JP2002189437A - Liquid crystal display device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of preventing the reduction (distortion) of a column voltage due to a voltage drop. SOLUTION: This display device can detect the position (display position) of the row electrode concerned with display by a display position detecting circuit 102. Then, a BGB(back gate bias) voltage generating circuit 103 is set so as to adjust the value of a column voltage which is to be outputted from a column electrode driving IC 105 based on the detected display position. As a result, it is made possible to compensate (cancel) the effect due to the voltage drop by the increase of the column voltage value in this device. Thus, the lowering of an effective voltage value of the column voltage to be applied from the column electrode driving IC 105 to a distant display position is suppressed and the degradation of picture quality due to crosstalk can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matrix type liquid crystal display device and an electronic apparatus using the liquid crystal display device.

[0002]

2. Description of the Related Art Heretofore, an image display device formed by arranging pixels composed of liquid crystal, EL (electroluminescence), LED (light emitting diode) and the like in a matrix has been used.

[0003] Such a matrix type display device comprises a display section, a voltage generating circuit, a row electrode driving IC and a column electrode driving IC.
C is provided. The display unit (display screen) includes row electrodes and column electrodes arranged in a grid, and is configured to perform display at intersections (pixels) between the row electrodes and the column electrodes. The voltage generating circuit includes a voltage (row voltage) for driving the row electrode,
And a circuit for generating a voltage (column voltage) for driving the column electrode.

Further, a row electrode drive IC (row electrode drive circuit)
Connects a row electrode to a voltage generation circuit and applies a row voltage (VRH, VCM, VRL) output from the voltage generation circuit to the row electrode. Similarly, a column electrode drive IC (column electrode drive circuit) connects a column electrode and a voltage generation circuit,
The column voltages (VDH, VC, V
DL) is applied to the column electrodes.

A typical matrix type display device is a matrix type liquid crystal display device as shown in FIG. In this device, the display unit is constituted by a liquid crystal panel having a structure in which a liquid crystal is sandwiched between two electrode substrates (a row electrode substrate and a column electrode substrate). Then, by selectively applying a plurality of levels of row voltage and column voltage to the liquid crystal panel, the optical characteristics of the liquid crystal are changed for each pixel,
A desired image is displayed (simple matrix type).

[0006] In addition, there is an active matrix type liquid crystal display device having an active element for controlling a driving voltage for each pixel in the matrix type liquid crystal display device. However, this type of device is difficult to perform high-definition large-screen display due to its complicated structure, and has a high manufacturing cost. On the other hand, since the simple matrix type has a simple structure, a large-screen display can be realized at relatively low cost.

In a simple matrix type liquid crystal display device, usually, a voltage averaging method, a multiple-row simultaneous selection driving method, or the like is used.
It drives row and column electrodes (for the voltage averaging method, see, for example, “Latest Liquid Crystal Technology (p.106, Published by the Industrial Research Institute)” and “Introduction to Liquid Crystal Displays (Nikkan Kogyo)” It is described in).

The voltage averaging method and the plural-row simultaneous selection driving method are based on the following basic principle. That is, in this basic principle, the row voltage waveform is represented by an orthogonal matrix (unit matrix or Walsh matrix). After that, the column information waveform is obtained by orthogonally transforming the display information using the orthogonal matrix. Next, on the display panel, an image is displayed by inversely converting the column voltage waveform into display information.

On the basis of this basic principle, a non-selected row (corresponding to a row having zero matrix elements in an orthogonal matrix)
A constant effective voltage is applied to the pixels belonging to the row electrode irrespective of the display information. On the other hand, an effective voltage based on the display information is applied to the pixels belonging to the row electrodes that are selected rows (rows other than the non-selected rows).

[0010]

However, in an actual simple matrix type liquid crystal display device, the output voltage of the column electrode driving IC, the electrode resistance of the column electrode, the load capacitance of the liquid crystal, and the like, cause the column voltage waveform to change. Distortion due to dulling or induction (distortion due to voltage drop) occurs. For this reason, when the display area of the display device is enlarged (large screen), the effective voltage value of the column voltage applied to each pixel becomes smaller than the basic principle, and crosstalk occurs to cause image deterioration. Further, such crosstalk becomes more prominent as the screen size and the definition become higher.

The present invention has been made to solve the above-mentioned conventional problems. An object of the present invention is to provide a liquid crystal display device capable of preventing a decrease in column voltage due to a voltage drop, and an electronic device using the display device.

[0012]

In order to achieve the above object, a liquid crystal display device (the present display device) of the present invention uses a liquid crystal in which intersections between row electrodes and column electrodes arranged in a lattice are used as pixels. In a liquid crystal display device comprising a panel and displaying an image by scanning a row electrode to which a display voltage is applied while controlling a column voltage to be applied to a column electrode, a column voltage for applying a column voltage to an input terminal of the column electrode An application unit, a display position detection unit that detects a display position that is a position of a row electrode to which a display voltage is applied, and an output of the column voltage application unit according to a distance between an input end of the column electrode and the display position. A voltage control unit for adjusting a column voltage value.

The present display device can be used for mobile phones, mobile devices,
This is a matrix type liquid crystal display device used as a display screen of a personal computer or the like. The liquid crystal panel of the present display device has a plurality of row electrodes arranged substantially in parallel with each other and a plurality of column electrodes similarly arranged in substantially parallel with each other.

The row electrodes and the column electrodes are arranged in a grid so as to cross each other. In the present display device, an intersection between the row electrode and the column electrode is used as a pixel.

That is, in the present display device, an image is displayed by applying a voltage (column voltage, display voltage) to the column electrode / row electrode corresponding to each pixel.

Here, the column voltage is a voltage for driving a column electrode. The value of the column voltage applied to each column electrode is set for each column electrode according to the display data. The column voltage is set so as to be applied from one end (input end) of the column electrode by the column voltage application unit. On the other hand, the display voltage is a voltage for driving a row electrode for display (when a selection voltage and a non-selection voltage are used, the display voltage is the selection voltage).

In this display device, when displaying an image,
While controlling the column voltage applied to the column electrodes within the display range,
A row electrode (display row; one row or a plurality of rows) to which a display voltage is applied is scanned. That is, in the present display device, the column voltage applied to the column electrode is set based on the display data when the display row is shifted. This makes it possible to perform display using all the pixels in the display range.

In the present display device, the voltage applying section is set so as to apply a column voltage to the input terminal of the column electrode. Therefore, at a position far from the input terminal of the column electrode, the column voltage value (effective voltage value) is smaller than the value immediately after the input due to the voltage drop.

Therefore, in order to cope with such a voltage drop, in the present display device, the position of the display row (display position) is detected by the display position detecting section. Then, based on the detected display position, the voltage control unit
It is set so as to adjust the value of the column voltage output from the column voltage application unit. That is, when the display position is far from the input terminal, the voltage control unit increases the column voltage value.

Thus, in the present display device, it is possible to compensate (cancel) the effect of the voltage drop by increasing the column voltage value. Therefore, it is possible to suppress a decrease in the column voltage value at a display position distant from the input terminal, and to prevent image quality deterioration due to crosstalk.

Preferably, the column voltage application section is set so as to apply a column voltage to column electrodes by switching a power supply voltage by an analog switch. With this configuration, the column voltage application unit can be easily configured.

In this configuration, it is preferable that the voltage control unit adjusts the column voltage output from the column voltage application unit by changing the output resistance (output impedance) of the analog switch. The output voltage value from the analog switch changes according to the output resistance. Therefore, by changing the output resistance of the analog switch,
The output voltage value of the column voltage application section can be easily adjusted.

Further, in this case, the voltage control section controls the back gate bias voltage value (BG
It is preferable that the output voltage of the analog switch be changed by adjusting the bias value. The output resistance of the analog switch is set to decrease as the BG bias value increases. Therefore, by adjusting the BG bias value, it is possible to easily change the output resistance and adjust the output voltage value in the column voltage application unit.

Further, the column voltage application section may be configured to apply the column voltage to the column electrodes by switching the power supply voltage using an analog switch group including a plurality of analog switches connected in parallel. Good.

Here, the parallel connection of the analog switches means that, for example, in the case of a MOSFET, the drain and the source are connected to each other. When an analog switch group including a plurality of analog switches connected in parallel is used as described above, the output impedance of the column voltage application unit is combined with the output resistance of the analog switch that is ON (mediates the output voltage). (Combined resistance).

Therefore, in this configuration, the voltage control unit
It is preferable that the setting is made such that by changing the analog switch set to N, the combined resistance in the analog switch group is changed to adjust the column voltage value output from the column voltage application unit. Thereby, the adjustment of the column voltage value can be performed very easily.

