Browse Prior Art Database

Discrimination of Type of Display Device

IP.com Disclosure Number: IPCOM000040145D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Inada, H: AUTHOR

Abstract

This article describes a discrimination between types of display devices, i.e., color and monochrome types, connected to a display controller. The discrimination is performed by connecting a feedback circuit at a blue signal output terminal of the display controller. The feedback circuit supplies a feedback signal indicating the type of the display device to the display controller. In the case where a color display device or a monochrome display device is connected to a display controller, it is necessary for the display controller to discriminate between the two types of connected display devices, i.e., color and monochrome.

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Discrimination of Type of Display Device

This article describes a discrimination between types of display devices, i.e., color and monochrome types, connected to a display controller. The discrimination is performed by connecting a feedback circuit at a blue signal output terminal of the display controller. The feedback circuit supplies a feedback signal indicating the type of the display device to the display controller. In the case where a color display device or a monochrome display device is connected to a display controller, it is necessary for the display controller to discriminate between the two types of connected display devices, i.e., color and monochrome. Referring to the figure, the color display device is provided with an input circuit 1 which is connected to a blue signal output terminal 2 of the display controller to receive blue signals, while the monochrome display device is not provided with the input circuit 1. The input circuit includes resistors R1 and R2 and an amplifier 2. A feedback circuit 3 is connected to the blue signal output terminal 2, which includes transistors 4 and 5 and resistors R3 and R4 . The transistor 4 operates as an open-collector-type circuit in which an output signal is generated at a node 6 only when a bias voltage +V is applied to the node 6. To discriminate between the two types of connected display devices, the display controller applies the blue signal on the blue signal output terminal 2, and determines whether an...