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Video Interface Circuit

IP.com Disclosure Number: IPCOM000039349D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 3 page(s) / 65K

Publishing Venue

IBM

Related People

Matsubara, K: AUTHOR [+2]

Abstract

This article describes a video interface circuit between a driver circuit and a display monitor. The video interface circuit is commonly used as an interface for three types of display monitor. Output characteristics of the video interface circuit are selectively switched to adapt to the input characteristics of the display monitor connected. (Image Omitted) There are three types of video interface between a display driver circuit and a display monitor, as shown in Fig. 1. When an input stage of a circuit of the display monitor has a circuit configuration as shown in the upper right area of Fig. 1, the final stage of the display drive circuit has to have a circuit configuration like that in the upper left area of Fig. 1. This combination is called a Type 1 interface. Similarly, Type 2 and Type 3 interfaces are shown in Fig.

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Video Interface Circuit

This article describes a video interface circuit between a driver circuit and a display monitor. The video interface circuit is commonly used as an interface for three types of display monitor. Output characteristics of the video interface circuit are selectively switched to adapt to the input characteristics of the display monitor connected.

(Image Omitted)

There are three types of video interface between a display driver circuit and a display monitor, as shown in Fig. 1. When an input stage of a circuit of the display monitor has a circuit configuration as shown in the upper right area of Fig. 1, the final stage of the display drive circuit has to have a circuit configuration like that in the upper left area of Fig. 1. This combination is called a Type 1 interface.

Similarly, Type 2 and Type 3 interfaces are shown in Fig. 1. The circuit configuration of the final stage of the display driver circuit is selected to match the type of the display monitor, i.e., the type of the circuit configuration of its input stage. A commonly used interface circuit to avoid the troublesome problem of selection is shown in Fig. 2. The circuit has three input terminals 21, 22 and 23 and an output terminal 24. The circuit includes inverters 25 and 26, NOR gate 27, OR gate 28, transistors 29 and 30 and resistors. Control signals A and B are applied to the input terminals 21 and 23, respectively, and a video signal is applied to the input terminal 22.

The control signals A and B are switched to provide one of the functions of the interface type 1, type 2 and type 3, as shown in below. Control Signal A Control Signal B Type of Interface 1 1 Type 1

1 0 Type 2

0 1 Type 3

0 0 (Not used) In the case that both the control signals A...