JP2003029715A - Display device and portable terminal with the device mounted thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of realizing a partial display mode with a simple constitution and also capable of realizing a more reduced power consumption and a portable terminal on which the display device is mounted. SOLUTION: In a liquid crystal display device having the partial display mode, at the time of driving a non-display area, for example, white signals to be supplied from an external driver IC 15 are simultaneously written in the non-display area by turning analog switches of the selection switching pat 13 all ON and also level shifting circuits which are provided in the selection switch control part 14 and which give driving pulses having high amplitude to respective analog switches of the selection switching part 13 are made to be in an inactive states under the control of a selection switch control circuit 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a portable terminal equipped with the display device, and more particularly to a display device using a liquid crystal cell or an EL (electroluminescence) element as an electro-optical element of a pixel, and the display apparatus. The present invention relates to a mobile terminal such as a mobile phone equipped with.

[0002]

2. Description of the Related Art Mobile phones and PDAs (Personal Digital
Assistant: mobile information devices, such as mobile information devices,
Liquid crystal display devices (or EL display devices) are widely used as low power consumption display devices because they have the characteristic that they do not require much driving power in principle. Then, for example, in a liquid crystal display device mounted on a mobile phone, as a display function such as a standby mode, image display may be performed only in a partial area in the vertical direction of the screen. Hereinafter, this display mode is referred to as a partial display (partial screen display) mode.

In the partial display, for example, the display of the receiving sensitivity and the display of the remaining amount of the battery capacity are performed.
As described above, in order to realize the partial display mode in which only a part of the screen is displayed in the standby mode or the like, in the liquid crystal display device (or EL display device), the desired image display is performed on the screen. It is necessary to perform the refresh operation not only in the area for performing the above-described operation but also in the non-display area by using a specific color signal (for example, a white signal or a black signal).

[0004]

As described above, in the liquid crystal display device (or EL display device), when realizing the partial display mode, it is necessary to perform the refresh operation even on the non-display area. Therefore, conventionally, in the horizontal direction, the same drive is performed for both the display area and the non-display area. This results in consumption, which has been a bottleneck in further reducing power consumption.

Further, in the normally white liquid crystal display device, when the non-display area in the partial display mode is displayed in black, the charging / discharging current with respect to the device capacity becomes large, which hinders reduction of power consumption. The same applies to the case where the non-display area is displayed in white in the normally black liquid crystal display device. Further, in the EL display device, when the non-display area is displayed in white, it is necessary to constantly supply the light emission current, which similarly hinders reduction in power consumption.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a display device which can realize a partial display mode with a simple structure and further reduce power consumption, and It is to provide a mobile terminal equipped with a display device.

[0007]

A display device according to the present invention is a display device having a partial display mode, in which a pixel portion in which pixels are arranged in a matrix and a pixel column of this pixel portion are arranged. Multiple analog switches that supply signals to each of the data lines, and sequentially turn on / off the multiple analog switches when driving the display area in the partial display mode, and multiple analog switches when driving the non-display area. It has a configuration including control means for turning on all the switches. This display device is used as a display unit in a mobile terminal having a display unit having a partial display mode.

In the display device having the above configuration or the portable terminal device using the display device as a display unit, a specific color, for example, white is displayed in the non-display area during partial display.
At this time, the white signal is continuously supplied as a display signal to the pixel portion. Therefore, when driving the non-display area, white display is performed in the non-display area by turning on all the plurality of analog switches. Further, unlike the case of driving the display area, the control for turning on / off the plurality of analog switches is not required, so that the power consumption of the control unit can be reduced accordingly.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a display device according to an embodiment of the present invention. Here, the case of application to a liquid crystal display device will be described as an example.

In the liquid crystal display device according to the present embodiment, as its driving method, individual pixel electrodes are arranged for each pixel, and a TFT, for example, is provided on each of these pixel electrodes.
A so-called active matrix drive type is used in which (Thin Film Transistor) is connected as a switching element to selectively drive pixels.

