KR930020309A

KR930020309A - Automatic Gain Control Circuit

Info

Publication number: KR930020309A
Application number: KR1019920004165A
Authority: KR
Inventors: 알 기바루 제임스
Original assignee: 시모야마 도시로오; 오림파스 고오가꾸 고오교오 가부시기가이샤
Priority date: 1992-03-13
Filing date: 1992-03-13
Publication date: 1993-10-19

Abstract

본 발명의 목적은 레저주사 시스템에 있어서, 바코드에서 반사된 빛을 수신하기 위하여 사용되는 수신기의 이득을 동적으로 조정하는 고속 자동이득제어(AGC)회로를 제공하는 것으로, 본 발명의 구성은 위 AGC회로는 수신기의 최종출력을 검지하는 것 외에 최종증폭단보다 앞에 위치되어 있는 증폭기로부터 부가적인 피드백경로를 포함한다. 즉, 이 AGC회로는 최종출력신호를 검지하여 수신기의 동작이득을 자동적으로 조정하는 종래부터 형성되어 있는 제1피드백경로와 최종증폭단보다 앞에 위치되어 있는 증폭기의 출력신호를 검지하여 상기 동작이득의 조정속도를 개선하는 제2피드백경로를 구비함으로써, 부가적인(제2) 피드백경로의 아택크시간은 무시할 수 있을 정도로 짧게 수신기의 이득을 신속하게 조정함으로써 안정상태에 도달하는데 필요한 시간을 최소화되고 따라서 해호가능한 신호를 얻기 위하여 바코드를 다수회 주사할 필요가 없게 된다. 제2피드백경로는 수신기가 안정상태에 도달하기 전에 떨어지고 그 후 AGC는 제1피드백경로에 의하여 미세하게 조정된다.SUMMARY OF THE INVENTION An object of the present invention is to provide a high speed automatic gain control (AGC) circuit for dynamically adjusting the gain of a receiver used to receive light reflected from a barcode in a leisure scanning system. In addition to detecting the final output of the receiver, the circuit includes an additional feedback path from the amplifier located before the final amplifier stage. In other words, the AGC circuit detects the final output signal and automatically adjusts the operation gain of the receiver. The AGC circuit detects the conventional first feedback path and the output signal of the amplifier located in front of the final amplifier stage and adjusts the operation gain. By having a second feedback path that improves speed, the attack time of the additional (second) feedback path is negligibly short, so that the gain of the receiver is quickly adjusted to minimize the time required to reach steady state and thus solve. There is no need to scan the barcode multiple times to get a possible signal. The second feedback path drops before the receiver reaches a steady state and then the AGC is finely adjusted by the first feedback path.

Description

Automatic Gain Control Circuit

본 내용은 요부공개 건이므로 전문내용을 수록하지 않았음Since this is an open matter, no full text was included.

제2도는 본 발명의 자동이득 제어회로의 블럭선도.2 is a block diagram of an automatic gain control circuit of the present invention.

제3도는 본 발명의 자동이득 제어회로의 제2실시예시 블럭선도.3 is a block diagram of a second embodiment of an automatic gain control circuit of the present invention.

제4도는 본 발명의 자동이득 제어회로의 회로도.4 is a circuit diagram of an automatic gain control circuit of the present invention.

Claims

A scanning device having an operating gain and having a receiver including optical means for generating a signal from light reflected from a target and an automatic gain control circuit for dynamically adjusting the operating gain, the scanning device repeatedly scanning the target, First feedback means in a receiver in which the automatic gain control circuit detects the signal to automatically steer the operating gain, and a second feedback from a receiver that detects the same signal to improve the speed of adjustment. A device comprising means.

2. The automatic gain control circuit according to claim 1, wherein the second feedback means includes means for lowering the operation gain until the operation gain reaches a stable state value.

The method of claim 1, wherein the first feedback means filters the receiver output signal representing the light reflected from the target and supplies the AC component from the signal and rectifies the AC component to obtain an average peak voltage signal from the component. An automatic gain control circuit comprising a rectifier means obtained and a peak detector means coupled to the rectifier means to maintain a voltage representing a value of the average peak voltage signal.

4. The automatic gain control circuit according to claim 3, wherein the second feedback means includes means for shortening the time required to obtain an average peak voltage signal.

5. The automatic gain control circuit according to claim 4, wherein the automatic gain control circuit dynamically adjusts the gain of the receiver to minimize the error voltage signal and error correction means for supplying an error voltage signal representing a voltage difference between the average peak voltage signal and the fixed reference voltage. Automatic gain control circuit including an adjustment means for adjusting by means of.

6. The second feedback means according to claim 5, wherein the second feedback means is in common with the first feedback means at the input of the error correction means, and the second feedback means is provided until the gain of the receiver reaches a stable state. Automatic gain control circuit comprising an insulation means for insulated from the first feedback means.

7. The automatic gain control circuit according to claim 6, wherein the second feedback means includes means for initializing the input of the error correcting means by using a fixed DC voltage irrelevant to the signal obtained from the light reflected from the target.

7. A receiver as claimed in claim 6, wherein the receiver comprises at least first, second and third dependent amplifier stages, the first feedback means at the receiver detecting the output of the third amplifier stage and the second feedback at the receiver. Means for detecting the output of the second amplifier stage, and the feedback means at the receiver is coupled between the first amplifier stage and the third amplifier stage.

9. The automatic gain control circuit of claim 8 wherein the first amplifier stage has variable gain control.

10. The automatic gain control circuit according to claim 9, wherein the first filter means is a high pass filter.

11. The automatic gain control circuit according to claim 10, wherein the first amplifier stage is an operational amplifier, and the adjusting means includes a voltage controlled variable resistance means.

12. The automatic gain control circuit according to claim 11, wherein the voltage control variable resistance means is a field effect transistor.

13. The automatic gain control circuit according to claim 12, wherein the insulation means is a semiconductor diode.

14. The automatic gain control circuit of claim 13 wherein the output of the third amplifier stage and the output of the second amplifier stage supply a signal of reverse polarity.

15. The automatic gain control circuit of claim 14 wherein the first, second and third dependent amplifier stages are dependent by capacitor coupling.

※ Note: The disclosure is based on the initial application.