JPH0213766B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a liquid crystal display device using a switch/capacitor array, and particularly to a liquid crystal display device that can switch between two display modes such as television image display and time display. Related to display devices.

[Technical background of the invention and its problems]

Recently, development of multi-pixel, high-density liquid crystal display devices aimed at displaying images and graphics has been progressing. In this display device, as a means for controlling the brightness or lighting/non-lighting of each pixel, a switch/pixel electrode including a switch element and a capacitor is formed in a matrix using semiconductor integrated circuit technology or thin film technology.
A capacitor array is used.

FIG. 1 is an equivalent circuit for explaining a configuration example of a switch/capacitor array. 1 is a MOSFET as a switch element, 2 is a MOS capacitor,
3 is the display pixel electrode that defines the pixel, MOSFET1
It is electrically connected to the connection point of the MOS capacitor 2 and the MOS capacitor 2. The gates of MOSFET1 are commonly connected in each row to provide address lines Y ₁ , Y ₂ , ..., _Yo , and the drains or sources are commonly connected in each column to provide data lines X ₁ , X ₂ , ..., X _n will be provided.
MOSFET 1, MOS capacitor 2, address lines Y ₁ , Y ₂ , ..., _Yo and data lines X ₁ , X ₂ ,
..., X _n are formed integratedly on a semiconductor substrate, for example,
A display pixel electrode 3 is formed on the surface with an interlayer insulating film interposed therebetween.

FIG. 2 is a sectional view showing a conventional liquid crystal display device using the switch/capacitor array shown in FIG. Reference numeral 4 designates, for example, a silicon substrate on which a switch/capacitor array is formed, and a display pixel electrode 3 is formed on the surface of this substrate with an interlayer insulating film 5 interposed therebetween. 7 is a counter electrode made of a transparent conductive film, 8 is a transparent insulating substrate, 9 is a spacer and a sealing part, 10 is a liquid crystal layer, and 6 is a reinforcing substrate.

The operation of the liquid crystal display device shown in FIG. 2 is as follows. In FIG. 1, address lines Y ₁ , Y ₂ ,
..., Y _o is sequentially scan-driven by the scan signal from the scan drive circuit, and MOSFET1 is T _F /
The conduction state is sequentially brought to n periods. T _F is the frame scanning period. When, for example, m parallel image signal voltages are supplied as data signals to the data lines X ₁ , X ₂ , . _. . Retained for a period of T _F. This held selection voltage is guided to the display pixel electrode 3 and excites the liquid crystal layer 10 held between the counter electrode 7 and the display pixel electrode 3 . This causes an image to be displayed.

Recently, a wristwatch (TV watch) has been developed which integrally incorporates this type of liquid crystal display device for displaying images and a segment type liquid crystal display device for displaying numbers. Figure 3 is an example, where 11 is the first
The television display section 12 is a time display section using a segment type liquid crystal display device which has been used in ordinary electronic digital watches.

As is clear from the figure, in such a television watch, since the television display section 11 is provided, the time display section 12 is inevitably pushed above (or below) the display surface. Therefore, the numerals on the time display cannot be made sufficiently large, making them difficult to read. Furthermore, in a state where only the time display is displayed, which takes up a much larger proportion of time than a television display, the display does not look good because it is displayed only in a small portion of one corner of the display surface.

These drawbacks can be solved in principle by using only the image display liquid crystal display device for television display to also display the time. In other words, when using only a liquid crystal display device for displaying images using a switch/capacitor array, and when the entire display surface is the TV display section 13 and no TV display is performed, the center part of the display surface is used as the time display. Display section 14
It can be configured to display the time as follows.

However, it is not preferable to manufacture a television watch using only a liquid crystal display device for displaying images in this way from the viewpoint of power consumption. This is because image display liquid crystal display devices that use a switch/capacitor array repeatedly charge and discharge the capacitor through the switch elements, which consumes much more power than segment type liquid crystal display devices. This is because it will be used to display the time of day.