As is apparent from FIG. 1, the liquid crystal display device according to this embodiment has a liquid crystal display section (pixel section) 11, a V (vertical) driver 12, a selection switch section 13, a selection switch control circuit 14, and an external driver. IC (Si chip) 1
5 is provided. The liquid crystal display unit 11 has a large number of pixels arranged in a matrix, and a TF in which, for example, a TFT of low temperature polysilicon is formed as a switching element.
It is manufactured by stacking a T substrate and a counter substrate on which a color filter, a counter electrode, etc. are formed, and enclosing a liquid crystal material between these two transparent insulating substrates (for example, glass substrates).

An example of the structure of the liquid crystal display unit 11 is shown in FIG. In FIG. 2, each of the pixels 20 arranged in a matrix has a TFT 21 which is a pixel transistor and
Liquid crystal cell 2 in which the pixel electrode is connected to the drain electrode of 21
2 and an auxiliary capacitor 23 in which one electrode is connected to the drain electrode of the TFT 21. Then, the gate electrode of the TFT 21 is a gate line ... 24 m
, -1,24m, 24m + 1, ..., and the source electrodes are data lines (signal lines) ..., 25n-1,25
, 25n + 1, ... The common potential VCOM is applied to the counter electrode of the liquid crystal cell 22 and the other electrode of the auxiliary capacitor 23.

In driving the liquid crystal display section 11, generally, a 1H inversion driving method is used in which the polarity of a signal applied to each pixel 20 is inverted every 1H (H is a horizontal period). Further, by combining the 1H inversion driving method with the common inversion driving method, it is possible to realize a lower voltage of the external driver IC 15 that constitutes the horizontal driving system together with the selection switch section 13. Here, the common inversion drive method is a drive method in which the common potential VCOM commonly applied to the counter electrode of the liquid crystal cell 22 in each pixel 20 is inverted every 1H.

The V driver 12 is composed of, for example, a shift register, and the gate lines of the liquid crystal display section 11 ...
Vertical scanning is performed by sequentially applying scanning pulses to 4m-1, 24m, 24m + 1, ... To sequentially select each pixel 20 of the liquid crystal display unit 11 in units of rows. Here, V
Although the driver 12 is arranged only on one side of the liquid crystal display unit 11, it may be arranged on both sides of the liquid crystal display unit 11. In this way, by adopting the configuration in which the V driver 12 is arranged on both sides of the liquid crystal display unit 11, the scanning pulse transmitted to each pixel 20 by the gate line ..., 24m-1, 24m, 24m + 1 ,. This has the effect of preventing delay.

Here, in the liquid crystal display device according to the present embodiment, a time division drive system (selector system) is adopted. This time-divisional drive system means data lines ...
Of n-1, 25n, 25n + 1, ..., a plurality of data lines adjacent to each other are divided as a unit, and a signal applied to the plurality of data lines in this division unit is output from each output pin of the external driver IC 15 in time series. On the other hand, the selection switch unit 13 is a drive system in which the time-series signals output from the external driver IC 15 are sampled in a time division manner and sequentially applied to a plurality of data lines.

In order to realize this time division driving system, the external driver IC 15 has a structure in which a plurality of data lines are used as a unit (group) and a signal voltage applied to the plurality of data lines is output in time series. ing. Correspondingly, the selection switch unit 13 time-divides the signal voltage applied to the plurality of data lines between one output line of the external driver IC 15 and the plurality of unit data lines. A plurality of analog switches are provided as a set. The external driver IC 15 is mounted by COG (Chip On Glass), for example.

FIG. 3 shows a selection switch section 1 in the case of three time division drive corresponding to R (red), G (green) and B (blue).
3 shows an example of the connection configuration of No. 3. Here for simplicity,
One output line 31 connected to one output pin of the external driver IC 15, and three analog switches connected between this output line 31 and three data lines 25n-1, 25n, 25n + 1 13-1, 13-
2 and 13-3 are shown. These analog switches 13-1, 13-2, 13-3 function as time-division switches, as will be apparent from the operation description below.