When a plurality of analog switches having mutually different output resistances are used, the combined resistance can be largely changed by changing the combination of the analog switches to be turned on. Therefore, the adjustment range of the column voltage value can be greatly expanded.

Also in this configuration, the voltage control section may vary the combined resistance by adjusting the BG bias value applied to the analog switch that is turned on. Thereby, the combined resistance in the analog switch group can be varied by both the combination of the analog switches and the BG bias value. This allows
Since the combined resistance can be varied over a wide range and in detail, the column voltage value applied to the column electrode can be adjusted over a wide range and precisely.

Further, the electronic apparatus of the present invention is characterized by including the present display device, and a control unit for controlling the present display device to perform image display. The control unit provides the display device with a clock signal for setting display data, a column voltage / display voltage application timing, a horizontal synchronization signal,
By providing a vertical synchronization signal or the like, image display is realized. And, in this electronic apparatus, since the present display device is used, it is possible to perform good image display with little deterioration due to crosstalk.

[0030]

[First Embodiment] A first embodiment of the present invention will be described. FIG. 1 is a block diagram showing a configuration of a matrix type liquid crystal display device (the present display device) according to the present embodiment. As shown in this figure, the display device includes a power supply circuit 101, a column electrode driving IC 105,
This is a simple matrix type liquid crystal display device having a row electrode driving IC 106 and a liquid crystal panel 107.

The liquid crystal panel 107 has a plurality of row electrodes arranged in parallel along the row direction and a plurality of column electrodes arranged in parallel along the column direction (both not shown). . The row electrodes and the column electrodes are arranged in a grid pattern so as to be orthogonal to each other with a liquid crystal layer (not shown) therebetween. The column electrodes are connected to a column electrode driving IC 105. The row electrodes are connected to a row electrode drive IC 106.

In the liquid crystal panel 107, the intersections between the row electrodes and the column electrodes are arranged in a matrix, and the intersections form pixels. Each pixel performs display by changing the optical characteristics of the liquid crystal according to the difference between the row voltage (voltage applied to the row electrode) and the column voltage (voltage applied to the column electrode). I have. Power supply circuit 10
1, includes a voltage generation circuit 104, a display position detection circuit 102, and a back gate bias voltage generation circuit (BGB voltage generation circuit) 103, as shown in FIG.

The voltage generation circuit 104 is connected to the row electrodes
Row voltages (VRH, VRL, V
CM) and column voltages (VDH, VDL, VC).

The display position detecting circuit 102 is a liquid crystal panel 1
At 07, the position (display position) of a pixel for display is detected. That is, the display position detection circuit 102
Are set to detect the display position from a vertical synchronization signal YD and a horizontal synchronization signal (horizontal scanning signal) LP input from the outside.

The BGB voltage generation circuit 103 supplies a back gate bias (BG bias; VRDH, VRDL, VRR) to the column electrode driving ICl05 and the row electrode driving IC 106.
H, VRRL). In particular, this BG
The B voltage generation circuit 103 changes the BG bias value according to the display position detected by the display position detection circuit 102. Note that the BGB voltage generation circuit 1
The setting of the BG bias value in 03 will be described later.

The column electrode driving IC 105 includes a voltage generation circuit 1
The column voltage output from the column 04 is applied to the column electrode of the liquid crystal panel 107 at a predetermined timing. The column voltage is a voltage for driving the column electrodes, and is set for each column electrode according to display data. In the present display device, the values are set so as to take one of VDH, VC, and VDL (VDL <VC <VDH). In addition, the column electrode driving IC 105 outputs a column voltage to all the column electrodes simultaneously (simultaneously) during one horizontal scanning period.

The row electrode driving IC 106 includes the voltage generation circuit 1
The row voltage output from the liquid crystal panel 04 is applied to the row electrodes of the liquid crystal panel 107 at a predetermined timing. The row voltage is a voltage for driving a row electrode, and in this display device, a selection voltage (a voltage applied to a selected row; a display voltage) V
RH · VRL and unselected voltage (voltage applied to unselected rows) VCM are set. Note that these voltage values are VRL <VCM <VRH
It is a value that satisfies.

Further, the row electrode drive IC 106 is set so that all the row electrodes are selected (scanned) in order from the top row in the vertical scanning period. Further, at the time of the transition of the selected row (after one horizontal period), the value of the column voltage is reset. The number of row electrodes selected at a time may be one or more.

FIG. 2 is an explanatory diagram showing the overall configuration of the column electrode driving IC 105. As shown in this figure, the column electrode driving IC 105 includes a plurality of column electrode driving elements 201 according to each column electrode.

FIG. 3 is an explanatory diagram showing the configuration of the column electrode driving element 201. As shown in this figure, the column electrode driving element 201 includes a data latch circuit 301, a line latch circuit 302, a level shifter 303, and a decoder circuit 30.
4, MOSFET 305-308, inverter 309
It has.

The data latch circuit 301 converts display data for one horizontal scanning period corresponding to each column electrode from the data signal Data (see FIG. 2) based on an externally input clock signal XCK (see FIG. 2). What you get.

The line latch circuit 302 holds the display data obtained by the data latch circuit 301 and outputs the display data based on the horizontal synchronizing signal LP. The level of the data signal output from the line latch circuit 302 is
This is a value corresponding to the logic voltage VDD.

The level shifter 303 converts the level of the data signal output from the line latch circuit 302 into a value corresponding to the reference voltages VEE1 and VSS1, and outputs the value to the decoder circuit 304.

The decoder circuit 304 includes a level shifter 3
03 is converted into a digital signal and a gate voltage (amplitude value is VEE1 or VS1) for controlling ON / OFF of MOSFETs 305 to 308.
This is output as S1).

As shown in FIG. 3, the MOSFETs (insulated gate type field effect transistors) 305 and 306 receive the column voltages VDH and VDL as the source voltages and input the output voltage of the decoder circuit 304 as the gate voltages. This is an analog switch. That is, the MOSFET 305 is a switch for outputting the column voltage VDH, and the MOSFET 306 is a switch for outputting the column voltage VDL.

Also, as shown in FIG.
ETs 305 and 306 have a back gate voltage of B
BG bias V output from GB voltage generation circuit 103
RDH / VRDL is input.

Further, the MOSFETs 307 and 308
A column voltage VC is input as a source voltage, and a decoder circuit 304 is input as a gate voltage and a back gate voltage.
The analog switch is adapted to receive the output voltage from the analog switch. That is, MOSFETs 307 and 308
Is a switch for outputting the column voltage VC. The gates of these MOSFETs 307 and 308 are connected via an inverter 309.

In the column electrode driving IC 105, based on a control signal and a data signal inputted from outside,
The decoder circuit 304 turns on any one of the MOSFETs 305 to 308. And O
VDH, VD
An output voltage having one of the levels of L and VC is set to be output to the output terminal VOUT.

As described above, VDH, VDL,
VC is generated in the voltage generation circuit 104, and VDH ≦ VEE1, VSS1 ≦ VDL, VC =
It is set so as to satisfy the relationship of (VDH + VDL) / 2.

The BG bias VRDH • VRDL input to the MOSFETs 305 and 306 is generated by the BGB voltage generation circuit 103,
The value satisfies the relationship of H ≦ VDH ≦ VEE1 and VSS1 ≦ VDL ≦ VRDL. The BG bias generated by the BGB voltage generation circuit 103 is input from a BG bias input terminal provided in the column electrode driving IC 105 and distributed to each column electrode driving element 201.

FIG. 4 is an explanatory diagram showing the overall configuration of the row electrode drive IC 106. As shown in this figure,
The row electrode drive IC 106 includes a plurality of row electrode drive elements 202 according to each row electrode.

FIG. 5 is an explanatory diagram showing the configuration of the row electrode driving element 202. As shown in this figure, the row electrode drive element 202 includes a shift register 401, a level shifter 4
02, decoder circuit 403, MOSFETs 404 to 40
7, an inverter 408 is provided.

The shift register 401 sequentially shifts the vertical synchronizing signal YD based on the horizontal synchronizing signal LP.

The row electrode driving IC 106 receives the vertical synchronizing signal Y
D, the most advanced row electrode (row electrode drive IC 106
Are set in the selected row in order from the row electrode closest to the selected row electrode. That is, when the vertical synchronization signal YD is received,
The row electrode drive element 202 corresponding to the most advanced row electrode outputs a selection voltage to this row electrode only for one horizontal scanning period. After one horizontal scanning period, the row electrode driving element 20
The second shift register 401 transmits to the shift registers 401 of the adjacent row electrode drive elements 202 that the row is to be selected.

