# US 5,347,197 A · Display device having a display tube including a cold cathode and a current mirror drive circuit for the cold cathode

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- Number: US 5,347,197 A
- Document ID: US5347197A
- Status: Granted
- Kind: A
- Application number: 08/035,131
- Filed: 1993-03-19
- Granted: 1994-09-13
- Earliest claimed: 1992-03-23
- Assignees: U.S. Philips Corporation
- Inventors: Terence Doyle; Matheus J. G. Lammers
- Web page: https://patentgrep.com/patent/US5347197A

## CPC

- H04N 5/148: {Video amplifiers (amplifiers in general H03F)}
- G05F 3/265: {using bipolar transistors only}
- H03F 1/302: {in bipolar transistor amplifiers (H03F1/303, H03F1/305, H03F1/307 take precedence)}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- H03F: AMPLIFIERS

## Abstract

A display device having a display tube including a cold cathode, for example a PN emitter (PNE), has the terminals of the PN emitter (PNE) coupled between first terminals of a first (CR1) and a second (CR2) current mirror. The first current repeater (CR1) is connected to an output of an amplifier (AMP) whose feedback input (FI) is connected to second terminals of the first (CR1) and second (CR2) current mirrors.

## Claims

### Claim 1

A display device having a display tube including a cold cathode, said display device comprising:
amplifying means having a signal input and a feedback input;
first current mirror means coupled to said amplifying means and having a first terminal and a second terminal;
second current mirror means having an input and an output;
said cold cathode having a first end coupled to said first terminal of said first current mirror means, and a second end coupled to said input of said second current mirror means; and
feedback means having a first end coupled to said second terminal of said first current mirror means and to said output of said second current mirror means, and a second end coupled to said feedback input of said amplifying means.

### Claim 2 (depends on 1)

A display device as claimed in claim 1, wherein said amplifying means have a voltage output coupled to a main terminal of said first current mirror means, while said first terminal of said first current mirror means is an input terminal, and said second terminal of said first current mirror means is an output terminal.

### Claim 3 (depends on 1)

A display device as claimed in claim 1, wherein said amplifying means have a current output coupled to an input of said first current mirror means, said first and second terminals of said first current mirror means being output terminals.