Liquid crystal display device

• US 6,023,252 A
• Filed: 10/05/1995
• Issued: 02/08/2000
• Est. Priority Date: 04/05/1995
• Status: Expired due to Fees

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Sato, Takahiko, Nakamura, Rikoku, Morokawa, Shigeru, Yano, Takakazu
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Laneau, Ronald
• Application Number:
  US08/539,585
• Time in Patent Office: 1,587 Days
• Field of Search: 345/103, 345/127, 345/130, 345/131, 345/1, 345/87, 382/358, 340/709, 340/784
• US Class Current: 345/1.1
• CPC Class Codes: G09G 2340/0414 Vertical resolution change
• CPC Class Codes: G09G 2340/045 Zooming at least part of an image, i.e. enlarging it or shrinking it
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3644 with the matrix divided into sections
• CPC Class Codes: G09G 5/397 Arrangements specially adapted for transferring the contents of two or more bit-mapped memories to the screen simultaneously, e.g. for mixing or overlay G09G5/02 takes precedence

Abstract

An LCD device comprising an LCD for changing the size of a displayed unit of pixels by electrically connecting a plurality of display electrodes in parallel with one another for time-sharing matrix driving liquid crystal pixels arranged as a matrix wherein image data is independently inputted into upper and lower half portions of the LCD, a display controller for outputting upper and lower side image data to be displayed on the upper and lower half portions of the LCD and synchronous signals. The LCD device further comprises an upper side image data-holding memory and a lower side image data-holding memory for dividing image data in a given display area from a screenful of image data outputted from the display controller into new upper and lower side image data to be written and held in the upper and lower side image data-holding memories. The upper and lower side image data held in the upper and lower side memories are read out to be repeatedly displayed on the upper and lower half portions of the LCD. As a result, the image from any desired display area of a full-screen area can be enlargedly displayed on a full-screen area of a display with high quality and be easily visible without being discontinuous.

Claims

1. An LCD device comprising:

an LCD having time-sharing matrix driving liquid crystal pixels arranged as a matrix in upper and lower half portions, for display of an initial screenful of image data made up of upper and lower side image data in a display area;

a display controller respectively displaying the upper and lower side image data on the upper and lower half portions of the LCD;

an upper side image data-holding memory holding the upper side image data;

a lower side image data-holding memory holding the lower side image data;

memory write control means for identifying a selected continuous portion of the initial screenful of image data for enlargement and dividing the selected continuous portion of the initial screenful of image data into new upper and lower side image data respectively written and held in the upper and lower side image data-holding memories; and

memory read control means for reading out the new upper and lower side image data held in the upper and lower side memories to be repeatedly displayed by the display controller on the upper and lower half portions of the LCD as a new screenful of image data in which a plurality of display electrodes of the pixels are connected in parallel to achieve an enlargement of the selected continuous portion of the initial screenful of image data.

2. An LCD device according to claim 1, wherein the memory write control means comprises:

display area determining means for identifying the selected continuous portion of the initial screenful of image data from the display area;

write reference determining means for determining a write reference in response to synchronous signals outputted from the display controller;

write means for controlling the upper and lower side image data-holding memories in response to output signals from the write reference determining means and display area determining means; and

select means for selecting the upper and lower side image data outputted from the display controller in response to output signals from the display area determining means to output the new upper and lower side image data to be respectively written in the upper and lower side image data-holding memories.

3. An LCD device according to claim 2, wherein the display area determining means selects at least one of different display areas which were previously set in response to inputted mode signals so as to determine a selected display area as the selected continuous portion of the initial screenful of image data in the display area.

4. An LCD device according to claim 2, wherein the display area determining means detects a cursor location in the initial screenful of image data to determine an area having a given range including the detected cursor location as the selected continuous portion of the initial screenful of image data in the display area.

5. An LCD device according to claim 1, wherein the memory read control means includes means for outputting a memory read latch pulse signal and a memory read clock signal to the upper and lower side image data-holding memories, wherein the memory read latch pulse signal and the memory read clock signal are divided in frequency in accordance with the plurality of parallel connections of the display electrodes for time-sharing matrix driving the liquid crystal pixels of the LCD.

6. An LCD device according to claim 1, further comprising:

means for detecting whether the display controller is operating or not, and write enabling restriction means for permitting the memory write control means to write only when the detection means detects operation of the display controller;

wherein the memory write control means repeatedly reads out the upper and lower side image data held in the upper and lower side image data-holding memories to be repeatedly displayed on the upper and lower half portions of the LCD respectively when at least the detection means detects that the display controller is not operating.

7. An LCD device according to claim 6, wherein the memory write control means divides the selected continuous portion of the initial screenful of image data into the new upper and lower side image data when a writing operation is enabled by the write enabling restriction circuit.

8. An LCD device according to claim 6, further comprising means for permitting the write enabling restriction circuit to enable the memory write control means to perform a writing operation when the detection circuit detects that the display controller is operating, and for stopping operation of said display controller after the memory write control means completes writing of the image data from the given area.

9. An LCD device comprising:

an LCD having time-sharing matrix driving liquid crystal pixels arranged as a matrix in upper and lower half portions, for display of an initial screenful of image data made up of upper and lower side image data;

a display controller respectively displaying the upper and lower side image data on the upper and lower half portions of the LCD; and

data converting means for dividing and converting a selected continuous portion of the initial screenful of image data into new upper and lower side image data to be respectively displayed by the display controller on the upper and lower half portions of the LCD as a new screenful of image data in which a plurality of display electrodes of the pixels are connected in parallel to achieve an enlargement of the selected continuous portion of the initial screenful of image data.

10. An LCD device according to claim 9, further comprising a display area determining circuit for selecting at least one of different display areas which were previously set in response to inputted mode signals so as to determine the selected display area as the given continuous display area.

11. An LCD device according to claim 9, further comprising a display area determining circuit for detecting a cursor location in the screenful of image data output from the display controller to determine an area having a given range including the detected cursor location as the given continuous display area.