JPH08254966A - Liquid crystal device and electronic equipment - Google Patents

Abstract

(57) [Summary] [Object] The object of the present invention is to fix the read start signal, the scan clock, and the read relationship of the RAM.
Another object of the present invention is to provide a liquid crystal device in which the AM built-in column driver 2 can also utilize an unused RAM portion. According to the present invention, in a liquid crystal device using a column driver 2 with a built-in RAM, arbitrary data stored in a RAM can be displayed on a liquid crystal screen 1 by changing a selection position of a row driver 3.
To be displayed.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a word processor, personal computer,
The present invention relates to a liquid crystal device and an electronic device which are display units of an information processing device such as a workstation.

[0002]

2. Description of the Related Art As shown in FIG. 8, a conventional liquid crystal display device has not been utilized because the RAM capacity of a RAM built-in column driver is larger than the display capacity. Alternatively, as shown in FIG. 9, a new control unit and control signal are added to add an address function that uses the entire RAM capacity in the RAM built-in column driver.

[0003]

In the above-mentioned prior art, since the scanning start signal, the scanning clock, and the read relation of the RAM are fixed, the portion of the RAM that does not correspond to the row driver cannot be utilized. Alternatively, there have been drawbacks such as an increase in the cost of a column driver with built-in RAM and an increase in control signals in an attempt to increase the degree of freedom by adding an address function. Therefore, the present invention solves such a problem, and its object is to fix the scanning start signal, the scanning clock, and the read relation of the RAM.
Another object of the present invention is to provide a liquid crystal device that can utilize the RAM part that has not been used in the conventional technique even with the AM built-in column driver. (A row means a common electrode to which a selection signal is applied, and a column means a signal electrode to which a signal corresponding to screen data is applied. The column driver and the row driver drive the corresponding electrodes, respectively.)

[0004]

The invention according to claim 1 is R
It is characterized in that arbitrary data stored in the RAM is displayed on the liquid crystal screen by changing the selection position of the row driver in the liquid crystal device using the AM built-in column driver.

The invention described in claim 2 is characterized in that the period of the scanning clock in the period corresponding to the non-display portion of claim 1 is shortened.

The invention according to claim 3 is characterized in that the driving method according to claim 1 or 2 is the IHAT method.

The invention described in claim 4 is characterized in that the liquid crystal device according to claim 1, claim 2 or claim 3 is used.

[0008]

According to the invention described in claim 1, arbitrary data stored in the RAM can be displayed on the liquid crystal screen by changing the selection position of the row driver.

According to the second aspect of the invention, the display duty can be reduced by shortening the period of the scanning clock in the period corresponding to the non-display portion of the first aspect.

According to the third aspect of the invention, the driving method of the first aspect is the IHAT method, so that the advantage of the IHAT method can be utilized.

According to the invention described in claim 4, since the liquid crystal device according to claim 1, claim 2 or claim 3 is used, a large amount of data can be handled with low power consumption.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 shows an embodiment of the present invention. In this embodiment, the liquid crystal screen 1 has 120 × 160 pixels. The RAM built-in column driver 2 outputs 160 columns and has a RAM for 240 row lines. The row driver 3 has an output of 120 lines. Conventionally 12
It can only be used for 0x160 pixels, and the latter half 12
I could not utilize 0 lines. However, in the present invention, the selected position can be changed to display any one portion of the RAM. FIG. 2 shows the driving state of the present invention in a timing chart.
The scanning start signal (START) is at the "H" level every time the scanning of one screen is started. Scan clock (SCN_C
K) is controlled by a number corresponding to the number of RAM row lines of the RAM built-in column driver. In this embodiment, the falling edge of SCN_CK is used. The row driver performs selective output during the period of Ef. In the figure, the "L" level indicates that the output is non-selective, and the "H" level indicates that the output is selective. Since this timing chart is just an example, various combinations are actually conceivable. For example, it is possible to use only up to 200 lines, or to output an extra scanning clock up to 255 for the convenience of logic design. Further FIG.
Will be described in detail. The timing chart is Fr,
It is roughly divided into periods of Ef and Bk. First, in the period of Fr, during this period, the column driver with built-in RAM outputs corresponding to the data of the corresponding RAM. However, all the output terminals ROW1 to ROW120 of the row driver are unselected. Therefore, it can be considered that the virtual screen is displayed on the real screen. Next, the period of Ef will be described. During this period, ROW1, ROW2, ROW3 ...
..Selected output corresponding to the output of ROW120 and column driver with built-in RAM. An image corresponding to the RAM data is displayed on the liquid crystal screen 1. The period of Bk will be described. In this period, the row driver is not selected as in the Fr period. Therefore, it can be considered that the virtual screen is displayed below the liquid crystal screen 1. The display start position of the liquid crystal screen 1 of the scanning clock is the (n + 1) th position. Then, the display end position is the n + 120th position. In FIG. 3, it is assumed that the first half 4 of the RAM of up to 120 lines has screen data "SEIKO EPSON" 6 and the second half 5 of the RAM of 121 to 240 lines has screen data "CORPORATION" 7. Therefore, if n = 0, the upper half will be displayed as shown in FIG. If n = 120, the lower half will be displayed as shown in FIG. Since the selection position can be arbitrarily changed, if the selection position is continuously changed, the screen can be scrolled arbitrarily. The functions described so far may be in either the controller or the row driver. Select start signal E
This can be realized by applying the signal to the row driver at the beginning of the period f, or by making a scan enable signal and masking the scan clock (SCN_CK) of the row driver during the period Fr, Bk. (However, although the control is relatively simple, the duty becomes 1/240 including the RAM portion 5 of the virtual screen in this embodiment.) Since the entire RAM can be utilized in this way, it corresponds to the RAM capacity. It has the excellent advantage that it can display the contents of any RAM part once the screen is captured.