Here, the signal voltages for three pixels of R, G and B are sequentially output in time series from the external driver IC 15 to one output line 31. This R, G, B time-series signal voltage has three analog switches 13-1, 13
3 data lines 2 by time division by -2, 13-3
5n-1, 25n, 25n + 1 are sequentially supplied. As described above, the period (sampling period) for selecting the signal voltage by the selection switch unit 13 is set to be 1/3 or less of 1H in response to the number of time divisions being 3 time divisions. There is.

Three analog switches 13-1, 13-
2, 13-3 are PchMO, as is clear from FIG.
The S-transistor and the N-ch MOS transistor are connected in parallel with each other, and are configured by a CMOS transmission switch. However, as the analog switches 13-1, 13-2, 13-3, C
The transmission switch is not limited to the MOS structure, and may be a transmission switch having a PMOS structure or an NMOS structure.

Further, the analog switches 13-1, 13-
When CMOS transmission switches 2 and 13-3 are used, two control lines 32-1 to 32-6 are provided for each analog switch, that is, two control lines 32-1 to 32-6. The two control input terminals of the analog switch 13-1 (that is, the gates of the Nch and Pch MOS transistors) are connected to the control lines 32-1 and 32-2, and the two control input terminals of the analog switch 13-2 are connected to the control line. Two control input terminals of the analog switch 13-3 are connected to the control lines 32-5 and 32-6, respectively.

These six control lines 32-1 to 32-
6 has three analog switches 13-1, 13-2,
Gate selection signals S1 to S for sequentially selecting 13-3
3, XS1 to XS3 are provided from the selection switch control circuit 14. Here, the gate selection signals XS1 to XS3 are
It is an inverted signal of the gate selection signals S1 to S3. These gate selection signals S1 to S3 and XS1 to XS3 are synchronized with the time-series signal voltage output from the external driver IC 15, and the three analog switches 13-1, 13-2, and 13 are used.
-3 are sequentially turned on.

FIG. 4 is a block diagram showing an example of a specific configuration of the selection switch control circuit 14.

As is apparent from FIG. 4, the selection switch control circuit 14 according to this example has a structure having a level shift circuit 41 and a DC bias control circuit 42. The level shift circuit 41 level-shifts a drive pulse (gate selection signal) having an amplitude of 0V to 2.25V, which is input to drive each analog switch of the selection switch unit 13 from the outside, and has an amplitude of, for example, -3V to 9V.
It is output as a drive pulse of. The DC bias control circuit 42 controls the DC bias of the level shift circuit 41 based on a control pulse given from the outside.

The V driver 12, the selection switch section 13 and the selection switch control circuit 14 described above are integrally formed with the liquid crystal display section 11 on the same transparent insulating substrate (for example, glass substrate). In particular, the selection switch unit 1
3 analog switches 13-1, 13-2, 13-3
Are formed of TFTs of low-temperature polysilicon, for example, like the TFTs of pixels.

The active matrix type liquid crystal display device having the above-described structure has a partial display (partial screen display) mode for displaying only a partial area in the vertical scanning direction of the screen as a display function of the standby mode or the like. . In this partial display mode, a normal image is displayed in the display area, and a simple image such as all white is displayed in the non-display area.

In the active matrix type liquid crystal display device having this partial display mode, the present invention displays an image by performing time-divisional drive in the selection switch section 13 as usual in the display area in the partial display mode. On the other hand, in the non-display area, the selection switch unit 1
All the analog switches 3 are turned on (closed), and time-division driving by the selection switch unit 13 is not performed, so that a simple image display such as all white is displayed.

Specific drive timing examples will be described below separately for driving the display area and driving the non-display area. Note that in the following description, only the driving by the horizontal driving system will be described, but the vertical scanning operation by the V driver 12 (see FIG. 1) is related to the driving of the display area and the driving of the non-display area. It goes without saying that the operation is performed as usual.