The level shifter 402 changes the power supply level from the logic voltage VDD to a reference voltage (liquid crystal drive voltage).
It switches to VEE2 and from the logic system ground voltage VSS1 to the reference voltage (liquid crystal drive voltage) VSS2.

The decoder circuit 403 includes the MOSFET 40
A gate voltage (gate signal; amplitude value is VEE2 or VSS2) for controlling ON / OFF of 4-407 is output.

The MOSFETs 404 and 405 are analog switches configured to input the row voltages VRH and VRL as source voltages and to input output signals from the decoder circuit 403 as gate voltages. That is, the MOSFET 404 is a switch that outputs the row voltage VRH, and the MOSFET 405 is a switch that outputs the row voltage VRL.
Is a switch for outputting. Also, MOSFET
404 and 405 have BGB as back gate voltage.
BG bias VRR output from voltage generation circuit 103
H.VRRL is set to be input.

Further, the MOSFETs 406 and 407
A row voltage VCM is input as a source voltage, and a decoder circuit 40 is input as a gate voltage and a back gate voltage.
3 is an analog switch adapted to receive the output voltage from the analog switch. That is, MOSFETs 406 and 40
Reference numeral 7 denotes a switch for outputting the row voltage VCM.
The gates of these MOSFETs 406 and 407 are
They are connected via an inverter 408.

The decoder circuit 403 turns on one of the MOSFETs 404 to 407 depending on whether the row electrode driven by the row electrode drive element 202 to which the decoder circuit 403 belongs is the selected row. I have. And ON
From the drain of the MOSFET that has become
-It is set so that either VRL or the non-selection voltage VCM is output to the output terminal VOUT.

As described above, the selection voltage VRH.
VRL and the non-selection voltage VCM are generated by the voltage generation circuit 104. Then, VRH ≦ VEE
2, VSS2 ≦ VRL, VCM = (VRH + VRL) /
2 is set.

The BG bias VRRH • VRRL input to the MOSFETs 404 and 405 is generated by the BGB voltage generation circuit 103,
≤VRRH≤VEE2, VSS2≤VRRL≤VRL. The BG bias generated by the BGB voltage generation circuit 103 is input from a BG bias input terminal provided in the row electrode drive IC 106 and distributed to each row electrode drive element 202.

Next, a characteristic configuration of the present display device will be described.
The operation of the display position detection circuit 102 and the BGB voltage generation circuit 103 will be described. As described above, the display position detection circuit 102 outputs the vertical synchronization signal YD and the horizontal synchronization signal LP.
Is used to detect the display position. here,
The display position is the position of the selected row within one vertical period.

The BGB voltage generation circuit 103 applies a BG bias VR to be applied to the column electrode driving ICl 05 in accordance with the display position detected by the display position detection circuit 102.
DH / VRDL is changed. That is, the BGB voltage generation circuit 103 has a function of adjusting the column voltage values (VDH, VDL) output from the MOSFETs 305 and 306 by changing the BG bias value.

Here, adjustment of the column voltage value by changing the BG bias value in the present display device will be described. The liquid crystal panel 107 has a load capacitance of liquid crystal or the like and an electric resistance of wiring. Therefore, the row electrodes of the liquid crystal panel 107
The column electrode is formed by the parallel plate capacitor and wiring resistance.
It can be represented by an equivalent circuit as shown in FIG. 6 (an equivalent circuit of a liquid crystal panel of N rows × M columns). Also, one of the column electrodes is shown by the equivalent circuit (resistor R ₁ to R _M and the capacitance C ₁ -C _M and the distributed constant circuit) as shown in FIG.

FIG. 8 is a graph showing the relationship between the distance (D) from the column electrode driving IC 105 and the effective column voltage (<E>). FIG. 9 is an explanatory diagram showing a pulse (applied pulse) of a column voltage applied to a column electrode.

As shown in FIG. 8, the effective voltage value decreases as the distance from the column electrode driving IC 105 increases due to the load capacitance and the electric resistance.

That is, the pulse waveform of the column voltage applied to the liquid crystal panel 107 shown in FIG.
5 has a bluntness (voltage drop) corresponding to the distance from the distance 5, and the blunting reduces the effective voltage value. For this reason, the waveform of the column voltage is
It has a gradation corresponding to the distance from 5.

Therefore, when a row electrode at a position distant from the column electrode drive IC 105 is selected, the effective voltage value of the column voltage at this position is too low, and this value deviates from the basic principle, and an image due to crosstalk is generated. Deterioration may occur.

FIG. 10 is a graph showing the relationship between the ON resistance (r _ON ; output resistance and output impedance) of the MOSFET and the BG bias value (V _B ; VRDH or VRDL). As shown in this figure, the ON resistance of the MOSFET decreases as the BG bias value increases.
In the MOSFET, as the ON resistance becomes smaller,
The output voltage value increases.

Therefore, in the present display device, when the display position is far from the column electrode driving IC 105, the BG bias value VRDH · VRDL is increased to increase the MOSFET.
It is set so as to reduce the ON resistances of the switches 305 and 306 and cancel the influence of the voltage drop.

That is, in the present display device, the display position detection circuit 102 detects the display position, and the BGB voltage generation circuit 103 controls the MOSFETs 305 and 306 in accordance with the increase in the distance between the display position and the column electrode driving IC 105. It is set so as to increase the applied BG bias value. As a result, the column voltage output from the MOSFETs 305 and 306 is increased.

Therefore, in this display device, the column electrode driving IC
It is possible to suppress a decrease in the effective voltage value of the column voltage applied to the display position distant from 105. Therefore, it is possible to prevent image quality deterioration due to crosstalk.

Note that the BGB voltage generation circuit 103
The bias value may be changed each time the selected row (display position) shifts, or may be changed when a predetermined number of selected rows shift.

Further, when the display position is close to the column electrode drive IC 105, the BGB voltage generation circuit 103 reduces the BG bias value so that the column voltage at the display position has an optimum value. I have.

Here, the MOS in the liquid crystal panel 107
The relationship between the ON resistance of the FET and the BG bias value, and
The relationship between the distance from the column electrode drive IC 105 and the effective voltage value will be described.

An equation showing the basic characteristics of the MOSFET is shown below. MOSFETs are classified into an unsaturated region and a saturated region according to the magnitude relationship between V _DS and (V _GS −V _th ). That is, a non-saturation region is obtained when [V _DS ] <[V _GS −V _th ], and a saturation region is obtained when [V _DS ] ≧ [V _GS −V _th ]. Here, V _DS is a symbol indicating a drain-source voltage, V _GS is a gate-source voltage, and V _th is a symbol indicating a threshold voltage. [] Is a symbol indicating an absolute value.

The current (I _DS ) between the drain and the source in the MOSFET is (1) in the unsaturated region.
Equation (2) can be expressed in the equation and the saturation region.

[0078]

(Equation 1)

Here, the threshold voltage V _th of the MOSFET is set to B
The expression of the G bias value is represented by the following expression (3).

[0080]

(Equation 2)

The ON resistance (output impedance) r _ON of the MOSFET is expressed by the following equation (4). Then, V _th is substituted into the equation (4), and MOSFE
Expressing ON resistance of T as a function of BG bias value V _B,
Equation (5) is obtained. From equation (5), the BG bias value V
_It can be seen that by increasing _B , the ON resistance r _ON of the MOSFET can be reduced.

[0082]

(Equation 3)

In FIG. 8, the column electrode driving IC 10
5 and the effective voltage value of the column voltage (<E>)
Is shown in a graph showing the relationship between the column electrode driving IC 10
The effective voltage value (<E>) applied to the i-th pixel from the fifth is
It can be expressed using the following equation (6).

[0084]

(Equation 4)

[Second Embodiment] A second embodiment of the present invention will be described. Note that, in the present embodiment, members having the same functions as the members described in Embodiment 1 are given the same reference numerals, and descriptions thereof are omitted.

The matrix type liquid crystal display device according to the present embodiment (this display device) has the same structure as that of the matrix type liquid crystal display device shown in the first embodiment except that the driving IC 105
A configuration including a column electrode driving IC 501 and a row electrode driving IC 502 instead of 106 is provided.

FIG. 11 is an explanatory diagram showing the overall configuration of the column electrode driving IC 501. As shown in this figure, the column electrode driving IC 501 includes a plurality of column electrode driving elements 601 according to each column electrode.

FIG. 12 is an explanatory diagram showing the structure of the column electrode driving element 601. As shown in this figure, the column electrode driving element 601 includes a data latch circuit 301 and a line latch circuit 3 similar to the column electrode driving element 201 (see FIG. 3).
02, level shifter 303, MOSFET 307.3
08 and an inverter 309.