[Second Embodiment] Next, a second embodiment will be described with reference to a timing chart of FIG. The basics are the same as in the first embodiment. The difference is that the periods Fr and Bk in the non-selected state are controlled to be short. Then, the scanning clock at the time of non-selection is fast-forwarded at high speed and the duty of the display screen (= 1/120)
It can be driven at a value close to, and the entire RAM can be used without degrading the image quality. It has an excellent advantage that one screen of arbitrary liquid crystal display capacity can be displayed by once capturing a screen corresponding to the RAM capacity. However, since the control is slightly more complicated than that of the first embodiment, it is necessary to select the first and second embodiments depending on the application.

[Third Embodiment] Next, a third embodiment will be described with reference to FIG. The number of simultaneously selected lines is two as an example. Any number of lines can be selected at the same time. The basics are the same as in Examples 1 and 2. The difference is that the IHAT method is adopted as the driving method. The non-selected periods Fr and Bk shown in FIG. 6 are exactly the same as those in the first and second embodiments. Since the number of simultaneous selections is 2, two scans are simultaneously performed on two lines. The drawing shows that there is a first selection period of f1 and a second selection period of f2. f1 and f
Since 2 has an orthogonal relationship, vector combinations such as (1, 1) and (1, -1) are selected. Details are IHAT
Literature of law (TN, RUCKMONGATHAN: "A generalized address
ing technique for rms responding matrix "1988 INTE
RNATIONAL DISPLAY RESEARCH CONFERENCE, P80). Then, the advantage of being able to lower the drive voltage can be used to manufacture the driver in a low withstand voltage process, and a low cost can be realized. In addition, it has an excellent advantage that one screen of arbitrary liquid crystal display capacity can be displayed by once capturing the screen corresponding to the RAM capacity.

[Fourth Embodiment] Next, a fourth embodiment will be described with reference to FIG. A mobile phone having a PDA function using the liquid crystal device of the present invention. RAM built-in column driver RA
Part of the MDA stores the PDA menu screen, part of the phone key screen, and part of the personal computer keyboard screen. Each data is from A of FIG.
It is displayed like C. Once the screen data of A to C is written in the liquid crystal device, A, B and C are instantly switched only by changing the selection position of the row driver. At that time, the write operation to the RAM is not necessary. Therefore, power consumption due to data transfer can be reduced to the utmost limit. RA
The M built-in column driver may have a RAM capacity three times as large in this embodiment as the number of rows on the screen. The degree of freedom in design is increased, standardization is implemented, and cost reduction is possible.

[0017]

As described above, it is possible to utilize all the capacity of the RAM-equipped column driver. In addition, the screens can be switched instantly without data transfer, enabling low power consumption and high speed. Also, by only having one large-capacity RAM built-in column driver, it is possible to utilize the RAM to various liquid crystal display capacities without waste, and it is possible to standardize and reduce the cost.

[Brief description of drawings]

FIG. 1 is a schematic view of a liquid crystal device of the present invention.

FIG. 2 is a timing chart of one embodiment of the present invention.

FIG. 3 is a diagram showing a state in which the upper half of the present invention is displayed.

FIG. 4 is a diagram showing a state in which the lower half of the present invention is displayed.

FIG. 5 is a timing chart of an embodiment in which the scanning clock of the present invention is changed.

FIG. 6 is a timing chart of an embodiment in which the IHAT method is applied to the driving method of the present invention.

FIG. 7 is an explanatory diagram of an embodiment in which the present invention is applied to an electronic device called a PDA having a mobile phone function.

FIG. 8 is a timing chart of conventional driving.

FIG. 9 is a block diagram showing address management of a conventional RAM built-in column driver.

[Explanation of symbols]

 1. LCD screen 2. RAM built-in column driver 3. Low driver 4. First half of RAM 5. RAM latter half 6. Screen data (ROW1 to ROW120) 7. Screen data (ROW121 to ROW240) 8. Layer 1 9. Layer 2 10. Layer 3 11. Layer 4 12. Address controller and above

Claims (4)

[Claims] 1. A liquid crystal display device characterized by displaying arbitrary data stored in a RAM on a liquid crystal screen by changing a selection position of a row driver in a liquid crystal device using a column driver with built-in RAM. 2. A liquid crystal device characterized in that a period of a scanning clock in a period corresponding to the non-display portion of claim 1 is shortened. 3. A liquid crystal device, wherein the driving method according to claim 1 or 2 is a plurality of line selections using an orthogonal function (hereinafter abbreviated as IHAT method). 4. An electronic apparatus using the liquid crystal display device according to claim 1, claim 2 or claim 3.