In FIG. 4, when the display area is driven, the DC bias control circuit 42 is turned on by externally applying a control pulse, and the DC bias control circuit 42 applies a predetermined DC bias to the level shift circuit 41. As a result, the level shift circuit 41 is always activated. Then, once in one horizontal period (1H), the data line R → data line G → data line B is sequentially selected by time-division driving by the selection switch unit 13, and these data lines are input in time series. The signals are sequentially driven.

On the other hand, when the non-display area is driven, all the analog switches of the selection switch section 13 are turned on under the control of the selection switch control circuit 14, and the selection switch section 13 is turned on.
The data line R, the data line G, and the data line B are simultaneously driven by a signal (for example, a white signal) input from the outside without performing the time-divisional driving by. At this time, the selection switch control circuit 14 controls the level shift circuit 4
Information for turning on all the analog switches of the selection switch unit 13 is latched in the final latch unit of No. 1 and then the DC bias applied from the DC bias control circuit 42 to the level shift circuit 41 is cut off. The shift circuit 41 is made inactive.

As described above, in the active matrix type liquid crystal display device, in the partial display mode,
In the non-display area, all the analog switches of the selection switch unit 13 are turned on, and the data line R, the data line G, and the data line B are driven at the same time by a signal input from the outside. Part 1
Since it is not necessary to perform the time-division driving by 3, the consumption current corresponding to the capacitance of the analog switch of the selection switch unit 13 and the consumption current corresponding to the DC bias of the level shift circuit 41 can be cut.

As described above, by adopting the driving method in which the time division driving is not performed in the non-display area, as compared with the conventional driving method in which the time division driving is performed similarly to the display area, 200 × 3.
In a liquid crystal panel of (RGB) × 320 pixels, 3-inch class, when the display area is a partial display of 120 lines, the present liquid crystal display device (external driver IC 15
It has been confirmed by the present inventor that the power consumption of (excluding) can be reduced by about 45%. Even when the analog switch of the selection switch unit 13 has a PMOS configuration or an NMOS configuration, power consumption can be similarly reduced.

Although the above embodiment has been described on the premise of the liquid crystal display device of the time-division driving system, the present invention is not limited to the application to the time-division driving system, and analogs connected in units of data lines can be used. The same can be applied to the case of the dot-sequential driving method in which each of the switches is dot-sequentially driven by a horizontal scanner and a signal is written in each data line. That is, in the partial display mode, the horizontal scanner is stopped in the non-display area and all analog switches are turned on, or a signal is written by a separately provided analog switch to reduce the consumption of the horizontal scanner. It is possible to reduce power consumption by that amount.

Further, in the above embodiment, the liquid crystal display section 11
The description has been given taking the case of the liquid crystal display device in which the external driver IC 15 for inputting a signal is mounted by COG as an example.
The same is applicable to a liquid crystal display device mounted by AB (Tape Automated Bonding).

Furthermore, the present invention is not limited to application to a liquid crystal display device using a liquid crystal cell as an electro-optical element of a pixel,
The present invention can be applied to all display devices having a partial display mode, such as EL display devices using EL elements.

FIG. 5 is an external view showing the outline of the configuration of a portable terminal to which the present invention is applied, for example, a portable telephone.

The mobile phone according to this example has a structure in which a speaker section 52, a display section 53, an operating section 54, and a microphone section 55 are arranged in this order from the upper side on the front surface side of the apparatus housing 51. In the mobile phone having such a configuration, the display unit 5
For example, a liquid crystal display device is used for 3, and the liquid crystal display device according to the above-described embodiment is used as this liquid crystal display device.

The display unit 53 in this type of mobile phone has a partial display mode for displaying an image only in a partial area in the vertical direction of the screen as a display function such as a standby mode. As an example, in standby mode,
As shown in FIG. 6, information such as the remaining battery level, the reception sensitivity, and the time is always displayed at the top of the screen. Then, for example, white display is performed in the remaining display area.