The column electrode driving element 601 is the same as the decoder circuit 304 and MOS
Instead of the FETs 305 and 306, a decoder circuit 504,
MOSFETs 505 (1) to 505 (k) · 506
(1) to (506) are provided.

The decoder circuit 504 includes the level shifter 3
03 is converted into a digital signal, and MOSFETs 505 (1) to 505 (k), MOS
FETs 506 (1) to 506 (k), MOSFET 30
It is output as a gate voltage (amplitude value is VEE1 or VSS1) for controlling ON / OFF of 7.308.

In the column electrode drive element 601, the decoder circuit 504 turns on one of the MOSFETs based on an external control signal and data signal. That is, when the decoder circuit 504
Any one (single or plural) of SFETs 505 (1) to 505 (k), MOSFETs 506 (1) to 506
Any of (k) (single or multiple), MOSFET
307 or the MOSFET 308 is turned on. Thereby, the output voltage having any level of VDH, VDL, and VC is set to be output to the output terminal VOUT.

MOSFETs 505 (1) to 505 (k)
Are k MOSFETs having different ON resistances and connected in parallel with each other. Also, MOSFET
In 505 (1) to 505 (k), the column voltage VDH is input to the sources connected to each other, and
The output voltage of the decoder circuit 504 is input as a gate voltage. That is, MOSFETs 505 (1) to
505 (k) is an analog switch for outputting the column voltage VDH from the drains connected to each other.

Further, these MOSFETs 505 (1) to 505 (1)
505 (k) includes a BG bias VRDH output from the BGB voltage generation circuit 103 as a back gate voltage.
(VRDH ≦ VDH ≦ VEE1) is input.

Also, MOSFETs 506 (1) to 506
(K) is k MOSFETs having different ON resistances and connected in parallel with each other. Also, MOS
In the FETs 506 (1) to 506 (k), the column voltage VDL is input to the sources connected to each other, and the output voltage of the decoder circuit 504 is input as the gate voltage. That is, MOSFET 506
(1) to 506 (k) are analog switches for outputting the column voltage VDL from the drains connected to each other.

The MOSFETs 506 (1) to 506 (1) to
506 (k) includes a BG bias VRDL output from the BGB voltage generation circuit 103 as a back gate voltage.
(VSS1 ≦ VDL ≦ VRDL) is input.

The BG bias VRDH / VRDL generated by the BGB voltage generation circuit 103 is applied to the column electrode drive I
Input is made from an input terminal for BG bias provided in C501 and distributed to each column electrode drive element 601.

FIG. 13 is an explanatory diagram showing the overall configuration of the row electrode driving IC 502. As shown in this figure, the row electrode drive IC 502 includes a plurality of row electrode drive elements 602 corresponding to each column electrode.

FIG. 14 is an explanatory diagram showing the configuration of the row electrode driving element 602. As shown in this figure, the row electrode drive element 602 includes a shift register 401 and a level shifter 40, similarly to the row electrode drive element 202 (see FIG. 5).
2, MOSFET 406/407, inverter 408
It has.

The row electrode driving element 602 includes the decoder circuit 403 and the MOS
Instead of the FETs 404 and 405, a decoder circuit 603,
MOSFET 604 (1) to 604 (k) · 605
(1) to (605) are provided.

The decoder circuit 603 includes a MOSFET 60
4 (1) to 604 (k), MOSFET 605 (1) to
605 (k), ON / O of MOSFET 406/407
The gate voltage (gate signal; amplitude value is VEE2 or VSS2) for controlling the FF is output.

Then, in the row electrode driving element 602, the decoder circuit 603 converts the row electrode driving element 602 to which the decoder circuit 603 belongs.
Is turned on depending on whether or not the row electrode to be driven is the selected row. That is, the decoder circuit 603 includes the MOSFET 6
04 (1) to 604 (k) (single or plural), MOSFETs 605 (1) to 605 (k) (single or plural), MOSFET 406, or MOS
The FET 407 is turned on. Thereby, the selection voltage VRH · VRL or the non-selection voltage VCM
Is output to the output terminal VOUT.

MOSFETs 604 (1) to 604 (k)
Are k MOSFETs having different ON resistances and connected in parallel with each other. Also, MOSFET
In 604 (1) to 604 (k), the row voltage VRH is input to the sources connected to each other, and
The output voltage of the decoder circuit 603 is input as a gate voltage. That is, MOSFET 604 (1)-
604 (k) is an analog switch for outputting the row voltage VRH from the drains connected to each other.

Further, these MOSFETs 604 (1) to
604 (k) includes a BG bias VRRH output from the BGB voltage generation circuit 103 as a back gate voltage.
(VRH ≦ VRRH ≦ VEE2) is input.

MOSFETs 605 (1) to 605 (k)
Are k MOSFETs having different ON resistances and connected in parallel with each other. Also, MOSFET
In 605 (1) to 605 (k), the row voltage VRL is input to the sources connected to each other, and
The output voltage of the decoder circuit 603 is input as a gate voltage. That is, the MOSFETs 605 (1) to
605 (k) is a switch for outputting the row voltage VRL from the drains connected to each other.

In addition, these MOSFETs 605 (1) to
605 (k) includes a BG bias VRRL output from the BGB voltage generation circuit 103 as a back gate voltage.
(VSS2 ≦ VRRL ≦ VRL).

The BG bias VRRH / VRRL generated by the BGB voltage generation circuit 103 is applied to the row electrode drive I
Input is made from an input terminal for BG bias provided in C502 and distributed to each row electrode drive element 602.

In the present display device having such a configuration,
In each column electrode driving element 601 of the column electrode driving IC 501, MOSFETs 505 (1) to 505 (k),
By controlling the gate voltages to the FETs 506 (1) to 506 (k), the ON / OF of each MOSFET is controlled.
F can be controlled individually.

Therefore, the MOSFETs 505 (1) to 505 (k) are determined by the combination of the MOSFETs to be turned on.
And the MOSFETs 506 (1) to 506 (50)
The combined resistance of 6 (k) can be adjusted to a desired value.

FIG. 15 is an explanatory diagram showing an equivalent circuit of one column electrode in the present display device. And k
The combined resistance (combined impedance) r _ON by the combination of the MOSFETs can be expressed by the following equation (7).

[0110]

(Equation 5)

FIG. 16 shows ON resistances r _ON (1) to r _ON of the three MOSFETs in the equivalent circuit shown in FIG.
₆ is a graph showing a relationship between _ON (3) and the combined resistance r _ON and a BG bias value (V _B ). As shown in this graph, the ON resistance of the MOSFET is
It is significantly reduced by combining with the ET ON resistance. For example, 930Ω, 840Ω, 770Ω O
When using three MOSFETs having N resistance and turning on two of them, 440Ω, 420Ω, 40Ω
Any combined resistance of 0Ω can be obtained.

In the present display device, the display position (the position of the selected row electrode) is displayed by the display position detection circuit 102.
And the display position and the column electrode driving IC 5
01, 505 (1) -5
05 (k) or MOSFETs 506 (1) to 506
The composite resistance of (k) is changed. Further, thereafter, MOSFETs 505 (1) to 505 (k)
Alternatively, the value of the column voltage is changed by changing the BG bias value applied to the MOSFETs 506 (1) to 506 (k).

That is, in the present display device, M
OSFET505 (1) -505 (k) · MOSFET
By changing the combination of 506 (1) to 506 (k), the combined resistance of the MOSFET is digitally (significantly) changed. And then,
In this display device, similar to the display device described in Embodiment 1, MOSFETs 505 (1) to 505 (k) .MOS
By changing the BG bias value applied to the FETs 506 (1) to 506 (k), the composite resistance of the MOSFET is set to be changed (smallly) in an analog manner. Therefore, more extensive and detailed control of the ON resistance can be performed.

As a result, in the present display device, a decrease in the effective voltage applied to the display position distant from the column electrode driving IC 501 can be suppressed in a wider range. Therefore, even if the liquid crystal panel 107 is increased in definition and size, deterioration in image quality due to crosstalk can be prevented.

In other words, the liquid crystal panel 107 has a higher definition.
When the size is increased, the load capacitance and the wiring resistance increase, and the voltage drop becomes remarkable. Therefore, it is difficult to suppress a decrease in the effective voltage value only by changing only the ON resistance (output impedance) of one MOSFET.
Therefore, in the present display device, the display position is set to the column electrode driving IC5.
01, the MOSFETs 505 (1) to 505 (k) .MOS so that the combined ON resistance is low.
The FETs 506 (1) to 506 (k) are combined, and then fine adjustment is performed by changing the BG bias value.

Here, a description will be given of the cause of image degradation due to crosstalk (pixels are affected by adjacent pixels) when the effective voltage value of the column voltage at the display position is too low.

