Display device with adaptive selection of the number of simultaneously displayed rows

• US 6,882,332 B2
• Filed: 11/29/2001
• Issued: 04/19/2005
• Est. Priority Date: 11/30/2000
• Status: Expired due to Term

• Current Assignee: Dynamic Data Technologies LLC
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Zeiter, Dominik, Duisters, Anthonius Franciscus
• Primary Examiner(s): Shankar, Vijay
• Assistant Examiner(s): Shapiro, Leonid
• Application Number:
  US09/998,055
• Publication Number:
  US 20020135551A1
• Time in Patent Office: 1,237 Days
• Field of Search: 345/50, 345/55, 345 87- 88, 345 99-100, 345/89, 345/82, 345/94, 345 95- 96, 345/98, 345204-206, 345209-210, 345213-214, 345692-693, 345/696, 345/699
• US Class Current: 345/87
• CPC Class Codes: G09G 2310/0208 using active addressing
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 3/3625 using active addressing
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

The invention relates to a display device which includes a driver circuit and a liquid crystal display with a plurality of rows R and columns C. The invention also relates to a driver circuit for driving a display. In order to reduce the power consumption of display devices, displays are operated in the partial display mode. According to the MRA (Multiple Row Addressing) technique a plurality of rows p is driven simultaneously. The number of rows p to be simultaneously driven, however, differs for displays of different size. When a display is operated in the partial display mode, therefore, for an optimum optical performance it is necessary that the value p of the rows to be simultaneously driven is other than this number in full size operation. In order to drive the rows R and columns C, at least p+1 voltages are required when F=G_MAX. Because the number of simultaneously driven rows is reduced upon a transition from the full size mode of operation to the partial display mode, it is also no longer necessary to generate as many voltages as would be required for operation in the full size mode. Therefore, upon transition to the partial display mode the voltage driver stages that are no longer required are switched off by way of a switching device. As a result, displays of different size can also be driven by means of one driver circuit.

Claims

1. A display device which includes a driver circuit, an image data memory coupled to the display, and a display, with a plurality of rows R and columns C, coupled to the driver circuit, where a number p_max indicates a maximum number of rows that can be simultaneously driven in the display device, where a number p indicates the number of rows selected to be simultaneously driven, where the rows R and the columns C can be driven by means of voltage values of the equally high voltages F and G_MAX, and where the display has a multiplexibility of m R, wherein the display device derives the number p from the display size to be driven, and is configured to adaptively select the number p in response to a change in a display mode that controls the display size to be driven, wherein the driver circuit includes a plurality of voltage driver stages for generating corresponding partial voltage values for driving the display, and is configured to selectively switch off driver voltage stages in response to a change in the selected number p such that the number of partial voltage values that are available for driving the display during the display mode varies in dependence on the number p selected for the display mode, and wherein the display device is operable such that a number of image data bits accessed from the image memory, is equal to p_max regardless of the value of p.

2. The display device as claimed in claim 1, characterized in that the number p is derived from the display size to be driven during a partial display mode or from a sub-region of the display.

3. The display device as claimed in claim 1, characterized in that a sequence for the supply of the image data to be displayed from a memory is the same for all values p.

4. The display device as claimed in claim 1, characterized in that the simultaneously driven rows p can be subdivided into p_max/p sub-regions for an optimum value p that is smaller than the maximum value of p_max.

5. The display device of claim 1, wherein p_max equals 8 and p is selected from the values consisting of 2, 4, and 8.

6. The display device of claim 1, wherein when p is less than p_max there are p_max/p groups of simultaneously driven rows, and one access of the image memory to provide image data for the p_max/p groups of simultaneously driven rows.