JP2000315071A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate cross talk on a display picture generated based on a data writing to a portion of an incorporated display memory that is not been used and to effectively utilize the portion that is remained as an unused part of the memory. SOLUTION: Under the control of a control circuit 9, a scanning electrode selecting circuit 5c selects a line shift circuit 5b side for the circuit portion that are connected to a scanning electrode 2 of a liquid crystal display panel 1 in a scanning electrode driving circuit 5a. For the circuit portion not connected to the electrode 2 of the panel 1, a GND level (an L level) side is selected. Moreover, a signal electrode selection circuit 6c selects a data latch circuit 6b side for the circuit portion connected to a signal electrode 3 of the panel 1. For the circuit portion not connected to the signal electrode 3 of the panel 1 in a signal electrode driving circuit 6a, the data latch circuit 6b side is selected. For the circuit portion not connected to the electrode 3 of the panel 1, the GND level (the L level) side is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device using a one-chip type liquid crystal display driver with a built-in control circuit in a portable device terminal or the like.

[0002]

2. Description of the Related Art In recent years, in a portable device terminal or the like, a liquid crystal driving circuit and a control circuit for the liquid crystal driving circuit and its control circuit have been optimized in order to promote miniaturization and low power consumption. A liquid crystal display device using a one-chip type liquid crystal display driver incorporating the above-mentioned circuit has been easily used.

An example of the configuration of the above-described conventional liquid crystal display device will be described below. FIG. 1 shows a general configuration of a conventional liquid crystal display device, and FIG. 1 is a block diagram showing an example of the configuration of a conventional liquid crystal display device. In FIG. 1, 1 is a liquid crystal display panel,
2 is a scanning electrode, 3 is a signal electrode, 4 is a liquid crystal display driver,
Reference numeral 5 denotes a scan electrode driver, 5a denotes a scan electrode driver, 5b denotes a line shift circuit, 6 denotes a signal electrode driver, 6a denotes a signal electrode driver, 6b denotes a data latch circuit, 7 denotes a display memory, and 8 denotes a drive power supply. The circuit 9 is a control circuit.

In the above-described liquid crystal display device, as shown in FIG. 1, a scanning electrode driving unit 5 and a signal electrode driving unit in a liquid crystal display driver 4 are provided on a scanning electrode 2 and a signal electrode 3 of a liquid crystal display panel 1, respectively. 6 are connected to respective terminals for outputting respective liquid crystal driving waveforms, and the capacity of image data when displaying images on the liquid crystal display panel 1 is:
When the total capacity of the display memory 7 in the liquid crystal display driver 4 is within the total capacity, the image data is written into a portion of the display memory 7 corresponding to the display image on the liquid crystal display panel 1 under the control of the control circuit 9, so that the liquid crystal display An image is displayed on the panel 1.

The liquid crystal driving waveform from the scanning electrode driving section 5 is controlled by the control circuit 9 based on a shift signal for line-sequential scanning from the line shift circuit 5b.
It is output from scan electrode drive circuit 5a. The liquid crystal drive waveform from the signal electrode drive unit 6 is controlled by the control circuit 9 to latch image data from the image data written in the display memory 7 into the data latch circuit 6b for each horizontal scan. Are output from the signal electrode drive circuit 6a based on the image data.

[0006]

However, in the conventional liquid crystal display device as described above, in the display memory 7,
For example, when there is some data which is not image data necessary for image display in a surplus unused portion for image display corresponding to a portion which does not contribute to image display of a liquid crystal drive circuit such as the signal electrode drive unit 6. Is operated on the basis of the data in the signal electrode drive section 6 so that a portion which is not connected to the liquid crystal display panel 1 and does not contribute to image display also operates.
As a result, crosstalk occurs in the image display portion.

In this case, it is necessary to clear the unused memory area in the display memory 7 once so as not to perform writing thereafter, and to effectively use the surplus portion of the display memory 7. There was a problem that it was not possible. SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, eliminates crosstalk on a display image caused by writing data to an unused portion in the built-in display memory, and reduces unused portions in the built-in display memory. The present invention provides a liquid crystal display device that can effectively use the surplus part.

[0008]

In order to solve the above-mentioned problems, a liquid crystal display device according to the present invention uses an unused portion for displaying an image in a built-in display memory corresponding to a portion of the liquid crystal drive circuit which does not contribute to image display. Is electrically separated from the liquid crystal driving circuit, so that even when data is written to an unused portion of the built-in display memory, the written data is not involved in a display image via the liquid crystal driving circuit. It is characterized by the following.

As described above, crosstalk on a display image caused by writing data to an unused portion in the built-in display memory is eliminated, and a portion remaining as an unused portion in the built-in display memory is effectively used. be able to.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device according to a first aspect of the present invention is a liquid crystal display device for displaying an image by time division driving based on a plurality of divisions of liquid crystal pixels based on image data in a display memory. A liquid crystal driving circuit that performs the time division driving on the liquid crystal during the image display based on image data in the display memory, and a control circuit that controls the time division driving by the liquid crystal driving circuit. The control circuit is configured to control separation of the display memory from the liquid crystal drive circuit in accordance with a state of participation in the image display in the display memory.

According to a second aspect of the present invention, in the liquid crystal display device, the control circuit according to the first aspect stores the display capacity data of an image at the time of image display, and stores the display capacity data in the display memory obtained from the display capacity data. It is configured to control so that an unused portion for image display is separated from the liquid crystal drive circuit. According to these configurations, an unused portion for image display in the built-in display memory corresponding to a portion of the liquid crystal drive circuit that does not contribute to image display is electrically separated from the liquid crystal drive circuit, so that the unused portion of the built-in display memory is Even when data is written to the used portion, the write data is not involved in the display image via the liquid crystal drive circuit.