As described above, in the mobile phone having the display unit 53 having the partial display function, the display unit 5 is provided.
By using the liquid crystal display device (or EL display device) according to the above-described embodiment as No. 3, these display devices adopt a driving method that does not perform time division driving in the non-display area at the time of partial display driving, Since it is possible to further reduce the power consumption, it is possible to extend the continuous usable time by the battery power supply.

Here, the case where the present invention is applied to a mobile phone has been described as an example, but the present invention is not limited to this, and the present invention can be applied to general mobile terminals such as a child device of a parent-child phone and a PDA.

[0040]

As described above, according to the present invention,
In a display device having a partial display mode, all the plurality of analog switches are turned on when the non-display area is driven, so that when the display area is driven,
The control for driving the analog switch on / off is not required, and the power consumption of the control system can be reduced accordingly, so that the power consumption can be reduced in the partial display mode.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a display device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a configuration of a liquid crystal display unit.

FIG. 3 is a circuit diagram showing an example of a connection configuration of a selection switch section in the case of 3-time-division driving.

FIG. 4 is a block diagram showing an example of a specific configuration of a selection switch control circuit.

FIG. 5 is an external view showing an outline of a configuration of a mobile phone to which the present invention is applied.

FIG. 6 is a diagram showing an example of a screen display in a partial display mode.

[Explanation of reference numerals] 11 ... Liquid crystal display section (pixel section), 12 ... V (vertical) driver, 13 ... Selection switch section, 13-1 to 13-3 ... Analog switch, 14 ... Selection switch control circuit, 15 ... External Driver IC

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 680 G09G 3/20 680S 680T (72) Inventor Yasushi Shimogaki 6-7 Kitashinagawa, Shinagawa-ku, Tokyo No. 35 Sony Corporation (72) Inventor Toshikazu Maekawa 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo F-terms at Sony Corporation (reference) 2H093 NA06 NC11 ND01 ND39 5C006 AC11 AC21 AF31 AF51 BB15 BC11 BC16 FA04 FA47 5C080 AA06 AA10 BB05 DD26 HH10 JJ01 JJ02 JJ03 JJ06 KK07

Claims (6)

[Claims] 1. A display device having a partial display mode in which an image is displayed only in a partial area of a screen in a vertical scanning direction, the pixel part having pixels arranged in a matrix, and the pixels of the pixel part. A plurality of analog switches for supplying a signal to each of the data lines arranged in each column, and when driving the display area in the partial display mode, the plurality of analog switches are sequentially turned on / off to drive the non-display area. A display device comprising: control means for turning on all the plurality of analog switches during driving. 2. The control means has a level shift circuit for level-shifting a drive pulse supplied from the outside and applying the level-shifted drive pulse to the plurality of analog switches, and when driving the non-display area, all of the plurality of analog switches are driven. The display device according to claim 1, wherein the level shift circuit is deactivated in a turned-on state. 3. The time division, wherein the analog switch is composed of a plurality of sets corresponding to a plurality of data lines and sequentially supplies signals given in time series to the plurality of data lines in a time division manner. The display device according to claim 1, comprising a switch. 4. The display device according to claim 1, wherein the electro-optical element of the pixel is a liquid crystal cell. 5. The display device according to claim 1, wherein the electro-optical element of the pixel is an electroluminescent element. 6. A mobile terminal having a display unit having a partial display mode for displaying an image only in a partial area in the vertical direction of the screen, wherein the display unit has pixels arranged in a matrix. The pixel section, a plurality of analog switches for supplying a signal to each of the data lines arranged for each pixel column of the pixel section, and the plurality of analog switches are sequentially turned on when the display area is driven in the partial display mode. A mobile terminal comprising: a display device including: a control unit that is turned on / off and turns on all of the plurality of analog switches when a non-display area is driven.