Liquid crystal display having a matrix of N rows × M columns
In the device, the pixel U at the i row and the j column _ijEffective voltage <E
_ij> Can be expressed by the following equation (8). In addition, this
The formula of "Nehring, J and Kmetz, A.," Ultimate Limit
s for Matrix Addressing ofRMS-Responding Liquid-Cr
ystal Display ''), `` A.R.Conner, T.J.Scheffer.,
`` Pulse-Hight Modulation (PHM) Gray Shading Methods
 for Passive Matrix LCDs "
You. Note that I in this equation_ijIs the pixel U_ijInformation in
(Information (pixel information; display data)).

[0118]

(Equation 6)

The equation (9) means that the effective voltage value of the other pixel is not affected without depending on the display pattern of the other pixel on the same j-th column.

On the other hand, if the waveform becomes dull, -1 <I _ij
<1. Therefore, A in equation (8) always remains instead of 1 and the effective voltage value at any pixel U _ij is:
It will be affected by information in other pixels. That is, due to the crosstalk, the effective voltage value applied to each pixel deviates from the basic principle, and image quality deteriorates.

For example, due to the blunted waveform, the pixel which should be turned ON is affected not by the effective voltage value for realizing ON as shown in the equation (9) but by other pixel information. Applying a voltage value may cause shadowing. Further, when the liquid crystal display device has a large screen and high definition, the electrode resistance (electrical resistance) of the row electrode and the column electrode and the load capacitance of the liquid crystal and the like increase. For this reason, the row electrode waveform and the column electrode waveform become dull or distorted due to induction, and the possibility of occurrence of the above-described crosstalk increases.

In the first and second embodiments, the output voltage is changed by changing the BG bias value applied to the MOSFET of the column electrode driving IC (and the row electrode driving IC). On the other hand, for example, in a method of changing one source voltage in a column electrode driving IC or a row electrode driving IC, a bias ratio, which is a ratio between a row voltage and a column voltage, is changed so that contrast (shading of an image)
Is undesirably caused. Further, in the method of changing both the source voltages of the column electrode drive IC and the row electrode drive IC, the bias ratio can be maintained, but the contrast is reduced as described above.

In the first and second embodiments, the BG bias value is set to VRH ≦ VRRH ≦ VEE2, VSS2 ≦ VR
RL ≦ VRL, VRDH ≦ VDH ≦ VEE1, VSS1
≤ VDL ≤ VRDL. However, the present invention is not limited to this, and the BG bias value is within the range of the withstand voltage in the process of manufacturing the liquid crystal display device (VEE2-
(Between VSS2), any value can be set.

Further, the liquid crystal display device described in Embodiment Mode 1 may be provided with a control unit for controlling the operation of the device. Then, from this control unit, a clock signal,
Control signals such as display data, a direct synchronizing signal YD and a horizontal synchronizing signal LP may be output.

In the first and second embodiments, the row electrode driving IC and the column voltage driving IC have MOSFETs as analog switches. However, the analog switch provided in the row / column electrode driving IC is
The switch is not limited to the MOSFET, and any switch may be used as long as the ON resistance can be changed by a change in the BG bias value.

In Embodiments 1 and 2, the liquid crystal display device of the present invention is shown as a single unit. However, this display device can be suitably applied to portable information devices such as a mobile phone and an electronic organizer.

FIG. 17 is an explanatory diagram showing an example of a portable information device provided with the liquid crystal display device shown in the first embodiment. As shown in this figure, this information device is a power supply circuit 101 and a column electrode driving IC 10 in the liquid crystal display device shown in FIG.
5 and a row electrode drive IC 106, a liquid crystal panel 107, and a CPU 410 for controlling these components. With this configuration, a portable information device with high display quality can be created.

When the information device is a mobile phone, CPU 410 may have a function of limiting the display range of liquid crystal panel 107 (displaying using only a specific area of liquid crystal panel 107). preferable. Thus, the power consumption of the information device can be reduced.

In this case, the CPU 410 changes the display on the liquid crystal panel 107 from the entire display to the specific area display (partial display). Therefore, the duty ratio of the liquid crystal panel 107 changes.

Therefore, the CPU 410 adjusts the drive voltage / bias ratio according to the duty ratio after the change by the voltage averaging method (described in “Latest Liquid Crystal Technology” published by the Industrial Research Institute, page 106,
It is preferable to set in accordance with Nikkan Kogyo “Introduction to liquid crystal displays”). That is, when the display area is limited from the full-screen display to the specific area display, the CPU 410 preferably changes the drive voltage / bias ratio according to the duty ratio of the specific area display.

In this case, CPU 410 gives this change instruction to voltage generation circuit 104 in power supply circuit 101. As a result, the voltage generation circuit 104 changes the voltage value / bias value supplied to the column electrode driving IC 105 and the row electrode driving IC 106.

When partial display is performed, display on liquid crystal panel 107 is started not from the end row electrode but from an arbitrary row electrode corresponding to the display range. For this reason,
The CPU 410 supplies the row electrode drive IC 106 with information indicating a row electrode that is a display start position.

Also, in the partial display, the display position detecting circuit 102 outputs the vertical synchronizing signal YD and the horizontal synchronizing signal L.
The display position is detected by P. Then, data of the detected display position is provided to the BGB voltage generation circuit 103. Thereafter, the BG bias generated in the BGB voltage generation circuit 103 is supplied to the column electrode driving IC 105 and the row electrode driving IC 106. In addition, the BGB voltage generation circuit 103 also controls the column electrode driving IC 1 in the partial display.
The BG bias value is set so as to increase as the distance between the display position 05 and the display position increases.

FIG. 18 is an explanatory diagram showing an example in which the liquid crystal display device described in Embodiment 1 is applied to a personal computer (personal computer). The personal computer shown in this figure is composed of a personal computer main body and the present display device (liquid crystal display device). And, in the PC body, CP
U701 and a display controller 702 are provided, and an ASIC (Application
Specific Integrated Circuit) 703 is provided.

The display controller 702 includes a CPU 701
Is a controller that generates display data and a timing signal in accordance with the display resolution in accordance with the instruction. AS
The IC 703 is an IC that generates a clock signal, a vertical synchronization signal YD, and a horizontal synchronization signal LP based on a timing signal provided from the display controller 702.

The display position detection circuit 102 is an ASIC 70
3 receives the vertical synchronizing signal YD and the horizontal synchronizing signal LP, and detects the display position based on these signals. Then, data of the detected display position is provided to the BGB voltage generation circuit 103. The BGB voltage generation circuit 103 outputs a B signal corresponding to the display position.
A G bias is generated and supplied to the column electrode driving IC 105 and the row electrode driving IC.

The display position detecting circuit 102 is an ASIC.
The display position detection circuit 102
And the ASIC 703 may be configured as the same member. In this configuration, the ASIC 703 detects the display position and outputs data indicating the display position to the BGB voltage generation circuit 103.
Will be supplied.

Further, the liquid crystal display device of the present invention is provided with a liquid crystal panel that uses, as pixels, intersections of row electrodes and column electrodes arranged in a grid, and controls the display voltage while controlling the column voltage applied to the column electrodes. In a liquid crystal display device that performs image display by scanning a row electrode to which a column voltage is applied, a column voltage application unit that applies a column voltage to an input terminal of the column electrode, and a display that is a position of the row electrode to which a display voltage is applied A configuration comprising: a display position detection unit that detects a position; and a voltage control unit that increases a column voltage output from a column voltage application unit according to an increase in a distance between an input end of a column electrode and a display position. It can also be expressed as

The present invention can be applied not only to a liquid crystal display device but also to other display devices (EL (electroluminescence), LED (light emitting diode)) as long as the display device performs display with a column voltage and a row voltage. And the like as a pixel).

The present invention also relates to a matrix type display device applicable to a wide range of various AV devices, OA devices, game devices, and the like, and a liquid crystal drive IC of the matrix type display device. Further, in a typical matrix type liquid crystal display device as a matrix type display device, the display portion is constituted by a liquid crystal panel in which liquid crystal is sandwiched between two electrode substrates having electrodes, and a row voltage to the liquid crystal panel is applied. The display is performed by changing the optical characteristics of the liquid crystal by applying a column voltage. Further, the matrix type liquid crystal display device can be roughly classified into an active matrix type in which an active element for controlling a driving voltage is provided in each pixel, and a simple matrix type in which an active element is not provided.