Hereinafter, a liquid crystal display device according to an embodiment of the present invention will be specifically described with reference to the drawings.
FIG. 2 is a block diagram illustrating a configuration example of the liquid crystal display device of the present embodiment. In FIG. 2, 1 is a liquid crystal display panel,
2 is a scanning electrode, 3 is a signal electrode, 4 is a liquid crystal display driver,
5 is a scan electrode drive unit, 5a is a scan electrode drive circuit, 5b is a line shift circuit, 5c is a scan electrode selection circuit, 6 is a signal electrode drive unit, 6a is a signal electrode drive circuit, 6b is a data latch circuit, and 6c is a signal. An electrode selection circuit, 7 is a display memory,
8 is a driving power supply circuit, and 9 is a control circuit.

In the above-described liquid crystal display device, the control circuit 9 is configured to have display capacitance data indicating a display capacitance corresponding to a display range when displaying an image on the liquid crystal display panel 1. Then, the control circuit 9 is connected to the signal electrode selection circuit 6c in the signal electrode drive unit 6 in the liquid crystal display driver 4 and to the signal electrode 3 of the signal electrode drive circuit 6a based on the content of the display capacitance data. Only the portion corresponding to the displayed image display range is electrically connected to the display memory 7 through the data latch circuit 6b, and the unused area not related to the image display in the display memory 7 is passed through the data latch circuit 6b. Electrical connection to the signal electrode drive circuit 6a is turned off,
It is controlled so as to be separated from the signal electrode drive circuit 6a.

The control circuit 9 sends a signal to the scan electrode selection circuit 5c in the scan electrode drive unit 5 in the liquid crystal display driver 4 based on the content of the display capacitance data. Are electrically connected to the line shift circuit 5b, and the unused portions not related to image display in the line shift circuit 5b are electrically connected to the scan electrode drive circuit 5a. The electrical connection to is controlled to be in an off state so as to be separated from the scan electrode drive circuit 5a.

The scan electrode selection circuit 5c of the control circuit 9
The above-described control state of the signal electrode selection circuit 6c can be fixed regardless of the image display content. Next, a specific example of the operation of the liquid crystal display device of the present embodiment will be described. FIG. 3 is a detailed block diagram for explaining the operation of the liquid crystal display device of the present embodiment. In this liquid crystal display device, as shown in FIG. 3, under the control of the control circuit 9, each switching circuit in the scan electrode selection circuit 5c is connected to the scan electrode 2 of the liquid crystal display panel 1 in the scan electrode drive circuit 5a. The line shift circuit 5b side is selected for the circuit portion in which
Is selected on the GND (L level) side for the circuit portion not connected to.

Further, under the control of the control circuit 9, each switching circuit in the signal electrode selection circuit 6c controls the circuit portion connected to the signal electrode 3 of the liquid crystal display panel 1 in the signal electrode drive circuit 6a. The data latch circuit 6b is selected, and the GND (L level) side is selected for a circuit portion not connected to the signal electrode 3 of the liquid crystal display panel 1.

As described above, the display memory area irrelevant to the image display on the liquid crystal display panel 1 is stored in the signal electrode driving circuit 6a.
From the display memory 7 which is not related to the image display in the display image on the liquid crystal display panel 1. Even if there is no other data, the influence of crosstalk can be eliminated.

In the above description, the circuit portion of the liquid crystal driving circuit which is not connected to the scanning electrode 2 or the signal electrode 3 of the liquid crystal display panel 1 is fixed at the GND level (L level). ) Does not pose any problem.

[0019]

As described above, according to the present invention, an unused portion for image display in the built-in display memory corresponding to a portion of the liquid crystal drive circuit that does not contribute to image display is electrically separated from the liquid crystal drive circuit. By doing so, even when data is written to an unused portion of the built-in display memory, it is possible to eliminate the involvement of the written data in a display image via the liquid crystal drive circuit.

Therefore, crosstalk on a display image caused by writing data to an unused portion in the built-in display memory is eliminated, and a portion remaining as an unused portion in the built-in display memory is effectively used. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a conventional liquid crystal display device.

FIG. 2 is a block diagram illustrating a configuration example of a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is a detailed block diagram for explaining the operation of the liquid crystal display device of the embodiment.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal display panel 2 scan electrode 3 signal electrode 4 liquid crystal display driver 5 scan electrode drive unit 5a scan electrode drive circuit 5b line shift circuit 5c scan electrode selection circuit 6 signal electrode drive unit 6a signal electrode drive circuit 6b data latch circuit 6c signal electrode Selection circuit 7 Display memory 8 Driving power supply circuit 9 Control circuit

Claims (2)

[Claims] 1. Based on image data in a display memory,
What is claimed is: 1. A liquid crystal display device which displays an image by time division driving of a plurality of pixels on a liquid crystal, and performs the time division driving on the liquid crystal when displaying the image based on image data in the display memory. And a control circuit for controlling the time-division driving by the liquid crystal drive circuit, wherein the control circuit controls the liquid crystal of the display memory in accordance with a state of participation in the image display in the display memory. A liquid crystal display device configured to control separation from a drive circuit. 2. A control circuit for storing display capacity data of an image at the time of image display, and separating an unused portion from the liquid crystal drive circuit for image display in the display memory obtained from the display capacity data. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is configured to perform such control.