceled, it is not necessary to provide an input signal from the set side again, the system can be simplified, and the load on the external CPU or the like can be reduced.

It is a block block diagram which shows the block of the liquid crystal display device of this invention. It is a circuit diagram which shows the structure of the interface comprised in the liquid crystal display device shown in FIG. FIG. 3 is a diagram showing a specific circuit configuration of a RamRSTgen circuit of the interface shown in FIG. 2. FIG. 4 is a circuit diagram illustrating a specific configuration example of an inverter configured in the RamRSTgen circuit illustrated in FIG. 3. FIG. 3 is a timing chart for explaining the operation of the liquid crystal display device shown in FIGS. 1 and 2. FIG. 3 is a timing chart for explaining the operation of the liquid crystal display device of FIG. 2. FIG. 7 is a diagram showing data for explaining the operation of the liquid crystal display device of FIGS. 2 and 6. FIG. 7 is a diagram showing data for explaining the operation of the liquid crystal display device of FIGS. 2 and 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device, 11 ... Liquid crystal panel, 13 ... RefDriverG (green reference driver; red drive circuit), 14 ... RefDriverRB (red, blue reference driver; red, blue drive circuit), 15, 50 ... InterFace (interface circuit) , 30 ... USB communication device, 16 ... VCOM Driver (common electrode drive circuit; VCOM), 17 ... Set power supply, 18 ... CPU (microcomputer), 51 ... RamRSTgen (ram reset signal generation circuit), 52 ... ED3 (edge signal) Generation circuit), 55 ... RamBlock (ram block, storage means), 56 ... phase correction circuit, INV3A to INV3D, INV3-1 to INV3-8 ... inverter, BUF3A to BUF3D, BUF3-1, BUF3-2 ... buff AND circuit, AND3A, AND3B, AND3-1 ... AND circuit, DFFA-DFFE ... D-type flip-flop, P1, P1A-P1nA ... PMOS transistor, N1-Nn, N1A ... NMOS transistor.

Claims (8)

An insulating substrate;
A display unit formed on the insulating substrate;
A drive unit that is formed on the insulating substrate and drives the display unit,
The drive unit is
It is driven by the power supply voltage supplied from the outside in response to power on, enter the gamma correction data for performing gamma correction on the input video signal, to have a possible storage means holding said data input Circuit,
A driving circuit that operates with an external power supply voltage that is supplied during driving and stopped during standby, and drives the display unit;
With
The storage means can hold data during a period when the power supply voltage is supplied, holds the final gamma correction data at the time of the previous drive during the standby, and rewrites the gamma correction data after the drive is resumed display panel that maintain the output state of the gamma correction data is retained until.   An insulating substrate;
  A display unit formed on the insulating substrate;
  A drive unit that is formed on the insulating substrate and drives the display unit,
  The drive unit is
  An input circuit that is driven by a power supply voltage supplied from the outside in response to power-on, inputs VCOM voltage data serving as a reference of a video signal for driving the pixels, and has a storage means capable of holding the data;
  A driving circuit that operates with an external power supply voltage that is supplied during driving and stopped during standby, and drives the display unit;
  With
  The storage means can hold data during a period when the power supply voltage is supplied, holds the data of the last VCOM voltage at the time of the previous driving during the standby, and rewrites the data of the VCOM voltage after the driving is resumed Until there is, the output state of the data of the held VCOM voltage is maintained.
  Display panel.   The input circuit includes a reset circuit that is connected to the storage unit and resets the content held in the storage unit when the power is turned on.
  The display panel according to claim 1. The display panel according to claim 3, wherein the display unit is a liquid crystal display unit. A display panel;
A power supply for supplying a power supply voltage to the display panel;
A control unit;
A power switch for controlling the interruption of the power supply voltage under the control of the control unit,
The display panel is
An insulating substrate;
A display unit formed on the insulating substrate;
A driving unit formed on the insulating substrate and driving the display unit;
Have
The drive unit is
Gamma correction data for performing gamma correction on the input video signal can be input from the control unit and held by the power supply voltage supplied from the power supply unit without passing through the power switch. an input circuit which have a Do storage means,
A drive circuit that operates when the power supply voltage from the power supply unit is supplied through the power switch in an on state during driving to drive the display unit, and the power supply is stopped by turning off the power switch during standby When,
With
The storage means can hold data during a period when the power supply voltage is supplied, holds the final gamma correction data at the time of the previous drive during the standby, and rewrites the gamma correction data after the drive is resumed display device to maintain the output state of the gamma correction data is retained until.   A display panel;
  A power supply for supplying a power supply voltage to the display panel;
  A control unit;
  A power switch for controlling the interruption of the power supply voltage under the control of the control unit,
  The display panel is
  An insulating substrate;
  A display unit formed on the insulating substrate;
  A driving unit formed on the insulating substrate and driving the display unit;
  Have
  The drive unit is
  A memory that is driven by a power supply voltage supplied from the power supply unit without passing through the power switch and that receives VCOM voltage data serving as a reference of a video signal for driving the pixels from the control unit, and can store the data An input circuit having means;
  A drive circuit that operates when the power supply voltage from the power supply unit is supplied through the power switch in an on state during driving to drive the display unit, and the power supply is stopped by turning off the power switch during standby When,
  With
  The storage means can hold data during a period when the power supply voltage is supplied, holds the data of the last VCOM voltage at the time of the previous driving during the standby, and rewrites the data of the VCOM voltage after the driving is resumed Until there is, the output state of the data of the held VCOM voltage is maintained.
  Display device.   The input circuit includes a reset circuit that is connected to the storage unit and resets the content held in the storage unit when the power is turned on.
  The display device according to claim 5 or 6. The display device according to claim 7, wherein the display unit is a liquid crystal display unit.

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