The principle of a simple matrix type liquid crystal display device is usually driven by a voltage averaging method or the like. further,
The voltage averaging method and the multiple simultaneous selection driving method use a row voltage waveform represented by an orthogonal matrix such as a unit matrix or a Walsh matrix to display a column voltage waveform represented by information orthogonally transformed using the orthogonal matrix. Inverse conversion to display information on the panel to obtain the display. Further, according to this basic principle, a constant effective voltage is applied to each pixel of a non-selected row in which the matrix element of the orthogonal matrix is equal to 0, regardless of display information, and each pixel of a selected row other than the non-selected row is applied. Is applied with an effective voltage based on display information.

In the conventional simple matrix type liquid crystal display device, the output voltage of the row electrode driving IC and the column electrode IC, the electrode resistance of the row electrode and the column electrode, the load capacitance of the liquid crystal, etc. Dull or induced distortion occurs in the column voltage waveform. For this reason, the effective voltage applied to each pixel deviates from the basic principle,
It appears on the display as crosstalk. This crosstalk becomes more remarkable as a large screen and high definition progress.

It is another object of the present invention to reduce distortion due to dullness or induction in row and column voltage waveforms due to output impedance in a row electrode driving IC and a column electrode IC, and to set an effective voltage applied to each pixel to a basic value. It can be said that the purpose is to reduce crosstalk due to deviation from the principle. It can also be said that the object is to reduce the density of display (gradation) due to separation from the column electrode driving IC.

The difference between the configuration shown in FIG. 1 and the prior art shown in FIG. 19 is that the power supply circuit 101 is constructed by combining the BGB voltage generation circuit 103 and the display position detection circuit 102 with the voltage generation circuit 104. It can be said that it is.

The power supply circuit 101 includes a voltage generation circuit 104 for generating a row voltage for driving a row electrode and a column voltage for driving a column electrode, and a column electrode driving IC for applying a column voltage to a column electrode.
105 and row electrode drive IC for applying row voltage to row electrodes
106 column electrode drive ICl05 and row electrode drive IC1
BGB voltage generation circuit 103 for controlling the back gate bias 06 and a display position detection circuit 1 for detecting a display position
02. Also, a column electrode drive IC
The 105 and the row electrode driving IC 106 are connected to a liquid crystal panel 107 including a row electrode and a column electrode. The display position detecting circuit 102 detects a position based on the vertical synchronizing signal YD and the horizontal synchronizing signal LP, is connected to the BGB voltage generating circuit 103, sets a BG bias, and is connected to the column electrode driving IC 105 and the row electrode driving IC 106. I have.

The data latch circuit 301 and the line latch circuit 302 hold display data for one horizontal scanning period, and the level shifter 303 changes the power supply level from the logic voltage (logic power supply) VDD to the liquid crystal drive power supply VEE1.
To switch to

In the decoder circuit 304, the MOSFETs 305 to 308 are turned off according to the display data held.
The gate potential of N or OFF is output, and MOSFETs 305, 306 and 307, 30 which are analog switches are output.
8 and 309, one of the analog switches is turned on, and the output potential level VDH,
It can also be said that one of the VDL and VC levels is output.

The shift register 401 sequentially shifts the vertical synchronizing signal YD by the horizontal synchronizing signal LP, switches the power supply level from the logic power supply VDD to the liquid crystal driving power supply VEE2 by the level shifter 402, and changes the power supply level from the logic system ground potential to the liquid crystal driving power supply. Switching to VSS2, decoder circuit 40
MOSFETs 404 to 4 depending on whether 3 is selected or not selected.
A gate potential of ON or OFF is output to the analog switch 07, and the analog switches 404, 405 and 406, 407 and 408 are output.
May be turned on to select one of the output voltage values VRH, VRL, and VCM.

In this display device, the column electrode driving IC 1
05 and the row electrode drive IC 106, the VDH and VDL output MOSFETs and VRH,
The manner in which the back gate voltage is applied to the VRL output MOSFET is different from that in the related art. A row displayed by the display position detection circuit 102 (selected row) is detected, and each row selected (every horizontal scanning period) or The BGB voltage generation circuit 103 sets a BG bias value every other row, and the column electrode driving IC 10
5 and the row electrode drive IC 106.

The decoder circuit 504 operates according to the data held by the data latch circuit 301 and the line latch circuit 302, according to the MOSFETs 505 (1) to 505.
(K) The analog switch composed of 506 (1) to 506 (k) and MOSFET 307, MOSFET 30
8. The gate potential of ON or OFF is output to the analog switch composed of the inverter 309, and VDH, VDH
It can be said that the analog switch for C and VDL output is turned on to select the output voltage value.

In the display device according to the second embodiment, the analog switch for VDH output includes a plurality of MOSFETs having different ON resistances connected in parallel, and the back gate voltage of the plurality of MOSFETs is VRDH ≦ VDH.
BGB voltage generation circuit 103 to satisfy ≦ VEE1
And may be connected to and controlled by a BG bias voltage control input terminal provided in the column electrode driving IC 501.

Similarly, in the analog switch for VDL output, a plurality of MOSFETs having different ON resistances are connected in parallel, and the back gate voltage of the plurality of MOSFETs is
It may be generated by the BGB voltage generation circuit 103 so as to satisfy VSS1 ≦ VDL ≦ VRDL, and may be connected to and controlled by an input terminal for BG bias voltage control provided in the column electrode driving IC 501.

The shift register 401 sequentially shifts the vertical synchronizing signal YD by the horizontal synchronizing signal LP, switches the power supply level from the logic power supply VDD to the liquid crystal driving power supply VEE2 by the level shifter 402, and changes the power supply level from the logic system ground potential to the liquid crystal driving power supply. Switching to VSS2, decoder circuit 60
MOSFET 604 depending on whether 3 is selected or not selected.
(1) to 604 (k), MOSFET 605 (1) to 6
05 (k) analog switch and MOSFET 406,
A gate potential of ON or OFF is output to an analog switch composed of a MOSFET 407 and an inverter 408, and an analog switch for outputting VRH, VCM, VRL is turned ON to select an output voltage value VRH, VCM, VRL. It can be said that.

In the display device according to the second embodiment, a plurality of MOSFETs having different ON resistances are connected in parallel to the analog switch for VRH output, and the back gate voltage of the plurality of MOSFETs is VRH ≦ VRRH.
BGB voltage generation circuit 103 so as to satisfy ≦ VEE2
And may be connected to and controlled by a BG bias voltage control input terminal provided in the row electrode drive IC 502.

Similarly, in the analog switch for VRL output, a plurality of MOSFETs having different ON resistances are connected in parallel, and the back gate voltage of the plurality of MOSFETs is
It may be generated by the BGB voltage generation circuit 103 so as to satisfy VSS2 ≦ VRRL ≦ VRL, and connected to and controlled by an input terminal for BG bias voltage control provided in the row electrode drive IC 502.

The row electrode driving waveform and the column electrode driving waveform applied to the liquid crystal panel 107 are separated from the row electrode driving IC and the column electrode driving IC. The bluntness of the column electrode drive waveform increases, losing the effective value of the bluntness,
It can be said that shading (gradation) is caused by moving away from the row electrode driving IC and the column electrode driving IC.

The display position detection circuit 102 detects the position of the selected row electrode, and changes the output impedance of the column electrode drive IC and the row electrode drive IC in an arbitrary horizontal scanning period as the distance from the column electrode drive IC increases. The setting may be made so that the BG bias voltage is supplied from the BGB voltage generation circuit 103 to the column electrode driving IC and the row electrode driving IC so as to become lower every time.

FIG. 17 shows an example of a configuration of an electronic device typified by a mobile phone and a portable information device (electronic notebook) according to the present invention. The column electrode driving IC 105, the row electrode driving IC 106, and the power supply circuit 101 are directly connected to and controlled by the CPU 410. CP used in mobile phones
U410 is a function of displaying the liquid crystal panel 107 from a full screen to a specific area of the display area at an arbitrary duty ratio in order to reduce power consumption. When the display is switched from the full screen display to the partial display, the driving duty ratio changes. Therefore, it is preferable to set the driving voltage and the bias ratio according to the duty in accordance with the voltage averaging method. The setting is such that when the CPU 410 switches from full screen display to partial display, an instruction to set a drive voltage and a bias ratio in accordance with the duty is given to the voltage generation circuit 104 constituting the power supply circuit 101. A voltage may be supplied from 104 to the column electrode drive IC 105 and the row electrode drive IC 106.

Since the partial display is displayed from an arbitrary row in the liquid crystal panel 107, it is preferable that an instruction of the position of the row electrode for starting the display is supplied from the CPU 410 to the row electrode drive IC. The display position detecting circuit 102 is supplied with the vertical synchronizing signal YD and the horizontal synchronizing signal LP, detects the display position, and outputs the detected data to the BG bias voltage generating circuit 10.
3, and the generated back gate voltage is preferably supplied to the column electrode driving IC 105 and the row electrode driving IC 106.