[Purpose of the invention]

The present invention has been made in view of the above points, and it is possible to selectively switch and control two types of display modes such as TV display and time display without completely separating the display surfaces, and moreover, it is possible to control switching between two types of display modes such as TV display and time display without completely separating the display surfaces. An object of the present invention is to provide a liquid crystal display device that eliminates power consumption.

[Summary of the invention]

The present invention is based on a liquid crystal display device for image display using a switch/capacitor array, and the counter electrode substrate thereof includes a group of segment electrodes constituting a plurality of display segments and an entire area other than the area covered by the segment electrodes. A structure including a control electrode formed electrically separated from the segment electrode so as to cover the segment electrode is used. In the first display mode, the segment electrode group and the control electrode are used as a common electrode facing each other, and a switch/capacitor array is driven to selectively apply a signal voltage to the display pixel electrode to perform television display or the like. The display modes are switched and controlled by using the display pixel electrode on the switch/capacitor array side as the opposing common electrode and selectively applying a signal voltage to the segment electrode group to display time or the like.

〔Effect of the invention〕

According to the present invention, when applied to a TV watch, for example, as shown in FIG. A time display with easy-to-read numbers and an attractive appearance can be obtained. Moreover, in the second display mode using segment electrodes, the operation of the switch/capacitor array is static, and as in conventional segment type liquid crystal display devices, power consumption is low and even when operated steadily and continuously. no problem.

[Embodiments of the invention]

FIG. 5 is a sectional view showing a liquid crystal display device according to an embodiment of the present invention. 20 is an array substrate, for example, a silicon substrate 21 has a switch/capacitor array integrated thereon, and an interlayer insulating film 22 is formed on its surface.
The display pixel electrodes 23 are arranged in an array through the display pixel electrodes 23. The counter electrode substrate 24 facing the array substrate 20 here is a transparent insulating substrate 25 made of glass or the like, on the surface of which a first layer of insulating conductive film is deposited and patterned to form segment electrodes 26, and further a transparent insulating film 27 is formed. The control electrode 28 is formed by depositing a second layer transparent conductive film through the wafer and patterning it.
A display device is constructed by sandwiching a liquid crystal layer 29 between the array substrate 20 and the counter electrode substrate 24. 30 is a spacer and sealing substance, 31 ₁ ,
31 ₂ is the segment electrode 2 on the counter electrode substrate 24 side
6. A conductive member for leading the control electrode 28 to terminal portions 32 ₁ and 32 ₂ provided on the array substrate 20 side, respectively; 33 is a reinforcing substrate.

6a to 6c show the electrode pattern on the counter electrode substrate 24 side in the order of manufacturing steps. As shown in a, the segment electrodes 26 made of the first transparent conductive film are arranged and formed approximately at the center of the substrate 25, that is, at the center of the display surface. Each segment electrode 26 is led to a terminal 35 at the end of the substrate 25 by a wiring 34, respectively. The control electrode 28 made of the second layer transparent conductive film is arranged so as to cover the entire area except for the area of the segment electrode 26 and the area of its terminal 36, as shown in FIG. 3(b). A spacer/sealing material 30 is provided around the thus formed counter electrode substrate 24 as shown in FIG.
By bonding them together, a liquid crystal container is formed.

The display operation of the liquid crystal display device configured as described above will be explained next. In the first display mode in which an image is displayed, the segment electrodes 2 on the counter electrode substrate 24
6 and the control electrode 28, and apply scanning signals and image signals to the address lines and data lines of the switch/capacitor array formed on the array substrate 20, respectively, as explained in FIGS. 1 and 2. supply. At this time, the segment electrodes 26 and the control electrodes 28 function as opposing electrodes in the conventional device shown in FIG. 2 to display a desired image.

Next, in a second display mode in which time is displayed, substantially the same potential is applied to all display pixel electrodes 23 and control electrodes 28 on the array substrate 20, and numeric display signals are supplied to a plurality of segment electrodes 26. At this time, the display pixel electrode 23 functions as a counter electrode facing the segment electrode 26, and a desired time display is performed. In addition, a control electrode 28 to which a constant potential is applied
is the wiring 3 that sends a signal voltage to each segment electrode 26.
4 to prevent the wiring 24 from lighting up.

In order to apply the same voltage to all display pixel electrodes 23, in the circuit shown in FIG.
A voltage that makes MOSFET 1 conductive is supplied to all of Y ₁ , Y ₂ , ..., _Yo , and data lines X ₁ , X ₂ ,
..., X _n may all be supplied with the same voltage.
Although this type of drive can be realized by devising the line drive circuit itself, it is easier to provide a switch in the ground line side wiring of the address line drive circuit and turn off this switch to turn off all addresses. It is sufficient to apply a power supply potential to the line. Normally, the address line drive circuit outputs a drive voltage to only one of n output terminals in order to sequentially drive the address lines Y ₁ , Y ₂ , ..., _Yo , but as described above, By disconnecting the ground wire side, the entire output can be made into the power supply voltage. A data line drive circuit is originally capable of outputting any signal voltage to its m output terminals, so all outputs can be kept at a constant potential depending on the input signal, but this is similar to the address line drive circuit. Alternatively, a changeover switch may be provided on the ground line side, and the entire output may be set to the power supply voltage by operating the switch.

As explained above, according to this embodiment, a liquid crystal display device having two display modes such as image display and numeric display is created using an array substrate on which display pixel electrodes equipped with switch elements are arranged. can get. When this device is used as a television watch, it is possible to switch between the television display and the time display at the center of the display screen, making the time display easier to read and more visually pleasing than conventional devices with a split display screen. Furthermore, the operation of the switch/capacitor array when displaying the time is static, and power consumption is low. Furthermore, if a method is used in which a switch is installed on the ground wiring side of the line drive circuit and the switch/capacitor array is statically driven, the supply of the time display signal is controlled by the switch linked with this switch, and the TV display and time can be controlled. It also becomes easier to switch the display. In addition, on the counter electrode substrate side, since the segment electrodes are formed by the first layer transparent conductive film and the area other than the segment electrodes is covered by the second layer transparent conductive film, the wiring for supplying the signal voltage to the segment electrodes is Lighting in some areas is prevented.

[Brief explanation of drawings]

FIG. 1 is an equivalent circuit diagram for explaining the configuration of a switch/capacitor array, and FIG. 2 is a sectional view showing a conventional liquid crystal display device using this array substrate.
FIG. 3 is a diagram showing the display section of a conventional TV watch, FIG. 4 is a diagram showing the display section of a preferable TV watch, and FIG. 5 is a sectional view showing a liquid crystal display device according to an embodiment of the present invention. FIGS. 6a to 6c are diagrams showing the electrode pattern of the counter electrode substrate in the order of manufacturing steps. 20...Array substrate, 21...Silicon substrate,
22... Interlayer insulating film, 23... Display pixel electrode, 2
4...Counter electrode substrate, 25...Transparent insulating substrate, 2
6... Segment electrode (first layer transparent conductive film), 2
7...Transparent insulating film, 28...Control electrode (second layer transparent conductive film), 29...Liquid crystal layer.

Claims (1)

[Scope of Claims] 1. A liquid crystal layer is sandwiched between an array substrate on which a switch/capacitor array and a large number of display pixel electrodes selectively driven by the switch/capacitor array are integrated and a counter electrode substrate facing the array substrate. In the liquid crystal display device configured as shown in FIG. , a second electrode including at least a region other than the region covered by the segment electrode group on the transparent insulating substrate, and formed electrically insulated from the segment electrode group.
a control electrode formed of a layered transparent conductive film, a first display mode in which the segment electrode group and the control electrode are set at a predetermined potential and a signal voltage is selectively applied to the display pixel electrode; a second set of display pixel electrodes and control electrodes at predetermined potentials and selectively applying a signal voltage to the segment electrode group;
A liquid crystal display device having a display mode. 2. The liquid crystal display device according to claim 1, wherein the segment electrode group is formed approximately at the center of the substrate. 3. The liquid crystal display device according to claim 1, wherein the first display mode displays an image, and the second display mode displays a time.