Column electrode drive IC 105 and row electrode drive IC
C106 is a column electrode driving IC 10
It is preferable that the BGB voltage generation circuit 103 be set so as to have a higher output impedance as the distance from the VBG increases.

The display controller 7 shown in FIG.
02 may be a controller that receives a command from the CPU 701, switches between the TFT liquid crystal mode and the STN liquid crystal mode, and generates timing in accordance with display resolution. The ASIC 703 includes a display controller 702.
May be an IC that generates a timing by matching a timing signal given from a liquid crystal display device.

The display position detecting circuit 102 constituting the power supply circuit 101 receives the vertical synchronizing signal YD and the horizontal synchronizing signal LP from the display controller 702, detects the display position, and sends the detected data to the BGB voltage generating circuit 103. Give
The generated BG bias may be supplied to the column electrode driving IC 105 and the row electrode driving IC 106. Further, the display position detection circuit 102 loads the ASIC 703
C703 detects the display position, and outputs the BGB voltage generation circuit 10
3 may be supplied.

The adjustment of the output voltage value by changing the BG bias value can be performed with the time constant of the drive waveform by adjusting the output impedance while maintaining the bias ratio. In addition, it can be said that, due to the electrode resistance of the column electrode and the liquid crystal load capacitance, the bluntness of the waveform applied to the liquid crystal increases as the distance from the drive IC increases. LCD panel 107
As the distance from the column electrode driving IC 105 increases, the effective voltage applied to each pixel deviates from the basic principle due to the blunting of the waveform. In order to alleviate this, the output impedance is changed from large to small as driving from the row electrode side to the first row to the Mth row, so that the effective voltage value applied to the liquid crystal is changed between the side closer to the column electrode and the side farther from the column electrode. By alleviating the difference, gradation (shading of display) can be reduced.

Further, under the influence of crosstalk, the portion that is originally turned on is not the effective voltage value indicating ON derived from the equation (9), but the effective voltage value affected by other pixel information, and appears as shadowing. .

FIG. 8 shows that the effective voltage applied to the pixel decreases as the distance from the driving IC increases. In the present invention, in order to suppress the difference in the effective voltage value applied to the pixel as the distance from the drive IC increases, the BG bias V increases so that the output impedance increases near the drive IC.
It is preferable to set _{B so} that the output impedance decreases as the distance increases.

In the present invention, the BG bias value of the row electrode may be controlled. This is because the effective voltage value applied to the pixel decreases as the distance from the column electrode driving IC increases, but if the difference between the column and the row is the voltage applied to the pixel in consideration of the row electrode, control can also be performed from the row side. . By decreasing the output impedance of the row electrode drive IC from large to small as the distance from the column electrode drive IC increases, it is possible to suppress a difference in voltage applied between a place far from the column electrode drive IC and a place near the column electrode drive IC.

The present invention can also be expressed as the following first and second liquid crystal display devices, first and second electronic devices, and first and second column electrode driving ICs and row electrode driving ICs. it can. That is, the first liquid crystal display device comprises: a row electrode and a column electrode arranged in a matrix; a voltage generating means for generating a plurality of voltage levels for driving the row electrode and the column electrode; A matrix-type display device, comprising: an electrode driving unit that selects a voltage level to be applied to the row electrode and the column electrode from a pixel, and displaying by a pixel formed at an intersection of the row electrode and the column electrode. And a power supply circuit having a BG bias voltage generating means and a display position detecting means of the liquid crystal panel, and a row electrode driving IC having an electrode driving means for selecting a voltage level to be applied to the row electrode, and a voltage level applied to the column electrode. And a column electrode driving IC provided with an electrode driving means for selecting the following. In this configuration, a uniform liquid crystal display can be realized by controlling the output impedance of the column electrode drive IC and the row electrode drive IC.

The second liquid crystal display device is the same as the first liquid crystal display device, wherein the electrode drive means of the column electrode drive IC and the row electrode drive drive IC comprises a plurality of MOSFETs (insulated gates) for selecting a certain voltage level. Type field effect transistor), and the back gates of the plurality of MOSFETs are BG of the power supply circuit.
This is a configuration connected to a bias voltage generation circuit. In this configuration, the electrode driving means includes a plurality of MOSFETs.
(Equivalent green gate type field effect transistor), and by controlling the back gate of the plurality of analog switches, a plurality of output impedances set by a combination of the plurality of analog switches are controlled. Since the values can be interpolated and controlled by the back gate in an analog manner, smooth output impedance control becomes possible, and more uniform liquid crystal display can be realized.

The first electronic apparatus has a configuration in which a power supply circuit, a column electrode driving IC, and a row electrode driving IC constituting a first liquid crystal display device are connected to a CPU and controlled by the CPU. In this configuration, by using the first liquid crystal display device, it is possible to provide an electronic device having a uniform liquid crystal display.

Further, in the second electronic device, in the first electronic device, the CPU controls a partial display function (partial display) for displaying a specific area of the liquid crystal display area at an arbitrary duty ratio and switching of full screen display. This is a configuration having functions. With this configuration, in an electronic device typified by a mobile phone, a uniform liquid crystal display can be achieved even when switching between partial display and full screen display.

Further, the first column electrode driving IC includes an analog switch composed of a MOSFET (insulated gate type field effect transistor) for selecting a voltage level in the electrode driving means, and controls the BG bias voltage of the MOSFET. This is a configuration having an input terminal for control.
In this configuration, a MOSFET for selecting a certain voltage level
By using a column electrode drive IC having an input terminal for controlling the BG bias voltage, a uniform liquid crystal display can be configured.

Further, the second column electrode driving IC is different from the first column electrode driving IC in that it comprises a plurality of MOSFETs (green gate type field effect transistors) for selecting a certain voltage level in the electrode driving means. An analog switch is provided, and the back gates of the plurality of MOSFETs are connected to the input terminals. In this configuration, a plurality of Ms for selecting a certain voltage level are provided to the column electrode driving means.
An analog switch composed of an OSFET (insulated gate field effect transistor);
By controlling the back gate of the SFET, a value between a plurality of output impedances set by a combination of a plurality of analog switches can be analogously interpolated and controlled by the back gate, so that a smooth output impedance control becomes possible. It is possible to configure a uniform liquid crystal display device.

The first row electrode driving IC includes a plurality of MOSFETs for selecting a voltage level in the electrode driving means.
(Absolute gate field effect transistor) and an input terminal for controlling the BG bias voltage of the MOSFET. In this configuration, the MO for selecting a certain voltage level
By using a row electrode driving IC having an input terminal for controlling the BG bias voltage of the SFET, a uniform liquid crystal display can be realized.

Further, the second row electrode drive IC is an analog of the first row electrode drive IC which is constituted by a plurality of MOSFETs (insulated gate type field effect transistors) for selecting a certain voltage level in the electrode drive means. A switch having a back gate connected to the input terminal. In this configuration, a plurality of Ms for selecting a certain voltage level are provided to the column electrode driving means.
An analog switch composed of an OSFET (insulated gate field effect transistor);
By controlling the back gate of the SFET, a value between a plurality of output impedances set by a combination of a plurality of analog switches can be analogously interpolated and controlled by the back gate, so that a smooth output impedance control becomes possible. It is possible to configure a uniform liquid crystal display device.

The first and second liquid crystal display devices described above,
A second electronic device and first and second column electrode driving ICs;
According to the configuration of the row electrode driving IC, the output impedance of the liquid crystal driving circuit IC controls the output impedance at every arbitrary horizontal scanning period, or the partial display function of displaying a specific area of the display area at an arbitrary duty ratio from the entire screen. Even after switching, by controlling the output impedance, uniform display independent of the liquid crystal panel surface or the displayed position can be realized.

In the embodiment of the present invention, the gate potential of the MOSFETs 154 and 155 is changed in (0042) of (Embodiment of the Invention) in JP-A-10-10497. , 1
55 may be changed. "However, a specific configuration is not disclosed. The configuration that can be considered from the context before and after "Similar configuration ..." is to set the back gate voltage of the MOSFET to
It is considered that the voltage is divided and applied by a variable resistor composed of an SFET. Drive I of several hundred outputs like liquid crystal drive IC
It is not easy to load a variable resistor composed of a resistor and a MOSFET on each output of C, such as enlarging the elements and keeping the accuracy variation constant.

[0177]

As described above, the liquid crystal display device of the present invention (the present display device) includes the liquid crystal panel using the intersections of the row electrodes and the column electrodes arranged in a grid as pixels, and applies the voltage to the column electrodes. A column voltage application unit that applies a column voltage to an input terminal of a column electrode in a liquid crystal display device that performs image display by scanning a row electrode to which a display voltage is applied while controlling a column voltage to be applied, A display position detecting unit for detecting a display position, which is a position of a row electrode, and a voltage control for adjusting a column voltage value output from a column voltage applying unit according to a distance between an input terminal of the column electrode and the display position. Section.

In the present display device, the position of the display row (display position) is detected by the display position detecting section. Then, based on the detected display position, the voltage control unit is set to adjust the value of the column voltage output from the column voltage application unit. That is, when the display position is far from the input terminal, the voltage control unit increases the column voltage value.

As a result, in the present display device, it is possible to compensate (cancel) the influence of the voltage drop at the column electrode by increasing the column voltage value. Therefore, it is possible to suppress a decrease in the column voltage value at a display position distant from the input terminal, and to prevent image quality deterioration due to crosstalk.

Preferably, the column voltage application section is set so as to apply the column voltage to the column electrodes by switching the power supply voltage by an analog switch. With this configuration, the column voltage application unit can be easily configured.

In this configuration, it is preferable that the voltage control unit adjusts the column voltage output from the column voltage application unit by changing the output resistance (output impedance) of the analog switch. The output voltage value from the analog switch changes according to the output resistance. Therefore, by changing the output resistance of the analog switch,
The output voltage value of the column voltage application section can be easily adjusted.

Also, in this case, the voltage control section applies the back gate bias voltage value (BG
It is preferable that the output voltage of the analog switch be changed by adjusting the bias value. The output resistance of the analog switch is set to decrease as the BG bias value increases. Therefore, by adjusting the BG bias value, it is possible to easily change the output resistance and adjust the output voltage value in the column voltage application unit.

The column voltage application section may be configured to apply a column voltage to column electrodes by switching the power supply voltage using an analog switch group including a plurality of analog switches connected in parallel. Good.

Here, the parallel connection of the analog switches means that, for example, in the case of a MOSFET, the drain and the source are connected to each other. When an analog switch group including a plurality of analog switches connected in parallel is used as described above, the output impedance of the column voltage application unit is combined with the output resistance of the analog switch that is ON (mediates the output voltage). (Combined resistance).

Therefore, in this configuration, the voltage control unit
It is preferable that the setting is made such that by changing the analog switch set to N, the combined resistance in the analog switch group is changed to adjust the column voltage value output from the column voltage application unit. Thereby, the adjustment of the column voltage value can be performed very easily.

When a plurality of analog switches having different output resistances are used, by changing the combination of the analog switches to be turned on, the combined resistance can be largely changed. Therefore, the adjustment range of the column voltage value can be greatly expanded.

[0187] Also in this configuration, the voltage control section may vary the combined resistance by adjusting the BG bias value applied to the analog switch that is turned on. Thereby, the combined resistance in the analog switch group can be varied by both the combination of the analog switches and the BG bias value. This allows
Since the combined resistance can be varied over a wide range and in detail, the column voltage value applied to the column electrode can be adjusted over a wide range and precisely.

Further, the electronic apparatus of the present invention is configured to include the present display device and a control section for controlling the present display device to perform image display. The control unit realizes image display by giving the display device a display data, a clock signal for setting the application timing of the column voltage and the display voltage, a horizontal synchronization signal, a vertical synchronization signal, and the like. . And, in this electronic apparatus, since the present display device is used, it is possible to perform good image display with little deterioration due to crosstalk.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a matrix-type liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an overall configuration of a column electrode driving IC provided in the liquid crystal display device shown in FIG.

FIG. 3 is an explanatory diagram showing a configuration of a column electrode driving element in the column electrode driving IC shown in FIG. 2;

FIG. 4 is an explanatory diagram showing an overall configuration of a row electrode driving IC provided in the liquid crystal display device shown in FIG.

5 is an explanatory diagram showing a configuration of a row electrode drive element in the row electrode drive IC shown in FIG.

FIG. 6 is an explanatory diagram showing an equivalent circuit of a row electrode and a column electrode in a liquid crystal panel provided in the liquid crystal display device shown in FIG.

FIG. 7 is an explanatory diagram showing an equivalent circuit of one column electrode in the liquid crystal panel.

FIG. 8 is a graph showing a relationship between a distance from a column electrode driving IC and an effective voltage value of a column voltage.

FIG. 9 is an explanatory diagram showing a pulse of a column voltage applied to a column electrode.

FIG. 10 is a graph showing a relationship between an ON resistance of a MOSFET and a BG bias value.

FIG. 11 is an explanatory diagram showing an overall configuration of a column electrode driving IC provided in a matrix type liquid crystal display device according to a second embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a configuration of a column electrode drive element in the column electrode drive IC shown in FIG.

FIG. 13 shows a row electrode drive I provided in the liquid crystal display device.
It is explanatory drawing which shows the whole structure of C.

14 is an explanatory diagram showing a configuration of a row electrode drive element in the row electrode drive IC shown in FIG.

FIG. 15 is an explanatory diagram showing an equivalent circuit of one column electrode in the liquid crystal display device.

16 shows three MOs in the equivalent circuit shown in FIG.
5 is a graph showing the relationship between the ON resistance of an SFET, their combined resistance, and the BG bias value.

FIG. 17 is an explanatory diagram illustrating an example of a portable information device including the liquid crystal display device according to the first embodiment.

FIG. 18 is an explanatory diagram showing an example in which the liquid crystal display device is applied to a personal computer.

FIG. 19 is an explanatory view showing a conventional matrix type display device.

[Explanation of symbols]

Reference Signs List 101 power supply circuit 102 display position detection circuit (display position detection unit) 103 BGB voltage generation circuit (voltage control unit) 104 voltage generation circuit 105 column electrode drive IC (column voltage application unit) 106 row electrode drive IC 107 liquid crystal panel 201 column electrode Driving element (column voltage applying unit) 202 Row electrode driving element 304 Decoder circuit 305 to 308 MOSFET (analog switch) 403 Decoder circuit 404 to 407 MOSFET 410 CPU (display control unit) 501 Column electrode driving IC (column voltage applying unit) 502 Row electrode drive IC 504 Decoder circuit 505 (1) to 505 (k) MOSFET (analog switch group) 505 (1) to 505 (k) MOSFET (analog switch group) 601 Column electrode drive element (column voltage application unit) 602 Electrode drive element 603 decoder times Road 604 (1) to 604 (k) MOSFET 605 (1) to 605 (k) MOSFET 701 CPU (display control unit) VRDH, VRDL BG bias VRRH, VRRL BG bias

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/36 G09G 3/36 F-term (Reference) 2H093 NA07 NC11 NC21 NC22 NC26 NC52 NC65 ND05 ND09 ND15 ND36 ND60 NE03 5C006 AC21 AF46 AF52 BB12 BC16 BF03 BF04 BF15 BF42 BF46 FA18 FA26 FA37 5C080 AA10 BB05 DD10 EE28 FF07 JJ02 JJ03 JJ05

Claims (6)

[Claims] 1. A liquid crystal panel using, as a pixel, an intersection of a row electrode and a column electrode arranged in a grid, and scanning a row electrode to which a display voltage is applied while controlling a column voltage applied to the column electrode. In a liquid crystal display device that performs image display by means of a column electrode, a column voltage application unit that applies a column voltage to an input terminal of a column electrode, and a display position detection unit that detects a display position that is a position of a row electrode to which a display voltage is applied And a voltage control unit that adjusts a column voltage value output by a column voltage application unit according to a distance between an input terminal of a column electrode and a display position. 2. The system according to claim 1, wherein the column voltage application unit is configured to apply a column voltage to a column electrode by switching a power supply voltage by an analog switch. The liquid crystal display device according to claim 1, wherein the column voltage value output from the column voltage application unit is adjusted by changing the resistance. 3. The method according to claim 2, wherein the voltage control unit adjusts a back gate bias voltage value applied to the analog switch,
3. The liquid crystal display device according to claim 2, wherein the output resistance of the analog switch is set to fluctuate. 4. The column voltage application section is configured to apply a column voltage to a column electrode by switching a power supply voltage using an analog switch group including a plurality of analog switches connected in parallel. The voltage control unit is set to change the analog switch to be turned on, thereby changing the combined resistance in the analog switch group, and adjusting the column voltage value output from the column voltage application unit. The liquid crystal display device according to claim 1, wherein: 5. The voltage control section is set so as to vary a combined resistance in an analog switch group by adjusting a back gate bias voltage value applied to an analog switch turned on. Claim 4
3. The liquid crystal display device according to 1. 6. An electronic apparatus comprising: the liquid crystal display device according to claim 1; and a display control unit that controls the liquid crystal driving device to display an image.